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17 pages, 2266 KiB

Open AccessArticle

WRF Physics Ensemble Performance Evaluation over Continental and Coastal Regions in Germany

by Ioannis Stergiou, Efthimios Tagaris and Rafaella-Eleni P. Sotiropoulou

Atmosphere 2023, 14(1), 17; https://doi.org/10.3390/atmos14010017 - 22 Dec 2022

Cited by 1 | Viewed by 1769

Abstract

WRF is used to simulate eight extreme precipitation events that occurred over the regions of Schleswig–Holstein and Baden–Wurttemberg in Germany. The events were chosen from the German Weather Service (DWD) catalog and exceeded the DWD’s warning level 3 (i.e., rainfall > 40 mm/h). [...] Read more.

WRF is used to simulate eight extreme precipitation events that occurred over the regions of Schleswig–Holstein and Baden–Wurttemberg in Germany. The events were chosen from the German Weather Service (DWD) catalog and exceeded the DWD’s warning level 3 (i.e., rainfall > 40 mm/h). A two-way nesting approach is used with 9 and 3 km spatial resolutions. Initial and boundary conditions are obtained from the ERA5 dataset at 0.25° × 0.25°. To model each event, thirty different parameterization configurations were used, accounting for all possible combinations of five microphysics (MP), three cumulus (CU), and two planetary boundary layer (PBL) parameterization methods, yielding a total of 240 simulations. TOPSIS multicriteria analysis technique is employed to determine the performance skill of each setup and rank them, using six categorical and five statistical metrics. Resolution increase from 9 to 3 km did not improve forecasting accuracy temporally or in intensity. According to TOPSIS ranking, when treating each event individually, the ideal parameterizations combination is spatiotemporally dependent, with certain members ranking higher. When all events are considered, the Morrison double-moment MP–Grell–Freitas CU–YSU PBL combination works best with a frequency of occurrence in the top five performing scenarios of 30%, 47.5%, and 57.5% respectively. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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18 pages, 11279 KiB

Open AccessArticle

A Comparative Analysis of Changes in Temperature and Precipitation Extremes since 1960 between China and Greece

by Zhen Li, Yingling Shi, Athanassios A. Argiriou, Panagiotis Ioannidis, Anna Mamara and Zhongwei Yan

Atmosphere 2022, 13(11), 1824; https://doi.org/10.3390/atmos13111824 - 2 Nov 2022

Cited by 4 | Viewed by 2362

Abstract

The temporal and spatial variations of 26 extreme temperature and precipitation indices for China and Greece were comparatively analysed. Also, their association with atmospheric circulation types was evaluated using multiple linear regression. The calculation of the extreme indices was based on homogenized daily [...] Read more.

The temporal and spatial variations of 26 extreme temperature and precipitation indices for China and Greece were comparatively analysed. Also, their association with atmospheric circulation types was evaluated using multiple linear regression. The calculation of the extreme indices was based on homogenized daily temperature and precipitation time series from 1960 to 2010 for Greece and 2021 for China. Extreme precipitation, intensity, and short-term heavy precipitation increased, while persistent heavy precipitation has decreased since 1960 in China. Short-term heavy precipitation has also shown an increasing trend in Greece, though total precipitation and persistent heavy precipitation decreased there between 1960 and 2010. Extreme cold events have tended to decrease, and extreme warm events have increased in both countries, a fact that can be attributed to global warming. For comparison, climatic warming in China was mainly seen in the half year of winter, while the extreme indices relevant to cold seasons such as FD0 and ID0 presented a small trend in Greece. The observed changes in many climatic indices, including RX5day and WSDI in China and R20MM, RX5day, CDD, PRCPTOT and FD0 in Greece, could be partly explained by those of the main large-scale circulation types in the corresponding regions. The significant multiple correlation coefficients of the main circulation types were up to 0.53 for RX5day and 0.54 for WSDI in China, and 0.74 for PRCPTOT and 0.71 for R20MM in Greece. The relationships between climatic indices and circulation types were closer in Greece than in China, especially for the precipitation indices. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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17 pages, 78319 KiB

Open AccessArticle

Projected Changes of Day-to-Day Precipitation and Choco Low-Level Jet Relationships over the Far Eastern Tropical Pacific and Western Colombia from Two CMIP6 GCM Models

by Juliana Valencia and John F. Mejía

Atmosphere 2022, 13(11), 1776; https://doi.org/10.3390/atmos13111776 - 28 Oct 2022

Cited by 1 | Viewed by 2250

Abstract

The far Eastern Tropical Pacific (EPAC) and Western Colombia are one of the rainiest places on Earth, and the Choco low-level jet (ChocoJet) is one of the processes that influence the formation of copious precipitation and convection organization in this region. This study [...] Read more.

The far Eastern Tropical Pacific (EPAC) and Western Colombia are one of the rainiest places on Earth, and the Choco low-level jet (ChocoJet) is one of the processes that influence the formation of copious precipitation and convection organization in this region. This study investigates the projected changes in precipitation in this region using historical and future simulations based on model output from two models contributing to the Coupled Model Intercomparison Project phase 6 (CMIP6). In close agreement with observations, models simulate that ChocoJet intensity is directly proportional to precipitation in the region. This relationship is also found far inland in Central America, the northwestern part of South America Pacific Coast, and the intermountain valleys of the Colombian Andes. Late 21st century simulations show a southward migration in mean and regional daily precipitation consistent with a decreased ChocoJet intensity. The weaker ChocoJet is related to a projected increase in EPAC tropical sea surface temperatures (SSTs) and an increased frequency and intensity of the warm phase of the Niño 1+2 SST interannual variability. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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17 pages, 6766 KiB

Open AccessArticle

Multi-Scale Numerical Assessments of Urban Wind Resource Using Coupled WRF-BEP and RANS Simulation: A Case Study

by Lihua Mi, Yan Han, Lian Shen, Chunsheng Cai and Teng Wu

Atmosphere 2022, 13(11), 1753; https://doi.org/10.3390/atmos13111753 - 25 Oct 2022

Cited by 3 | Viewed by 2181

Abstract

Urban wind resource assessments (WRAs) contribute to the effective exploitation of wind energy and thus are of significant importance to the sustainable development of cities. To improve the simulation accuracy of urban wind flow with high spatial resolution, this study implemented a multi-scale [...] Read more.

Urban wind resource assessments (WRAs) contribute to the effective exploitation of wind energy and thus are of significant importance to the sustainable development of cities. To improve the simulation accuracy of urban wind flow with high spatial resolution, this study implemented a multi-scale numerical assessment of the wind power potential in a highly-urbanized region with realistic terrain conditions by integrating the Reynolds-averaged Navier-Stokes (RANS) equations into the Weather Research and Forecasting (WRF) model with Building Effect Parameterization (WRF-BEP). The sensitivity analyses are first conducted to obtain an appropriate combination of physical parameterization schemes in the WRF-BEP model. Then, the wind tunnel tests are performed to validate the computational accuracy of urban wind flow using the RANS equations. Based on a close examination of the urban wind flow resulting from the coupled WRF-BEP and RANS simulations, the integration of micro-wind turbines into the building skin is not recommended in the highly-urbanized region. Furthermore, five optimum roof installation locations with low turbulence intensities (smaller than 18%) and high wind power densities (approximately 220 W/m², 260 W/m², 270 W/m², 300 W/m² and 400 W/m², respectively) are identified. Finally, the important effects of the terrain conditions, planetary boundary layer (PBL) parameterization schemes and turbulence models on WRAs are discussed. The results of WRAs in this multi-scale numerical case study presented a systemic approach to effectively determine the installation locations of micro-wind turbines that possess the greatest potential to harness wind energy in a realistic highly-urbanized area. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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24 pages, 8638 KiB

Open AccessArticle

Multivariable Characterization of Atmospheric Environment with Data Collected in Flight

by Aliia Shakirova, Leonid Nichman, Nabil Belacel, Cuong Nguyen, Natalia Bliankinshtein, Mengistu Wolde, Stephanie DiVito, Ben Bernstein and Yi Huang

Atmosphere 2022, 13(10), 1715; https://doi.org/10.3390/atmos13101715 - 19 Oct 2022

Cited by 3 | Viewed by 1977

Abstract

The In-Cloud Icing and Large-drop Experiment (ICICLE) flight campaign, led by the United States Federal Aviation Administration, was conducted in the geographical region over US Midwest and Western Great Lakes, between January and March 2019, with the aim to collect atmospheric data and [...] Read more.

The In-Cloud Icing and Large-drop Experiment (ICICLE) flight campaign, led by the United States Federal Aviation Administration, was conducted in the geographical region over US Midwest and Western Great Lakes, between January and March 2019, with the aim to collect atmospheric data and study the aircraft icing hazard. Measurements were taken onboard the National Research Council of Canada (NRC) Convair-580 aircraft, which was equipped with more than 40 in situ probes, sensors, and remote sensing instruments in collaboration with Environment and Climate Change Canada (ECCC). In each flight, aerosol, cloud microphysics, atmospheric and aircraft state data were collected. Atmospheric environment characterization is critical both for cloud studies and for operational decision making in flight. In this study, we use the advantage of multiple input parameters collected in-flight together with machine learning and clustering techniques to characterize the flight environment. Eleven parameters were evaluated for the classification of the sampled environment along the flight path. Namely, aerosol concentration, temperature, hydrometeor concentration, hydrometeor size, liquid water content, total water content, ice accretion rate, and radar parameters in the vicinity of the aircraft. In the analysis of selected flights, we were able to identify periods of supercooled liquid clouds, glaciated clouds, two types of mixed-phase clouds, and clear air conditions. This approach offers an alternative characterization of cloud boundaries and a complementary identification of flight periods with hazardous icing conditions. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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12 pages, 5385 KiB

Open AccessArticle

The Emissions of Water Vapour and NO_x from Modelled Hydrogen-Fuelled Aircraft and the Impact of NO_x Reduction on Climate Compared with Kerosene-Fuelled Aircraft

by M. Anwar H. Khan, Joel Brierley, Kieran N. Tait, Steve Bullock, Dudley E. Shallcross and Mark H. Lowenberg

Atmosphere 2022, 13(10), 1660; https://doi.org/10.3390/atmos13101660 - 12 Oct 2022

Cited by 15 | Viewed by 4355

Abstract

A kerosene fuelled aircraft was modelled within a performance tool and fuel burn and the emissions of nitrogen oxides (NO_x) and water vapour at different stages of flight throughout the mission were estimated. Adaptions were made to engine and aircraft parameters [...] Read more.

A kerosene fuelled aircraft was modelled within a performance tool and fuel burn and the emissions of nitrogen oxides (NO_x) and water vapour at different stages of flight throughout the mission were estimated. Adaptions were made to engine and aircraft parameters within the performance tool to accommodate a liquid hydrogen fuel over the same given mission. Once an iterative design process had been completed to ensure the aircraft could perform the given mission, the performance tool was again used to calculate total fuel burn. Fuel burn results alongside predicted emission indices were used to estimate the emissions of NO_x, water vapour from hydrogen-fuelled aircraft. The use of hydrogen fuel over kerosene fuel in the modelled aircraft resulted in the removal of carbon-based emission species alongside 86% reduction in NO_x and 4.3 times increase in water vapour emission. The climate impact of this switch with the reduction in NO_x emission was assessed by a 3D global atmospheric chemistry and transport model, STOCHEM-CRI, which found a significant reduction in the concentration of a potent greenhouse gas, ozone, and an oxidizing agent, OH, by up to 6% and 25%, respectively. The reduction of OH levels could induce a positive radiative forcing effect as the lifetime of another important greenhouse gas, methane, is increased. However, the magnitude of this increase is very small (~0.3%), thus the overall impact of the reduction in NO_x emissions is likely to have a net negative radiative forcing effect, improving aviation’s impact on the environment. However, further work is warranted on effects of other emission species, specifically water vapour, particulate matter and unburned hydrogen. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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27 pages, 12687 KiB

Open AccessArticle

Validation and Comparison of Climate Reanalysis Data in the East Asian Monsoon Region

by Minseok Kim and Eungul Lee

Atmosphere 2022, 13(10), 1589; https://doi.org/10.3390/atmos13101589 - 28 Sep 2022

Cited by 14 | Viewed by 3097

Abstract

Understanding East Asian monsoon (EAM) has been a crucial issue due to its socio-economic effects on one-fifth of the world’s population and its interactions with the global climate system. However, the reliabilities of climate reanalysis data are still uncertain at varying temporal and [...] Read more.

Understanding East Asian monsoon (EAM) has been a crucial issue due to its socio-economic effects on one-fifth of the world’s population and its interactions with the global climate system. However, the reliabilities of climate reanalysis data are still uncertain at varying temporal and spatial scales. In this study, we examined the correlations and differences for climate reanalyses with weather observations and suggested the best climate reanalysis for the EAM region. The three reanalyses of ERA5, JRA55, and NCEP2 along with a gridded observation (CRU) were evaluated using the correlation coefficients (Pearson, Spearman, and Kendall), difference statistics (RMSE and bias), and Taylor diagrams, comparing their annual and seasonal temperatures and precipitations with those from the total of 537 weather stations across China, North Korea, South Korea, and Japan. We found that ERA5 showed the best performance in reproducing temporal variations in temperature with the highest correlations in annual, summer, and autumn, and the smallest RMSEs and biases for all seasons and annually. For precipitation, among the three reanalysis datasets, ERA5 had the highest correlations, annually and in four seasons, with the smallest RMSEs, annually and in spring, summer and autumn, and the smallest biases, annually and in summer and autumn. Regarding spatial variations, ERA5 was also the most suitable reanalysis data in representing the annual and seasonal climatological averages. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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22 pages, 2134 KiB

Open AccessArticle

Regime Changes in Atmospheric Moisture under Climate Change

by Roger N. Jones and James H. Ricketts

Atmosphere 2022, 13(10), 1577; https://doi.org/10.3390/atmos13101577 - 27 Sep 2022

Cited by 4 | Viewed by 3238

Abstract

Recent work attributing decadal regime changes in temperature to radiative forcing is extended to atmospheric moisture. Temperature, and specific and relative humidity (T, q, RH) from the HadISDH data set were analyzed for regime shifts using the bivariate test. Most shifts in q [...] Read more.

Recent work attributing decadal regime changes in temperature to radiative forcing is extended to atmospheric moisture. Temperature, and specific and relative humidity (T, q, RH) from the HadISDH data set were analyzed for regime shifts using the bivariate test. Most shifts in q and T for global and northern hemisphere (NH), and tropical land occurred within a year of each other. Only one shift of q was recorded in the southern hemisphere (SH). RH increased in the NH in 1990–91 and decreased in a series of shifts from the late 1990s, while in the SH decreased from 2001. The tropics have remained neutral, shifting negative over land and positive over the ocean. The global decreases in 2001 and 2011 was −0.56%. Global RH from 32 climate models from the CMIP5 RCP4.5 archive all contained regime shifts but only 4 reached or exceeded the observed decreases by 2100, the earliest in 2056. Regime shifts in RH and fire danger over Australia are consistent with the SH decreases in RH, shifting within one year of global fire season length in 2002, showing that impacts are also being underestimated by current analyses. Methods for nonlinear attribution and the contributing processes for nonlinear change are discussed. These results show that developing a better understanding of nonlinear change in moisture-related climate risk is an urgent task. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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13 pages, 2911 KiB

Open AccessArticle

Graduation Towers Impact on the Concentration and Chemical Composition of Ambient Aerosol: A Case Study from Wieliczka Salt Mine in Poland

by Wioletta Rogula-Kozłowska, Artur Badyda, Marzena Rachwał, Patrycja Rogula-Kopiec, Małgorzata Majder-Łopatka, Magdalena Kostrzon and Barbara Mathews

Atmosphere 2022, 13(10), 1576; https://doi.org/10.3390/atmos13101576 - 27 Sep 2022

Cited by 2 | Viewed by 2141

Abstract

The aim of the research was to determine the effect of graduation towers on the aerosol concentration and its composition not only in the vicinity of the graduation tower itself, but also at a distance from it, on the example of the brine [...] Read more.

The aim of the research was to determine the effect of graduation towers on the aerosol concentration and its composition not only in the vicinity of the graduation tower itself, but also at a distance from it, on the example of the brine graduation tower in the Wieliczka Salt Mine health resort. Two measurement sites were selected for the research, one located inside the graduation tower and the other at the guard booth—at a considerable distance from the graduation tower. Total suspended particulate (TSP) and PM₁₀ (particulate matter with a diameter that does not exceed 10 µm) samples were taken simultaneously using the aspiration method. The collected samples were subjected to analyses of TSP and PM₁₀ concentrations, the content of organic carbon (OC), elemental carbon (EC) and selected ions. It was confirmed that the composition of the aerosol in the Wieliczka Salt Mine significantly differs from the typical aerosol composition in inland locations and is similar to the aerosol composition in coastal zones. The comparison of the aerosol composition at both measuring sites clearly indicates a very favorable influence of the brine graduation tower on the composition of the atmospheric aerosol, even at a certain distance from it. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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25 pages, 26202 KiB

Open AccessArticle

Present and Future Changes in Winter Cyclonic Activity in the Mediterranean–Black Sea Region in the 21st Century Based on an Ensemble of CMIP6 Models

by Elena N. Voskresenskaya, Veronika N. Maslova, Andrey S. Lubkov and Viktor Y. Zhuravskiy

Atmosphere 2022, 13(10), 1573; https://doi.org/10.3390/atmos13101573 - 26 Sep 2022

Cited by 1 | Viewed by 2089

Abstract

A better understanding of expected future cyclonic activity, especially in winter in the Mediterranean basin, is essential in developing scientifically based adaptation and mitigation methods to study extreme precipitation and wind anomalies. The aim of this study was to analyze the changes in [...] Read more.

A better understanding of expected future cyclonic activity, especially in winter in the Mediterranean basin, is essential in developing scientifically based adaptation and mitigation methods to study extreme precipitation and wind anomalies. The aim of this study was to analyze the changes in winter cyclonic activity in the Mediterranean–Black Sea region, as part of the North Atlantic–European sector, at three 15 year periods: the beginning, middle, and end of the 21st century. Our projections were based on an ensemble of seven Coupled Model Intercomparison Project (CMIP), phase 6, models, which showed the best agreement with NCEP/NCAR and ERA5 reanalyses under the intermediate SSP2-4.5 and highest-emission SSP5-8.5 scenarios. The results showed a consistent increase in the frequency of cyclones over Central Europe and the British Isles, which was associated with shifts in cyclone tracks: northward from the western Mediterranean region and southward from the Icelandic Low region. The latter shift led to a decrease in the frequency in the northern Atlantic–European region. At the same time, there was a reduction in the frequency of cyclones over the eastern region of the Mediterranean Sea, consistent with the decrease in cyclogenesis events. Area-averaged cyclone numbers in the western and eastern Mediterranean and Black Sea subregions reduced at the end of the century under the highest-emission scenario, but not constantly. There was a rise in the middle of the 21st century under both scenarios, which may be linked to long-term multidecadal variability or regional features. In general, our study showed that the future winter cyclonic activity in the Mediterranean–Black Sea region will respond unevenly to global climate changes, due to regional and monthly features and long-term quasiperiodic variability. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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18 pages, 3068 KiB

Open AccessArticle

A Holistic Approach Based on Biomonitoring Techniques and Satellite Observations for Air Pollution Assessment and Health Risk Impact of Atmospheric Trace Elements in a Semi-Rural Area of Southern Italy (High Sauro Valley)

by Rosa Caggiano, Antonio Speranza, Vito Imbrenda, Nicola Afflitto and Serena Sabia

Atmosphere 2022, 13(9), 1501; https://doi.org/10.3390/atmos13091501 - 15 Sep 2022

Cited by 10 | Viewed by 2207

Abstract

Air pollution is one of the most important environmental problems for rural, urban and industrial areas. This study assesses the concentrations, the possible interaction with the vegetation conditions and the sources of trace elements in atmospheric aerosol particles. To this aim, a novel [...] Read more.

Air pollution is one of the most important environmental problems for rural, urban and industrial areas. This study assesses the concentrations, the possible interaction with the vegetation conditions and the sources of trace elements in atmospheric aerosol particles. To this aim, a novel holistic approach integrating biomonitoring techniques, satellite observations and multivariate statistical analysis was carried out in a semi-rural area before an on-shore reservoir (crude oil and gas) and an oil/gas pre-treatment plant identified as “Tempa Rossa” (High Sauro Valley—Southern Italy) were fully operative. The atmospheric trace element concentrations (i.e., Al, Ca, Cd, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, S, Ti and Zn) were assessed by “lichen-bag” monitoring. Satellite-derived normalized difference vegetation index (NDVI’) estimates were used to support the identification of environmental imbalances affecting vegetation conditions and linked to possible anthropogenic drivers. Principal component analysis (PCA) allowed identifying both natural and anthropogenic trace element sources, such as crustal resuspension, soil and road dust, traffic, biomass burning and agriculture practices. Empirical evidence highlighted an interaction between NDVI’ and S, Ni, Pb and Zn. The health risk impact of atmospheric trace elements on the exposed population, both adults and children, considering inhalation, ingestion and the dermal contact pathway, highlighted a possible non-carcinogenic risk concerning Ni and a not-negligible carcinogenic risk related to Cr(VI) for the adult population in the study area. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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21 pages, 9630 KiB

Open AccessArticle

How Should a Numerical Weather Prediction Be Used: Full Field or Anomaly? A Conceptual Demonstration with a Lorenz Model

by Jun Du and Guo Deng

Atmosphere 2022, 13(9), 1487; https://doi.org/10.3390/atmos13091487 - 13 Sep 2022

Cited by 1 | Viewed by 3059

Abstract

A forecast from a numerical weather prediction (NWP) model can be decomposed into model climate and anomaly. Each part contributes to forecast error. To avoid errors from model climate, an anomaly, rather than a full field, should be used in a model. Model [...] Read more.

A forecast from a numerical weather prediction (NWP) model can be decomposed into model climate and anomaly. Each part contributes to forecast error. To avoid errors from model climate, an anomaly, rather than a full field, should be used in a model. Model climate is replaced by the observed climate to reconstruct a new forecast for application. Using a Lorenz model, which has similar error characteristics to an NWP model, the following results were obtained. (a) The new anomaly-based method can significantly and steadily increase forecast accuracy throughout the entire forecast period (28 model days). On average, the total forecast error was reduced ~25%, and the correlation was increased by ~100–200%. The correlation improvement increases with the increasing of forecast length. (b) The method has different impacts on different types of error. Bias error was almost eliminated (over 90% in reduction). However, the change in flow-dependent error was mixed: a slight reduction (~5%) for model day 1–14 forecasts and increase (~15%) for model day 15–28 forecasts on average. The larger anomaly forecast error leads to the worsening of flow-dependent error. (c) Bias error stems mainly from model climate prediction, while flow-dependent error is largely associated with anomaly forecast. The method works more effectively for a forecast that has larger bias and smaller flow-dependent error. (d) A more accurate anomaly forecast needs to be constructed relative to model climate rather than observed climate by taking advantage of cancelling model systematic error (i.e., perfect-model assumption). In principle, this approach can be applicable to any model-based prediction. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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13 pages, 2855 KiB

Open AccessArticle

Using Daylight Saving Time Clock Changes to Study the Impact of Meteorology on Air Pollution

by Yuval, Yoav Levi and David M. Broday

Atmosphere 2022, 13(9), 1458; https://doi.org/10.3390/atmos13091458 - 8 Sep 2022

Cited by 1 | Viewed by 2284

Abstract

Implementation of Daylight Savings Time (DST) started in various jurisdictions during the first half of the 20th century. Much debate on the merits of the twice-yearly change in the official local time has ensued since then regarding energy usage, sleep patterns, health outcomes, [...] Read more.

Implementation of Daylight Savings Time (DST) started in various jurisdictions during the first half of the 20th century. Much debate on the merits of the twice-yearly change in the official local time has ensued since then regarding energy usage, sleep patterns, health outcomes, traffic safety, etc. The DST switch in the official time abruptly shifts anthropogenic emissions that are related to human activities relative to the Coordinated Universal Time (UTC) but does not affect meteorological processes that disperse them, which day-to-day variability is affected by longer time scales. Here, we utilized the DST clock changes as a repeating biannual experiment to study the impact of meteorology on air pollution. We analyzed traffic volume data and up to 20 years of nitrogen oxides (NOx), fine particulate matter (PM_2.5), ozone (O₃) and carbon monoxide (CO) concentrations, observed at different air quality monitoring (AQM) stations in Israel, demonstrating a clear and significant impact of the daily meteorological cycle on traffic related air pollution (TRAP). In particular, traffic emissions are prerequisite for TRAP, but meteorology was found to dominate the daily patterns of the NOx, O₃ and CO concentration fields in the study area. On the other hand, the impact of vehicle emissions on PM_2.5 concentrations seems to be very small. Our results highlight the multiscale interplay between pollutant emissions and dispersion processes, especially for pollutants that are emitted near the surface. We demonstrate that while DST clock changes do not affect the emissions intensity, nor the meteorological processes vigor, they do shift human activity-related emissions with respect to the DST-blind dispersion processes. This results in short-term effects on primary traffic-related pollutant concentrations that cancel out over the day, and a consistent yet small effect on secondary traffic-related pollutant concentrations (O₃). Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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21 pages, 6845 KiB

Open AccessArticle

Atmospheric CO₂ and CH₄ Fluctuations over the Continent-Sea Interface in the Yenisei River Sector of the Kara Sea

by Alexey Panov, Anatoly Prokushkin, Igor Semiletov, Karl Kübler, Mikhail Korets, Ilya Putilin, Anastasiya Urban, Mikhail Bondar and Martin Heimann

Atmosphere 2022, 13(9), 1402; https://doi.org/10.3390/atmos13091402 - 31 Aug 2022

Cited by 2 | Viewed by 1917

Abstract

Observations of the atmospheric sources and sinks of carbon dioxide (CO₂) and methane (CH₄) in the pan-Arctic domain are extremely scarce, limiting our knowledge of carbon turnover in this climatically sensitive environment and the fate of the enormous carbon [...] Read more.

Observations of the atmospheric sources and sinks of carbon dioxide (CO₂) and methane (CH₄) in the pan-Arctic domain are extremely scarce, limiting our knowledge of carbon turnover in this climatically sensitive environment and the fate of the enormous carbon reservoirs conserved in the permafrost. Especially critical are the gaps in the high latitudes of Siberia, covered by the vast permafrost underlain tundra, where only several atmospheric monitoring sites are operational. This paper presents the first two years (September 2018–January 2021) of accurate continuous observations of atmospheric CO₂ and CH₄ dry mole fractions at the recently deployed tower-based measurement station “DIAMIS” (73.5068° N, 80.5198° E) located on the southwestern coast of the Taimyr Peninsula, Siberia, at the Gulf of the Yenisei River that opens to the Kara Sea (Arctic Ocean). In this paper, we summarized the scientific rationale of the site, examined the seasonal footprint of the station with an analysis of terrestrial vegetation and maritime sector contributing to the captured atmospheric signal, and illustrated temporal patterns of CO₂ and CH₄ for the daytime mixed atmospheric layer over the continent–sea interface. Along with the temporal variations reflecting a signal caused pan-Arctic and not very much influenced by the local processes, we analyzed the spatiotemporal distribution of the synoptic anomalies representing the atmospheric signatures of regional sources and sinks of CO₂ and CH₄ for the studied high-arctic Siberian domain of ~625 thousand km², with nearly equal capturing the land surface (54%) and the ocean (46%) throughout the year. Both for CO₂ and CH₄, we have observed a sea–continent declining trend, presuming a larger depletion of trace gases in the maritime air masses compared to the continental domain. So far, over the Kara Sea, we have not detected any prominent signals of CH₄ that might have indicated processes of subsea permafrost degradation and occurrence of cold seeps–still mainly observed in the eastern Arctic Seas—The Laptev Sea and the East-Siberian Sea. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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13 pages, 1580 KiB

Open AccessArticle

Changes in Air Pollutants from Fireworks in Chinese Cities

by Yonghang Lai and Peter Brimblecombe

Atmosphere 2022, 13(9), 1388; https://doi.org/10.3390/atmos13091388 - 29 Aug 2022

Cited by 5 | Viewed by 2365

Abstract

Chinese New Year has traditionally been welcomed with fireworks, but this has meant this holiday can experience intense peaks of pollutants, particularly as particulate matter. Such environmental issues add to other risks (e.g., accident, fire, and ecological and health threats) posed by firework [...] Read more.

Chinese New Year has traditionally been welcomed with fireworks, but this has meant this holiday can experience intense peaks of pollutants, particularly as particulate matter. Such environmental issues add to other risks (e.g., accident, fire, and ecological and health threats) posed by firework displays, but cultural reasons encourage such celebrations. This study examines air pollution from fireworks across a time of increasingly stringent bans as a time series from 2014–2021 using a random forest (decision-tree) model to explore the effect of year-to-year weather changes on pollutant concentrations at Chinese New Year. Peak concentrations of firework pollutants have decreased in cities and hint at the importance of well-enforced regulation of these traditional celebrations, e.g., Beijing, Tianjin, and Chongqing. The model suggested relative humidity was an important controlling variable, perhaps as the presence of water vapor might also accelerate particle growth but also as a surrogate parameter related to atmospheric mixing. Bans on fireworks, resisted at first, have shown evidence of growing public acceptance. The regulations are increasingly effective, even in the outer parts of cities. Celebrations might safely return as public firework displays, including light shows and the use of lanterns. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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18 pages, 9484 KiB

Open AccessArticle

Temperature and Precipitation Bias Patterns in a Dynamical Downscaling Procedure over Europe during the Period 1951–2010

by Ioannis Stergiou, Efthimios Tagaris and Rafaella-Eleni P. Sotiropoulou

Atmosphere 2022, 13(8), 1338; https://doi.org/10.3390/atmos13081338 - 22 Aug 2022

Cited by 1 | Viewed by 1819

Abstract

The Weather Research and Forecasting (WRF) mesoscale meteorological model is used to dynamically downscale data from the Goddard Institute for Space Studies (GISS) atmospheric general circulation model (GCM) CMIP5 version (Model E2-R) over Europe at a 0.25° grid size resolution, for the period [...] Read more.

The Weather Research and Forecasting (WRF) mesoscale meteorological model is used to dynamically downscale data from the Goddard Institute for Space Studies (GISS) atmospheric general circulation model (GCM) CMIP5 version (Model E2-R) over Europe at a 0.25° grid size resolution, for the period of 1951 to 2010. The model configuration is single nested with grid resolutions of 0.75° to 0.25°. Two 30-year datasets are produced for the periods of 1951–1980 and 1981–2010, representing the historic and current periods, respectively. Simulated changes in climate normals are estimated and compared against the change derived from the E-OBS gridded dataset at 0.25° spatial analysis. Results indicate that the model consistently underpredicts the temperature fluctuations observed across all subregions, indicative of a colder model climatology. Winter has the strongest bias of all seasons, with the northeastern part of the domain having the highest. This is largely due to the land–atmosphere interactions. Conversely, spring and summer have the lowest regional biases, owing to a combination of low snow cover (relative to winter) and milder radiation effects (as opposed to summer). Precipitation has a negative bias in most cases, regardless of the subregion analyzed, due to the physical mechanism employed and the topographic features of each region. Both the change in the number of days when the temperature exceeds 25 °C and the change in the number of days when precipitation exceeds 5 mm/day are captured by the model reasonably well, exhibiting similar characteristics with their counterpart means. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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9 pages, 1631 KiB

Open AccessCommunication

Network Theory to Reveal Ionospheric Anomalies over North America and Australia

by Ilya V. Zhivetiev and Yury V. Yasyukevich

Atmosphere 2022, 13(8), 1333; https://doi.org/10.3390/atmos13081333 - 22 Aug 2022

Cited by 1 | Viewed by 2343

Abstract

There are significant challenges to model the ionosphere due to different anomalies, especially under the increasing requirements for precision level. We used network theory to construct an ionospheric network analysis based on the data of global ionospheric maps for the period from 1998 [...] Read more.

There are significant challenges to model the ionosphere due to different anomalies, especially under the increasing requirements for precision level. We used network theory to construct an ionospheric network analysis based on the data of global ionospheric maps for the period from 1998 to 2015. The network approach revealed different domains in the ionosphere. Besides the well-known equatorial anomaly, we revealed two more essential areas with “anomalous” behavior in the total electron content (TEC). Both anomalies are located at mid-latitudes: the first over most of North America, and the second one over the southeast part of Australia and the adjacent part of the Indian Ocean. The revealed areas partly coincide with the winter anomaly regions. Our results demonstrate that complex ionosphere/magnetic field/neutral atmosphere interaction can result in atypical ionosphere dynamics in huge areas. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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19 pages, 9028 KiB

Open AccessArticle

Radiological Atmospheric Risk Modelling of NORM Repositories in Hungary

by Anita Csordás, Amin Shahrokhi, Gergely Tóth and Tibor Kovács

Atmosphere 2022, 13(8), 1305; https://doi.org/10.3390/atmos13081305 - 17 Aug 2022

Cited by 3 | Viewed by 1807

Abstract

The human population is continuously exposed to natural radionuclides in environmental elements. The concentration of these nuclides is usually low, but different technological processes and activities can concentrate them in products, by-products, or wastes. These activities are, for example, coal mining, fertilizer production, [...] Read more.

The human population is continuously exposed to natural radionuclides in environmental elements. The concentration of these nuclides is usually low, but different technological processes and activities can concentrate them in products, by-products, or wastes. These activities are, for example, coal mining, fertilizer production, ore mining, metal production, etc. These materials are labelled as NORM (Naturally Occurring Radioactive Material). The most common method of disposal for NORMs is deposition in different types of depositories. The long-term effects of these depositories on the environment and on human health are hard to estimate. The aim of the study is to assess radiation risk from the five selected NORM depositories (Ajka coal ash, Ajka red mud, Almásfüzitő red mud, Zalatárnok drilling mud, and Úrkút manganese residue) for members of the public and biota. The radionuclide concentrations were determined by HPGe gamma-spectrometry. The measured concentration was between 31 Bq/kg and 1997 Bq/kg for Ra-226, between 33 Bq/kg and 283 Bq/kg for Th-232, and between 48 Bq/kg and 607 Bq/kg for K-40. The dose estimation was investigated using RESRAD-ONSITE and RESRAD BIOTA, which are computer codes developed by the Argonne National Laboratory (USA). RESRAD-ONSITE can estimate the radiation risk from the radionuclides in the contaminated sites. The highest dose was observed in the case of the Ajka coal ash depository–without cover (12.38 mSv/y), and the lowest was in the case of Zalatárnok (0.53 mSv/y). The most significant contributors to the population dose are the uptakes through plants and external pathways, which account for more than 80% of the total dose on average. RESRAD-BIOTA code was used to estimate the radiation exposure of terrestrial organisms (plants and animals). During this work, the values of sum ratio factor (SRF), biota concentration guide (BCG), external dose, internal dose, and total dose were determined. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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11 pages, 1109 KiB

Open AccessArticle

Atmospheric Degradation of Two Hydrofluoroketones: Theoretical Rate Constants for the Gas-Phase OH-Oxidation of HFK-447mcc and HFK-465mc

by Luís Pedro Viegas

Atmosphere 2022, 13(8), 1256; https://doi.org/10.3390/atmos13081256 - 8 Aug 2022

Cited by 4 | Viewed by 1777

Abstract

Accurate calculation of rate constants for gas-phase OH-oxidation reactions of fluorinated compounds is crucial for the understanding of atmospheric processes that are subject of the Kigali Agreement. Here, we have determined two such rate constants for two hydrofluoroketones, HFK-447mcc and HFK-465mc. The calculations [...] Read more.

Accurate calculation of rate constants for gas-phase OH-oxidation reactions of fluorinated compounds is crucial for the understanding of atmospheric processes that are subject of the Kigali Agreement. Here, we have determined two such rate constants for two hydrofluoroketones, HFK-447mcc and HFK-465mc. The calculations were performed with a cost-effective multiconformer transition state theory protocol coupled with the constrained transition state randomization sampling method. The calculated rate constants of

k ({HO}^{•} + HFK - 447 mcc) = 3.1 \times 10^{- 15} {cm}^{3} {molecule}^{- 1} s^{- 1}

and

k ({HO}^{•} + HFK - 465 mc) = 3.2 \times 10^{- 14} {cm}^{3} {molecule}^{- 1} s^{- 1}

at 298.15 K imply an atmospheric lifetime of 10 years and 1 year, respectively. To our knowledge, these rate constants have never been determined experimentally or theoretically, and the similarity between the ratios of these two rate constants and of the well-studied acetone and diethyl ketone suggest the validity of our approach toward obtaining accurate rate constants and branching ratios. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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22 pages, 6474 KiB

Open AccessArticle

Using an Ensemble Filter to Improve the Representation of Temporal Source Variations in a Volcanic Ash Forecasting System

by Meelis J. Zidikheri

Atmosphere 2022, 13(8), 1243; https://doi.org/10.3390/atmos13081243 - 5 Aug 2022

Viewed by 1438

Abstract

The use of ensemble models to forecast the dispersion and transport of airborne volcanic ash in operational contexts is increasingly being explored. The ensemble members are usually constructed to represent a priori uncertainty estimates in meteorological fields and volcanic ash source parameters. Satellite [...] Read more.

The use of ensemble models to forecast the dispersion and transport of airborne volcanic ash in operational contexts is increasingly being explored. The ensemble members are usually constructed to represent a priori uncertainty estimates in meteorological fields and volcanic ash source parameters. Satellite data can be used to further filter ensemble members within an analysis time window by rejecting poorly performing members, leading to improved forecasts. In this study, the ensemble filtering technique is used to improve the representation of temporal source variations. Ensemble members are initially created by representing the source time variations as random functions of time that are modulated by crude initial estimates of the variations estimated from satellite imagery. Ensemble filtering is then used to remove members whose fields match poorly with observations within a specified analysis time window that are represented by satellite retrievals of volcanic ash properties such as mass load, effective radius, and cloud top height. The filtering process leads to an ensemble with statistics in closer agreement with the observations. It is shown in the context of the 30 May 2014 Sangeang Api eruption case study that this method leads to significantly enhanced forecasting skill beyond the analysis time window—about 20% improvement on average—when compared to a system that assumes constant emission rates for the duration of the eruption, as is the case in many operational volcanic ash forecasting systems. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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19 pages, 2959 KiB

Open AccessArticle

Analysis of MONARC and ACTIVATE Airborne Aerosol Data for Aerosol-Cloud Interaction Investigations: Efficacy of Stairstepping Flight Legs for Airborne In Situ Sampling

by Hossein Dadashazar, Ewan Crosbie, Yonghoon Choi, Andrea F. Corral, Joshua P. DiGangi, Glenn S. Diskin, Sanja Dmitrovic, Simon Kirschler, Kayla McCauley, Richard H. Moore, John B. Nowak, Claire E. Robinson, Joseph Schlosser, Michael Shook, Kenneth Lee Thornhill, Christiane Voigt, Edward L. Winstead, Luke D. Ziemba and Armin Sorooshian

Atmosphere 2022, 13(8), 1242; https://doi.org/10.3390/atmos13081242 - 5 Aug 2022

Cited by 9 | Viewed by 2360

Abstract

A challenging aspect of conducting airborne in situ observations of the atmosphere is how to optimize flight plans for specific objectives and constraints associated with weather and flight restrictions. For aerosol-cloud interaction research, two recent campaigns utilized a “stairstepping” approach whereby an aircraft [...] Read more.

A challenging aspect of conducting airborne in situ observations of the atmosphere is how to optimize flight plans for specific objectives and constraints associated with weather and flight restrictions. For aerosol-cloud interaction research, two recent campaigns utilized a “stairstepping” approach whereby an aircraft conducts level legs at various altitudes while moving forward with each subsequent leg: the 2019 MONterey Aerosol Research Campaign (MONARC) over the northeast Pacific and the 2020–2022 Aerosol Cloud meTeorology Interactions oVer the western ATlantic Experiment (ACTIVATE) over the northwest Atlantic. We examine the homogeneity of several atmospheric variables both vertically and horizontally in the marine boundary layer with a focus on the sub-cloud environment. In well-mixed boundary layers, there was generally good horizontal and vertical homogeneity in potential temperature, winds, water vapor mixing ratio, various trace gases, and many aerosol variables. Selected aerosol variables exhibited the most variability owing to sensitivity to humidity and near-cloud conditions (supermicrometer aerosol concentrations), coastal pollution gradients (e.g., organic aerosol mass), and small spatial scale phenomena such as new particle formation (aerosol number concentration for particles with diameter >3 nm). Illustrative cases are described when stairstepping can pose issues requiring extra caution for data analysis: (i) poor vertical mixing and layers decoupled from those below; (ii) multiple cloud layers; (iii) fluctuating cloud base/top and boundary layer top heights; and (iv) horizontal variability across specific features leading to sharp gradients such as right near coastlines and over the Gulf Stream with strong sea surface temperature changes. Results from this study provide a guide both for future studies aiming to examine these mission datasets and for designing new airborne campaigns. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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19 pages, 6751 KiB

Open AccessArticle

Differences in Air and Sea Surface Temperatures in the Northern and Southern Part of the Adriatic Sea

by Ognjen Bonacci and Adrijana Vrsalović

Atmosphere 2022, 13(7), 1158; https://doi.org/10.3390/atmos13071158 - 21 Jul 2022

Cited by 12 | Viewed by 2940

Abstract

The paper compares air and sea surface temperatures in recent years on two islands in the Adriatic Sea. The data measured at the climatological station Krk on the island of Krk and the main meteorological station Lastovo on the island of Lastovo are [...] Read more.

The paper compares air and sea surface temperatures in recent years on two islands in the Adriatic Sea. The data measured at the climatological station Krk on the island of Krk and the main meteorological station Lastovo on the island of Lastovo are used. The island of Krk is located in the north of the Adriatic Sea and Lastovo in the south. Since a significant increase in air and sea surface temperatures has been observed over the last thirty years, the goal is to establish how they reflect at these two stations, 313 km apart. The goal of the analysis is to monitor the changes in these two islands to reduce the negative impacts they may cause. The analysis of sea temperatures showed that global warming has a greater impact in the northern Adriatic than in the southern Adriatic. Air and sea surface temperatures have a faster upward trend on Krk than on Lastovo. Similar to the Mediterranean Sea, a positive trend was observed in the Adriatic Sea for both sea surface temperature and air temperature. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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11 pages, 1123 KiB

Open AccessArticle

Effects of Climate Change on Forest Regeneration in Central Spain

by Álvaro Enríquez-de-Salamanca

Atmosphere 2022, 13(7), 1143; https://doi.org/10.3390/atmos13071143 - 18 Jul 2022

Cited by 8 | Viewed by 2782

Abstract

The Mediterranean climate has dry and hot summers, which is harsh for plants, especially seedlings. During the 1950s and 1960s, most reforestations carried out in Central Spain, a Mediterranean climate area, were successful, but in recent decades an increasing difficulty in forest regeneration [...] Read more.

The Mediterranean climate has dry and hot summers, which is harsh for plants, especially seedlings. During the 1950s and 1960s, most reforestations carried out in Central Spain, a Mediterranean climate area, were successful, but in recent decades an increasing difficulty in forest regeneration has been observed, often attributed to increased summer drought. This study analyses changes in climatic parameters related to forest regeneration through statistical treatment of meteorological data series from the mid-twentieth century to the present. Simple and multiple regressions and ANOVAs were performed for five parameters, considering annual, summer and extended summer values. Rainfall reduction and prolongation of the summer drought period were not statistically significant. The change that better explains regeneration problems is the increase in temperature, especially in July and August, which was mostly significant between 2002 and 2021. Raising temperatures increase the vapor pressure deficit, exacerbating drought effects and plant mortality. Climate change scenarios point to an increase in temperatures until 2100; thus, the tipping point for natural regeneration of some species could be passed. The most affected species are those at their ecological limit. It is necessary to facilitate the adaptation of these forests to climate change, since their future will depend on the actions carried out today. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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17 pages, 1811 KiB

Open AccessArticle

Oscillatory Signatures in the Raindrop Motion Relative to the Air Medium with Terminal Velocity

by Dmitrii N. Gabyshev, Miklós Szakáll, Dmitrii V. Shcherbakov, Alexander A. Fedorets and Sergey M. Dyachkov

Atmosphere 2022, 13(7), 1137; https://doi.org/10.3390/atmos13071137 - 18 Jul 2022

Cited by 4 | Viewed by 2042

Abstract

This paper aims to study the path oscillations of single, spherical water droplets levitated in a wind tunnel to better comprehend the mechanical motion of small raindrops. The observations were carried out in the Mainz vertical wind tunnel. The discrete, fast Fourier transform [...] Read more.

This paper aims to study the path oscillations of single, spherical water droplets levitated in a wind tunnel to better comprehend the mechanical motion of small raindrops. The observations were carried out in the Mainz vertical wind tunnel. The discrete, fast Fourier transform was used to determine the oscillatory frequencies of the droplet paths, and the Hilbert transform was applied to analyze their instantaneous frequency stability. Both transversal and streamwise components of the path oscillations are described with typical frequencies of several tens of Hertz. The studied oscillations elongate the paths, reduce the terminal velocity of the smallest droplets, and make the rain droplet fall in a non-uniform motion even after reaching terminal velocity. The terminal velocity can be considered as physically having been reached if our proposed practical criterion is satisfied. From a fluid mechanics perspective, the paper fills an experimental gap in the studies of the paths oscillations of single, liquid spheres of microscopic sizes at low Bond numbers <1 and relatively low Reynolds numbers ~10². Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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14 pages, 22726 KiB

Open AccessArticle

Precipitation Extremes and Their Synoptic Models in the Northwest European Sector of the Arctic during the Cold Season

by Alexander Kislov, Tatiana Matveeva and Uliana Antipina

Atmosphere 2022, 13(7), 1116; https://doi.org/10.3390/atmos13071116 - 15 Jul 2022

Cited by 7 | Viewed by 1775

Abstract

Precipitation extrema over the Barents Sea and the neighbouring locations in Europe were analysed using data obtained from station observations and a highly detailed ERA5 re-analysis dataset. These data did not always spatially coincide (on average, coincidence was ~50%). Daily amounts of precipitation [...] Read more.

Precipitation extrema over the Barents Sea and the neighbouring locations in Europe were analysed using data obtained from station observations and a highly detailed ERA5 re-analysis dataset. These data did not always spatially coincide (on average, coincidence was ~50%). Daily amounts of precipitation were typically higher in the observation data, although there may be a reverse picture. The analysis revealed that at several stations and in many of the ERA5 grids, the set of precipitation extremes exists as a mixture of two different subsets. The cumulative distribution functions (CDF) of the largest population in the context of both the re-analysis and observational data are well described by Pareto’s law. However, very rare cases exist in which the values deviate and exceed this base distribution value in regions possessing large values. These super-large anomalies do not obey the statistical law common to all other extremes. However, this does not mean that the extremes can be arbitrarily large. They do not exceed the marginal values that are typical for this type of climate and season. The analysis confirms that extreme precipitation in the western sector of the Arctic is caused by the penetration of moist air masses from the Atlantic in the circulation systems of intense cyclones. At certain times, mesoscale convective systems are embedded in atmospheric fronts and can significantly contribute to the formation of precipitation. Intensification of such cyclones corresponding to global warming should lead to a transformation of typical CDF, as modern outliers will become regular components of the Pareto law. This change in the statistics of extreme events reflects the nonstationarity of the climate state. The influence of polar lows on the formation of large daily precipitation amounts is not felt. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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16 pages, 5624 KiB

Open AccessArticle

Trends in Summer-Time Tropospheric Ozone during COVID-19 Lockdown in Indian Cities Might Forecast a Higher Future Risk

by Sujit Das, Abhijit Sarkar, Usha Mina, Senjuti Nandy, Md Najmus Saadat, Ganesh Kumar Agrawal and Randeep Rakwal

Atmosphere 2022, 13(7), 1115; https://doi.org/10.3390/atmos13071115 - 14 Jul 2022

Cited by 5 | Viewed by 2224

Abstract

High concentrations of tropospheric ozone (O₃) is a serious concern in India. The generation and atmospheric dynamics of this trace gas depend on the availability of its precursors and meteorological variables. Like other parts of the world, the COVID-19 imposed lockdown [...] Read more.

High concentrations of tropospheric ozone (O₃) is a serious concern in India. The generation and atmospheric dynamics of this trace gas depend on the availability of its precursors and meteorological variables. Like other parts of the world, the COVID-19 imposed lockdown and restrictions on major anthropogenic activities executed a positive impact on the ambient air quality with reduced primary pollutants/precursors load. In spite of this, several reports pointed towards a higher O₃ in major Indian cities during the lockdown. The present study designed with 30 pan-Indian mega-, class I-, and class II-cities revealed critical and contrasting aspects of the geographical location, source, precursor, and meteorological variable dependency of the spatial and temporal O₃ formation. This unexpected O₃ increase in the major cities might forecast the probable future risks for the National Air Quality policies, especially O₃ pollution management, in the Indian sub-continent. The results also pointed towards the severity of the north Indian air quality, followed by the western and eastern parts. We believe these results will definitely pave the way for researchers and policy-makers for predicting/framing regional and/or national O₃ management strategies in the future. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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15 pages, 4328 KiB

Open AccessArticle

Tropopause Characteristics Based on Long-Term ARM Radiosonde Data: A Fine-Scale Comparison at the Extratropical SGP Site and Arctic NSA Site

by Jinqiang Zhang

Atmosphere 2022, 13(6), 965; https://doi.org/10.3390/atmos13060965 - 14 Jun 2022

Cited by 1 | Viewed by 2427

Abstract

The variations in the characteristics of the tropopause are sensitive indicators for the climate system and climate change. By using Atmospheric Radiation Measurement (ARM) radiosonde data that were recorded at the extratropical Southern Great Plains (SGP) and Arctic North Slope of Alaska (NSA) [...] Read more.

The variations in the characteristics of the tropopause are sensitive indicators for the climate system and climate change. By using Atmospheric Radiation Measurement (ARM) radiosonde data that were recorded at the extratropical Southern Great Plains (SGP) and Arctic North Slope of Alaska (NSA) sites over an 18-year period (January 2003 to December 2020), this study performs a fine-scale comparison of the climatological tropopause features between these two sites that are characterized by different climates. The static stability increases rapidly above the tropopause at both sites, indicating the widespread existence of a tropopause inversion layer. The structures of both the tropopause inversion layer and the stability transition layer are more obvious at NSA than at SGP, and the seasonal variation trends of the tropopause inversion layer and stability transition layer are distinctly different between the two sites. A fitting method was used to derive the fitted tropopause height and tropopause sharpness (λ). Although this fitting method may determine a secondary tropopause rather than the primary tropopause when multiple tropopause heights are identified on one radiosonde profile, the fitted tropopause heights generally agree well with the observed tropopause heights. Broad tropopause sharpness values (λ > 2 km) occur more frequently at SGP than at NSA, resulting in a greater average tropopause sharpness at SGP (1.0 km) than at NSA (0.6 km). Significant positive trends are exhibited by the tropopause heights over the two sites, with rates of increase of 23.7 ± 6.5 m yr⁻¹ at SGP and 28.0 ± 4.0 m yr⁻¹ at NSA during the study period. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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17 pages, 2044 KiB

Open AccessArticle

On the Possibility of Modeling the IMF B_y-Weather Coupling through GEC-Related Effects on Cloud Droplet Coalescence Rate

by Arseniy Karagodin, Eugene Rozanov and Irina Mironova

Atmosphere 2022, 13(6), 881; https://doi.org/10.3390/atmos13060881 - 28 May 2022

Cited by 5 | Viewed by 1943

Abstract

The meteorological response to the fluctuation of the interplanetary magnetic field (IMF), known as the Mansurov effect, is well established. It is hypothesized that the IMF B

_{y}

fluctuation can modulate the atmospheric global electric circuit (GEC) over the polar regions and affect [...] Read more.

The meteorological response to the fluctuation of the interplanetary magnetic field (IMF), known as the Mansurov effect, is well established. It is hypothesized that the IMF B

_{y}

fluctuation can modulate the atmospheric global electric circuit (GEC) over the polar regions and affect surface meteorology. The influence of electric charges on the rate of droplet coalescence in fair-weather clouds is one of several cloud microphysical mechanisms that have been hypothesized to be involved. However, although meteorological effects associated with IMF B

_{y}

have been observed, the role of cloud droplet coalescence in this solar–weather coupling mechanism has not yet been confirmed. In addition, studies demonstrating the solar wind-driven effects are based on observations without using global climate models to support the IMF B

_{y}

-weather linkage. In this study, we investigate the Mansurov effect over the period 1999–2002 using ensemble experiments modeled with the chemistry-climate model (CCM) SOCOLv3 (SOlar Climate Ozone Links, version 3.0). Using observed IMF B

_{y}

, we model its effect on ground-level air pressure and temperature to examine one of the proposed GEC-cloud hypotheses: that surface meteorology response on IMF B

_{y}

fluctuations occurs through the J

_{z}

-associated intensification of cloud droplet coalescence rate. The results showed that we cannot explain and confirm the hypothesis that the rate of cloud droplet coalescence is an intermediate link for the IMF B

_{y}

-weather coupling. Anomalies in surface air pressure and temperature from the control run, where IMF B

_{y}

is omitted, do not robustly differ from experiments in which the dependence of cloud droplet coalescence rate on IMF B

_{y}

is included. In addition, the standard deviation of anomalies in surface air pressure and temperature between ensemble members is consistent with the magnitude of the observed effect even in the control run, suggesting that the model has a strong internal variability that prevents the IMF B

_{y}

effect from being properly detected in the model. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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20 pages, 2247 KiB

Open AccessArticle

Air Quality Impact Assessment of a Waste-to-Energy Plant: Modelling Results vs. Monitored Data

by Giovanni Lonati, Stefano Cernuschi and Paolo Giani

Atmosphere 2022, 13(4), 516; https://doi.org/10.3390/atmos13040516 - 23 Mar 2022

Cited by 5 | Viewed by 2988

Abstract

The impact of the emissions from a municipal Waste-to-Energy (WtE) plant in Northern Italy on local air quality was assessed using the CALMET-CALPUFF atmospheric dispersion modelling system. Model simulations were based on hourly emission rates measured by continuous stack monitoring systems and considered [...] Read more.

The impact of the emissions from a municipal Waste-to-Energy (WtE) plant in Northern Italy on local air quality was assessed using the CALMET-CALPUFF atmospheric dispersion modelling system. Model simulations were based on hourly emission rates measured by continuous stack monitoring systems and considered both air quality-regulated pollutants (nitrogen oxides, particulate matter, toxic elements, benzo(a)pyrene), and other trace pollutants typical of WtE plants (dioxins, furans, and mercury). The model results were compared to both long-term observations from the air quality monitoring network and with short-term measurements from dedicated monitoring campaigns in the vicinity of the WtE plant, in both warm and cold season conditions. Modelling and observational results showed that the estimated plant contributions are very limited. This suggests that the observed concentration levels were the result of the contribution of all the sources distributed over the area and that they were not solely driven by the activity of the plant. Estimated contributions from the plant’s emissions were usually at least two orders of magnitudes lower than the ambient levels at the nearest monitoring site and even lower at the farthest sites. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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20 pages, 5285 KiB

Open AccessArticle

Testing HYSPLIT Plume Dispersion Model Performance Using Regional Hydrocarbon Monitoring Data during a Gas Well Blowout

by Gunnar W. Schade and Mitchell L. Gregg

Atmosphere 2022, 13(3), 486; https://doi.org/10.3390/atmos13030486 - 17 Mar 2022

Cited by 6 | Viewed by 3552

Abstract

A gas well blowout in south central Texas in November 2019 that lasted for 20 days provided a unique opportunity to test the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model’s plume dispersion against hydrocarbon air monitoring data at two nearby state monitoring stations. [...] Read more.

A gas well blowout in south central Texas in November 2019 that lasted for 20 days provided a unique opportunity to test the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model’s plume dispersion against hydrocarbon air monitoring data at two nearby state monitoring stations. We estimated daily blowout hydrocarbon emission rates from satellite measurement-based results on methane emissions in conjunction with previously reported composition data of the local hydrocarbon resource. Using highly elevated hydrocarbon mixing ratios observed during several days at the two downwind monitoring stations, we calculated excess abundances above expected local background mixing ratios. Subsequent comparisons to HYSPLIT plume dispersion model outputs, generated using High-Resolution Rapid Refresh (HRRR) or North American Mesoscale (NAM) forecast meteorological input data, showed that the model generally reproduces both the timing and magnitude of the plume in various meteorological conditions. Absolute hydrocarbon mixing ratios could typically be reproduced within a factor of two. However, when lower emission rate estimates provided by the company in charge of the well were used, downwind hydrocarbon observations could not be reproduced. Overall, our results suggest that HYSPLIT, in combination with high-resolution meteorological input data, is a useful tool to accurately forecast chemical plume dispersion and potential human exposure in disaster situations. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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16 pages, 2243 KiB

Open AccessArticle

Secondary Organic and Inorganic Aerosol Formation from a GDI Vehicle under Different Driving Conditions

by Weihan Peng, Cavan McCaffery, Niina Kuittinen, Topi Rönkkö, David R. Cocker and Georgios Karavalakis

Atmosphere 2022, 13(3), 433; https://doi.org/10.3390/atmos13030433 - 8 Mar 2022

Cited by 2 | Viewed by 2582

Abstract

This study investigated the primary emissions and secondary aerosol formation from a gasoline direct injection (GDI) passenger car when operated over different legislative and real-world driving cycles on a chassis dynamometer. Diluted vehicle exhaust was photooxidized in a 30 m³ environmental chamber. [...] Read more.

This study investigated the primary emissions and secondary aerosol formation from a gasoline direct injection (GDI) passenger car when operated over different legislative and real-world driving cycles on a chassis dynamometer. Diluted vehicle exhaust was photooxidized in a 30 m³ environmental chamber. Results showed elevated gaseous and particulate emissions for the cold-start cycles and higher secondary organic aerosol (SOA) formation, suggesting that cold-start condition will generate higher concentrations of SOA precursors. Total secondary aerosol mass exceeded primary PM emissions and was dominated by inorganic aerosol (ammonium and nitrate) for all driving cycles. Further chamber experiments in high temperature conditions verified that more ammonium nitrate nucleates to form new particles, forming a secondary peak in particle size distribution instead of condensing to black carbon particles. The results of this study revealed that the absorption of radiation by black carbon particles can lead to changes in secondary ammonium nitrate formation. Our work indicates the potential formation of new ammonium nitrate particles during low temperature conditions favored by the tailpipe ammonia and nitrogen oxide emissions from gasoline vehicles. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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23 pages, 10218 KiB

Open AccessArticle

Learning Calibration Functions on the Fly: Hybrid Batch Online Stacking Ensembles for the Calibration of Low-Cost Air Quality Sensor Networks in the Presence of Concept Drift

by Evangelos Bagkis, Theodosios Kassandros and Kostas Karatzas

Atmosphere 2022, 13(3), 416; https://doi.org/10.3390/atmos13030416 - 3 Mar 2022

Cited by 18 | Viewed by 3475

Abstract

Deployment of an air quality low-cost sensor network (AQLCSN), with proper calibration of low-cost sensors (LCS), offers the potential to substantially increase the ability to monitor air pollution. However, to leverage this potential, several drawbacks must be ameliorated, thus the calibration of such [...] Read more.

Deployment of an air quality low-cost sensor network (AQLCSN), with proper calibration of low-cost sensors (LCS), offers the potential to substantially increase the ability to monitor air pollution. However, to leverage this potential, several drawbacks must be ameliorated, thus the calibration of such sensors is becoming an essential component in their use. Commonly, calibration takes place in a laboratory environment using gasses of known composition to measure the response and a linear calibration is often reached. On site calibration is a promising complementary technique where an LCS and a reference instrument are collocated with the former being calibrated to match the measurements of the latter. In a scenario where an AQLCSN is already operational, both calibration approaches are resource and time demanding procedures to be implemented as frequently repeated actions. Furthermore, sensors are sensitive to the local meteorology and adaptation is a slow process making relocation a complex and expensive option. We concentrate our efforts in keeping the LCS positions fixed and propose to blend a genetic algorithm (GA) with a hybrid stacking (HS) ensemble into the GAHS framework. GAHS employs a combination of batch machine learning algorithms and regularly updated online machine learning calibration function(s) for the whole network when a small number of reference instruments are present. Furthermore, we introduce the concept of spatial online learning to achieve better spatial generalization. The frameworks are tested for the case of Thessaloniki where a total of 33 devices are installed. The AQLCSN is calibrated on the basis of on-site matching with high quality observations from three reference station measurements. The O₃ LCS are successfully calibrated for 8–10 months and the PM₁₀ LCS calibration is evaluated for 13–24 months showing a strong seasonal dependence on their ability to correctly capture the pollution levels. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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26 pages, 34698 KiB

Open AccessArticle

A Heuristic Method for Modeling Odor Emissions from Open Roof Rectangular Tanks

by Roberto Bellasio and Roberto Bianconi

Atmosphere 2022, 13(3), 367; https://doi.org/10.3390/atmos13030367 - 22 Feb 2022

Cited by 2 | Viewed by 1807

Abstract

This paper presents heuristic equations for estimating odor emissions from open-roof rectangular tanks as a function of the tank orientation, wind direction, wind speed and distance of the emitting surface from the tank top. These types of equations are important because they may [...] Read more.

This paper presents heuristic equations for estimating odor emissions from open-roof rectangular tanks as a function of the tank orientation, wind direction, wind speed and distance of the emitting surface from the tank top. These types of equations are important because they may help to improve emission calculations to avoid overestimations, which are damaging to the plant owner, and underestimations, which are negative for the population around the plant. Odor emissions were determined for four tanks with the same area, different shape factors and two different orientations and then used as inputs for a dispersion model in order to calculate separation distances and evaluate their differences. The results show that different separation distances were obtained depending on the tank orientation, shape factor and level of filling. Future field applications to verify and improve the proposed equations are desirable. If the effect of the tank orientation on odor emission is proven, the design of future industrial plants containing open-roof rectangular tanks should consider the results of detailed wind data analysis. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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12 pages, 1927 KiB

Open AccessArticle

Zinc Oxide Nanoparticles Promote YAP/TAZ Nuclear Localization in Alveolar Epithelial Type II Cells

by Vincent Laiman, Didik Setyo Heriyanto, Yueh-Lun Lee, Ching-Huang Lai, Chih-Hong Pan, Wei-Liang Chen, Chung-Ching Wang, Kai-Jen Chuang, Jer-Hwa Chang and Hsiao-Chi Chuang

Atmosphere 2022, 13(2), 334; https://doi.org/10.3390/atmos13020334 - 16 Feb 2022

Cited by 5 | Viewed by 2709

Abstract

We investigated roles of Hippo signaling pathway components in alveolar type II cells (AECII) after zinc oxide nanoparticle (ZnONP) exposure. ZnONPs physicochemistry was characterized using field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX) microanalysis. ZnONP deposition in human respiratory tract was estimated [...] Read more.

We investigated roles of Hippo signaling pathway components in alveolar type II cells (AECII) after zinc oxide nanoparticle (ZnONP) exposure. ZnONPs physicochemistry was characterized using field emission-scanning electron microscopy (FE-SEM) and energy-dispersive X-ray (EDX) microanalysis. ZnONP deposition in human respiratory tract was estimated using multiple-path particle dosimetry (MPPD) model. MLE-12 AECII were cultured and exposed to 0, 1, and 5 μg/mL of ZnONPs for 24 h. Western blots were used to investigate signaling pathways associated with Yes-associated protein (YAP)/transcriptional co-activator with PDZ-binding motif (TAZ), cell adherens junctions, differentiation, and senescence. ZnONPs morphology was irregular, with Zn and O identified. Approximately 72% of inhaled ZnONPs were deposited in lungs, with 26% being deposited in alveolar regions. ZnONP exposure increased nuclear YAP expression and decreased cytoplasmic YAP expression by AECII. Adherens junction proteins, E-cadherin, α-catenin, and β-catenin, on AECII decreased after ZnONP exposure. ZnONP exposure of AECII increased alveolar type I (AECI) transition protein, LGALS3, and the AECI protein, T1α, while decreasing AECII SPC expression. ZnONP exposure induced Sirt1 and p53 senescence proteins by AECII. Our findings showed that inhalable ZnONPs can deposit in alveoli, which promotes YAP nuclear localization in AECII, resulting in decrease tight junctions, cell differentiation, and cell senescence. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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9 pages, 1758 KiB

Open AccessArticle

Spatial Evolution of Energetic Electrons Affecting the Upper Atmosphere during the Last Two Solar Cycles

by Alexei V. Dmitriev, Alla V. Suvorova, Sayantan Ghosh, Gennady V. Golubkov and Maxim G. Golubkov

Atmosphere 2022, 13(2), 322; https://doi.org/10.3390/atmos13020322 - 15 Feb 2022

Cited by 5 | Viewed by 2463

Abstract

Future commercial, scientific, and other satellite missions require low-Earth-orbit (LEO) altitudes of

300

–

400

km for long-term successful space operations. The Earth’s radiation belt (ERB) is an inevitable obstacle for manned and other space missions. Precipitation of >

30

keV energetic electrons [...] Read more.

Future commercial, scientific, and other satellite missions require low-Earth-orbit (LEO) altitudes of

300

–

400

km for long-term successful space operations. The Earth’s radiation belt (ERB) is an inevitable obstacle for manned and other space missions. Precipitation of >

30

keV energetic electrons from the ERB is one of the sources of ionization in LEO, space vehicles, in the ionosphere, and in the upper atmosphere. We show, in this work, that the area of electron precipitation from the outer ERB shifts equator-wards to Siberia. We further show a substantive decrease in the intensity of energetic electrons in the area of the South Atlantic Anomaly (SAA) from the 23rd to the 24th solar cycles. These results can be attributed to, and explained by, variations in geomagnetic activity, with a noticeable change in the configuration of the Earth’s magnetic field during the 24th solar cycle. The diminishing SAA area and electron fluxes should allow elevation of the International Space Station to higher altitudes, thereby making these altitudes accessible to relevant space missions. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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23 pages, 8304 KiB

Open AccessArticle

Impact of Wildfires on Meteorology and Air Quality (PM_2.5 and O₃) over Western United States during September 2017

by Amit Sharma, Ana Carla Fernandez Valdes and Yunha Lee

Atmosphere 2022, 13(2), 262; https://doi.org/10.3390/atmos13020262 - 3 Feb 2022

Cited by 11 | Viewed by 3672

Abstract

In this study, we investigated the impact of wildfires on meteorology and air quality (PM_2.5 and O₃) over the western United States during the September 2017 period. This is done by using Weather Research and Forecasting model coupled with Chemistry [...] Read more.

In this study, we investigated the impact of wildfires on meteorology and air quality (PM_2.5 and O₃) over the western United States during the September 2017 period. This is done by using Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) to simulate scenarios with wildfires (base case) and without wildfires (sensitivity case). Our analysis performed during the first half of September 2017 (when wildfire activity was more intense) reveals a reduction in modelled daytime average shortwave surface downward radiation especially in locations close to wildfires by up to 50 W m⁻², thus resulting in the reduction of the diurnal average surface temperature by up to 0.5 °C and the planetary boundary layer height by up to 50 m. These changes are mainly attributed to aerosol-meteorology feedbacks that affect radiation and clouds. The model results also show mostly enhancements for diurnally averaged cloud optical depth (COD) by up to 10 units in the northern domain due to the wildfire-related air quality. These changes occur mostly in response to aerosol–cloud interactions. Analysis of the impact of wildfires on chemical species shows large changes in daily mean PM_2.5 concentrations (exceeding by 200 μg m⁻³ in locations close to wildfires). The 24 h average surface ozone mixing ratios also increase in response to wildfires by up to 15 ppbv. The results show that the changes in PM_2.5 and ozone occur not just due to wildfire emissions directly but also in response to changes in meteorology, indicating the importance of including aerosol-meteorology feedbacks, especially during poor air quality events. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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26 pages, 6830 KiB

Open AccessArticle

Variability of the Aerosol Content in the Tropical Lower Stratosphere from 2013 to 2019: Evidence of Volcanic Eruption Impacts

by Mariam Tidiga, Gwenaël Berthet, Fabrice Jégou, Corinna Kloss, Nelson Bègue, Jean-Paul Vernier, Jean-Baptiste Renard, Adriana Bossolasco, Lieven Clarisse, Ghassan Taha, Thierry Portafaix, Terry Deshler, Frank G. Wienhold, Sophie Godin-Beekmann, Guillaume Payen, Jean-Marc Metzger, Valentin Duflot and Nicolas Marquestaut

Atmosphere 2022, 13(2), 250; https://doi.org/10.3390/atmos13020250 - 31 Jan 2022

Cited by 4 | Viewed by 3078

Abstract

This paper quantifies the tropical stratospheric aerosol content as impacted by volcanic events over the 2013–2019 period. We use global model simulations by the Whole Atmosphere Community Climate Model (WACCM) which is part of the Community Earth System Model version 1.0 (CESM1). WACCM [...] Read more.

This paper quantifies the tropical stratospheric aerosol content as impacted by volcanic events over the 2013–2019 period. We use global model simulations by the Whole Atmosphere Community Climate Model (WACCM) which is part of the Community Earth System Model version 1.0 (CESM1). WACCM is associated with the Community Aerosol and Radiation Model for Atmospheres (CARMA) sectional aerosol microphysics model which includes full sulphur chemical and microphysical cycles with no a priori assumption on particle size. Five main volcanic events (Kelud, Calbuco, Ambae, Raikoke and Ulawun) have been reported and are shown to have significantly influenced the stratospheric aerosol layer in the tropics, either through direct injection in this region or through transport from extra-tropical latitudes. Space-borne data as well as ground-based lidar and balloon-borne in situ observations are used to evaluate the model calculations in terms of aerosol content, vertical distribution, optical and microphysical properties, transport and residence time of the various volcanic plumes. Overall, zonal mean model results reproduce the occurrence and vertical extents of the plumes derived from satellite observations but shows some discrepancies for absolute values of extinction and of stratospheric aerosol optical depth (SAOD). Features of meridional transport of the plumes emitted from extra-tropical latitudes are captured by the model but simulated absolute values of SAOD differ from 6 to 200% among the various eruptions. Simulations tend to agree well with observed in situ vertical profiles for the Kelud and Calbuco plumes but this is likely to depend on the period for which comparison is done. Some explanations for the model–measurement discrepancies are discussed such as the inaccurate knowledge of the injection parameters and the presence of ash not accounted in the simulations. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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31 pages, 22063 KiB

Open AccessArticle

Effects of Density Current, Diurnal Heating, and Local Terrain on the Mesoscale Environment Conducive to the Yarnell Hill Fire

by Jan Ising, Michael Lewis Kaplan and Yuh-Lang Lin

Atmosphere 2022, 13(2), 215; https://doi.org/10.3390/atmos13020215 - 28 Jan 2022

Cited by 2 | Viewed by 3602

Abstract

The Yarnell Hill Fire, triggered by dry lightning on 28 June 2013, was initiated by hot and dry westerly winds, which rapidly shifted to north-northeast by convective-induced outflows. This sudden wind shift led to the demise of 19 firefighters. This study focuses on [...] Read more.

The Yarnell Hill Fire, triggered by dry lightning on 28 June 2013, was initiated by hot and dry westerly winds, which rapidly shifted to north-northeast by convective-induced outflows. This sudden wind shift led to the demise of 19 firefighters. This study focuses on the environment and its predictive potential in terms of erratically changing the fire spread. Three numerical sensitivity tests are performed investigating the evolving synoptic-meso-β scale environmental wind flow: (1) deactivating the evaporative cooling, (2) deactivating surface-driven diurnal heating/cooling, and (3) removing the mountain. Results show the strong north-northeasterly wind induced by the density current(s) and the diurnal surface sensible heating played the most significant roles in enhancing the mesoscale environment conducive to the rapid change in the fire spread direction. While the mountain played a less significant role in weakening the magnitude of the airflow affecting the fire, it still had an impact. Additionally, the Hot-Dry-Windy (HDW) index is calculated to determine its predictor role with respect to the atmosphere affecting the fire. The focus is not on feedback from explicit fire heating on the larger environment but rather the role of the environmental physical processes in causing the convectively induced rapid wind shifts. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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13 pages, 2458 KiB

Open AccessArticle

Multi-Case Analysis of Ice Particle Properties of Stratiform Clouds Using In Situ Aircraft Observations in Hebei, China

by Siyao Liu, Chuanfeng Zhao, Yuquan Zhou, Zhihui Wu and Zhijin Hu

Atmosphere 2022, 13(2), 200; https://doi.org/10.3390/atmos13020200 - 26 Jan 2022

Cited by 1 | Viewed by 2184

Abstract

This study investigates the size distribution, the mean diameter, and the concentration of ice particles within stratiform clouds by using in situ observations from 29 flights in Hebei, China. Furthermore, it examines the empirical fitting of ice particle size distributions at different temperatures [...] Read more.

This study investigates the size distribution, the mean diameter, and the concentration of ice particles within stratiform clouds by using in situ observations from 29 flights in Hebei, China. Furthermore, it examines the empirical fitting of ice particle size distributions at different temperatures using Gamma and exponential functions. Without considering the first three bins of ice particles, the mean diameter of ice particles (size range 100–1550 µm) is found to increase with temperature from −15 to −9 °C but decrease with temperature from −9 to 0 °C. By considering the first three bins of ice particles using the empirical Gamma fitting relationship found in this study, the mean diameter of ice particles (size range 25–1550 µm) shows a similar variation trend with temperature, while the turning point changes from −9 to −10 °C. The ice particle number concentration increases from 13.37 to 50.23 L⁻¹ with an average of 31.27 L⁻¹ when temperature decreases from 0 to −9 °C. Differently, the ice concentration decreases from 50.23 to about 22.4 L⁻¹ when temperature decreases from −9 to −12 °C. The largest mean diameter of ice particles at temperatures around −9 and −10 °C is most likely associated with the maximum difference of ice and water supersaturation at that temperature, making the ice particles grow the fastest. These findings provide valuable information for future physical parameterization development of ice crystals within stratiform clouds. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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20 pages, 12909 KiB

Open AccessArticle

Rate Constants and Branching Ratios for the Self-Reaction of Acetyl Peroxy (CH₃C(O)O₂^•) and Its Reaction with CH₃O₂

by Mohamed Assali and Christa Fittschen

Atmosphere 2022, 13(2), 186; https://doi.org/10.3390/atmos13020186 - 24 Jan 2022

Cited by 4 | Viewed by 3229

Abstract

The self-reaction of acetylperoxy radicals (CH₃C(O)O₂^•) (R1) as well as their reaction with methyl peroxy radicals (CH₃O₂^•) (R2) have been studied using laser photolysis coupled to a selective time resolved detection of three [...] Read more.

The self-reaction of acetylperoxy radicals (CH₃C(O)O₂^•) (R1) as well as their reaction with methyl peroxy radicals (CH₃O₂^•) (R2) have been studied using laser photolysis coupled to a selective time resolved detection of three different radicals by cw-CRDS in the near-infrared range: CH₃C(O)O₂^• was detected in the Ã-

\tilde{X}

electronic transition at 6497.94 cm⁻¹, HO₂^• was detected in the 2ν₁ vibrational overtone at 6638.2 cm⁻¹, and CH₃O₂^• radicals were detected in the Ã-

\tilde{X}

electronic transition at 7489.16 cm⁻¹. Pulsed photolysis of different precursors at different wavelengths, always in the presence of O₂, was used to generate CH₃C(O)O₂^• and CH₃O₂^• radicals: acetaldehyde (CH₃CHO/Cl₂ mixture or biacetyle (CH₃C(O)C(O)CH₃) at 351 nm, and acetone (CH₃C(O)CH₃) or CH₃C(O)C(O)CH₃ at 248 nm. From photolysis experiments using CH₃C(O)C(O)CH₃ or CH₃C(O)CH₃ as precursor, the rate constant for the self-reaction was found with k₁ = (1.3 ± 0.3) × 10⁻¹¹ cm³s⁻¹, in good agreement with current recommendations, while the rate constant for the cross reaction with CH₃O₂^• was found to be k₂ = (2.0 ± 0.4) × 10⁻¹¹ cm³s⁻¹, which is nearly two times faster than current recommendations. The branching ratio of (R2) towards the radical products was found at 0.67, compared with 0.9 for the currently recommended value. Using the reaction of Cl^•-atoms with CH₃CHO as precursor resulted in radical profiles that were not reproducible by the model: secondary chemistry possibly involving Cl^• or Cl₂ might occur, but could not be identified. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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16 pages, 2422 KiB

Open AccessArticle

How Much Green Is Really “Cool”? Target Setting for Thermal Comfort Enhancement in a Warm, Humid City (Jakarta, Indonesia)

by Hanna Meiria Naomi Stepani and Rohinton Emmanuel

Atmosphere 2022, 13(2), 184; https://doi.org/10.3390/atmos13020184 - 24 Jan 2022

Cited by 6 | Viewed by 3443

Abstract

Green infrastructure is well recognized as a key urban climate mitigation strategy. In line with this, and following a central government decree, Jakarta Municipal Government has created a green infrastructure target of 30% underpinned by a green space weighting factor. This study questions [...] Read more.

Green infrastructure is well recognized as a key urban climate mitigation strategy. In line with this, and following a central government decree, Jakarta Municipal Government has created a green infrastructure target of 30% underpinned by a green space weighting factor. This study questions the efficacy of such a “universal” target setting from the point of view of outdoor thermal comfort and demonstrates the basis for an alternative approach. Based on a “new’ green factor developed from a systematic analysis of the literature, thermal comfort simulations of representative local climate zones (LCZ) show that improvements in current green space policy are possible. We enumerate a rational basis for specifying green space targets per local area based on contextual realities as captured by the LCZ approach. Such a nuanced approach to mitigate the human comfort consequences of inadvertent urban growth is not only more contextually appropriate but also enhances the feasibility of achieving the intended goal of urban greening in Jakarta. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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16 pages, 2531 KiB

Open AccessArticle

Air Quality outside Schools in Newcastle upon Tyne, UK: An Investigation into NO₂ and PM Concentrations and PM Respiratory Deposition

by Laura Keast, Lindsay Bramwell, Kamal Jyoti Maji, Judith Rankin and Anil Namdeo

Atmosphere 2022, 13(2), 172; https://doi.org/10.3390/atmos13020172 - 21 Jan 2022

Cited by 9 | Viewed by 4938

Abstract

Air pollution is the principal environmental threat to public health in the UK. Ever-increasing evidence links ambient air pollutants, preventable diseases, and health inequalities. Children are particularly vulnerable to harmful effects due to their short height, developing lungs, and higher rate of respiration. [...] Read more.

Air pollution is the principal environmental threat to public health in the UK. Ever-increasing evidence links ambient air pollutants, preventable diseases, and health inequalities. Children are particularly vulnerable to harmful effects due to their short height, developing lungs, and higher rate of respiration. Using data from air quality monitors around schools, we investigated 2018–2019 ambient NO₂, PM₁₀, PM_2.5, and PM₁ concentrations at 12 schools in Newcastle upon Tyne, UK. We compared findings with EU/UK air quality regulations and guidelines, identified patterns, and calculated PM respiratory deposition doses (RDDs). The range of annual average (AA) concentrations across the schools for the two-year period was 23.7–39.2 µg/m³ for NO₂, 7.4–22.2 µg/m³ for PM₁₀, 3.5–11.6 µg/m³ for PM_2.5, and 1.7–9.0 µg/m³ for PM₁. The highest PM RDD children were exposed to at school was 30 µg/h. One school’s AA NO₂, two schools’ hourly PM_2.5 averages, and one school’s 24-h PM₁₀ averages exceeded EU/UK regulations. All schools exceeded WHO₂₀₀₅ 24-h PM₁₀ and PM_2.5 guidelines in 2018, less in 2019. All 12 schools would have exceeded WHO₂₀₂₁ NO₂ AA guidelines (10 µg/m³), 2 the WHO₂₀₂₁ PM₁₀ AA (15 µg/m³), and 10 the WHO₂₀₂₁ PM_2.5 AA (5 µg/m³). Evidence-based policy is required to improve school ambient air quality and reduce children’s exposure. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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20 pages, 2335 KiB

Open AccessArticle

Emissions of H₂S from Hog Finisher Farm Anaerobic Manure Treatment Lagoons: Physical, Chemical and Biological Influence

by Richard H. Grant and Matthew T. Boehm

Atmosphere 2022, 13(2), 153; https://doi.org/10.3390/atmos13020153 - 18 Jan 2022

Cited by 1 | Viewed by 1816

Abstract

Hydrogen sulfide (H₂S) from hog operations contributes to noxious odors in the surrounding environment and can be life-threatening. There is, however, limited understanding of what influences H₂S emissions from these farms. Emissions of H₂S were measured periodically [...] Read more.

Hydrogen sulfide (H₂S) from hog operations contributes to noxious odors in the surrounding environment and can be life-threatening. There is, however, limited understanding of what influences H₂S emissions from these farms. Emissions of H₂S were measured periodically over the course of two years at hog finisher farms in humid mesothermal (North Carolina, NC, USA) and semi-arid (Oklahoma, OK, USA) climates. Emissions were determined using an inverse dispersion backward Lagrangian stochastic model in conjunction with line-sampled H₂S concentrations and measured turbulence. Daily emissions at the two lagoons were characterized by low emissions on most days with occasional days of high emissions. Mean annual area-specific emissions were much lower for the NC lagoon (1.32 µg H₂S m⁻² s⁻¹ ± 0.07 µg H₂S m⁻² s⁻¹) than the OK lagoon (6.88 µg H₂S m⁻² s⁻¹ ± 0.13 µg H₂S m⁻² s⁻¹). Mean annual hog-specific emissions for the NC lagoon were 0.75 g H₂S hd⁻¹ d⁻¹ while those for the OK lagoon were 1.92 g H₂S hd⁻¹ d⁻¹. Emissions tended to be higher during the afternoon, likely due to higher mean winds. Daily H₂S emissions from both lagoons were greatest during the first half of the year and decreased as the year progressed and a reddish color (indicating high populations of purple sulfur bacteria (PSB)) appeared in the lagoon. The generally low emissions at the NC lagoon and higher emissions at the OK lagoon were likely a result of the influence of wind on mixing the lagoon and not the presence of PSB. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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17 pages, 5715 KiB

Open AccessArticle

Long-Term Analysis of Tropospheric Ozone in the Urban Area of Guadalajara, Mexico: A New Insight of an Alternative Criterion

by José de Jesús Díaz-Torres, Valeria Ojeda-Castillo, Leonel Hernández-Mena, Josefina Vergara-Sánchez, Hugo Albeiro Saldarriaga-Noreña and Mario Alfonso Murillo-Tovar

Atmosphere 2022, 13(2), 152; https://doi.org/10.3390/atmos13020152 - 18 Jan 2022

Cited by 3 | Viewed by 2395

Abstract

Tropospheric ozone is an obligatorily-regulated pollutant, to ensure health protection and better air quality. Most countries have established maximum permissible limits (MPL) equal to 0.06 or 0.070 ppmv, but these could be insufficient considering the strictest MPL of the World Health Organization (WHO) [...] Read more.

Tropospheric ozone is an obligatorily-regulated pollutant, to ensure health protection and better air quality. Most countries have established maximum permissible limits (MPL) equal to 0.06 or 0.070 ppmv, but these could be insufficient considering the strictest MPL of the World Health Organization (WHO) guidelines. Such concentrations may still cause health damage to some groups of the population in urban areas. Additionally, the mean value is the principal statistical parameter for monitoring air pollution. This factor may be hiding critical ozone concentrations for public health. This work examines the mean and maximum ozone based on a multi-temporal analysis, to explore the use of a maximum average value as an air quality standard. The mean ozone had a remarkably stationary contrast; while, the maximum ozone emphasized a semi-permanent state of high pollution over the year. Diurnal variation highlights the differences of frequency between the mean and maximum ozone above any MPL, which is accentuated when compared with the WHO guidelines. Under the WHO-MPL, the mean ozone underestimates the highest concentrations; while the maximum ozone represents the extremely high concentrations observed over the year. Instead, the maximum average ozone becomes moderate; this preserves the proper, but conservative high concentrations, following similar temporal patterns as the mean ozone. This parameter is proposed to be adapted as an alternative statistical criterion to prevent negative effects on public health due to high and frequent ozone concentrations in subsequent years. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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23 pages, 6681 KiB

Open AccessArticle

Simulating the Effects of Land Surface Characteristics on Planetary Boundary Layer Parameters for a Modeled Landfalling Tropical Cyclone

by Yu Wang and Corene J. Matyas

Atmosphere 2022, 13(1), 138; https://doi.org/10.3390/atmos13010138 - 14 Jan 2022

Cited by 5 | Viewed by 3000

Abstract

This study examined whether varying moisture availability and roughness length for the land surface under a simulated Tropical Cyclone (TC) could affect its production of precipitation. The TC moved over the heterogeneous land surface of the southeastern U.S. in the control simulation, while [...] Read more.

This study examined whether varying moisture availability and roughness length for the land surface under a simulated Tropical Cyclone (TC) could affect its production of precipitation. The TC moved over the heterogeneous land surface of the southeastern U.S. in the control simulation, while the other simulations featured homogeneous land surfaces that were wet rough, wet smooth, dry rough, and dry smooth. Results suggest that the near-surface atmosphere was modified by the changes to the land surface, where the wet cases have higher latent and lower sensible heat flux values, and rough cases exhibit higher values of friction velocity. The analysis of areal-averaged rain rates and the area receiving low and high rain rates shows that simulations having a moist land surface produce higher rain rates and larger areas of low rain rates in the TC’s inner core. The dry and rough land surfaces produced a higher coverage of high rain rates in the outer regions. Key differences among the simulations happened as the TC core moved over land, while the outer rainbands produced more rain when moving over the coastline. These findings support the assertion that the modifications of the land surface can influence precipitation production within a landfalling TC. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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13 pages, 2218 KiB

Open AccessArticle

Trends of Ground-Level Ozone in New York City Area during 2007–2017

by Subraham Singh and Ilias G. Kavouras

Atmosphere 2022, 13(1), 114; https://doi.org/10.3390/atmos13010114 - 12 Jan 2022

Cited by 7 | Viewed by 3230

Abstract

The spatiotemporal patterns of ground level ozone (O₃) concentrations in the New York City (NYC) metropolitan region for the 2007–2017 period were examined conjointly with local emissions of O₃ precursors and the frequency of wildfires. Daily 8-h and 1-h O [...] Read more.

The spatiotemporal patterns of ground level ozone (O₃) concentrations in the New York City (NYC) metropolitan region for the 2007–2017 period were examined conjointly with local emissions of O₃ precursors and the frequency of wildfires. Daily 8-h and 1-h O₃ and nitric oxide (NO) concentrations were retrieved from the US Environmental Protection Agency (EPA) Air Data. Annual emission inventories for 2008 and 2017 were acquired from EPA National Emissions Inventory (NEI). The number and area burnt by natural and human-ignited wildfires were acquired from the National Interagency Fire Center (NIFC). The highest daily 8-h max O₃ concentrations varied from 90 to 111 parts per billion volume (ppbv) with the highest concentrations measured perimetrically to NYC urban agglomeration. The monthly 8-h max O₃ levels have been declining for most of the peri-urban sites but increasing (from +0.18 to +1.39 ppbv/year) for sites within the urban agglomeration. Slightly higher O₃ concentrations were measured during weekend than those measured during the weekdays in urban sites probably due to reduced O₃ titration by NO. Significant reductions of locally emitted anthropogenic nitrogen oxides (NO_x) and volatile organic compounds (VOCs) may have triggered the transition from VOC-limited to NO_X-limited conditions, with downwind VOCs sources being critically important. Strong correlations between the monthly 8-h max O₃ concentrations and wildfires in Eastern US were computed. More and destructive wildfires in the region were ignited by lightning for years with moderate and strong La Niña conditions. These findings indicate that climate change may counterbalance current and future gains on O₃ precursor’s reductions by amending the VOCs-to-NO_x balance. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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23 pages, 6477 KiB

Open AccessArticle

Vertical Profiling of Fresh Biomass Burning Aerosol Optical Properties over the Greek Urban City of Ioannina, during the PANACEA Winter Campaign

by Christina-Anna Papanikolaou, Alexandros Papayannis, Maria Mylonaki, Romanos Foskinis, Panagiotis Kokkalis, Eleni Liakakou, Iasonas Stavroulas, Ourania Soupiona, Nikolaos Hatzianastassiou, Maria Gavrouzou, Eleni Kralli and Dimitra Anagnou

Atmosphere 2022, 13(1), 94; https://doi.org/10.3390/atmos13010094 - 7 Jan 2022

Cited by 11 | Viewed by 2947

Abstract

Vertical profiling of aerosol particles was performed during the PANhellenic infrastructure for Atmospheric Composition and climatE chAnge (PANACEA) winter campaign (10 January 2020–7 February 2020) over the city of Ioannina, Greece (39.65° N, 20.85° E, 500 m a.s.l.). The middle-sized city of Ioannina [...] Read more.

Vertical profiling of aerosol particles was performed during the PANhellenic infrastructure for Atmospheric Composition and climatE chAnge (PANACEA) winter campaign (10 January 2020–7 February 2020) over the city of Ioannina, Greece (39.65° N, 20.85° E, 500 m a.s.l.). The middle-sized city of Ioannina suffers from wintertime air pollution episodes due to biomass burning (BB) domestic heating activities. The lidar technique was applied during the PANACEA winter campaign on Ioannina city, to fill the gap of knowledge of the spatio-temporal evolution of the vertical mixing of the particles occurring during these winter-time air pollution episodes. During this campaign the mobile single-wavelength (532 nm) depolarization Aerosol lIdAr System (AIAS) was used to measure the spatio-temporal evolution of the aerosols’ vertical profiles within the Planetary Boundary Layer (PBL) and the lower free troposphere (LFT; up to 4 km height a.s.l.). AIAS performed almost continuous lidar measurements from morning to late evening hours (typically from 07:00 to 19:00 UTC), under cloud-free conditions, to provide the vertical profiles of the aerosol backscatter coefficient (b_aer) and the particle linear depolarization ratio (PLDR), both at 532 nm. In this study we emphasized on the vertical profiling of very fresh (~hours) biomass burning (BB) particles originating from local domestic heating activities in the area. In total, 33 out of 34 aerosol layers in the lower free troposphere were characterized as fresh biomass burning ones of local origin, showing a mean particle linear depolarization value of 0.04 ± 0.02 with a range of 0.01 to 0.09 (532 nm) in a height region 1.21–2.23 km a.s.l. To corroborate our findings, we used in situ data, particulate matter (PM) concentrations (PM_2.5) from a particulate sensor located close to our station, and the total black carbon (BC) concentrations along with the respective contribution of the fossil fuel (BC_ff) and biomass/wood burning (BC_wb) from the Aethalometer. The PM_2.5 mass concentrations ranged from 5.6 to 175.7 μg/m³, while the wood burning emissions from residential heating were increasing during the evening hours, with decreasing temperatures. The BC_wb concentrations ranged from 0.5 to 17.5 μg/m³, with an extremely high mean contribution of BC_wb equal to 85.4%, which in some cases during night-time reached up to 100% during the studied period. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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34 pages, 11305 KiB

Open AccessArticle

A Study to Explore the Dew Condensation Potential of Cars

by Marc Muselli, Danilo Carvajal and Daniel A. Beysens

Atmosphere 2022, 13(1), 65; https://doi.org/10.3390/atmos13010065 - 30 Dec 2021

Cited by 4 | Viewed by 3199

Abstract

The metal surfaces of a car exhibit favorable properties for the passive condensation of atmospheric water. Under certain nocturnal climatic conditions (high relative humidity, weak windspeed, and total nebulosity), dew is often observed on cars, and it is appropriate to ask the question [...] Read more.

The metal surfaces of a car exhibit favorable properties for the passive condensation of atmospheric water. Under certain nocturnal climatic conditions (high relative humidity, weak windspeed, and total nebulosity), dew is often observed on cars, and it is appropriate to ask the question of using a vehicle as a standard condenser for estimating the dew yield. In order to see whether cars can be used as reference dew condensers, we report a detailed study of radiative cooling and dew formation on cars in the presence of radiating obstacles and for various windspeeds. Measurements of temperature and condensed dew mass on different car parts (rooftop, front and back hoods, windshield, lateral and back windows, inside and outside air) are compared with the same data obtained on a horizontal, thermally isolated planar film. The paper concludes that heat transfer coefficients, evaluated from temperature and dew yield measurements, are found nearly independent of windspeed and tilt angles. Moreover, this work describes the relation between cooling and dew condensation with the presence or not of thermal isolation. This dependence varies with the surface tilt angle according to the angular dependence of the atmosphere radiation. This work also confirms that cars can be used to estimate the dew yields in a given site. A visual observation scale h = Kn, with h the dew yield (mm) and n = 0, 1 2, 3 an index, which depends whether dew forms or not on rooftop, windshield, and lateral windows, is successfully tested with 8 different cars in 5 sites with three different climates, using K = (0.067 ± 0.0036) mm·day⁻¹. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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23 pages, 37958 KiB

Open AccessArticle

Santa Ana Winds: Fractal-Based Analysis in a Semi-Arid Zone of Northern Mexico

by Yeraldin Serpa-Usta, Alvaro Alberto López-Lambraño, Dora-Luz Flores, Ena Gámez-Balmaceda, Luisa Martínez-Acosta, Juan Pablo Medrano-Barboza, John Freddy Remolina López, Alvaro López-Ramos and Mariangela López-Lambraño

Atmosphere 2022, 13(1), 48; https://doi.org/10.3390/atmos13010048 - 28 Dec 2021

Cited by 2 | Viewed by 2597

Abstract

A fractal analysis based on the time series of precipitation, temperature, pressure, relative humidity, and wind speed was performed for 16 weather stations located in the hydrographic basin of the Guadalupe River in Baja California, Mexico. Days on which the phenomenon known as [...] Read more.

A fractal analysis based on the time series of precipitation, temperature, pressure, relative humidity, and wind speed was performed for 16 weather stations located in the hydrographic basin of the Guadalupe River in Baja California, Mexico. Days on which the phenomenon known as Santa Ana winds occurs were identified based on the corresponding criteria of wind speed (≥4.5 m/s) and wind direction (between 0° and 90°). Subsequently, the time series was formed with data representing the days on which this phenomenon occurs in each of the analyzed weather stations. A time series was additionally formed from the days in which the Santa Ana winds condition does not occur. Hurst exponents and fractal dimension were estimated applying the rescaled range method to characterize the established time series in terms of characteristics of persistence, anti-persistence, or randomness along with the calculation of the climate predictability Index. This enabled the behavior and correlation analysis of the meteorological variables associated with Santa Ana winds occurrence. Finally, this type of research study is instrumental in understanding the regional dynamics of the climate in the basin, and allows us to establish a basis for developing models that can forecast the days of occurrence of the Santa Ana winds, in such a way that actions or measures can be taken to mitigate the negative consequences generated when said phenomenon occurs, such as fires and droughts. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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20 pages, 5783 KiB

Open AccessArticle

Drought Assessment in São Francisco River Basin, Brazil: Characterization through SPI and Associated Anomalous Climate Patterns

by Aline A. Freitas, Anita Drumond, Vanessa S. B. Carvalho, Michelle S. Reboita, Benedito C. Silva and Cintia B. Uvo

Atmosphere 2022, 13(1), 41; https://doi.org/10.3390/atmos13010041 - 28 Dec 2021

Cited by 22 | Viewed by 3971

Abstract

The São Francisco River Basin (SFRB) is one of the main watersheds in Brazil, standing out for generating energy and consumption, among other ecosystem services. Hence, it is important to identify hydrological drought events and the anomalous climate patterns associated with dry conditions. [...] Read more.

The São Francisco River Basin (SFRB) is one of the main watersheds in Brazil, standing out for generating energy and consumption, among other ecosystem services. Hence, it is important to identify hydrological drought events and the anomalous climate patterns associated with dry conditions. The Standard Precipitation Index (SPI) for 12 months was used to identify hydrological drought episodes over SFRB 1979 and 2020. For these episodes, the severity, duration, intensity, and peak were obtained, and SPI-1 was applied for the longest and most severe episode to identify months with wet and dry conditions within the rainy season (Nov–Mar). Anomalous atmospheric and oceanic patterns associated with this episode were also analyzed. The results revealed the longest and most severe hydrological drought episode over the basin occurred between 2012 and 2020. The episode over the Upper portion of the basin lasted 103 months. The results showed a deficit of monthly precipitation up to 250 mm in the southeast and northeast regions of the country during the anomalous dry months identified through SPI-1. The dry conditions observed during the rainy season of this episode were associated with an anomalous high-pressure system acting close to the coast of Southeast Brazil, hindering the formation of precipitating systems. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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21 pages, 3488 KiB

Open AccessArticle

Patterns and Controls of the Latent and Sensible Heat Fluxes in the Brazilian Pampa Biome

by Gisele Cristina Dotto Rubert, Vanessa de Arruda Souza, Tamíres Zimmer, Gustavo Pujol Veeck, Alecsander Mergen, Tiago Bremm, Anderson Ruhoff, Luis Gustavo Gonçalves de Gonçalves and Débora Regina Roberti

Atmosphere 2022, 13(1), 23; https://doi.org/10.3390/atmos13010023 - 24 Dec 2021

Cited by 6 | Viewed by 2981

Abstract

Energy and water exchange between the surface and the atmosphere are important drivers to Earth’s climate from local to global scale. In this study, the energy dynamic and the biophysical mechanisms that control the energy partitioning over a natural grassland pasture over the [...] Read more.

Energy and water exchange between the surface and the atmosphere are important drivers to Earth’s climate from local to global scale. In this study, the energy dynamic and the biophysical mechanisms that control the energy partitioning over a natural grassland pasture over the Brazilian Pampa biome are investigated using two micrometeorological sites located 300 km apart, in Southern Brazil. The latent heat flux, LE, was the main component of the energy balance in both autumn-winter (AW) and spring-summer (SS) periods. Annually, approximately 60% of the available energy is used for evapotranspiration (ET). However, the Bowen ratio presents seasonal variability greater in AW than SS. Global radiation, Rg, is the atmospheric variable controlling LE and sensible heat flux, H. Hysteresis curves in the daily cycle were observed for ET and surface conductance, Cs, regarding the environmental variables, net radiation, vapor pressure deficit, and air temperature. Among the variables analyzed in the Pampa biome, surface conductance and evapotranspiration respond more strongly to the vapor pressure deficit. The hysteresis cycles formed by ET and conductance show a substantial biophysical control in the ET process. The results obtained here allowed a comprehension of the biophysical mechanisms involved in the energy partition process in natural grassland. Therefore, this study can be used as a base for research on land-use changes in this unique ecosystem of the Pampa biome. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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12 pages, 1748 KiB

Open AccessArticle

Atmospheric Effects on the Isotopic Composition of Ozone

by Mao-Chang Liang, Yi-Chun Chen, Yi-Qin Gao, Xi Zhang and Yuk L. Yung

Atmosphere 2021, 12(12), 1673; https://doi.org/10.3390/atmos12121673 - 13 Dec 2021

Cited by 2 | Viewed by 2350

Abstract

The delta values of the isotope composition of atmospheric ozone is ~100‰ (referenced to atmospheric O₂). Previous photochemical models, which considered the isotope fractionation processes from both formation and photolysis of ozone, predicted δ⁴⁹O₃ and δ⁵⁰O [...] Read more.

The delta values of the isotope composition of atmospheric ozone is ~100‰ (referenced to atmospheric O₂). Previous photochemical models, which considered the isotope fractionation processes from both formation and photolysis of ozone, predicted δ⁴⁹O₃ and δ⁵⁰O₃ values, in δ⁴⁹O₃ versus δ⁵⁰O₃ space, that are >10‰ larger than the measurements. We propose that the difference between the model and observations could be explained either by the temperature variation, Chappuis band photolysis, or a combination of the two and examine them. The isotopic fractionation associated with ozone formation increases with temperature. Our model shows that a hypothetical reduction of ~20 K in the nominal temperature profile could reproduce the observations. However, this hypothesis is not consistent with temperatures obtained by in situ measurements and NCEP Reanalysis. Photolysis of O₃ in the Chappuis band causes O₃ to be isotopically depleted, which is supported by laboratory measurements for ¹⁸O¹⁸O¹⁸O but not by recent new laboratory data made at several wavelengths for ⁴⁹O₃ and ⁵⁰O₃. Cloud reflection can significantly enhance the photolysis rate and affect the spectral distribution of photons, which could influence the isotopic composition of ozone. Sensitivity studies that modify the isotopic composition of ozone by the above two mechanisms are presented. We conclude isotopic fractionation occurring in photolysis in the Chappuis band remains the most plausible solution to the model-observation discrepancy. Implications of our results for using the oxygen isotopic signature for constraining atmospheric chemical processes related to ozone, such as CO₂, nitrate, and the hydroxyl radical, are discussed. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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9 pages, 688 KiB

Open AccessArticle

Polarity Asymmetry in Lightning Return Stroke Speed Caused by the Momentum Associated with Radiation

by Vernon Cooray, Gerald Cooray, Marcos Rubinstein and Farhad Rachidi

Atmosphere 2021, 12(12), 1642; https://doi.org/10.3390/atmos12121642 - 8 Dec 2021

Viewed by 2077

Abstract

In positive lightning return strokes, the net momentum transported by the radiation field has the same direction as the momentum associated with electrons, whereas the momentum associated with electrons is in opposite direction to the momentum of radiation in negative return strokes. It [...] Read more.

In positive lightning return strokes, the net momentum transported by the radiation field has the same direction as the momentum associated with electrons, whereas the momentum associated with electrons is in opposite direction to the momentum of radiation in negative return strokes. It is shown here that this polarity asymmetry could limit the maximum speed of positive return strokes with respect to the negative return strokes. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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24 pages, 2930 KiB

Open AccessReview

Review of Road Dust Resuspension Modelling Approaches and Comparisons Analysis for a UK Case Study

by Fabio Galatioto, Nicola Masey, Tim Murrells, Scott Hamilton and Matthieu Pommier

Atmosphere 2022, 13(9), 1403; https://doi.org/10.3390/atmos13091403 - 31 Aug 2022

Cited by 6 | Viewed by 2945

Abstract

This report provides a review of several measurement studies and campaigns focusing on road dust resuspension (RDS), which is becoming an important source of ambient particulate matter (PM) concentrations. There is a growing requirement from stakeholders, policy makers and scientists for gathering additional [...] Read more.

This report provides a review of several measurement studies and campaigns focusing on road dust resuspension (RDS), which is becoming an important source of ambient particulate matter (PM) concentrations. There is a growing requirement from stakeholders, policy makers and scientists for gathering additional data around RDS, since there is a lack of well-established methodologies or those developed for measuring or modelling this source of emissions are not very recent. Moreover, conventional inventory methodologies are not available for this source of emissions, and it is not yet covered in the UK’s National Atmospheric Emissions Inventory (NAEI) neither in the inventory guidebooks at European level. Based on the available literature and models, this paper also seeks to provide some preliminary considerations whether an approach can be tailored for application in air quality models used for modelling ambient PM concentrations in the UK in a consistent manner and demonstrated using a state-of-art air quality modelling tool, namely RapidAir^®. The impact of including resuspension emissions on roadside concentrations was modelled in a UK case study with the greatest increases in modelled road PM₁₀ concentrations observed on or near the road surface. The paper concludes with recommendations for longer-term implementation of the proposed improvements such as investigation of the temporal effects of RDS on PM levels; of the influence of different type of tyre materials and mixture (e.g., composition) and designs (e.g., shape, dimensions and tread); and influence of different existing pavements or of new road surface types. Full article

(This article belongs to the Special Issue Feature Papers in Atmosphere Science)

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