Atmosphere

1862 KiB

Open AccessArticle

Air Quality of Beijing and Impacts of the New Ambient Air Quality Standard

by Wei Chen, Fusheng Wang, Guofeng Xiao, Kai Wu and Shixuan Zhang

Atmosphere 2015, 6(8), 1243-1258; https://doi.org/10.3390/atmos6081243 - 20 Aug 2015

Cited by 41 | Viewed by 9909

Beijing has been publishing daily reports on its air quality since 2000, and while the air pollution index (API) shows that the air quality has improved greatly since 2000, this is not the perception of Beijing’s residents. The new national ambient air quality [...] Read more.

Beijing has been publishing daily reports on its air quality since 2000, and while the air pollution index (API) shows that the air quality has improved greatly since 2000, this is not the perception of Beijing’s residents. The new national ambient air quality standard (NAAQS-2012), which includes the monitoring of PM_2.5, has posed stricter standards for evaluating air quality. With the new national standard, the air quality in Beijing is calculated using both NAAQS-2012 and the previous standard. The annual attainment rate has dropped from 75.5% to 50.7%. The spatial analysis of air quality shows that only a background station could attain the national standard, while urban and suburban stations exceed the national standard. Among the six pollutants included in the NAAQS-2012, PM_2.5 is the major contributor to the air quality index (AQI) comparing with the five other pollutants. The results indicate that under previous NAAQS without PM_2.5 monitoring, the air quality has improved greatly in the past decade. By considering PM_2.5, the air quality attainment has dropped greatly. Furthermore, a great effort is needed for local government to bring down the PM_2.5 concentration. Full article

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1449 KiB

Open AccessArticle

Spatial and Temporal Analysis of Organic and Black Carbon Mass Concentrations in Lithuania

by Julija Pauraitė, Genrik Mordas, Steigvilė Byčenkienė and Vidmantas Ulevicius

Atmosphere 2015, 6(8), 1229-1242; https://doi.org/10.3390/atmos6081229 - 19 Aug 2015

Cited by 21 | Viewed by 5762

Abstract

Both organic carbon (OC) and black carbon (BC) mass concentrations were measured in Lithuania at coastal/marine (Preila), rural (Rūgšteliškis), and urban background (Vilnius) environments have been analyzed to infer the spatial and temporal distributions of the OC/BC ratios from May 2013 to October [...] Read more.

Both organic carbon (OC) and black carbon (BC) mass concentrations were measured in Lithuania at coastal/marine (Preila), rural (Rūgšteliškis), and urban background (Vilnius) environments have been analyzed to infer the spatial and temporal distributions of the OC/BC ratios from May 2013 to October 2014. OC/BC ratios reflected the location of the different sites, as well as possible different sources influencing air quality. The results from an industrialized and populated urban background area indicated that biomass combustion for heating contributed to BC and OC mass concentration. Typically, BC mean concentrations (±st.deviation) were higher in urban areas (1.72(±1.22 μg·m⁻³)) than in rural (0.40(±0.35 μg·m⁻³)) and coastal/marine (0.53(±0.43 μg·m⁻³)) during warm and cold (2.34(±2.15); 0.77(±0.52) and 0.84(±0.50) μg·m⁻³, respectively) periods, while OC concentrations were higher in urban backgrounds (5.91(±1.99 μg·m⁻³)) and rural areas (4.56(±3.98 μg·m⁻³)) during warm periods. The air mass backward trajectory analysis indicated influence of local sources in urban environment and strong influence of long-range transport in rural environment. A clear seasonal dependence of OC/BC ratios was observed at rural and urban environments. The highest OC/BC ratios were calculated in coastal/marine (6.3) and rural (9.5) environments in summer. Full article

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995 KiB

Open AccessArticle

UV Irradiance Enhancements by Scattering of Solar Radiation from Clouds

by Uwe Feister, Nathalie Cabrol and Donat Häder

Atmosphere 2015, 6(8), 1211-1228; https://doi.org/10.3390/atmos6081211 - 18 Aug 2015

Cited by 41 | Viewed by 10827

Abstract

Scattering of solar radiation by clouds can reduce or enhance solar global irradiance compared to cloudless-sky irradiance at the Earth’s surface. Cloud effects to global irradiance can be described by Cloud Modification Factors (CMF). Depending on strength and duration, irradiance enhancements affect the [...] Read more.

Scattering of solar radiation by clouds can reduce or enhance solar global irradiance compared to cloudless-sky irradiance at the Earth’s surface. Cloud effects to global irradiance can be described by Cloud Modification Factors (CMF). Depending on strength and duration, irradiance enhancements affect the energy balance of the surface and gain of solar power for electric energy generation. In the ultraviolet region, they increase the risk for damage to living organisms. Wavelength-dependent CMFs have been shown to reach 1.5 even in the UV-B region at low altitudes. Ground-based solar radiation measurements in the high Andes region at altitudes up to 5917 m a.s.l showed cloud-induced irradiance enhancements. While UV-A enhancements were explained by cloud scattering, both radiation scattering from clouds and Negative Ozone Anomalies (NOA) have been discussed to have caused short-time enhancement of UV-B irradiance. Based on scenarios using published CMF and additional spectroradiometric measurements at a low-altitude site, the contribution of cloud scattering to the UV-B irradiance enhancement in the Andes region has been estimated. The range of UV index estimates converted from measured UV-B and UV-A irradiance and modeled cloudless-sky ratios UV-B/erythemal UV is compatible with an earlier estimate of an extreme UV index value of 43 derived for the high Andes. Full article

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5310 KiB

Open AccessArticle

Characteristics of PM₁₀ and PM_2.5 at Mount Wutai Buddhism Scenic Spot, Shanxi, China

by Zhihui Wu, Fenwu Liu and Wenhua Fan

Atmosphere 2015, 6(8), 1195-1210; https://doi.org/10.3390/atmos6081195 - 18 Aug 2015

Cited by 16 | Viewed by 9211

Abstract

A survey was conducted to effectively investigate the characteristics of airborne particulate pollutants PM₁₀ and PM_2.5during the peak tourist season at Mount Wutai Buddhism scenic spot, Shanxi, China. Characteristics of the PM₁₀ and PM_2.5 in Wu Ye Temple [...] Read more.

A survey was conducted to effectively investigate the characteristics of airborne particulate pollutants PM₁₀ and PM_2.5during the peak tourist season at Mount Wutai Buddhism scenic spot, Shanxi, China. Characteristics of the PM₁₀ and PM_2.5 in Wu Ye Temple (core incense burners), Manjusri Temple (a traffic hub), Yang Bai Lin Village (a residential district), and Nan Shan Temple (located in a primitive forest district), were determined. The results showed that the PM₁₀ concentration was more than 1.01–1.14 times higher than the threshold (50 μg/m³) of World Health Organization Air Quality Guidelines (2005), and the PM_2.5 concentration was 1.75–2.70 times higher than the above standard (25 μg/m³). Particle size analysis indicated that the distribution of fine particulate matter in Wu Ye Temple ranged from 0 to 3.30 μm. In other sampling points, the fine particulate was mainly distributed in the range of 0–5.90 μm. The particulates in Wu Ye Temple were mainly characterized by spherical, rod-like, and irregular soot aggregates (PM₁₀) and spherical particles of dust (PM_2.5). Manjusri Temple and Yang Bai Lin Village predominantly exhibited irregular soil mineral particulate matter (PM₁₀), and amorphous ultrafine soot particulate matter (PM_2.5). Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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3195 KiB

Open AccessArticle

Study of Black Sand Particles from Sand Dunes in Badr, Saudi Arabia Using Electron Microscopy

by Haider Abbas Khwaja, Omar Siraj Aburizaiza, Daniel L. Hershey, Azhar Siddique, David A. Guerrieri P. E., Jahan Zeb, Mohammad Abbass, Donald R. Blake, Mirza Mozammel Hussain, Abdullah Jameel Aburiziza, Malissa A. Kramer and Isobel J. Simpson

Atmosphere 2015, 6(8), 1175-1194; https://doi.org/10.3390/atmos6081175 - 17 Aug 2015

Cited by 4 | Viewed by 11647

Abstract

Particulate air pollution is a health concern. This study determines the microscopic make-up of different varieties of sand particles collected at a sand dune site in Badr, Saudi Arabia in 2012. Three categories of sand were studied: black sand, white sand, and volcanic [...] Read more.

Particulate air pollution is a health concern. This study determines the microscopic make-up of different varieties of sand particles collected at a sand dune site in Badr, Saudi Arabia in 2012. Three categories of sand were studied: black sand, white sand, and volcanic sand. The study used multiple high resolution electron microscopies to study the morphologies, emission source types, size, and elemental composition of the particles, and to evaluate the presence of surface “coatings or contaminants” deposited or transported by the black sand particles. White sand was comprised of natural coarse particles linked to wind-blown releases from crustal surfaces, weathering of igneous/metamorphic rock sources, and volcanic activities. Black sand particles exhibited different morphologies and microstructures (surface roughness) compared with the white sand and volcanic sand. Morphological Scanning Electron Microscopy (SEM) and Laser Scanning Microscopy (LSM) analyses revealed that the black sand contained fine and ultrafine particles (50 to 500 nm ranges) and was strongly magnetic, indicating the mineral magnetite or elemental iron. Aqueous extracts of black sands were acidic (pH = 5.0). Fe, C, O, Ti, Si, V, and S dominated the composition of black sand. Results suggest that carbon and other contaminant fine particles were produced by fossil-fuel combustion and industrial emissions in heavily industrialized areas of Haifa and Yanbu, and transported as cloud condensation nuclei to Douf Mountain. The suite of techniques used in this study has yielded an in-depth characterization of sand particles. Such information will be needed in future environmental, toxicological, epidemiological, and source apportionment studies. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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713 KiB

Open AccessArticle

The Impact of Selected Parameters on Visibility: First Results from a Long-Term Campaign in Warsaw, Poland

by Grzegorz Majewski, Wioletta Rogula-Kozłowska, Piotr O. Czechowski, Artur Badyda and Andrzej Brandyk

Atmosphere 2015, 6(8), 1154-1174; https://doi.org/10.3390/atmos6081154 - 12 Aug 2015

Cited by 35 | Viewed by 8073

Abstract

The aim of this study was to investigate how atmospheric air pollutants and meteorological conditions affected atmospheric visibility in the largest Polish agglomeration. The correlation analysis, principal component analysis (PCA) and generalized regression models (GRMs) were used to accomplish this objective. The meteorological [...] Read more.

The aim of this study was to investigate how atmospheric air pollutants and meteorological conditions affected atmospheric visibility in the largest Polish agglomeration. The correlation analysis, principal component analysis (PCA) and generalized regression models (GRMs) were used to accomplish this objective. The meteorological parameters (temperature, relative humidity, precipitation, wind speed and insolation) and concentrations of the air pollutants (PM₁₀, SO₂, NO₂, CO and O₃) were recorded in 2004–2013. The data came from the Ursynów-SGGW, MzWarszUrsynów and Okęcie monitoring stations, located in the south of Warsaw (Poland). It was shown that the PM₁₀ concentration was the most important parameter affecting the visibility in Warsaw. The concentration, and indirectly the visibility, was mainly affected by the pollutant emission from the flat/building heating (combustion of various fuels). It changed intensively during the research period. There were also periods in which this emission type did not have a great influence on the pollutant concentrations (mainly PM₁₀) and visibility. In such seasons, the research revealed the influence of the traffic emission and secondary aerosol formation processes on the visibility. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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545 KiB

Open AccessArticle

A Case Study of Chemical Characteristics of Daytime and Nighttime Ambient Particles in Shanghai, China

by Chongshu Zhu, Junji Cao, Jiamao Zhou, Suixin Liu, Wenting Dai, Ting Zhang, Zhuzi Zhao, Zhenxing Shen, Hua Li and Ping Wang

Atmosphere 2015, 6(8), 1141-1153; https://doi.org/10.3390/atmos6081141 - 7 Aug 2015

Cited by 10 | Viewed by 5432

Abstract

Ambient daytime and nighttime PM_2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) and TSP (the total suspended particulates) samples were collected at two sites (named Pudong and Jinshan) in Shanghai. The concentrations of PM_2.5 and TSP were lower at [...] Read more.

Ambient daytime and nighttime PM_2.5 (particulate matter with aerodynamic diameter less than 2.5 μm) and TSP (the total suspended particulates) samples were collected at two sites (named Pudong and Jinshan) in Shanghai. The concentrations of PM_2.5 and TSP were lower at Pudong than at Jinshan. Higher PM_2.5 and TSP concentrations were observed during daytime than nighttime for both sites. Carbonaceous aerosol and secondary sulfate were the most abundant components. Larger enrichment factor (EFs) of Zn, Pb, Cl, and S for Jinshan nighttime were observed than for other sampling periods. PM_2.5 showed higher relative spatial uniformity (the coefficients of divergence, COD = 0.18) than TSP (COD = 0.23) during the sampling period. The variations of chemical components and the species ratios showed that the contributions of primary particulate emissions in Jinshan (industrial zone) were more significant than in Pudong (residential zone). Full article

(This article belongs to the Special Issue Sources, Formation and Impacts of Secondary Aerosol)

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848 KiB

Open AccessArticle

Mie LIDAR Observations of Tropospheric Aerosol over Wuhan

by Wei Gong, Boming Liu, Yingying Ma and Miao Zhang

Atmosphere 2015, 6(8), 1129-1140; https://doi.org/10.3390/atmos6081129 - 7 Aug 2015

Cited by 17 | Viewed by 5756

Abstract

Wuhan is a rapidly developing large city in central China. To analyze the aerosol characteristics over Wuhan, the optical properties of the nocturnal aerosol layers in the lower troposphere were observed using a ground-based LIDAR(Light Detection And Ranging) located in the Laboratory of [...] Read more.

Wuhan is a rapidly developing large city in central China. To analyze the aerosol characteristics over Wuhan, the optical properties of the nocturnal aerosol layers in the lower troposphere were observed using a ground-based LIDAR(Light Detection And Ranging) located in the Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing (LIESMARS) from Wuhan University, China (114°21′E, 30°32′N) in January 2013–January 2015. The vertical distribution and temporal variation of tropospheric aerosols over Wuhan were summarized. The atmospheric boundary layer height (ABLH) was mainly at an altitude of 1.5–2 km (~33.1% probability), with an annual average of 1.66 km. The ABLH was higher in spring–summer (~2 km) and lower in autumn–winter (~1.2 km). The aerosol optical depth (AOD) was higher in spring–autumn than in summer–winter. The highest AOD was about 0.79 in October and the lowest was about 0.08 in January. The annual average was about 0.3. To study the relationship between the AOD and the particulate matter ≤2.5 µm in the aerodynamic diameter (PM_2.5) in the lower troposphere, a typical haze event from 9–14 October 2014 was investigated. The results showed a correlation coefficient of 0.5165 between these two variables. Full article

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1999 KiB

Open AccessArticle

Effect of the Standard Nomenclature for Air Pollution (SNAP) Categories on Air Quality over Europe

by Efthimios Tagaris, Rafaella Eleni P. Sotiropoulou, Nikos Gounaris, Spyros Andronopoulos and Diamando Vlachogiannis

Atmosphere 2015, 6(8), 1119-1128; https://doi.org/10.3390/atmos6081119 - 31 Jul 2015

Cited by 20 | Viewed by 6149

Abstract

The contribution of different anthropogenic source-sectors on ozone mixing ratios and PM_2.5 concentrations over Europe is assessed for a summer month (July 2006) using the US Environmental Protection Agency’s (EPA’s) Models-3 framework and the Netherlands Organization for Applied Scientific Research (TNO) anthropogenic [...] Read more.

The contribution of different anthropogenic source-sectors on ozone mixing ratios and PM_2.5 concentrations over Europe is assessed for a summer month (July 2006) using the US Environmental Protection Agency’s (EPA’s) Models-3 framework and the Netherlands Organization for Applied Scientific Research (TNO) anthropogenic emissions for 2006. Anthropogenic emission sources have been classified into 10 different Standard Nomenclature for Air Pollution (SNAP) categories. The road transport category, which is mainly responsible for NO_X emissions, is estimated to have the major impact on Max8hrO₃ mixing ratio suggesting an increase of 6.8% on average over Europe, while locally it is more than 20%. Power generation category is estimated to have the major impact on PM_2.5 concentrations since it is the major source of SO₂ emissions, suggesting an increase of 22.9% on average over Europe, while locally it is more than 60%. Agriculture category is also contributing significantly on PM_2.5 concentrations, since agricultural activities are the major source of NH₃ emissions, suggesting an increased by 16.1% on average over Europe, while in regions with elevated NH₃ emissions the increase is up to 40%. Full article

(This article belongs to the Special Issue Indoor and Outdoor Air Quality)

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2929 KiB

Open AccessArticle

Assessing the Correlation between Land Cover Conversion and Temporal Climate Change—A Pilot Study in Coastal Mediterranean City, Fethiye, Turkey

by İsmail Cinar

Atmosphere 2015, 6(8), 1102-1118; https://doi.org/10.3390/atmos6081102 - 31 Jul 2015

Cited by 15 | Viewed by 6662

Abstract

The rapid growth and expansion of urbanized landscapes in cities has resulted in an increase in air temperature and has lowered the bioclimatic comfort levels in urban landscapes. Recent studies to estimate the climatic response of urban landscape conversion have mostly examined the [...] Read more.

The rapid growth and expansion of urbanized landscapes in cities has resulted in an increase in air temperature and has lowered the bioclimatic comfort levels in urban landscapes. Recent studies to estimate the climatic response of urban landscape conversion have mostly examined the relationship between land use/land cover (LULC) change and land surface temperature (LST) data collected using advanced remote sensing (RS) techniques instead of atmospheric temperature. In this respect, four decadal Landsat images from the 1980s were used to investigate the impact of landscape transformation on atmospheric temperature. The mean and average minimum and maximum monthly air temperature datasets were used in the analysis. The CORINE (Coordination of Information on Environment) index was used to determine LULC diversity in an urban development boundary and urban periphery. Consequently, clustered LULC change values for the last three decades were integrated with decadal air temperature anomalies. The findings revealed an important relationship between monthly mean air temperature and land changes over recent decades, which resulted in an increase in urban fabric land use, deforestation land cover changes and conversion of permanent crop fields to artificial green houses for earlier vegetable production; the R-sqr values for these regressions were 97.7%, 88.5% and 90.6% respectively. On the other hand, the most important increasing temperature trends were obtained for the average monthly minimum air temperature, which supports the global warming concerns of the IPCC (Intergovernmental Panel on Climate Change) and related studies, which have concluded that an increased nighttime temperature results in urban heat islands (UHIs). The results should be used to support better urban landscape plans and architectural designs to improve human thermal comfort for sustainable urban life in Mediterranean cities. Street geometry and orientation to wind breeze, the Height/Width H/W ratio of buildings, and sizes of open and green spaces should be examined carefully in urban planning and design for climate adaptation. Full article

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2362 KiB

Open AccessArticle

Airborne Aerosol in Situ Measurements during TCAP: A Closure Study of Total Scattering

by Evgueni Kassianov, Larry K. Berg, Mikhail Pekour, James Barnard, Duli Chand, Connor Flynn, Mikhail Ovchinnikov, Arthur Sedlacek, Beat Schmid, John Shilling, Jason Tomlinson and Jerome Fast

Atmosphere 2015, 6(8), 1069-1101; https://doi.org/10.3390/atmos6081069 - 31 Jul 2015

Cited by 15 | Viewed by 8037

Abstract

We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and [...] Read more.

We present a framework for calculating the total scattering of both non-absorbing and absorbing aerosol at ambient conditions from aircraft data. Our framework is developed emphasizing the explicit use of chemical composition data for estimating the complex refractive index (RI) of particles, and thus obtaining improved ambient size spectra derived from Optical Particle Counter (OPC) measurements. The feasibility of our framework for improved calculations of total scattering is demonstrated using three types of data collected by the U.S. Department of Energy’s (DOE) aircraft during the Two-Column Aerosol Project (TCAP). Namely, these data types are: (1) size distributions measured by a suite of OPC’s; (2) chemical composition data measured by an Aerosol Mass Spectrometer and a Single Particle Soot Photometer; and (3) the dry total scattering coefficient measured by a integrating nephelometer and scattering enhancement factor measured with a humidification system. We demonstrate that good agreement (~10%) between the observed and calculated scattering can be obtained under ambient conditions (RH < 80%) by applying chemical composition data for the RI-based correction of the OPC-derived size spectra. We also demonstrate that ignoring the RI-based correction or using non-representative RI values can cause a substantial underestimation (~40%) or overestimation (~35%) of the calculated scattering, respectively. Full article

(This article belongs to the Special Issue Atmospheric Composition Observations)

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10463 KiB

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The Role of Aerosol-Cloud-Radiation Interactions in Regional Air Quality—A NU-WRF Study over the United States

by Zhining Tao, Hongbin Yu and Mian Chin

Atmosphere 2015, 6(8), 1045-1068; https://doi.org/10.3390/atmos6081045 - 30 Jul 2015

Cited by 13 | Viewed by 6930

Abstract

This work assessed the impact of aerosol-cloud-radiation (ACR) interactions on U.S. regional ozone and PM2.5 using the NASA Unified Weather Research and Forecasting modeling system. A series of three-month simulations have been carried out for the year 2010, in which the factor separation [...] Read more.

This work assessed the impact of aerosol-cloud-radiation (ACR) interactions on U.S. regional ozone and PM2.5 using the NASA Unified Weather Research and Forecasting modeling system. A series of three-month simulations have been carried out for the year 2010, in which the factor separation method has been applied in order to isolate the contributions from aerosol-radiation (AR), aerosol-cloud (AC), and their synergistic effects. The overall ACR effects were to reduce the average cloud liquid water path by 25 g·m⁻² (ca. 40% of the baseline) and to increase the downward shortwave radiation by 8 W·m⁻² (ca. 3% of the baseline). The spatial difference in response to ACR was large, with ca. 50 W·m⁻², 1 K, and 100 m increases in downward shortwave radiation, surface temperature, and planetary boundary layer height (PBLH), respectively, while ca. 60 g·m⁻² decrease in cloud liquid water path in central Texas. The AC effect dominated for changes in downward shortwave radiation, cloud liquid water path, wind, and temperature, while both AC and AR effects contributed profoundly to PBLH change. As a result, surface ozone and PM2.5 changed with large temporal-spatial variations. More than a 10 ppbv of surface ozone and a 5 μg·m⁻³ of PM2.5 difference induced by ACR occurred frequently in the eastern U.S. Full article

(This article belongs to the Special Issue Climate-Chemistry Interactions)

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904 KiB

Open AccessLetter

Scaling Flux Tower Observations of Sensible Heat Flux Using Weighted Area-to-Area Regression Kriging

by Maogui Hu, Jianghao Wang, Yong Ge, Mengxiao Liu, Shaomin Liu, Ziwei Xu and Tongren Xu

Atmosphere 2015, 6(8), 1032-1044; https://doi.org/10.3390/atmos6081032 - 24 Jul 2015

Cited by 17 | Viewed by 5514

Abstract

Sensible heat flux (H) plays an important role in characterizations of land surface water and heat balance. There are various types of H measurement methods that depend on observation scale, from local-area-scale eddy covariance (EC) to regional-scale large aperture scintillometer (LAS) and remote [...] Read more.

Sensible heat flux (H) plays an important role in characterizations of land surface water and heat balance. There are various types of H measurement methods that depend on observation scale, from local-area-scale eddy covariance (EC) to regional-scale large aperture scintillometer (LAS) and remote sensing (RS) products. However, methods of converting one H scale to another to validate RS products are still open for question. A previous area-to-area regression kriging-based scaling method performed well in converting EC-scale H to LAS-scale H. However, the method does not consider the path-weighting function in the EC- to LAS-scale kriging with the regression residue, which inevitably brought about a bias estimation. In this study, a weighted area-to-area regression kriging (WATA RK) model is proposed to convert EC-scale H to LAS-scale H. It involves path-weighting functions of EC and LAS source areas in both regression and area kriging stages. Results show that WATA RK outperforms traditional methods in most cases, improving estimation accuracy. The method is considered to provide an efficient validation of RS H flux products. Full article

(This article belongs to the Special Issue Land-Atmosphere Interaction in Micrometeorology and Pollution Dispersal)

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3324 KiB

Open AccessArticle

Cluster Analysis of the Wind Events and Seasonal Wind Circulation Patterns in the Mexico City Region

by Susana Carreón-Sierra, Alejandro Salcido, Telma Castro and Ana-Teresa Celada-Murillo

Atmosphere 2015, 6(8), 1006-1031; https://doi.org/10.3390/atmos6081006 - 24 Jul 2015

Cited by 25 | Viewed by 7266

Abstract

The residents of Mexico City face serious problems of air pollution. Identifying the most representative scenarios for the transport and dispersion of air pollutants requires the knowledge of the main wind circulation patterns. In this paper, a simple method to recognize and characterize [...] Read more.

The residents of Mexico City face serious problems of air pollution. Identifying the most representative scenarios for the transport and dispersion of air pollutants requires the knowledge of the main wind circulation patterns. In this paper, a simple method to recognize and characterize the wind circulation patterns in a given region is proposed and applied to the Mexico City winds (2001–2006). This method uses a lattice wind approach to model the local wind events at the meso-β scale, and hierarchical cluster analysis to recognize their agglomerations in their phase space. Data of the meteorological network of Mexico City was used as input for the lattice wind model. The Ward’s clustering algorithm with Euclidean distance was applied to organize the model wind events in seasonal clusters for each year of the period. Comparison of the hourly population trends of these clusters permitted the recognition and detailed description of seven circulation patterns. These patterns resemble the qualitative descriptions of the Mexico City wind circulation modes reported by other authors. Our method, however, permitted also their quantitative characterization in terms of the wind attributes of velocity, divergence and vorticity, and an estimation of their seasonal and annual occurrence probabilities, which never before were quantified. Full article

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3913 KiB

Open AccessArticle

Topography and Data Mining Based Methods for Improving Satellite Precipitation in Mountainous Areas of China

by Ting Xia, Zhong-Jing Wang and Hang Zheng

Atmosphere 2015, 6(8), 983-1005; https://doi.org/10.3390/atmos6080983 - 24 Jul 2015

Cited by 23 | Viewed by 6208

Abstract

Topography is a significant factor influencing the spatial distribution of precipitation. This study developed a new methodology to evaluate and calibrate the Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis (TMPA) products by merging geographic and topographic information. In the proposed method, firstly, the [...] Read more.

Topography is a significant factor influencing the spatial distribution of precipitation. This study developed a new methodology to evaluate and calibrate the Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis (TMPA) products by merging geographic and topographic information. In the proposed method, firstly, the consistency rule was introduced to evaluate the fitness of satellite rainfall with measurements on the grids with and without ground gauges. Secondly, in order to improve the consistency rate of satellite rainfall, genetic programming was introduced to mine the relationship between the gauge rainfall and location, elevation and TMPA rainfall. The proof experiment and analysis for the mean annual satellite precipitation from 2001–2012, 3B43 (V7) of TMPA rainfall product, was carried out in eight mountainous areas of China. The result shows that the proposed method is significant and efficient both for the assessment and improvement of satellite precipitation. It is found that the satellite rainfall consistency rates in the gauged and ungauged grids are different in the study area. In addition, the mined correlation of location-elevation-TMPA rainfall can noticeably improve the satellite precipitation, both in the context of the new criterion of the consistency rate and the existing criteria such as Bias and RMSD. The proposed method is also efficient for correcting the monthly and mean monthly rainfall of 3B43 and 3B42RT. Full article

(This article belongs to the Special Issue Climate Variable Forecasting)

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3113 KiB

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Assessment of Community Exposure to Ambient Respirable Crystalline Silica near Frac Sand Processing Facilities

by John Richards and Todd Brozell

Atmosphere 2015, 6(8), 960-982; https://doi.org/10.3390/atmos6080960 - 24 Jul 2015

Cited by 10 | Viewed by 8221

Abstract

Due the rapid expansion of frac sand production, local residents, community leaders, and state regulatory authorities have expressed concerns regarding the lack of ambient respirable crystalline silica concentration data for areas near to these facilities. Long-term average data are needed to compare the [...] Read more.

Due the rapid expansion of frac sand production, local residents, community leaders, and state regulatory authorities have expressed concerns regarding the lack of ambient respirable crystalline silica concentration data for areas near to these facilities. Long-term average data are needed to compare the fence line concentrations against chronic reference exposure guidelines such as the one adopted by the California Office of Environmental Health Hazard Assessment (OEHHA). This paper provides comprehensive sets of 24 h respirable crystalline silica concentration measurements compiled during multi-year sampling programs at the fence lines of four Wisconsin facilities—three frac sand mines and one frac sand processing plant. The authors adapted Environmental Protection Agency (EPA) reference method PM2.5 filter-based samplers to provide respirable (PM4) filter samples. Crystalline silica content of the PM4 particulate matter samples was measured using National Institute of Occupational Safety and Health (NIOSH) Method 7500 X-ray diffraction. The respirable crystalline silica limit of quantification was 0.31 µg/m³. The geometric mean (GM) respirable crystalline silica concentrations at the fence lines of the frac sand-producing facilities were less than 10% of the 3.0 µg/m³ California OEHHA chronic exposure level and were consistent with background concentrations throughout the upper Midwest of the U.S. Full article

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Atmosphere, Volume 6, Issue 8 (August 2015) – 16 articles , Pages 960-1258

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