Atmosphere

477 KiB

Open AccessArticle

Source Localization in the Duct Environment with the Adjoint of the PE Propagation Model

by Xiaofeng Zhao

Atmosphere 2015, 6(9), 1388-1398; https://doi.org/10.3390/atmos6091388 - 22 Sep 2015

Cited by 3 | Viewed by 4817

Owing to the absorbing, refracting and scattering effects of the propagation medium, electromagnetic (EM) energy will degrade with the increment of propagation range, and the maximum value exists at the point of the radiating source. Employing this phenomenon, this paper introduces a novel [...] Read more.

Owing to the absorbing, refracting and scattering effects of the propagation medium, electromagnetic (EM) energy will degrade with the increment of propagation range, and the maximum value exists at the point of the radiating source. Employing this phenomenon, this paper introduces a novel approach to detect the location of EM transmitters in an atmospheric duct environment. Different from previous matched-field processing (MFP) methods, the proposed method determines the source location through reconstructing the forward propagation field pattern by the backward adjoint integration of the parabolic equation (PE) propagation model. With this method, the repeated computations of PE used in the MFP methods are not needed. The performance of the method is evaluated via numerical simulations, where the influences of the measurement noise and the geometry of the receiver array on the localization results are considered. Full article

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757 KiB

Open AccessArticle

Characteristics of PM_1.0, PM_2.5, and PM₁₀, and Their Relation to Black Carbon in Wuhan, Central China

by Wei Gong, Tianhao Zhang, Zhongmin Zhu, Yingying Ma, Xin Ma and Wei Wang

Atmosphere 2015, 6(9), 1377-1387; https://doi.org/10.3390/atmos6091377 - 22 Sep 2015

Cited by 51 | Viewed by 8856

Abstract

Hourly average monitoring data for mass concentrations of PM₁, PM_2.5, PM₁₀, and black carbon (BC) were measured in Wuhan from December 2013 to December 2014, which has a flourishing steel industry, to analyze the characteristics of PM [...] Read more.

Hourly average monitoring data for mass concentrations of PM₁, PM_2.5, PM₁₀, and black carbon (BC) were measured in Wuhan from December 2013 to December 2014, which has a flourishing steel industry, to analyze the characteristics of PM and their relation to BC, using statistical methods. The results indicate that variations in the monthly average mass concentrations of PM have similar concave parabolic shapes, with the highest values occurring in January and the lowest values appearing in August or September. The correlation coefficient of the linear regression model between PM₁ and PM_2.5 is quite high, reaching 0.99. Furthermore, the proportion of PM₁ contained within PM_2.5 is roughly 90%, directly proving that ultrafine particles whose diameter less than 1 μm may be a primary component of PM_2.5 in Wuhan. Additionally, better seasonal correlation between PM and BC occurs only in summer and autumn, due to multiple factors such as topography, temperature, and the atmosphere in winter and spring. Finally, analysis of the diurnal variation of PM and BC demonstrates that the traffic emissions during rush hour, exogenous pollutants, and the shallow PBLH with stagnant atmosphere, all contribute to the severe pollution of Wuhan in winter. Full article

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374 KiB

Open AccessArticle

An Observational Study of Entrainment Rate in Deep Convection

by Xiaohao Guo, Chunsong Lu, Tianliang Zhao, Guang J. Zhang and Yangang Liu

Atmosphere 2015, 6(9), 1362-1376; https://doi.org/10.3390/atmos6091362 - 22 Sep 2015

Cited by 15 | Viewed by 5443

Abstract

This study estimates entrainment rate and investigates its relationships with cloud properties in 156 deep convective clouds based on in-situ aircraft observations during the TOGA-COARE (Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment) field campaign over the western Pacific. To the authors’ [...] Read more.

This study estimates entrainment rate and investigates its relationships with cloud properties in 156 deep convective clouds based on in-situ aircraft observations during the TOGA-COARE (Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment) field campaign over the western Pacific. To the authors’ knowledge, this is the first study on the probability density function of entrainment rate, the relationships between entrainment rate and cloud microphysics, and the effects of dry air sources on the calculated entrainment rate in deep convection from an observational perspective. Results show that the probability density function of entrainment rate can be well fitted by lognormal, gamma or Weibull distribution, with coefficients of determination being 0.82, 0.85 and 0.80, respectively. Entrainment tends to reduce temperature, water vapor content and moist static energy in cloud due to evaporative cooling and dilution. Inspection of the relationships between entrainment rate and microphysical properties reveals a negative correlation between volume-mean radius and entrainment rate, suggesting the potential dominance of homogeneous mechanism in the clouds examined. In addition, entrainment rate and environmental water vapor content show similar tendencies of variation with the distance of the assumed environmental air to the cloud edges. Their variation tendencies are non-monotonic due to the relatively short distance between adjacent clouds. Full article

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4300 KiB

Open AccessArticle

A Method for Deriving the Boundary Layer Mixing Height from MODIS Atmospheric Profile Data

by Xueliang Feng, Bingfang Wu and Nana Yan

Atmosphere 2015, 6(9), 1346-1361; https://doi.org/10.3390/atmos6091346 - 15 Sep 2015

Cited by 30 | Viewed by 8362

Abstract

The planetary boundary layer is the medium of energy, moisture, momentum and pollutant exchange between the surface and the atmosphere. In this paper, a method to derive the boundary layer mixing height (MH) was introduced and applied over the Heihe river basin. Atmospheric [...] Read more.

The planetary boundary layer is the medium of energy, moisture, momentum and pollutant exchange between the surface and the atmosphere. In this paper, a method to derive the boundary layer mixing height (MH) was introduced and applied over the Heihe river basin. Atmospheric profiles from the MODerate Resolution Imaging Sepctroradiometer (MODIS) instrument onboard the NASA-Aqua satellite were used for the high spatial resolution of this method. A gap-filling method was used to replace missing MODIS data. In situ MH data were also calculated from HIWATER (Heihe Watershed Allied Telemetry Experimental Research) and WATER (Watershed Allied Telemetry Experimental Research) observational radiosonde sounding data from 2008 and 2012 using the Richardson number method combined with a subjective method. The MH occurs where there is an abrupt decrease in the MR (water vapor mixing ratio). The minimum vertical gradient of the MR is used to determine the MH. The method has an average RMSE of 370 m under clear skies and convective conditions. The seasonal variation in the MH at the Gaoya radiosonde station is also presented. The study demonstrates that remote sensing methodologies can successfully estimate the MH without the help of field measurements. Full article

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

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445 KiB

Open AccessReview

An Overview of Particulate Matter Measurement Instruments

by Simone Simões Amaral, João Andrade De Carvalho, Jr., Maria Angélica Martins Costa and Cleverson Pinheiro

Atmosphere 2015, 6(9), 1327-1345; https://doi.org/10.3390/atmos6091327 - 9 Sep 2015

Cited by 145 | Viewed by 29987

Abstract

This review article presents an overview of instruments available on the market for measurement of particulate matter. The main instruments and methods of measuring concentration (gravimetric, optical, and microbalance) and size distribution Scanning Mobility Particle Sizer (SMPS), Electrical Low Pressure Impactor (ELPI), and [...] Read more.

This review article presents an overview of instruments available on the market for measurement of particulate matter. The main instruments and methods of measuring concentration (gravimetric, optical, and microbalance) and size distribution Scanning Mobility Particle Sizer (SMPS), Electrical Low Pressure Impactor (ELPI), and others were described and compared. The aim of this work was to help researchers choose the most suitable equipment to measure particulate matter. When choosing a measuring instrument, a researcher must clearly define the purpose of the study and determine whether it meets the main specifications of the equipment. ELPI and SMPS are the suitable devices for measuring fine particles; the ELPI works in real time. In health-related studies, a Diffusion Charger is the instrument that best characterizes the surface of ultrafine particles. Several methods and different particle measuring instruments should be used to confirm the values obtained during sampling. Full article

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

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2218 KiB

Open AccessArticle

Spatiotemporal Interpolation of Rainfall by Combining BME Theory and Satellite Rainfall Estimates

by Tingting Shi, Xiaomei Yang, George Christakos, Jinfeng Wang and Li Liu

Atmosphere 2015, 6(9), 1307-1326; https://doi.org/10.3390/atmos6091307 - 7 Sep 2015

Cited by 20 | Viewed by 6710

Abstract

The accurate assessment of spatiotemporal rainfall variability is a crucial and challenging task in many hydrological applications, mainly due to the lack of a sufficient number of rain gauges. The purpose of the present study is to investigate the spatiotemporal variations of annual [...] Read more.

The accurate assessment of spatiotemporal rainfall variability is a crucial and challenging task in many hydrological applications, mainly due to the lack of a sufficient number of rain gauges. The purpose of the present study is to investigate the spatiotemporal variations of annual and monthly rainfall over Fujian province in China by combining the Bayesian maximum entropy (BME) method and satellite rainfall estimates. Specifically, based on annual and monthly rainfall data at 20 meteorological stations from 2000 to 2012, (1) the BME method with Tropical Rainfall Measuring Mission (TRMM) estimates considered as soft data, (2) ordinary kriging (OK) and (3) cokriging (CK) were employed to model the spatiotemporal variations of rainfall in Fujian province. Subsequently, the performance of these methods was evaluated using cross-validation statistics. The results demonstrated that BME with TRMM as soft data (BME-TRMM) performed better than the other two methods, generating rainfall maps that represented the local rainfall disparities in a more realistic manner. Of the three interpolation (mapping) methods, the mean absolute error (MAE) and root mean square error (RMSE) values of the BME-TRMM method were the smallest. In conclusion, the BME-TRMM method improved spatiotemporal rainfall modeling and mapping by integrating hard data and soft information. Lastly, the study identified new opportunities concerning the application of TRMM rainfall estimates. Full article

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5884 KiB

Open AccessArticle

Effects of Stratospheric Conditions on the Viability, Metabolism and Proteome of Prokaryotic Cells

by Dagmar Chudobova, Kristyna Cihalova, Pavlina Jelinkova, Jan Zitka, Lukas Nejdl, Roman Guran, Martin Klimanek, Vojtech Adam and Rene Kizek

Atmosphere 2015, 6(9), 1290-1306; https://doi.org/10.3390/atmos6091290 - 28 Aug 2015

Cited by 18 | Viewed by 5909

Abstract

The application of ultraviolet (UV) radiation to inhibit bacterial growth is based on the principle that the exposure of DNA to UV radiation results in the formation of cytotoxic lesions, leading to inactivation of microorganisms. Herein, we present the impacts of UV radiation [...] Read more.

The application of ultraviolet (UV) radiation to inhibit bacterial growth is based on the principle that the exposure of DNA to UV radiation results in the formation of cytotoxic lesions, leading to inactivation of microorganisms. Herein, we present the impacts of UV radiation on bacterial cultures’ properties from the biological, biochemical and molecular biological perspective. For experiments, commercial bacterial cultures (Staphylococcus aureus, methicillin-resistant Staphylococcus aureus, Escherichia coli and Salmonella typhimurium) and isolates from patients with bacterial infections (Proteus mirabilis and Pseudomonas aeruginosa) were employed. The above-mentioned strains were exposed to UV using a laboratory source and to stratospheric UV using a 3D printed probe carried by a stratospheric balloon. The length of flight was approximately two hours, and the probe was enriched by sensors for the external environment (temperature, pressure and relative humidity). After the landing, bacterial cultures were cultivated immediately. Experimental results showed a significant effect of UV radiation (both laboratory UV and UV from the stratosphere) on the growth, reproduction, behavior and structure of bacterial cultures. In all parts of the experiment, UV from the stratosphere showed stronger effects when compared to the effects of laboratory UV. The growth of bacteria was inhibited by more than 50% in all cases; moreover, in the case of P. aeruginosa, the growth was even totally inhibited. Due to the effect of UV radiation, an increased susceptibility of bacterial strains to environmental influences was also observed. By using commercial tests for biochemical markers of Gram-positive and Gram-negative strains, significant disparities in exposed and non-exposed strains were found. Protein patterns obtained using MALDI-TOF mass spectrometry revealed that UV exposure is able to affect the proteins’ expression, leading to their downregulation, observed as the disappearance of their peaks from the mass spectrum. Full article

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1878 KiB

Open AccessArticle

Characteristics of Gravity Waves over an Antarctic Ice Sheet during an Austral Summer

by Daniela Cava, Umberto Giostra and Gabriel Katul

Atmosphere 2015, 6(9), 1271-1289; https://doi.org/10.3390/atmos6091271 - 25 Aug 2015

Cited by 22 | Viewed by 5258

Abstract

While occurrences of wavelike motion in the stable boundary layer due to the presence of a significant restoring buoyancy force are rarely disputed, their modalities and interaction with turbulence remain a subject of active research. In this work, the characteristics of gravity waves [...] Read more.

While occurrences of wavelike motion in the stable boundary layer due to the presence of a significant restoring buoyancy force are rarely disputed, their modalities and interaction with turbulence remain a subject of active research. In this work, the characteristics of gravity waves and their impact on flow statistics, including turbulent fluxes, are presented using data collected above an Antarctic Ice sheet during an Austral Summer. Antarctica is an ideal location for exploring the characteristics of gravity waves because of persistent conditions of strong atmospheric stability in the lower troposphere. Periods dominated by wavelike motion have been identified by analysing time series measured by fast response instrumentation. The nature and characteristic of the dominant wavy motions are investigated using Fourier cross-spectral indicators. Moreover, a multi-resolution decomposition has been applied to separate gravity waves from turbulent fluctuations in case of a sufficiently defined spectral gap. Statistics computed after removing wavy disturbances highlight the large impact of gravity waves on second order turbulent quantities including turbulent flux calculations. Full article

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

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551 KiB

Open AccessArticle

Analysis of PAHs Associated with Particulate Matter PM_2.5 in Two Places at the City of Cuernavaca, Morelos, México

by Hugo Saldarriaga-Noreña, Rebecca López-Márquez, Mario Murillo-Tovar, Leonel Hernández-Mena, Efrén Ospina-Noreña, Enrique Sánchez-Salinas, Stefan Waliszewski and Silvia Montiel-Palma

Atmosphere 2015, 6(9), 1259-1270; https://doi.org/10.3390/atmos6091259 - 25 Aug 2015

Cited by 16 | Viewed by 5269

Abstract

This study was carried out between January and February 2013, at two sites in the city of Cuernavaca, México, using low-volume equipment. Fifteen Polycyclic aromatic hydrocarbons (PAHs), were identified by gas chromatography coupled with mass spectrometry. The total average concentration observed for PAHs [...] Read more.

This study was carried out between January and February 2013, at two sites in the city of Cuernavaca, México, using low-volume equipment. Fifteen Polycyclic aromatic hydrocarbons (PAHs), were identified by gas chromatography coupled with mass spectrometry. The total average concentration observed for PAHs was 24.0 ng·m⁻³, with the high molecular weight compounds being the most abundant. The estimated equivalent concentration for Benzo (a) P (BaPE) was 4.05 ng·m⁻³. Diagnostic ratios together with the principal components analysis (PCA) allowed for establishing coal burning and vehicle emissions as being the main sources of these compounds in the area. The PAHs used to calculate this index account for 51% of the 15 PAHs identified, which probably involves a risk to the exposed population. Full article

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

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Atmosphere, Volume 6, Issue 9 (September 2015) – 9 articles , Pages 1259-1398

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