Editor’s Choice Articles

Editor’s Choice articles are based on recommendations by the scientific editors of MDPI journals from around the world. Editors select a small number of articles recently published in the journal that they believe will be particularly interesting to readers, or important in the respective research area. The aim is to provide a snapshot of some of the most exciting work published in the various research areas of the journal.

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Article

13 pages, 7074 KiB  
Article
Analysis of Ionospheric Perturbations Possibly Related to Yangbi Ms6.4 and Maduo Ms7.4 Earthquakes on 21 May 2021 in China Using GPS TEC and GIM TEC Data
by Lei Dong, Xuemin Zhang and Xiaohui Du
Atmosphere 2022, 13(10), 1725; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13101725 - 20 Oct 2022
Cited by 6 | Viewed by 1584
Abstract
On 21 May 2021 (UT), Yangbi Ms6.4 and Maduo Ms7.4 earthquakes occurred in mainland China. This paper analyzed the ionospheric perturbations possibly related to the earthquake, based on global positioning system (GPS) total electron content (TEC) and global ionosphere map (GIM) TEC data. [...] Read more.
On 21 May 2021 (UT), Yangbi Ms6.4 and Maduo Ms7.4 earthquakes occurred in mainland China. This paper analyzed the ionospheric perturbations possibly related to the earthquake, based on global positioning system (GPS) total electron content (TEC) and global ionosphere map (GIM) TEC data. We identified GPS TEC anomalies by the sliding quartile, based on statistical analysis. After eliminating the days with high solar activity levels and strong geomagnetic disturbances, the time series analysis of GPS TEC data showed that there were significant TEC anomalies from 5 to 10 May. TEC anomalies were mainly positive anomalies. We obtained the spatial and temporal distributions of TEC anomalies using natural neighbor interpolation (NNI). The results showed that the TEC anomalies were distributed in the seismogenic zone and surrounded the epicenters of the Maduo and Yangbi earthquakes, indicating that they may be related to the earthquakes. From the GIM TEC difference map, we found the TEC enhancement in the seismogenic zone and its magnetic conjugate area of the Maduo and Yangbi earthquakes at 10:00–12:00 (UT) on the 5 and 6 May. We discussed our results according to the lithosphere-atmosphere-ionosphere coupling mechanism. Finally, based our results, we suggested that the Yangbi and Maduo earthquakes may affect the ionosphere through seismogenic electric field and thermal anomalies generated during the process of lithosphere-atmosphere-ionosphere coupling. Full article
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16 pages, 4321 KiB  
Article
Estimation of Short-Term and Long-Term Ozone Exposure Levels in Beijing–Tianjin–Hebei Region Based on Geographically Weighted Regression Model
by Zequn Qiao, Yusi Liu, Chen Cui, Mei Shan, Yan Tu, Yaxin Liu, Shiwen Xu, Ke Mi, Li Chen, Zhenxing Ma, Hui Zhang, Shuang Gao and Yanling Sun
Atmosphere 2022, 13(10), 1706; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13101706 - 17 Oct 2022
Cited by 2 | Viewed by 1244
Abstract
In recent years, ozone (O3) concentration has shown a decreasing trend in the Beijing–Tianjin–Hebei (BTH) region in China. However, O3 pollution remains a prominent problem. Accurate estimation of O3 exposure levels can provide support for epidemiological studies. A total [...] Read more.
In recent years, ozone (O3) concentration has shown a decreasing trend in the Beijing–Tianjin–Hebei (BTH) region in China. However, O3 pollution remains a prominent problem. Accurate estimation of O3 exposure levels can provide support for epidemiological studies. A total of 13 variables were combined to estimate short- and long-term O3 exposure levels using the geographically weighted regression (GWR) model in the BTH region with a spatial resolution of 1 × 1 km from 2017 to 2020. Five variables were left in the GWR model. O3 concentration was positively correlated with temperature, wind speed, and SO2, whereas is was negatively correlated with precipitation and NO2. Results showed that the model performed well. Leave-one-out cross-validation (LOOCV) R2 for short- and long-term simulation results were 0.91 and 0.71, and the values for RMSE were 11.14 and 3.49 μg/m3, respectively. The annual maximum 8 h average O3 concentration was the highest in 2018 and the lowest in 2020. Decreasing concentrations of major precursors of O3 due to the regional joint prevention and control may be the reason. O3 concentration was high in the southeast of the BTH region, including in Hengshui, Handan, Xingtai and Cangzhou. Full article
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15 pages, 3535 KiB  
Article
Moisture Transport and Contribution to the Continental Precipitation
by Yazhu Yang, Chunlei Liu, Niansen Ou, Xiaoqing Liao, Ning Cao, Ni Chen, Liang Jin, Rong Zheng, Ke Yang and Qianye Su
Atmosphere 2022, 13(10), 1694; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13101694 - 16 Oct 2022
Cited by 2 | Viewed by 1202
Abstract
Understanding the water cycle change under a warming climate is essential, particularly the ocean to land moisture transport, which affects the precipitation over land areas and influences society and the ecosystem. Using ERA5 data from 1988 to 2020, the time series of moisture [...] Read more.
Understanding the water cycle change under a warming climate is essential, particularly the ocean to land moisture transport, which affects the precipitation over land areas and influences society and the ecosystem. Using ERA5 data from 1988 to 2020, the time series of moisture transport and the trend across the boundary of each continent, including Eurasia, Africa, North America, South America, Antarctic, Australia, and Greenland, have been investigated. The inflow and outflow sections of the moisture have been identified for each continent. The trends of moisture convergence over Eurasia, Africa, North America, and Antarctic are all positive, with the values of 2.59 ± 3.12, 2.60 ± 3.17, 12.98 ± 2.28, and 0.32 ± 0.47 (in 106 kg/s/decade), respectively, but only the trend over North America is statistically significant at a 0.1 significance level. The moisture convergence trend of −0.59 ± 3.63 (in 106 kg/s/decade) over South America is negative but insignificant. The positive trend of 0.10 ± 0.35 (in 106 kg/s/decade) over Greenland is very weak. The precipitation, evaporation, and moisture convergence are well balanced at middle and low latitudes, but the combination of moisture convergence and evaporation is systematically lower than the precipitation over Antarctic and Greenland. Contributions of evaporation and moisture convergence (or transport) to the continental precipitation vary with the continent, but the moisture convergence dominates the precipitation variability over all continents, and the significant correlation coefficients between the anomaly time series of continental mean moisture convergence and precipitation are higher than 0.8 in all continents. Full article
(This article belongs to the Section Climatology)
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21 pages, 8490 KiB  
Article
PM2.5 Pollution in Six Major Chinese Urban Agglomerations: Spatiotemporal Variations, Health Impacts, and the Relationships with Meteorological Conditions
by Zhuofan Li, Xiangmin Zhang, Xiaoyong Liu and Bin Yu
Atmosphere 2022, 13(10), 1696; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13101696 - 16 Oct 2022
Cited by 3 | Viewed by 1660
Abstract
To investigate the spatiotemporal patterns of fine particulate matter (PM2.5) under years of control measures in China, a comprehensive analysis including statistical analysis, geographical analysis, and health impact assessment was conducted on millions of hourly PM2.5 concentrations data during the [...] Read more.
To investigate the spatiotemporal patterns of fine particulate matter (PM2.5) under years of control measures in China, a comprehensive analysis including statistical analysis, geographical analysis, and health impact assessment was conducted on millions of hourly PM2.5 concentrations data during the period of 2017–2020 in six typical major urban agglomerations. During the period of 2017–2020, PM2.5 concentrations in the Beijing–Tianjin–Hebei urban agglomeration (BTH-UA), Central Plains urban agglomeration (CP-UA), Yangtze River Delta urban agglomeration (YRD-UA), Triangle of Central China urban agglomeration (TC-UA), Chengdu–Chongqing urban agglomeration (CY-UA), and Pearl River Delta urban agglomeration (PRD-UA) decreased at a rate of 6.69, 5.57, 5.45, 3.85, 4.66, and 4.1 µg/m3/year, respectively. PM2.5 concentration in BTH-UA decreased by 30.5% over four years, with an annual average of 44.6 µg/m3 in 2020. CP-UA showed the lowest reduction ratio (22.1%) among the six regions, making it the most polluted urban agglomeration. In southern BTH-UA, northeastern CP-UA, and northwestern TC-UA, PM2.5 concentrations with high levels formed a high–high agglomeration, indicating pollution caused by source emission in these areas was high and hard to control. Atmospheric temperature, pressure, and wind speed have important influences on PM2.5 concentrations. RH has a positive correlation with PM2.5 concentration in north China but a negative correlation in south China. We estimated that meteorological conditions can explain 16.7–63.9% of the PM2.5 changes in 129 cities, with an average of 33.4%, indicating other factors including anthropogenic emissions dominated the PM2.5 changes. Among the six urban agglomerations, PM2.5 concentrations in the CP-UA were most influenced by the meteorological change. Benefiting from the reduction in PM2.5 concentration, the total respiratory premature mortalities in six regions decreased by 73.1%, from 2017 to 2020. The CP-UA had the highest respiratory premature mortality in six urban agglomerations. We suggested that the CP-UA needs more attention and stricter pollution control measures. Full article
(This article belongs to the Special Issue Air Quality Assessments and Management)
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35 pages, 1750 KiB  
Article
Air Pollution Dispersion Modelling in Urban Environment Using CFD: A Systematic Review
by Mariya Pantusheva, Radostin Mitkov, Petar O. Hristov and Dessislava Petrova-Antonova
Atmosphere 2022, 13(10), 1640; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13101640 - 09 Oct 2022
Cited by 15 | Viewed by 5190
Abstract
Air pollution is a global problem, which needs to be understood and controlled to ensure a healthy environment and inform sustainable development. Urban areas have been established as one of the main contributors to air pollution, and, as such, urban air quality is [...] Read more.
Air pollution is a global problem, which needs to be understood and controlled to ensure a healthy environment and inform sustainable development. Urban areas have been established as one of the main contributors to air pollution, and, as such, urban air quality is the subject of an increasing volume of research. One of the principal means of studying air pollution dispersion is to use computational fluid dynamics (CFD) models. Subject to careful verification and validation, these models allow for analysts to predict air flow and pollution concentration for various urban morphologies under different environmental conditions. This article presents a detailed review of the use of CFD to model air pollution dispersion in an urban environment over the last decade. The review extracts and summarises information from nearly 90 pieces of published research, categorising it according to over 190 modelling features, which are thematically systemised into 7 groups. The findings from across the field are critically compared to available urban air pollution modelling guidelines and standards. Among the various quantitative trends and statistics from the review, two key findings stand out. The first is that, despite the existence of best practice guidelines for pollution dispersion modelling, anywhere between 12% and 34% of the papers do not specify one or more aspects of the utilised models, which are required to reproduce the study. The second is that none of the articles perform verification and validation according to accepted standards. The results of this review can, therefore, be used by practitioners in the field of pollution dispersion modelling to understand the general trends in current research and to identify open problems to be addressed in the future. Full article
(This article belongs to the Special Issue Feature Papers in Air Quality)
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19 pages, 3328 KiB  
Article
Coupling Effects of Sandstorm and Dust from Coal Bases on the Atmospheric Environment of Northwest China
by Yun Liu, Tingning Zhao, Ruoshui Wang, Xianfeng Ai, Mengwei Wang, Tao Sun and Qunou Jiang
Atmosphere 2022, 13(10), 1629; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13101629 - 06 Oct 2022
Cited by 2 | Viewed by 1563
Abstract
The coupling effects of sandstorm and dust from coal bases themselves can have a major impact on the atmospheric environment as well as on human health. The typical coal resource city of Wuhai in Inner Mongolia was selected in order to study these [...] Read more.
The coupling effects of sandstorm and dust from coal bases themselves can have a major impact on the atmospheric environment as well as on human health. The typical coal resource city of Wuhai in Inner Mongolia was selected in order to study these impacts during a severe sandstorm event in March 2021. Particulate matter (PM1, PM2.5 and PM10) and total suspended particulate matter (TSP) samples were collected during the sandstorm event of 15–19 March 2021 and non-sandstorm weather (11–13 March 2021) and analyzed for their chemical composition. The concentrations of PM1, PM2.5, PM10 and TSP in Wuhai city during the sandstorm were 2.2, 2.6, 4.8 and 6.0 times higher than during non-sandstorm days, respectively. Trace metals concentrations in particles of different sizes generally increased during the sandstorm, while water-soluble ions decreased. Positive matrix fraction (PMF) results showed that the main sources of particles during both sandstorm and non-sandstorm days were industrial emissions, traffic emissions, combustion sources and dust. The proportion of industrial emissions and combustion sources increased compared with non-sandstorm days, while traffic emissions and dust decreased. The backward trajectory analysis results showed that airflows were mainly transported over short distances during non-sandstorm days, and high concentration contribution source areas were from southern Ningxia, southeast Gansu and western Shaanxi. The airflow was mainly transported over long distances during the sandstorm event, and high concentration contribution source areas were from northwestern Inner Mongolia, southern Russia, northern and southwestern Mongolia, and northern Xinjiang. A health risk analysis showed that the risk to human health during sandstorm days related to the chemical composition of particles was generally 1.2–13.1 times higher than during non-sandstorm days. Children were more susceptible to health risks, about 2–6.3 times more vulnerable than adults to the risks from heavy metals in the particles under both weather conditions. Full article
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21 pages, 10156 KiB  
Article
Characteristics of Low-Latitude Ionosphere Activity and Deterioration of TEC Model during the 7–9 September 2017 Magnetic Storm
by Jianfeng Li, Yongqian Wang, Shiqi Yang and Fang Wang
Atmosphere 2022, 13(9), 1365; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13091365 - 26 Aug 2022
Cited by 1 | Viewed by 1961
Abstract
Under the influence of space weather, abnormal disturbances in the ionosphere will distort the ionosphere model seriously and affect the global navigation satellite system negatively. This study analyzes the ionospheric activity characteristics and the ionospheric model performance in low latitude during a strong [...] Read more.
Under the influence of space weather, abnormal disturbances in the ionosphere will distort the ionosphere model seriously and affect the global navigation satellite system negatively. This study analyzes the ionospheric activity characteristics and the ionospheric model performance in low latitude during a strong geomagnetic storm from 7 to 9 September 2017. The research goals are to determine the abnormal behavior of the ionosphere during the geomagnetic storm and to refine the ionosphere model in the low latitude. In the experiment, the vertical total electron content (VTEC) peak value at low latitudes caused by this geomagnetic storm was significantly higher than that on the geomagnetic quiet day, and the VTEC peak value increased by approximately 75%. In the main phase of the geomagnetic storm, the degree of VTEC variation with longitude is significantly higher than that of the geomagnetic quiet day. The VTEC variation trend in the northern hemisphere is more severe than that in the southern hemisphere. In the region where VTEC decreases with longitude, the VTEC in the northern hemisphere is higher than that in the southern hemisphere on the same longitude at low latitudes, and this phenomenon is not significantly affected by the geomagnetic disturbance of the recovery phase. During the geomagnetic storm, the daily minimum value of VTEC at different latitudes was basically the same, approximately 5 TECU, indicating that the nighttime VTEC of the ionosphere in low latitudes was weakly affected by latitude and geomagnetic storms. Geomagnetic disturbances during geomagnetic storms will lead to anomalous features of the “Fountain effect” in the ionosphere at low latitudes. In addition, this geomagnetic storm event caused the accuracy of spherical harmonics (SH), polynomial, and ICE models to decrease by 7.12%, 27.87%, and 48.56%, respectively, and caused serious distortion, which is negative VTEC values fitted by the polynomial model. Full article
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20 pages, 8632 KiB  
Article
Spatiotemporal Variations of XCH4 across China during 2003–2021 Based on Observations from Multiple Satellites
by Jiayao Qin, Xiuying Zhang, Linjing Zhang, Miaomiao Cheng and Xuehe Lu
Atmosphere 2022, 13(9), 1362; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13091362 - 25 Aug 2022
Cited by 5 | Viewed by 1836
Abstract
Atmospheric methane (CH4) is an important greenhouse gas that can reflect variations of CH4 emissions and sinks. This study aimed to detect spatial and temporal variations of atmospheric CH4 concentrations in China during 2003–2021 based on CH4 column-averaged [...] Read more.
Atmospheric methane (CH4) is an important greenhouse gas that can reflect variations of CH4 emissions and sinks. This study aimed to detect spatial and temporal variations of atmospheric CH4 concentrations in China during 2003–2021 based on CH4 column-averaged dry-air mole fraction (XCH4) products from three satellites, namely, Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), Greenhouse Gases Observing Satellite (GOSAT), and Copernicus Sentinel-5 Precursor (S5P). The results revealed that XCH4 observed from three satellites showed high agreement in spatiotemporal variations and demonstrated good consistency with ground station measurements. The correlation coefficients (r) between the three satellites were 0.72 and 0.73, and the correlation coefficients for the ground stations were 0.79, 0.66, 0.03, 0.21, 0.70, and 0.80. The spatial distribution of XCH4 in China was generally high in the east and low in the west and close to that of CH4 emissions, indicating that CH4 emission sources dominated the spatial variations of atmospheric XCH4. From 2003 to 2006, XCH4 remained stable with an annual growth rate of 0.51 ppb·yr−1 and then abruptly increased with an overall growth rate of 6.96 ppb·yr−1. There were obvious seasonal changes in XCH4, with peaks in autumn and summer and nadir in winter and spring. These seasonal variations of XCH4 were related to CH4 emissions from rice planting. Rice cultivation areas generally had high XCH4 concentrations, and the growth cycle of rice plants significantly contributed to seasonal variations of XCH4 in the main rice planting areas. These results provide scientific data that could encourage decision-makers to enact policies and processes to reduce methane emissions. Full article
(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)
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25 pages, 12983 KiB  
Article
Impacts of Radio Occultation Data on Typhoon Forecasts as Explored by the Global MPAS-GSI System
by Tzu-Yu Chien, Shu-Ya Chen, Ching-Yuang Huang, Cheng-Peng Shih, Craig S. Schwartz, Zhiquan Liu, Jamie Bresch and Jia-Yang Lin
Atmosphere 2022, 13(9), 1353; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13091353 - 25 Aug 2022
Cited by 3 | Viewed by 1659
Abstract
Global Navigation Satellite System (GNSS) radio occultation (RO) provides plentiful sounding profiles over regions lacking conventional observations. The Gridpoint Statistical Interpolation (GSI) hybrid system for assimilating RO data is integrated in this study with the Model for Prediction Across Scales–Atmosphere (MPAS) to improve [...] Read more.
Global Navigation Satellite System (GNSS) radio occultation (RO) provides plentiful sounding profiles over regions lacking conventional observations. The Gridpoint Statistical Interpolation (GSI) hybrid system for assimilating RO data is integrated in this study with the Model for Prediction Across Scales–Atmosphere (MPAS) to improve tropical cyclone forecasts. After the MPAS-GSI assimilation cycles, dynamical vortex initialization (DVI) that may effectively spin up the initial inner typhoon vortex through cycled model integration is implemented to improve the initial analysis fit to the best track position as well as maximum wind or pressure intensity for Typhoon Nepartak (2016) that moved northwestward toward southern Taiwan. During the cycling assimilation, assimilation with RO data improves the temperature and moisture analysis, and largely reduces the forecast errors compared to those without RO data assimilation. The two RO operators that assimilate local bending angle or refractivity produce similar analyses, but the temperature and moisture increments from bending angle assimilation are slightly larger than those from refractivity assimilation. The MPAS forecasts at 60-15 km resolution show that the typhoon track prediction is improved with RO data, especially using bending angle data. The reduction in track deviations is explained by the wavenumber-one potential vorticity budget for several forecasts associated with the track deflection near southern Taiwan. Assimilation of RO data has fewer impacts on the typhoon intensity forecast compared to the DVI that largely improves the initial and thus forecasted intensity of the typhoon but at the cost of a slightly degraded track. Use of the enhanced 3 km resolution in the typhoon path also further improved the forecasts with and without the DVI. The feasible performance of the MPAS-GSI system with the RO data impact is also illustrated for Typhoon Mitag (2019), that passed around northern Taiwan. Full article
(This article belongs to the Special Issue Typhoon/Hurricane Dynamics and Prediction)
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21 pages, 2776 KiB  
Article
GIS-Based Spatial Modeling of Snow Avalanches Using Analytic Hierarchy Process. A Case Study of the Šar Mountains, Serbia
by Uroš Durlević, Aleksandar Valjarević, Ivan Novković, Nina B. Ćurčić, Mirjana Smiljić, Cezar Morar, Alina Stoica, Danijel Barišić and Tin Lukić
Atmosphere 2022, 13(8), 1229; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13081229 - 03 Aug 2022
Cited by 10 | Viewed by 2936
Abstract
Snow avalanches are one of the most devastating natural hazards in the highlands that often cause human casualties and economic losses. The complex process of modeling terrain susceptibility requires the application of modern methods and software. The prediction of avalanches in this study [...] Read more.
Snow avalanches are one of the most devastating natural hazards in the highlands that often cause human casualties and economic losses. The complex process of modeling terrain susceptibility requires the application of modern methods and software. The prediction of avalanches in this study is based on the use of geographic information systems (GIS), remote sensing, and multicriteria analysis—analytic hierarchy process (AHP) on the territory of the Šar Mountains (Serbia). Five indicators (lithological, geomorphological, hydrological, vegetation, and climatic) were processed, where 14 criteria were analyzed. The results showed that approximately 20% of the investigated area is highly susceptible to avalanches and that 24% of the area has a medium susceptibility. Based on the results, settlements where avalanche protection measures should be applied have been singled out. The obtained data can will help local self-governments, emergency management services, and mountaineering services to mitigate human and material losses from the snow avalanches. This is the first research in the Republic of Serbia that deals with GIS-AHP spatial modeling of snow avalanches, and methodology and criteria used in this study can be tested in other high mountainous regions. Full article
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15 pages, 1361 KiB  
Article
Stratospheric Chemical Lifetime of Aviation Fuel Incomplete Combustion Products
by William Bains, Eleanor Viita, Janusz J. Petkowski and Sara Seager
Atmosphere 2022, 13(8), 1209; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13081209 - 01 Aug 2022
Cited by 1 | Viewed by 2124
Abstract
The stratosphere contains haze rich in sulfuric acid, which plays a significant role in stratospheric chemistry and in global climate. Commercial aircraft deposit significant amounts of incomplete combustion products into the lower stratosphere. We have studied the stability of these incomplete combustion products [...] Read more.
The stratosphere contains haze rich in sulfuric acid, which plays a significant role in stratospheric chemistry and in global climate. Commercial aircraft deposit significant amounts of incomplete combustion products into the lower stratosphere. We have studied the stability of these incomplete combustion products to reaction with sulfuric acid, using a predictive model based on experimental reaction kinetics. We demonstrate that sulfuric acid chemistry is likely to be a significant component of the chemistry of organics in the stratosphere. We find that at least 25 of the 40 known incomplete combustion products from aviation fuel have lifetimes to reaction with aerosol sulfuric acid of at least months. We estimate that ~109 kg of long-lived products could be deposited per year in the lower stratosphere. We suggest that the high molecular weight organic compounds formed as incomplete combustion products of commercial long-haul aviation could play a significant role in the stratosphere. Full article
(This article belongs to the Section Upper Atmosphere)
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28 pages, 4442 KiB  
Article
Urban Heat Island and Thermal Comfort Assessment in a Medium-Sized Mediterranean City
by Georgios Kalogeropoulos, Argiro Dimoudi, Pavlos Toumboulidis and Stamatis Zoras
Atmosphere 2022, 13(7), 1102; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13071102 - 13 Jul 2022
Cited by 7 | Viewed by 2681
Abstract
One of the greatest issues nowadays is that of the urban heat island effect on the thermal conditions inside cities. The air temperature inside the city core is warmer than that in suburbs, thus deteriorating the quality of life for citizens and making [...] Read more.
One of the greatest issues nowadays is that of the urban heat island effect on the thermal conditions inside cities. The air temperature inside the city core is warmer than that in suburbs, thus deteriorating the quality of life for citizens and making outdoor spaces uncomfortable in terms of thermal comfort. This phenomenon is usually assessed in large scale cities worldwide and less often in medium-sized towns. The current study aimed to investigate the urban heat island effect and, therefore, to assess the outdoor thermal comfort conditions in a medium-sized city. More specifically, the methodology of the current study includes: (i) the combination of different monitoring techniques to quantify the urban heat island effect in a medium-sized Mediterranean city. Both in situ measurements and remote sensing techniques were applied to assess the urban heat island effect in terms of both the canopy layer (CUHI) and the surface (SUHI); (ii) the identification of the parameters that affect thermal comfort and the identification of the most appropriate bioclimatic indices that determine outdoor thermal comfort in the city of interest. Both questionnaire survey and in situ measurements took place on a sidewalk in the city of Xanthi, Northern Greece, during the summer. The CUHI effect was obvious, especially in the morning and afternoon. Downscaled MODIS satellite images also showed that the intensity of SUHI was higher in the morning and afternoon. Apart from air temperature, important differences in the values of most microclimatic parameters were recorded between the meteorological station placed inside the urban area and those gathered from a nearby meteorological station. The narrow roads, the thermal properties of construction materials, and the absence of greenery characterized the area of interest and may be the key factors creating these differences in climate. Concerning the thermal comfort assessment, the most significant parameters were the air temperature and solar radiation, although, both empirical and direct indices were found to describe the comfort values well. According to the results, downscaling techniques are also important for the SUHI effect to be investigating in detail in medium-sized urban environments. Full article
(This article belongs to the Special Issue Strategies for Mitigation and Adaptation to Urban Heat)
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11 pages, 914 KiB  
Article
Quantitative Prediction of Sea Clutter Power Based on Improved Grey Markov Model
by Zihao Chen, Bin Tian, Siyun Zhang and Quanjun Xu
Atmosphere 2022, 13(7), 1085; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13071085 - 10 Jul 2022
Cited by 2 | Viewed by 1187
Abstract
The detection and prediction of sea clutter power is the basis of inversing atmospheric duct. At present, the technology of atmospheric duct within radar detection range is relatively perfect, but the long-distance inversion of atmospheric duct is limited by radar detection range, and [...] Read more.
The detection and prediction of sea clutter power is the basis of inversing atmospheric duct. At present, the technology of atmospheric duct within radar detection range is relatively perfect, but the long-distance inversion of atmospheric duct is limited by radar detection range, and the prediction of the echo power of the measured sea clutter is the basis of long-distance inversion of atmospheric duct. Based on the theory of weighted Markov model and grey Markov model, a weighted grey Markov model is constructed, and the sliding method is introduced to establish the sliding weighted grey Markov model. The relative error between the measured sea clutter power and predicted values of the above four models is calculated and analyzed using the experimental data collected. The results show that the sliding weighted grey Markov model has better accuracy not only in short-range prediction but also in long-distance prediction, which could provide data support for inversing atmospheric duct. Full article
(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)
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19 pages, 6792 KiB  
Article
Probability Forecasting of Short-Term Short-Duration Heavy Rainfall Combining Ingredients-Based Methodology and Fuzzy Logic Approach
by Fuyou Tian, Xiaoling Zhang, Kun Xia, Jianhua Sun and Yongguang Zheng
Atmosphere 2022, 13(7), 1074; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13071074 - 07 Jul 2022
Cited by 1 | Viewed by 1430
Abstract
Highly convection-related short-duration heavy rainfall (SDHR), defined as rainfall greater than 20 mm h−1 of a whole hour, causes severe damage every year in China. An objective forecasting method is developed to provide guidance products for the short-term probability of SDHR. Representative [...] Read more.
Highly convection-related short-duration heavy rainfall (SDHR), defined as rainfall greater than 20 mm h−1 of a whole hour, causes severe damage every year in China. An objective forecasting method is developed to provide guidance products for the short-term probability of SDHR. Representative parameters of environmental moisture content, instability, and dynamical forcing are selected as predictors based on the ingredients-based methodology. The predictors are selected by comparing their ability to discriminate between SDHR and both no rainfall and ordinary rainfall with hourly rainfall records and the NCEP reanalysis dataset during the warm seasons of 2002 and 2009. A fuzzy logic approach is obtained for the calculation of SDHR probability. Intervals of intensities are obtained based on specific percentiles and various weight settings examined. The probabilistic SDHR forecasts during the 2015 warm seasons with the NCEP GFS dataset are obtained, and forecasts are evaluated by using an operational used spatial verification method. Results show that the reference operational SDHR forecasts are surpassed by the 00–12 h period objective SDHR forecasts measured with the maximum critical success index (CSI), and even the average CSI (CSIave) for the top groups is better than the reference. The guidance SDHR products are skillful within 60 h. Although the weights vary significantly, the short-term patterns of the SDHR probability are mainly determined by the environmental conditions. The objective forecasting method is ingredients-based but is combined with fuzzy logic algorithms. The new approach provides a feasible exploration of the convective weather phenomenon. Full article
(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)
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13 pages, 1776 KiB  
Article
Influence of Meteorological Factors and Chemical Processes on the Explosive Growth of PM2.5 in Shanghai, China
by Wenwen Sun, Juntao Huo, Qingyan Fu, Yuxin Zhang and Xiangde Lin
Atmosphere 2022, 13(7), 1068; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13071068 - 06 Jul 2022
Cited by 8 | Viewed by 1487
Abstract
In order to explore the mechanism of haze formation, the meteorological effect and chemical reaction process of the explosive growth (EG) of PM2.5 were studied. In this study, the level of PM2.5, water-soluble inorganic ions, carbonaceous aerosols, gaseous precursors, and [...] Read more.
In order to explore the mechanism of haze formation, the meteorological effect and chemical reaction process of the explosive growth (EG) of PM2.5 were studied. In this study, the level of PM2.5, water-soluble inorganic ions, carbonaceous aerosols, gaseous precursors, and meteorological factors were analyzed in Shanghai in 2018. The EG event is defined by a net increase of PM2.5 mass concentration greater than or equal to 100 μg m−3 within 3, 6, or 9 h. The results showed that the annual average PM2.5 concentration in Shanghai in 2018 was 43.2 μg m−3, and secondary inorganic aerosols and organic matter (OM) accounted for 55.8% and 20.1% of PM2.5, respectively. The increase and decrease in the contributions of sulfate, nitrate, ammonium (SNA), and elemental carbon (EC) to PM2.5 from clean days to EG, respectively, indicated a strong, secondary transformation during EG. Three EG episodes (Ep) were studied in detail, and the PM2.5 concentration in Ep3 was highest (135.7 μg m−3), followed by Ep2 (129.6 μg m−3), and Ep1 (82.3 μg m−3). The EG was driven by stagnant conditions and chemical reactions (heterogeneous and gas-phase oxidation reactions). This study improves our understanding of the mechanism of haze pollution and provides a scientific basis for air pollution control in Shanghai. Full article
(This article belongs to the Special Issue Physical Models and Statistical Methods in Atmospheric Environment)
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19 pages, 3963 KiB  
Article
Analyzing Thermal Comfort Sensations in Semi-Outdoor Space on a University Campus: On-Site Measurements in Tehran’s Hot and Cold Seasons
by Sevil Zafarmandi, Mohammadjavad Mahdavinejad, Leslie Norford and Andreas Matzarakis
Atmosphere 2022, 13(7), 1034; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13071034 - 29 Jun 2022
Cited by 7 | Viewed by 2059
Abstract
Outdoor and semi-outdoor thermal comfort on the university campus is essential for encouraging students’ outdoor activities and interactions and reducing energy consumption in occupied buildings. For this reason, the current study presents on-site measurements and questionnaire surveys on a university campus in Tehran, [...] Read more.
Outdoor and semi-outdoor thermal comfort on the university campus is essential for encouraging students’ outdoor activities and interactions and reducing energy consumption in occupied buildings. For this reason, the current study presents on-site measurements and questionnaire surveys on a university campus in Tehran, Iran. It aims to investigate the most applicable thermal indices in Tehran’s cold and hot seasons. Measurements were conducted over winter and summer days; in addition, the survey collected 384 responses. The results confirm that the Predicted Mean Vote (PMV) and Physiological Equivalent Temperature (PET) indices are better predictors of semi-outdoor thermal comfort in summer and winter than Universal Thermal Climate Index (UTCI) and New Standard Effective Temperature (SET*), respectively, highlighting the importance of considering accurate thermal indices in different seasons. Finally, all analyses were gathered in a predictive empirical model, knowledge of which may be helpful in the planning and design of outdoor and semi-outdoor environments in Tehran and similar climates. Full article
(This article belongs to the Section Biometeorology)
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29 pages, 27260 KiB  
Article
Summertime Assessment of an Urban-Scale Numerical Weather Prediction System for Toronto
by Sylvie Leroyer, Stéphane Bélair, Vanh Souvanlasy, Marcel Vallée, Simon Pellerin and David Sills
Atmosphere 2022, 13(7), 1030; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13071030 - 28 Jun 2022
Cited by 7 | Viewed by 1888
Abstract
Urban-scale Numerical Weather Prediction (NWP) systems will be important tools for decision-making in and around large cities in a changing climate exposed to more extreme weather events. Such a state-of-the-art real-time system down to 250-m grid spacing was implemented in the context of [...] Read more.
Urban-scale Numerical Weather Prediction (NWP) systems will be important tools for decision-making in and around large cities in a changing climate exposed to more extreme weather events. Such a state-of-the-art real-time system down to 250-m grid spacing was implemented in the context of the Toronto 2015 Panamerican games, Canada (PanAm). Combined with the Global Environmental Multiscale (GEM) model, attention was brought to the representation of the detailed urban landscape, and to the inclusion of sub-daily variation of the Great Lakes surface temperature. Results show a refined representation of the urban coastal environment micro-meteorology with a strong anisotropy of the urban heat island reaching about 2 °C on average for the summer season, coastal upwelling, and mesoscale features such as cumulus clouds and lake-breeze flow. Objective evaluation at the surface with a dense observational network reveals an overall good performance of the system and a clear improvement in comparison to reference forecasts at 2.5-km grid spacing in particular for standard deviation errors in urban areas up to 0.3 °C for temperature and dew point temperature, and up to 0.5 m s1 for the wind speed, as well as for precipitation with an increased Equitable Threat Score (ETS) by up to 0.3 for the evening accumulation. The study provides confidence in the capacity of the new system to improve weather forecasts to be delivered to urban dwellers although further investigation of the initialization methods in urban areas is needed. Full article
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25 pages, 58887 KiB  
Article
Characterization of Terrain-Induced Turbulence by Large-Eddy Simulation for Air Safety Considerations in Airport Siting
by Sai Wang, Frederik De Roo, Ludovic Thobois and Joachim Reuder
Atmosphere 2022, 13(6), 952; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13060952 - 11 Jun 2022
Cited by 2 | Viewed by 1889
Abstract
Topography-induced turbulence poses a potential hazard for aviation safety, in particular during the final approach and landing. In this context, it is essential to assure that the impact of topography-induced turbulence on the flight paths during take-off and landing is minimized already during [...] Read more.
Topography-induced turbulence poses a potential hazard for aviation safety, in particular during the final approach and landing. In this context, it is essential to assure that the impact of topography-induced turbulence on the flight paths during take-off and landing is minimized already during the design and planning phase. As an example of the siting and planning of a potential new airport in complex terrain, this study investigates the distribution of terrain-induced boundary layer turbulence in the vicinity of the current Lofoten airport at Leknes (LKN). For that purpose, large-eddy simulations (LES) have been performed with the PAralellized Large-eddy Simulation Model (PALM) on a 40×45×4km3 computational domain around LKN. An initial parametric sensitivity study resulted in a grid spacing of 50 m and an overall simulation time of 12 h for our individual model runs. A suite of 32 model simulations for 16 different wind directions and two geostrophic wind speeds of 10 ms1 and 20 ms1, was then performed and analysed. A turbulence risk analysis along idealized flight trajectories shows that the high-risk conditions are substantially determined by the wind conditions and their interaction with the topography. With respect to wind speed, the results indicate that for a geostrophic flow below 10 ms1, the risk of aviation critical, terrain-induced boundary layer turbulence (BLT), is rather low in the vicinity of LKN. At 20 ms1 the situation has completely changed, as for 14 out of 16 investigated wind directions the 9 m2s2 aviation critical threshold of turbulent kinetic energy per unit air mass (TKE) is exceeded. In the northwesterly wind scenarios, the largest areas with critical turbulence in the vicinity of LKN are observed. Full article
(This article belongs to the Special Issue Low Level Windshear and Turbulence for Aviation Safety)
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16 pages, 4606 KiB  
Article
Trends of Tropical Cyclone Translation Speed over the Western North Pacific during 1980−2018
by Danyi Gong, Xiaodong Tang, Johnny C. L. Chan and Qiuyun Wang
Atmosphere 2022, 13(6), 896; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13060896 - 01 Jun 2022
Cited by 2 | Viewed by 2165
Abstract
Tropical cyclone (TC) translation speed often affects the time of strong wind attacks and precipitation accumulation in the areas that TCs pass through. Therefore, the trend of TC translation speed has important implications for TC-related risks in the current and future climate. In [...] Read more.
Tropical cyclone (TC) translation speed often affects the time of strong wind attacks and precipitation accumulation in the areas that TCs pass through. Therefore, the trend of TC translation speed has important implications for TC-related risks in the current and future climate. In this paper, the trends of TC translation speed over the Western North Pacific (WNP) from 1980 to 2018 are analyzed, and TC lifetime maximum intensity (LMI) is proposed as a factor related to the interdecadal change of translation speed. During the periods with accurate data, 1980–1997 shows a decreasing trend in TC translation speed while an increasing trend was found in 1998–2018. The main lifetime period contributing to a TC translation speed change is before the occurrence of the LMI. The change in the trend is related to both the TC’s characteristics itself and the environmental factors. For the period 1998–2018, an increasing trend of TC intensity has a significant influence on the trend of translation speed. For the environmental factors, a trend of east wind enhancement at and above 500 hPa as the steering flow is found mostly correlated in the active TC region of the WNP with westward translation before reaching LMI, accompanied by a weakening trend of 200–850 hPa vertical wind shear, and an increasing trend of potential intensity. Full article
(This article belongs to the Special Issue Tropical Cyclone Forecasting - Analysis and Methods)
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15 pages, 4113 KiB  
Article
Evaluation of TROPOMI and OMI Tropospheric NO2 Products Using Measurements from MAX-DOAS and State-Controlled Stations in the Jiangsu Province of China
by Kun Cai, Shenshen Li, Jibao Lai, Yu Xia, Yapeng Wang, Xuefei Hu and Ang Li
Atmosphere 2022, 13(6), 886; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13060886 - 30 May 2022
Cited by 3 | Viewed by 2046
Abstract
The tropospheric vertical column density of NO2 (Trop NO2 VCD) can be obtained using satellite remote sensing, but it has been discovered that the Trop NO2 VCD is affected by uncertainties such as the cloud fraction, terrain reflectivity, and aerosol [...] Read more.
The tropospheric vertical column density of NO2 (Trop NO2 VCD) can be obtained using satellite remote sensing, but it has been discovered that the Trop NO2 VCD is affected by uncertainties such as the cloud fraction, terrain reflectivity, and aerosol optical depth. A certain error occurs in terms of data inversion accuracy, necessitating additional ground observation verification. This study uses surface NO2 mass concentrations from the China National Environmental Monitoring Center (CNEMC) sites in Jiangsu Province, China in 2019 and the Trop NO2 VCD measured by MAX-DOAS, respectively, to verify the Trop NO2 VCD product (daily and monthly average data), that comes from the TROPOspheric Monitoring Instrument (TROPOMI) and Ozone Monitoring Instrument (OMI). The results show that the spatial distributions of NO2 in TROPOMI and OMI exhibit a similar tendency and seasonality, showing the characteristics of being high in spring and winter and low in summer and autumn. On the whole, the concentration of NO2 in the south of Jiangsu Province is higher than that in the north. The Pearson correlation coefficient (r) between the monthly average TROPOMI VCD NO2 and the CNEMC NO2 mass concentration is 0.9, which is greater than the r (0.78) between OMI and CNEMC; the r (0.69) between TROPOMI and the MAX-DOAS VCD NO2 is greater than the r (0.59) between OMI and the MAX-DOAS. As such, the TROPOMI is better than the previous generation of OMI at representing the spatio-temporal distribution of NO2 in the regional scope. On the other hand, the uncertainties of the satellite products provided in this study can constrain regional air quality forecasting models and top-down emission inventory estimation. Full article
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14 pages, 3446 KiB  
Article
Response of Population Canopy Color Gradation Skewed Distribution Parameters of the RGB Model to Micrometeorology Environment in Begonia Fimbristipula Hance
by Pei Zhang, Zhengmeng Chen, Fuzheng Wang, Rong Wang, Tingting Bao, Xiaoping Xie, Ziyue An, Xinxin Jian and Chunwei Liu
Atmosphere 2022, 13(6), 890; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13060890 - 30 May 2022
Cited by 3 | Viewed by 1491
Abstract
The high quality and efficient production of greenhouse vegetation depend on micrometeorology environmental adjusting such as system warming and illumination supplement. In order to improve the quantity, quality, and efficiency of greenhouse vegetation, it is necessary to figure out the relationship between the [...] Read more.
The high quality and efficient production of greenhouse vegetation depend on micrometeorology environmental adjusting such as system warming and illumination supplement. In order to improve the quantity, quality, and efficiency of greenhouse vegetation, it is necessary to figure out the relationship between the crop growth conditions and environmental meteorological factors, which could give constructive suggestions for precise control of the greenhouse environment and reduce the running costs. The parameters from the color information of the plant canopy reflect the internal physiological conditions, thus, the RGB model has been widely used in the color analysis of digital pictures of leaves. We take photographs of Begonia Fimbristipula Hance (BFH) growing in the greenhouse at a fixed time every day and measure the meteorological factors. The results showed that the color scale for the single leaf, single plant, and the populated canopy of the BFH photographs all have skewed cumulative distribution histograms. The color gradation skewness-distribution (CGSD) parameters of the RGB model were increased from 4 to 20 after the skewness analysis, which greatly expanded the canopy leaf color information and could simultaneously describe the depth and distribution characteristics of the canopy color. The 20 CGSD parameters were sensitive to the micrometeorology factors, especially to the radiation and temperature accumulation. The multiple regression models of mean, median, mode, and kurtosis parameters to microclimate factors were established, and the spatial models of skewness parameters were optimized. The models can well explain the response of canopy color to microclimate factors and can be used to monitor the variation of plant canopy color under different micrometeorology. Full article
(This article belongs to the Special Issue Agrometeorology)
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23 pages, 12565 KiB  
Article
Impact of Stratosphere on Cold Air Outbreak: Observed Evidence by CrIS on SNPP and Its Comparison with Models
by Xiaozhen Xiong, Xu Liu, Wan Wu, K. Emma Knowland, Fanglin Yang, Qiguang Yang and Daniel K. Zhou
Atmosphere 2022, 13(6), 876; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13060876 - 28 May 2022
Cited by 5 | Viewed by 1742
Abstract
A cold air outbreak (CAO) is an extreme weather phenomenon that has significant social and economic impacts over a large region of the midlatitudes. However, the dynamical mechanism of the occurrence and evolution of CAO events, particularly the role of the stratosphere, is [...] Read more.
A cold air outbreak (CAO) is an extreme weather phenomenon that has significant social and economic impacts over a large region of the midlatitudes. However, the dynamical mechanism of the occurrence and evolution of CAO events, particularly the role of the stratosphere, is not well understood. Through an analysis of one extreme CAO episode that occurred on 27–31 January 2019 across much of the US Midwest, this study examined its thermodynamic structure and the impact of stratospheric downward transport using the single-field-view (SFOV) satellite products (with a spatial resolution of ~14 km at nadir) from the Cross-track Infrared Sounder (CrIS) onboard Suomi National Polar-Orbiting Partnership (SNPP) in conjunction with MERRA-2 and ERA-5 reanalysis products. It is found that along the path of cold air transport, particularly near the coldest surface center, there exists a large enhancement of O3, deep tropopause folding, significant downward transport of stratospheric dry air, and a warm center above the tropopause. The upper warm center can be observed directly using the brightness temperature (BT) of CrIS stratospheric sounding channels. While similar large-scale patterns of temperature (T), relative humidity (RH), and ozone (O3) are captured from CrIS, MERRA-2, and ERA-5 products, it is found that, in the regions impacted by CAO, MERRA-2 has a thicker dry layer under the tropopause (with the difference of RH up to ~10%) and the total column ozone (TCO) from ERA-5 has a relatively large positive bias of 2.8 ± 2.8% compared to that measured by Ozone Mapping and Profiler Suite (OMPS). This study provides some observational evidence from CrIS that confirm the impact of the stratosphere on CAO through downward transport and demonstrates the value of the SFOV retrieval products for CAO dynamic transport study and model evaluation. Full article
(This article belongs to the Special Issue Advanced Technologies in Satellite Observations)
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24 pages, 18118 KiB  
Article
Advances in Ionospheric Space Weather by Using FORMOSAT-7/COSMIC-2 GNSS Radio Occultations
by Jann-Yenq Liu, Chien-Hung Lin, Panthalingal Krishnanunni Rajesh, Chi-Yen Lin, Fu-Yuan Chang, I-Te Lee, Tzu-Wei Fang, Dominic Fuller-Rowell and Shih-Ping Chen
Atmosphere 2022, 13(6), 858; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13060858 - 24 May 2022
Cited by 12 | Viewed by 2236
Abstract
This paper provides an overview of the contributions of the space-based global navigation satellite system (GNSS) radio occultation (RO) measurements from the FORMOSAT-7/COSMIC2 (F7/C2) mission in advancing our understanding of ionospheric plasma physics in the purview of space weather. The global positioning system [...] Read more.
This paper provides an overview of the contributions of the space-based global navigation satellite system (GNSS) radio occultation (RO) measurements from the FORMOSAT-7/COSMIC2 (F7/C2) mission in advancing our understanding of ionospheric plasma physics in the purview of space weather. The global positioning system (GPS) occultation experiment (GOX) onboard FORMOSAT-3/COSMIC (F3/C), with more than four and half million ionospheric RO soundings during April 2006–May 2020, offered a unique three-dimensional (3D) perspective to examine the global electron density distribution and unravel the underlying physical processes. The current F7/C2 carries TGRS (Tri-GNSS radio occultation system) has tracked more than 4000 RO profiles within ±35° latitudes per day since 25 June 2019. Taking advantage of the larger number of low-latitude soundings, the F7/C2 TGRS observations were used here to examine the 3D electron density structures and electrodynamics of the equatorial ionization anomaly, plasma depletion bays, and four-peaked patterns, as well as the S4 index of GNSS signal scintillations in the equatorial and low-latitude ionosphere, which have been previously investigated by using F3/C measurements. The results demonstrated that the denser low-latitude soundings enable the construction of monthly global electron density maps as well the altitude-latitude profiles with higher spatial and temporal resolution windows, and revealed longitudinal and seasonal characteristics in greater detail. The enhanced F7/C2 RO observations were further applied by the Central Weather Bureau/Space Weather Operation Office (CWB/SWOO) in Taiwan and the National Oceanic and Atmospheric Administration/Space Weather Prediction Center (NOAA/SWPC) in the United States to specify the ionospheric conditions for issuing alerts and warnings for positioning, navigation, and communication customers. A brief description of the two models is also provided. Full article
(This article belongs to the Special Issue Advances in GNSS Radio Occultation Technique and Applications)
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21 pages, 4915 KiB  
Article
Versatile Modelling of Extreme Surges in Connection with Large-Scale Circulation Drivers
by Lisa Baulon, Emma Imen Turki, Nicolas Massei, Gaël André, Yann Ferret and Nicolas Pouvreau
Atmosphere 2022, 13(5), 850; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050850 - 23 May 2022
Cited by 2 | Viewed by 1493
Abstract
In this article, we investigate the dependence of extreme surges on the North Atlantic weather regime variability across different timescales using the North Atlantic Oscillation (NAO) and Scandinavian blocking (SCAND) indices. The analysis was done using time series of surges along the North [...] Read more.
In this article, we investigate the dependence of extreme surges on the North Atlantic weather regime variability across different timescales using the North Atlantic Oscillation (NAO) and Scandinavian blocking (SCAND) indices. The analysis was done using time series of surges along the North French Coast, covering long time periods (43 to 172 years of data). Time series that exhibited gaps were filled using linear interpolation to allow spectral analyses to be conducted. First, a continuous wavelet analysis on monthly maxima surges in the North French Coast was conducted to identify the multi-timescale variability. Second, a wavelet coherence analysis and maximum overlap discrete wavelet transform (MODWT) were used to study the timescale-dependent relationships between maxima surges and NAO or SCAND. Finally, NAO and SCAND were tested as physical covariates for a nonstationary generalized extreme value (GEV) distribution to fit monthly maxima surge series. Specific low-frequency variabilities characterizing these indices (extracted using MODWT) were also used as covariates to determine whether such specific variabilities would allow for even better GEV fitting. The results reveal common multi-annual timescales of variability between monthly maxima surge time series along the North French coasts: ~2–3 years, ~5–7 years, and ~12–17 years. These modes of variability were found to be mainly induced by the NAO and the SCAND. We identified a greater influence of the NAO on the monthly maxima surges of the westernmost stations (Brest, Cherbourg, Le Havre), while the SCAND showed a greater influence on the northernmost station (Dunkirk). This shows that the physical climate effects at multi-annual scales are manifested differently between the Atlantic/English Channel and the North Sea regions influenced by NAO and SCAND, respectively. Finally, the introduction of these two climate indices was found to clearly enhance GEV models as well as a few timescales of these indices. Full article
(This article belongs to the Special Issue Multi-Hazard Risk Assessment)
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12 pages, 2577 KiB  
Article
Unusual Enhancement of Midlatitude Sporadic-E Layers in Response to a Minor Geomagnetic Storm
by Qiong Tang, Haiyang Sun, Zhitao Du, Jiaqi Zhao, Yi Liu, Zhengyu Zhao and Xueshang Feng
Atmosphere 2022, 13(5), 816; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050816 - 16 May 2022
Cited by 2 | Viewed by 1623
Abstract
This study investigates the variations of middle and low latitude sporadic-E (Es) layers in response to a geomagnetic storm. Es layers are observed by five ionosondes located in the Eastern Asian sector. The critical frequencies of Es layers (foEs) at six stations increased [...] Read more.
This study investigates the variations of middle and low latitude sporadic-E (Es) layers in response to a geomagnetic storm. Es layers are observed by five ionosondes located in the Eastern Asian sector. The critical frequencies of Es layers (foEs) at six stations increased in sequence from high latitude stations to low latitude stations after IMF/Bz turning southward. Lomb–Scargle analysis shows the amplification of semidiurnal oscillation amplitude in the vertical height of Es layers during geomagnetic disturbance. Modeling results of the NCAR Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) show the enhancement of the wind field in the mesosphere and the lower thermosphere (MLT) region. Our study provides evidence that the enhanced wind field in the MLT region during the storm period could result in the enhancement of Es layers at middle and low latitude. Full article
(This article belongs to the Special Issue Mesosphere and Lower Thermosphere)
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17 pages, 12346 KiB  
Article
Dual-Polarization Radar Observations of the Evolution of a Supercell Tornado and Analysis of the Echo Mechanisms
by Bin Wu, Ming Wei and Yanfang Li
Atmosphere 2022, 13(5), 797; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050797 - 13 May 2022
Cited by 5 | Viewed by 2201
Abstract
To gain a deeper understanding of the structural and evolutionary characteristics of supercell tornadoes that occurred in eastern China on 14 May 2021, observations from the S-band dual-polarization radars, soundings and other instruments are used to investigate the evolutionary process of the tornado [...] Read more.
To gain a deeper understanding of the structural and evolutionary characteristics of supercell tornadoes that occurred in eastern China on 14 May 2021, observations from the S-band dual-polarization radars, soundings and other instruments are used to investigate the evolutionary process of the tornado formation by the mergering and strengthening of supercell storms. The results are described as follows. The updraft by upper divergence and vertical thermal instability induced by the cold source at the tropopause provided the environmental conditions suitable for tornado formation. The tornado event involved three storm merger processes, each of which was associated with an increase in the echo intensity, vertical rising speed, and vertical vorticity of the supercell. Furthermore, during the last merger, the merging of the two vortices resulted in the reduction of the rotation radius of the new vortex, which also provided a favorable condition for tornadogenesis. A schematic was proposed to describe storm mergers. The characteristics of the velocity spectrum width were indicative of the occurrence and evolution of the tornado in this case. During the tornado stage, distinct polarimetric variable signatures (e.g., a tornado debris signature and a differential reflectivity arc) and radial velocity signatures (i.e., a tornadic vortex signature) were observed. Full article
(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)
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17 pages, 5566 KiB  
Article
European Grid Dataset of Actual Evapotranspiration, Water Availability and Effective Precipitation
by Mărgărit-Mircea Nistor, Alfrendo Satyanaga, Ştefan Dezsi and Ionel Haidu
Atmosphere 2022, 13(5), 772; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050772 - 10 May 2022
Cited by 6 | Viewed by 2085
Abstract
The sustainability of a territory is closely related to its resources. Due to climate change, the most precious natural resource, water, has been negatively affected by climatic conditions in terms of quantity and quality. CLIMAT datasets of 1 km2 spatial resolution were [...] Read more.
The sustainability of a territory is closely related to its resources. Due to climate change, the most precious natural resource, water, has been negatively affected by climatic conditions in terms of quantity and quality. CLIMAT datasets of 1 km2 spatial resolution were used and processed in the ArcGIS environment to generate maps of actual evapotranspiration, water availability, and effective precipitation for the periods of 1961–1990 (1990s), 2011–2040 (2020s), and 2041–2070 (2050s). The product is of paramount importance for the analysis of the actual situation in Europe indicating high water availability in the Alps Range, the Carpathians Mountains, Northern European countries, and the British Islands. On the other hand, low water availability has been evidenced in the Southern and Eastern European areas. For the future period (2050s), the monthly potential evapotranspiration is expected to increase by 30%. The climate models also show an increase in the actual evapotranspiration between past and future periods by 40%. The changes in water availability and effective precipitation between the past (1990s) and future (2050s) indicate decreases of 10%. The most affected areas by climate change are located within the Mediterranean areas, the Iberian Peninsula, and Eastern Europe. Full article
(This article belongs to the Section Climatology)
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15 pages, 24502 KiB  
Article
Two Large Earthquakes Registered by the CSES Satellite during Its Earthquake Prediction Practice in China
by Mei Li, Haitao Wang, Jie Liu and Xuhui Shen
Atmosphere 2022, 13(5), 751; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050751 - 06 May 2022
Cited by 9 | Viewed by 2804
Abstract
Two large earthquakes, the Maduo MS 7.4 earthquake and the Menyuan MS 6.9 earthquake, have been successfully recorded on the Chinese mainland, since the data of the CSES satellite were put into service for earthquake prediction work on the Chinese mainland [...] Read more.
Two large earthquakes, the Maduo MS 7.4 earthquake and the Menyuan MS 6.9 earthquake, have been successfully recorded on the Chinese mainland, since the data of the CSES satellite were put into service for earthquake prediction work on the Chinese mainland at the end of April 2020. Obvious variations in O+ density and electron density were found during our weekly data processing work during 5–11 May 2021 and 28 December 2021–2 January 2022, respectively. Two warnings of impending events around the anomalous areas within two weeks had been reported immediately after the anomaly appearance. The Maduo MS 7.4 earthquake occurred on 22 May 2021 and the Menyuan MS 6.9 earthquake on 8 January 2022, during these two warning periods. More details were revealed after these two large shocks occurred. Ionospheric enhancement took place on 8 May 2021, with a magnitude of 41.6% for O+ density and 22.2% for electron density, a distance of 680 km from the Maduo epicenter, 14 days prior to the event. Before the Menyuan earthquake, ionospheric enhancement took place on 28 December 2021, as well as during its revisiting orbit on 2 January 2022, with a magnitude of 47.3% for O+ density and 38.4% for electron density, an epicentral distance of 120 km, 11 and 6 days prior to this event. The Kp index was also examined to avoid the influence from solar activities. Despite this, accurate earthquake prediction is not possible due to much uncertainty, such as the correct location and magnitude of an impending event. Thus, long-term practice and comprehensive investigation of the seismo-ionospheric influence are necessary in the future. Full article
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12 pages, 32563 KiB  
Article
Density Estimation of Fog in Image Based on Dark Channel Prior
by Hong Guo, Xiaochun Wang and Hongjun Li
Atmosphere 2022, 13(5), 710; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050710 - 29 Apr 2022
Cited by 2 | Viewed by 3632
Abstract
This paper proposes a method and an original index for the estimation of fog density using images or videos. The proposed method had the advantages of convenient operation and low costs for applications in automatic driving and environmental monitoring. The index was constructed [...] Read more.
This paper proposes a method and an original index for the estimation of fog density using images or videos. The proposed method had the advantages of convenient operation and low costs for applications in automatic driving and environmental monitoring. The index was constructed based on a dark channel map and the pseudo-edge details of the foggy image. The effectiveness of the fog density index was demonstrated and validated through experiments on the two existing open datasets. The experimental results showed that the presented index could correctly estimate the fog density of images: (1) the estimated fog density value was consistent with the corresponding label in the Color Hazy Image Database (CHIC) in terms of rank order; (2) the estimated fog density level was consistent with the corresponding label in the Cityscapes database and the accuracy reached as high as 0.9812; (3) the proposed index could be used to evaluate the performance of a video defogging algorithm in terms of residual fog. Full article
(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)
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20 pages, 2512 KiB  
Article
Aerosol Optical Thickness Retrieval in Presence of Cloud: Application to S3A/SLSTR Observations
by Marta Luffarelli, Yves Govaerts and Lucio Franceschini
Atmosphere 2022, 13(5), 691; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050691 - 26 Apr 2022
Cited by 2 | Viewed by 2614
Abstract
The Combined Inversion of Surface and AeRosols (CISAR) algorithm for the joint retrieval of surface and aerosol single scattering properties has been further developed in order to extend the retrieval to clouds and overcome the need for an external cloud mask. Pixels located [...] Read more.
The Combined Inversion of Surface and AeRosols (CISAR) algorithm for the joint retrieval of surface and aerosol single scattering properties has been further developed in order to extend the retrieval to clouds and overcome the need for an external cloud mask. Pixels located in the transition zone between pure cloud and pure aerosol are often discarded by both aerosol and cloud algorithms, despite being essential for studying aerosol–cloud interactions, which still represent the largest source of uncertainty in climate predictions. The proposed approach aims at filling this gap and deepening the understanding of aerosol properties in cloudy environments. The new CISAR version is applied to Sentinel-3A/SLSTR observations and evaluated against different satellite products and ground measurements. The spatial coverage is greatly improved with respect to algorithms processing only pixels flagged as clear sky by the SLSTR cloud mask. The continuous retrieval of aerosol properties without any safety zone around clouds opens new possibilities for studying aerosol properties in cloudy environments. Full article
(This article belongs to the Special Issue Atmospheric Aerosol Optical Properties)
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12 pages, 2203 KiB  
Article
Influence of the Interdecadal Pacific Oscillation on Super Cyclone Activities over the Bay of Bengal during the Primary Cyclone Season
by Zhi Li, Zecheng Xu, Yue Fang and Kuiping Li
Atmosphere 2022, 13(5), 685; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050685 - 25 Apr 2022
Cited by 1 | Viewed by 1519
Abstract
An obvious interdecadal change can be measured in the super cyclones (SCs, categories 4 and 5) that occur from October to November over the Bay of Bengal (BoB). This change may be modulated by the interdecadal Pacific oscillation (IPO). A La Niña-like difference [...] Read more.
An obvious interdecadal change can be measured in the super cyclones (SCs, categories 4 and 5) that occur from October to November over the Bay of Bengal (BoB). This change may be modulated by the interdecadal Pacific oscillation (IPO). A La Niña-like difference between the 1977–1998 (IP1) and 1999–2014 (IP2) periods forced a local Hadley circulation in the eastern tropical Indian Ocean by strengthening the Walker circulation, which caused plummeting upper-level temperatures and ultimately created favorable thermodynamic conditions to enhance the cyclone intensity. Meanwhile, an equatorial downwelling Kelvin wave caused by heating and westerly wind differences entered the BoB rim along the coast and aptly intensified the cyclone, such that the downwelling Kevin wave and Rossby wave generated by its reflection deepened the thermocline in the BoB. The favorable atmospheric and oceanic conditions in IP2 jointly and preferentially cause far more SC activities from October to November over the BoB compared to IP1. Full article
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27 pages, 4753 KiB  
Article
A Climatology of Mesoscale Convective Systems in Northwest Mexico during the North American Monsoon
by Omar Ramos-Pérez, David K. Adams, Carlos A. Ochoa-Moya and Arturo I. Quintanar
Atmosphere 2022, 13(5), 665; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050665 - 22 Apr 2022
Cited by 6 | Viewed by 2341
Abstract
Mesoscale Convective Systems (MCS) may vary greatly with respect to their morphology, propagation mechanism, intensity, and under which synoptic-scale conditions as a function of topographic complexity. In this study, we develop a long-term climatology of MCS during the North American Monsoon focusing on [...] Read more.
Mesoscale Convective Systems (MCS) may vary greatly with respect to their morphology, propagation mechanism, intensity, and under which synoptic-scale conditions as a function of topographic complexity. In this study, we develop a long-term climatology of MCS during the North American Monsoon focusing on MCS morphology, lifecycle, and intensity as well as possible propagation mechanisms. We employ an MCS tracking and classification technique based on 23 years (1995 to 2017) of GOES IR satellite data. MCS intensity is also gauged with 7 years (2011 to 2017) of Vaisala GLD360 lightning data and, finally, monthly and interannual variability in synoptic conditions are examined with ERA5 reanalysis data. Our results based on 1594 identified MCS reveal that 98% are morphologically classified as Persistent Elongated Convective Systems. During the 23 summers (June through September) observed, the number of MCS varied considerably, averaging 70 MCS with minimum of 41 and maximum of 94. MCS typically have an average duration of around 8 h ± with a 2 h standard deviation. Propagation speeds, estimated with Hovmöller diagrams in addition to MCS centroid initial and final position, vary slightly depending on the trajectory. A notable result suggests that MCS propagation speeds are more consistent density currents or cold pools and not gravity waves nor steering-level winds. The results of this study could also provide a dataset for examining larger-scale controls on MCS frequency in addition to assesing convective parameterization and convective-resolving models in regions of complex topography. Full article
(This article belongs to the Special Issue Moist Atmospheric Convection)
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19 pages, 7333 KiB  
Article
Automated Recognition of Macro Downburst Using Doppler Weather Radar
by Xu Wang, Hailong Wang, Jianxin He, Zhao Shi and Chenghua Xie
Atmosphere 2022, 13(5), 672; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050672 - 22 Apr 2022
Cited by 1 | Viewed by 1785
Abstract
In light of the macro downburst’s ground divergent flow field characteristics and high reflectivity, this paper proposes an algorithm for identifying the downburst area using a Doppler weather radar low-level radial velocity and reflectivity factor (abbreviated as reflectivity, the same below). To binarize [...] Read more.
In light of the macro downburst’s ground divergent flow field characteristics and high reflectivity, this paper proposes an algorithm for identifying the downburst area using a Doppler weather radar low-level radial velocity and reflectivity factor (abbreviated as reflectivity, the same below). To binarize the radial velocity, perform quality control on the radial velocity and reflectivity, then combine the reflectivity and the radial velocity threshold. Following that, use the Eight-Neighborhood method to retrieve the positive and negative velocity connected regions and perform the connected regions. The positive and negative velocity pairs are then matched, and the zero Doppler velocity line between the positive and negative velocity pairs is extracted, followed by the center recognition of the positive and negative velocity downburst areas. The data of downbursts detected by Doppler radar in Jinan, Shandong Province, are used for algorithm verification in this paper. The results show that the proposed algorithm can detect the macro downburst area and identify the downburst center. Full article
(This article belongs to the Special Issue Identification and Optimization of Retrieval Model in Atmosphere)
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12 pages, 2722 KiB  
Article
Forecasting the June Ridge Line of the Western Pacific Subtropical High with a Machine Learning Method
by Cunyong Sun, Xiangjun Shi, Huiping Yan, Qixiao Jiang and Yuxi Zeng
Atmosphere 2022, 13(5), 660; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050660 - 21 Apr 2022
Cited by 2 | Viewed by 1333
Abstract
The ridge line of the western Pacific subtropical high (WPSHRL) plays an important role in determining the shift in the summer rain belt in eastern China. In this study, we developed a forecast system for the June WPSHRL index based on the latest [...] Read more.
The ridge line of the western Pacific subtropical high (WPSHRL) plays an important role in determining the shift in the summer rain belt in eastern China. In this study, we developed a forecast system for the June WPSHRL index based on the latest autumn and winter sea surface temperature (SST). Considering the adverse condition created by the small observed sample size, a very simple neural network (NN) model was selected to extract the non-linear relationship between input predictors (SST) and target predictands (WPSHRL) in the forecast system. In addition, some techniques were used to deal with the small sample size, enhance the stabilization of the forecast skills, and analyze the interpretability of the forecast system. The forecast experiments showed that the linear correlation coefficient between the predictions from the forecast system and their corresponding observations was around 0.6, and about three-fifths of the observed abnormal years (the years with an obviously high or low WPSHRL index) were successfully predicted. Furthermore, sensitivity experiments showed that the forecast system is relatively stable in terms of forecast skill. The above results suggest that the forecast system would be valuable in real-life applications. Full article
(This article belongs to the Section Climatology)
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22 pages, 184758 KiB  
Article
Concept of Using an Unmanned Aerial Vehicle (UAV) for 3D Investigation of Air Quality in the Atmosphere—Example of Measurements Near a Roadside
by Abdul Samad, Diego Alvarez Florez, Ioannis Chourdakis and Ulrich Vogt
Atmosphere 2022, 13(5), 663; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13050663 - 21 Apr 2022
Cited by 16 | Viewed by 3086
Abstract
A substantial amount of air pollution is emitted from urban sources. Hence, investigating air pollutant dispersion from urban sources is of great importance. The mechanisms influencing air pollutant dispersion also need to be studied thoroughly. Unmanned Aerial Vehicle (UAV)-based systems offer great potential [...] Read more.
A substantial amount of air pollution is emitted from urban sources. Hence, investigating air pollutant dispersion from urban sources is of great importance. The mechanisms influencing air pollutant dispersion also need to be studied thoroughly. Unmanned Aerial Vehicle (UAV)-based systems offer great potential for mobile exploration of air pollutants in the lower atmosphere due to the high maneuverability of multi-rotor UAVs. The aim of this study was to develop an effective UAV system that can perform high-resolution three-dimensional profiling of pollutants, such as particulate matter (PM), ultrafine particles (UFP), black carbon (BC), as well as meteorological parameters, including air temperature, relative humidity, pressure, wind speed, and wind direction. Different experiments were performed to finalize the positioning of the instruments on the UAV platform so as not to destabilize the drone during flight, even when the wind speed is high and during turbulent flight conditions. Another very crucial question is where to place the air inlet of the measurement devices. In addition, field tests were conducted to evaluate the stability of the UAV platform and the in-flight performance of the sensors. This UAV platform was deployed to perform vertical profiles at the University campus in Stuttgart-Vaihingen and in an area near the campus, close to the federal highway B14. The measurement campaign was performed on three days in February 2021, with a maximum flight height of 120 m above ground. The vertical profiles showed that concentrations were higher on the ground due to the proximity to the source and that high wind speeds assisted pollutant dispersion. The horizontal profiles showed that the pollutant concentrations were higher at the roadside and decreased with increasing distance from the road. In conclusion, this UAV platform represented a low-cost, practical, and reliable method for studying the three-dimensional distribution of pollutants near the source. Full article
(This article belongs to the Special Issue Novel Developments in Mobile Monitoring of Air Pollution)
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28 pages, 8213 KiB  
Article
Experimental Investigation of the Near-Surface Flow Dynamics in Downburst-like Impinging Jets Immersed in ABL-like Winds
by Federico Canepa, Massimiliano Burlando, Horia Hangan and Djordje Romanic
Atmosphere 2022, 13(4), 621; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13040621 - 13 Apr 2022
Cited by 5 | Viewed by 1613
Abstract
Downburst winds are strong downdrafts of cold air that embed into the atmospheric boundary layer (ABL) and produce intense horizontal outflow upon impingement on the ground. They are highly transient and three-dimensional extreme wind phenomena with a limited spatiotemporal structure that often makes [...] Read more.
Downburst winds are strong downdrafts of cold air that embed into the atmospheric boundary layer (ABL) and produce intense horizontal outflow upon impingement on the ground. They are highly transient and three-dimensional extreme wind phenomena with a limited spatiotemporal structure that often makes the anemometric measurements in nature inadequate for reconstructing their complex flow fields. In the framework of the project THUNDERR, an experimental campaign on downburst outflows has been carried out at the WindEEE Dome at Western University, Canada. The present study analyzes the three-dimensional interaction between downburst (DB) outflows produced as large-scale impinging jets and ABL winds. Most experimental, numerical and analytical models in the literature neglect this flow interplay or treat it in an oversimplistic manner through a vector superposition. We found that the generated near-surface outflow is asymmetric, and a high-intensity wind zone develops at the interface between DB and ABL winds. The time variability of the leading edge of the outflow was investigated by synchronizing all wind measurements across the testing chamber. The three-dimensional flow structure was studied using a refined grid of Cobra probes that sampled the flow at high frequencies. The passage of the primary vortex produced a significant decrease in the height of maximum radial wind speed, predominantly in the ABL-streamwise direction. The turbulence intensity was the highest in the region where DB propagates into oppositely directed ABL winds. Full article
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20 pages, 3528 KiB  
Article
Low- and Medium-Cost Sensors for Tropospheric Ozone Monitoring—Results of an Evaluation Study in Wrocław, Poland
by Marek Badura, Piotr Batog, Anetta Drzeniecka-Osiadacz and Piotr Modzel
Atmosphere 2022, 13(4), 542; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13040542 - 29 Mar 2022
Cited by 2 | Viewed by 2143
Abstract
The paper presents the results of a 1.5-year evaluation study of low- and medium-cost ozone sensors. The tests covered electrochemical sensors: SensoriC O3 3E 1 (City Technology) and semiconductor gas sensors: SM50 OZU (Aeroqual), SP3-61-00 (FIS) and MQ131 (Winsen). Three copies of each [...] Read more.
The paper presents the results of a 1.5-year evaluation study of low- and medium-cost ozone sensors. The tests covered electrochemical sensors: SensoriC O3 3E 1 (City Technology) and semiconductor gas sensors: SM50 OZU (Aeroqual), SP3-61-00 (FIS) and MQ131 (Winsen). Three copies of each sensor were enclosed in a measurement box and placed near the reference analyser (MLU 400). In the case of SensoriC O3 3E 1 sensors, the R2 values for the 1-h data were above 0.90 for the first 9 months of deployment, but a performance deterioration was observed in the subsequent months (R2 ≈ 0.6), due to sensor ageing processes. High linear relationships were observed for the SM50 devices (R2 > 0.94), but some periodic data offsets were reported, making regular checking and recalibration necessary. Power-law functions were used in the case of SP3-61-00 (R2 = 0.6–0.7) and MQ131 (R2 = 0.4–0.7). Improvements in the fittings were observed for models that included temperature and relative humidity data. In the case of SP3-61-00, the R2 values increased to above 0.82, while for MQ131 they increased to above 0.86. The study also showed that the measurement uncertainty of tested sensors meets the EU Directive 2008/50/EC requirements for indicative measurements and, in some cases, even for fixed measurements. Full article
(This article belongs to the Special Issue Air Pollution, Air Quality and Human Health)
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22 pages, 5283 KiB  
Article
A Sensitivity Study on High Resolution NWP ICON—LAM Model over Italy
by Carmine De Lucia, Edoardo Bucchignani, Andrea Mastellone, Marianna Adinolfi, Myriam Montesarchio, Davide Cinquegrana, Paola Mercogliano and Pasquale Schiano
Atmosphere 2022, 13(4), 540; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13040540 - 29 Mar 2022
Cited by 6 | Viewed by 2205
Abstract
In this work, the results of a sensitivity study based on ICON-LAM simulations at 2.5 km of spatial resolution over the Italian area, driven by ECMWF IFS global data, are presented. The main aim is to provide a contribution to the selection of [...] Read more.
In this work, the results of a sensitivity study based on ICON-LAM simulations at 2.5 km of spatial resolution over the Italian area, driven by ECMWF IFS global data, are presented. The main aim is to provide a contribution to the selection of suitable parameterization schemes that result in more effective for a proper representation of the Italian climate features. Model evaluation was conducted in terms of the air temperature and precipitation for three subregions, comparing a set of 13 simulations against SCIA and E-OBS standard datasets. In addition, evaluation was also conducted against selected data stations scattered over the Italian area. We found that the ICON-LAM model was able to provide a good representation of the temperature over Italy, whereas non-negligible biases were observed for precipitation in certain regions. The model proved to be sensitive to changes in physical parameterization schemes. In particular, we found that the explicit treatment of deep convection and the “clouds as in turbulence” scheme for cloud cover allowed for a better representation of precipitation in the summer over the Alpine region. The single moment scheme is currently the best option for cloud microphysics. Full article
(This article belongs to the Section Meteorology)
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10 pages, 236 KiB  
Article
Effects of Indoor Air Pollution on the Development of Children under Five Years of Age in Sri Lanka
by Nayomi Ranathunga, Priyantha Perera, Sumal Nandasena, Nalini Sathiakumar, Anuradhani Kasturiratne and Rajitha Wickremasinghe
Atmosphere 2022, 13(4), 509; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13040509 - 23 Mar 2022
Viewed by 2170
Abstract
Air pollution is a multifaceted environmental toxin affecting the Central Nervous System (CNS) through diverse pathways. The CNS of young children is particularly susceptible to the detrimental effects of toxins, as brain development continues postnatally with the formation of interneuronal connections, glial cell [...] Read more.
Air pollution is a multifaceted environmental toxin affecting the Central Nervous System (CNS) through diverse pathways. The CNS of young children is particularly susceptible to the detrimental effects of toxins, as brain development continues postnatally with the formation of interneuronal connections, glial cell proliferation and myelination of axons. Indoor air pollution (IAP) from solid fuel combustion is more harmful than outdoor air pollution. Numerous air pollutants hazardous to health are released during the burning of unprocessed biomass. The primary source of fuel in Sri Lanka for cooking is biomass, mainly wood. In this study, we evaluated the influence of IAP resulting from biomass combustion on the neurodevelopment of children. In a cohort of children under five years living in a semi-urban area of Sri Lanka, neurodevelopment was assessed using Denver II developmental screening test. Air quality levels were measured (Carbon Monoxide (CO) and Particulate Matter 2.5 (PM2.5)) in a subsample. There were significantly high levels of CO and PM2.5 in the ambient air of households using biomass as the primary fuel for cooking. Children living in these households had a significantly higher number of children with ‘suspect’ developmental assessment scores in the language, social behavior and play and gross motor development domains. Full article
18 pages, 43177 KiB  
Article
The Impact of Intra-Seasonal Oscillation on Westward Track Deflection of Super Typhoon Fitow (2013)
by Xinxin Bi, Guanghua Chen and Weican Zhou
Atmosphere 2022, 13(3), 474; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030474 - 14 Mar 2022
Viewed by 1716
Abstract
Typhoon Fitow (2013) took an unusual westward track deflection after a lengthy northward movement over the western North Pacific (WNP). Based on observation and wave analysis, it is found that the track deflection of Fitow is attributed to the transition of environmental flow [...] Read more.
Typhoon Fitow (2013) took an unusual westward track deflection after a lengthy northward movement over the western North Pacific (WNP). Based on observation and wave analysis, it is found that the track deflection of Fitow is attributed to the transition of environmental flow from meridional to zonal orientation, which is closely associated with a low-frequency intra-seasonal oscillation (ISO). Furthermore, the impact of ISO on tropical cyclone (TC) unusual movement is investigated using the Advanced Research version of Weather Research and Forecasting (WRF-ARW) model. The control simulation (CTL) reproduces well the synoptic pattern and track deflection of the TC. The TC moves straightly westward and northwestward without track deflection in the sensitivity experiments with the removal of total ISOs and the west-propagating ISO component, while keeping the recurving track with the removal of east-propagating ISO, which suggests that the west-propagating ISO plays a dominant role in the westward track deflection. In the experiment of removing west-propagating ISOs, an anomalous southeast–northwest-oriented wave train around the TC is modified, the mid-latitude trough decays, and the enhanced zonally elongated subtropical high is responsible for the straight northwestward motion of the TC. However, after removing a weaker convection anomaly associated with east-propagating ISOs in the form of a southwest–northeast oriented dipole circulation, the TC is affected by a sustained shallow mid-latitude trough and a west-extended ridge of subtropical high to keep the cyclonic track turning analogous to the counterpart in CTL. The piecewise potential vorticity inversion diagnosis further assesses the contribution of the different ISO components to TC track deflection. Full article
(This article belongs to the Section Meteorology)
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13 pages, 4760 KiB  
Article
Meteorological Analysis of the 2021 Extreme Wildfires in Greece: Lessons Learned and Implications for Early Warning of the Potential for Pyroconvection
by Theodore M. Giannaros, Georgios Papavasileiou, Konstantinos Lagouvardos, Vassiliki Kotroni, Stavros Dafis, Athanasios Karagiannidis and Eleni Dragozi
Atmosphere 2022, 13(3), 475; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030475 - 14 Mar 2022
Cited by 28 | Viewed by 4187
Abstract
The 2021 fire season in Greece was the worst of the past 13 years, resulting in more than 130,000 ha of burnt area, with about 70% consumed by five wildfires that ignited and spread in early August. Common to these wildfires was the [...] Read more.
The 2021 fire season in Greece was the worst of the past 13 years, resulting in more than 130,000 ha of burnt area, with about 70% consumed by five wildfires that ignited and spread in early August. Common to these wildfires was the occurrence of violent pyroconvection. This work presents a meteorological analysis of this outbreak of extreme pyroconvective wildfires. Our analysis shows that dry and warm antecedent weather preconditioned fuels in the fire-affected areas, creating a fire environment that alone could effectively support intense wildfire activity. Analysis of surface conditions revealed that the ignition and the most active spread of all wildfires coincided with the most adverse fire weather since the beginning of the fire season. Further, the atmospheric environment was conducive to violent pyroconvection, as atmospheric instability gradually increased amid the breakdown of an upper-air ridge ahead of an approaching long-wave trough. In summary, we highlight that the severity and extent of the 2021 Greek wildfires were not surprising considering the fire weather potential for the period when they ignited. Continuous monitoring of the large- and local-scale conditions that promote extreme fire behavior is imperative for improving Greece’s capacity for managing extreme wildfires. Full article
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17 pages, 9378 KiB  
Article
Signal Simulation of Dual-Polarization Weather Radar and Its Application in Range Ambiguity Mitigation
by Shaojun Dai, Xuehua Li, Zhichao Bu, Yajun Chen, Jianxin He, Minghua Li and Maojie Xiong
Atmosphere 2022, 13(3), 432; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030432 - 08 Mar 2022
Cited by 1 | Viewed by 2656
Abstract
In this paper, a dual-polarization weather radar echo signal simulation method is proposed for the evaluation of the performance enhancement of dual-polarization weather radar systems, the optimization of signal processing algorithms and the improvement of scanning strategies. The actual weather radar base data [...] Read more.
In this paper, a dual-polarization weather radar echo signal simulation method is proposed for the evaluation of the performance enhancement of dual-polarization weather radar systems, the optimization of signal processing algorithms and the improvement of scanning strategies. The actual weather radar base data are used in the simulation as the reference weather scene, which avoids using a complex algorithm for weather modeling. Moreover, based on radar weather equations, the radar system parameters are added into the radar echo signal modeling to establish the relationship between the simulated echo signal and radar system. As a result, the final simulated echo signal not only shows both the time and frequency domain characteristics of the weather target, but also includes the effects of the important performance of the dual-polarization weather radar system. In addition, to evaluate the performance of range ambiguity mitigation using phase coding and batch working modes, two different simulation methods for the radar signal are established on the method above; one is for batch working mode with long-PRT (pulse repetition time) and short-PRT transmission and receiving, and the other is for phase-coded mode with phase-coded transmission and phase-uncoded receiving. Under the same weather scene, the observation of these two different methods of range ambiguity mitigation are simulated and compared. Results show that the performance of the phase coding mode for mitigating range ambiguity is better than that of the batch mode. Obviously, the simulation method can be used to directly show the observation of different algorithms for mitigation range ambiguity under the same weather process, and quickly compare and evaluate the algorithm’s performance, which is not possible for real radars. Full article
(This article belongs to the Special Issue Radar Sensing Atmosphere: Modelling, Imaging and Prediction)
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17 pages, 5774 KiB  
Article
Analysis of Wildfires in the Mid and High Latitudes Using a Multi-Dataset Approach: A Case Study in California and Krasnoyarsk Krai
by Lerato Shikwambana and John Bosco Habarulema
Atmosphere 2022, 13(3), 428; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030428 - 07 Mar 2022
Viewed by 2250
Abstract
In this study, we investigate the emissions from wildfires in the mid latitude (California) and high latitude (Krasnoyarsk Krai) during the periods of 16–17 August 2020 and 28 July 2019, respectively. Wildfires are unique in themselves as they are driven by various factors [...] Read more.
In this study, we investigate the emissions from wildfires in the mid latitude (California) and high latitude (Krasnoyarsk Krai) during the periods of 16–17 August 2020 and 28 July 2019, respectively. Wildfires are unique in themselves as they are driven by various factors such as fuel type, topology, and meteorology. In this study, we analyze whether there are any major variations in the emissions and transport of pollutants between two large wildfire cases in the mid latitude of California and high latitude of Krasnoyarsk Krai. The study is important to understand and characterize the emission regime from biomass burning of different land covers using a mutli-dataset approach. We analyze whether there are any major variations in the emissions and transport of pollutants from these wildfires. For example, the aerosol extinction coefficient profile showed smoke detected at the highest altitude of 9 km in Krasnoyarsk Krai, whereas in California the highest altitude was observed at approximately 6 km. Moreover, large values of black carbon (BC) concentration were observed in Krasnoyarsk Krai approximately 7 µg/m3 compared to the 0.44 µg/m3 observed in California. Areas with an immense dense vegetation are prone to large emissions. The results from this case study suggest that high latitude wildfires emit more pollutants than mid latitude wildfires. However, more studies in the future will be conducted to conclude this observation and finding with certainty. Full article
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22 pages, 8743 KiB  
Article
Aviation Turbulence Forecasting over the Portuguese Flight Information Regions: Algorithm and Objective Verification
by Margarida Belo-Pereira
Atmosphere 2022, 13(3), 422; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030422 - 05 Mar 2022
Cited by 1 | Viewed by 2273
Abstract
Aviation turbulence remains one of the leading causes of weather-related aviation accidents. Therefore, turbulence prediction is a major concern of aviation forecasters. This paper describes the turbulence index (TURBIPMA) developed and used operationally at the Portuguese Institute of Sea and [...] Read more.
Aviation turbulence remains one of the leading causes of weather-related aviation accidents. Therefore, turbulence prediction is a major concern of aviation forecasters. This paper describes the turbulence index (TURBIPMA) developed and used operationally at the Portuguese Institute of Sea and Atmosphere (IPMA), based on several diagnostics derived from ECMWF forecasts, using a new calibration approach. The forecast skill of the TURBIPMA and of individual diagnostics are evaluated using turbulence observations over the Portuguese Flight Information Regions and surrounding areas, for 12 months between February 2020 and March 2021 (excluding May and June). The forecasting skill of the predictors is discussed in terms of the Relative Operating Characteristic (ROC) curves, which is widely applied, but also in terms of novel measures such as the Symmetric Extremal Dependence Index (SEDI) and Symmetric Extreme Dependency Score (SEDS). The new measures are particularly relevant in assessing forecasts of rare events, such as moderate-or-greater turbulence. The operational index outperforms individual diagnostics (such as Ellrod) in terms of all verification measures. Furthermore, the use of a new Richardson number function was proven to be beneficial. Finally, the turbulence prediction by IPMA was comparable to that of the London WAFC for one turbulence episode. Full article
(This article belongs to the Special Issue Atmospheric Turbulence: Observations and Models)
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16 pages, 1911 KiB  
Article
Sources and Seasonal Variance of Ambient Volatile Organic Compounds in the Typical Industrial City of Changzhi, Northern China
by Xiangyu Zhang, Yulong Yan, Xiaolin Duan, Jianwei Chai, Rumei Li, Yang Xu, Zhiyong Li and Lin Peng
Atmosphere 2022, 13(3), 393; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030393 - 27 Feb 2022
Cited by 8 | Viewed by 2635
Abstract
Volatile organic compounds (VOCs) emitted from industrial processes, which are major emission sources of air pollutants, could cause significant impacts on air quality. However, studies on the comprehensive analysis from sources contributing to the health risk perspective regarding ambient VOCs in industrial cities [...] Read more.
Volatile organic compounds (VOCs) emitted from industrial processes, which are major emission sources of air pollutants, could cause significant impacts on air quality. However, studies on the comprehensive analysis from sources contributing to the health risk perspective regarding ambient VOCs in industrial cities are limited. In this study, VOC samples were collected from 15 April 2018 to 19 October 2018 in Changzhi, a typical industrial city in northern China, and a total of 57 VOCs were measured for analysis. The average VOC concentrations were 54.4 µg·m−3, with the highest concentrations in autumn (58.4 µg·m−3). Ambient VOCs in spring, summer and autumn were all dominated by alkanes (66.8%), with contributions of 70.3%, 66.3% and 63.8%, respectively. The top five concentrations of total VOCs were isopentane (19.0%), ethane (9.5%), n-butane (8.1%), benzene (7.9%) and propane (5.2%), indicating that vehicle exhaust and coal combustion are the main sources of VOCs. Source apportionment by principal component analysis showed that vehicle exhaust (27.5%) and coal combustion (23.5%) were the main sources of VOCs in Changzhi, followed by industrial production (17.4%), solvent evaporation (13.5%), liquefied petroleum gas/natural gas leaking (9.5%), and biogenic emissions (8.7%). Sources of coal combustion and vehicle exhaust contributed more VOCs than industrial production. The carcinogenic risks of benzene (3.4 × 10−5) and ethylbenzene (2.2 × 10−6) were higher than the limit levels (1 × 10−6). Coal combustion contributed most (25.3%) to the carcinogenic risks because of its high VOC emissions. In an industrial city such as Changzhi, vehicle exhaust and coal combustion have become major sources of ambient air VOCs owing to the increasingly stringent industrial standards. Therefore, VOCs from vehicle exhaust and coal combustion also need to take into account mitigation measures for VOCs from the perspective of source contribution to health risk. Full article
(This article belongs to the Section Air Quality and Human Health)
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11 pages, 370 KiB  
Article
Ionospheric Science: An Example of the Importance of Diversity in Approaches to Scientific Research
by Mike Hapgood
Atmosphere 2022, 13(3), 394; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030394 - 27 Feb 2022
Cited by 4 | Viewed by 2609
Abstract
This paper discusses the strategic importance of contemporary ionospheric science. It outlines some key features of the evolution of the science from the first practical experiments in the 1920s through to the diverse inter-disciplinary science of today. This science includes fundamental studies of [...] Read more.
This paper discusses the strategic importance of contemporary ionospheric science. It outlines some key features of the evolution of the science from the first practical experiments in the 1920s through to the diverse inter-disciplinary science of today. This science includes fundamental studies of partially ionised plasmas and of the complex systems that arise when those plasmas are coupled to neutral atmospheres and magnetospheres. However, the science also has great potential to deliver societal benefits if the science can be refined to obtain a deep physical understanding of ionospheric phenomena and that understanding is then transitioned into use by operational services such as forecasts of ionospheric conditions. Thus, ionospheric science is now very similar in form to other environment sciences and, the same as them, needs to be positioned in a diverse scientific culture that supports the full range of science research, including not only curiosity-driven studies, but also targeted research to deepen our physical understanding to a level that is sufficient to enable a transition to operational services. That diversity also includes support for that transition and also facilitates feedback from operations teams to researchers. Such feedback can be a powerful stimulus for future research. Full article
(This article belongs to the Special Issue Ionospheric Monitoring and Modelling for Space Weather)
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14 pages, 2271 KiB  
Article
Ionospheric Variability during the 2020–2021 SSW: COSMIC-2 Observations and WACCM-X Simulations
by Nicholas Pedatella
Atmosphere 2022, 13(3), 368; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030368 - 22 Feb 2022
Cited by 6 | Viewed by 1977
Abstract
Variability in the ionosphere during the 2020–2021 sudden stratospheric warming (SSW) is investigated using a combination of Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2) observations and the Whole Atmosphere Community Climate Model with thermosphere–ionosphere eXtension (WACCM-X) simulations. The unprecedented spatial–temporal sampling [...] Read more.
Variability in the ionosphere during the 2020–2021 sudden stratospheric warming (SSW) is investigated using a combination of Constellation Observing System for Meteorology, Ionosphere, and Climate-2 (COSMIC-2) observations and the Whole Atmosphere Community Climate Model with thermosphere–ionosphere eXtension (WACCM-X) simulations. The unprecedented spatial–temporal sampling of the low latitude ionosphere afforded by COSMIC-2 enables investigating the short-term (<5 days) variability in the ionosphere during the SSW event. The COSMIC-2 observations reveal a reduction in the diurnal and zonal mean ionosphere total electron content (ITEC) and reduced amplitude of the diurnal variation in the ionosphere during the SSW. Enhanced ITEC amplitudes of the semidiurnal solar and lunar migrating tides and the westward propagating semidiurnal tide with zonal wavenumber 3 are also observed. The WACCM-X simulations demonstrate that these variations are driven by variability in the stratosphere–mesosphere during the 2020–2021 SSW event. The results show the impact of the 2020–2021 SSW on the mean state, diurnal, and semidiurnal variations in the ionosphere, as well as the capabilities of the COSMIC-2 mission to observe short-term variability in the ionosphere that is driven by meteorological variability in the lower atmosphere. Full article
(This article belongs to the Special Issue Advances in GNSS Radio Occultation Technique and Applications)
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17 pages, 2800 KiB  
Article
Evaluating Probability Distribution Functions for the Standardized Precipitation Evapotranspiration Index over Ethiopia
by Estifanos Addisu Yimer, Bert Van Schaeybroeck, Hans Van de Vyver and Ann van Griensven
Atmosphere 2022, 13(3), 364; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13030364 - 22 Feb 2022
Cited by 11 | Viewed by 3474
Abstract
Drought indices are used to identify and monitor drought events. The standardized precipitation evapotranspiration index (SPEI) is a widely used index based on accumulated water balance. There is, however, no broad consensus on which probability distribution is the most appropriate for water balances. [...] Read more.
Drought indices are used to identify and monitor drought events. The standardized precipitation evapotranspiration index (SPEI) is a widely used index based on accumulated water balance. There is, however, no broad consensus on which probability distribution is the most appropriate for water balances. This issue is investigated for Ethiopia using 125 meteorological stations spread across the country. Based on long-term series, a selection was made among the generalized extreme value, Pearson type 3, and generalized logistics (Genlog) distributions. Additionally, the effect of using actual, instead of potential, evapotranspiration and a limited amount of data (10, 15, 20, and 25 years) is explored. Genlog is found to be the best distribution for all accumulation periods. Furthermore, there is a considerable difference amongst the SPEI values estimated from the three distributions on the identification of extreme wet or extreme dry periods. Next, there are significant differences between standardized precipitation actual evapotranspiration index (SPAEI) and SPEI, signifying the importance of drought index selection for proper drought monitoring. Finally, time series of 20 or 25 years of data lead to almost similar SPEI values to those estimated using more than 30 years of data, so could potentially be used to assess drought in Ethiopia. Full article
(This article belongs to the Special Issue Agrometeorology)
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16 pages, 2025 KiB  
Article
A New Method for the Assessment of the Oxidative Potential of Both Water-Soluble and Insoluble PM
by Maria Agostina Frezzini, Gianluca Di Iulio, Caterina Tiraboschi, Silvia Canepari and Lorenzo Massimi
Atmosphere 2022, 13(2), 349; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13020349 - 19 Feb 2022
Cited by 5 | Viewed by 1895
Abstract
Water-soluble and insoluble fractions of airborne particulate matter (PM) exhibit different toxicological potentials and peculiar mechanisms of action in biological systems. However, most of the research on the oxidative potential (OP) of PM is focused exclusively on its water-soluble fraction, since experimental criticisms [...] Read more.
Water-soluble and insoluble fractions of airborne particulate matter (PM) exhibit different toxicological potentials and peculiar mechanisms of action in biological systems. However, most of the research on the oxidative potential (OP) of PM is focused exclusively on its water-soluble fraction, since experimental criticisms were encountered for detaching the whole PM (soluble and insoluble species) from field filters. However, to estimate the actual potential effects of PM on human health, it is essential to assess the OP of both its water-soluble and insoluble fractions. In this study, to estimate the total OP (TOP), an efficient method for the detachment of intact PM10 from field filters by using an electrical toothbrush was applied to 20 PM10 filters in order to obtain PM10 water suspensions to be used for the DCFH, AA and DTT oxidative potential assays (OPDCFH, OPAA and OPDTT). The contribution of the insoluble PM10 to the TOP was evaluated by comparing the TOP values to those obtained by applying the three OP assays to the water-soluble fraction of 20 equivalent PM10 filters. The OP of the insoluble fraction (IOP) was calculated as the difference between the TOP and the WSOP. Moreover, each PM10 sample was analyzed for the water-soluble and insoluble fractions of 10 elements (Al, Cr, Cs, Cu, Fe, Li, Ni, Rb, Sb, Sn) identified as primary elemental tracers of the main emission sources in the study area. A principal component analysis (PCA) was performed on the data obtained to identify the predominant sources for the determination of TOP, WSOP, and IOP. Results showed that water-soluble PM10 released by traffic, steel plant, and biomass burning is mainly responsible for the generation of the TOP as well as of the WSOP. This evidence gave strength to the reliability of the results from OP assays performed only on the water-soluble fraction of PM. Lastly, the IOPDCFH and IOPDTT were found to be principally determined by insoluble PM10 from mineral dust. Full article
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15 pages, 3463 KiB  
Article
Clustering Analysis on Drivers of O3 Diurnal Pattern and Interactions with Nighttime NO3 and HONO
by Xue Wang, Shanshan Wang, Sanbao Zhang, Chuanqi Gu, Aimon Tanvir, Ruifeng Zhang and Bin Zhou
Atmosphere 2022, 13(2), 351; https://0-doi-org.brum.beds.ac.uk/10.3390/atmos13020351 - 19 Feb 2022
Cited by 4 | Viewed by 2253
Abstract
The long-path differential optical absorption spectroscopy (LP-DOAS) technique was deployed in Shanghai to continuously monitor ozone (O3), formaldehyde (HCHO), nitrogen dioxide (NO2), nitrous acid (HONO), and nitrate radical (NO3) mixing ratios from September 2019 to August 2020. [...] Read more.
The long-path differential optical absorption spectroscopy (LP-DOAS) technique was deployed in Shanghai to continuously monitor ozone (O3), formaldehyde (HCHO), nitrogen dioxide (NO2), nitrous acid (HONO), and nitrate radical (NO3) mixing ratios from September 2019 to August 2020. Through a clustering method, four typical clusters of the O3 diurnal pattern were identified: high during both the daytime and nighttime (cluster 1), high during the nighttime but low during the daytime (cluster 2), low during both the daytime and nighttime (cluster 3), and low during the nighttime but high during the daytime (cluster 4). The drivers of O3 variation for the four clusters were investigated for the day- and nighttime. Ambient NO caused the O3 gap after midnight between clusters 1 and 2 and clusters 3 and 4. During the daytime, vigorous O3 generation (clusters 1 and 4) was found to accompany higher temperature, lower humidity, lower wind speed, and higher radiation. Moreover, O3 concentration correlated with HCHO for all clusters except for the low O3 cluster 3, while O3 correlated with HCHO/NOx, but anti-correlated with NOx for all clusters. The lower boundary layer height before midnight hindered O3 diffusion and accordingly determined the final O3 accumulation over the daily cycle for clusters 1 and 4. The interactions between the O3 diel profile and other atmospheric reactive components established that higher HONO before sunrise significantly promoted daytime O3 generation, while higher daytime O3 led to a higher nighttime NO3 level. This paper summarizes the interplays between day- and nighttime oxidants and oxidation products, particularly the cause and effect for daytime O3 generation from the perspective of nighttime atmospheric components. Full article
(This article belongs to the Special Issue Recent Advances in Optical Remote Sensing of Atmosphere)
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