Atmosphere

26 pages, 9032 KiB

Open AccessArticle

Relative Humidity and Air Temperature Characteristics and Their Drivers in Africa Tropics

by Isaac Kwesi Nooni, Faustin Katchele Ogou, Abdoul Aziz Saidou Chaibou, Samuel Koranteng Fianko, Thomas Atta-Darkwa and Nana Agyemang Prempeh

Atmosphere 2025, 16(7), 828; https://doi.org/10.3390/atmos16070828 - 8 Jul 2025

Abstract

In a warming climate, rising temperature are expected to influence atmospheric humidity. This study examined the spatio-temporal dynamics of temperature (TEMP) and relative humidity (RH) across Equatorial Africa from 1980 to 2020. The analysis used RH data from European Centre of Medium-range Weather [...] Read more.

In a warming climate, rising temperature are expected to influence atmospheric humidity. This study examined the spatio-temporal dynamics of temperature (TEMP) and relative humidity (RH) across Equatorial Africa from 1980 to 2020. The analysis used RH data from European Centre of Medium-range Weather Forecasts Reanalysis v.5 (ERA5) reanalysis, TEMP and precipitation (PRE) from Climate Research Unit (CRU), and soil moisture (SM) and evapotranspiration (ET) from the Global Land Evaporation Amsterdam Model (GLEAM). In addition, four teleconnection indices were considered: El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). This study used the Mann–Kendall test and Sen’s slope estimator to analyze trends, alongside multiple linear regression to investigate the relationships between TEMP, RH, and key climatic variables—namely evapotranspiration (ET), soil moisture (SM), and precipitation (PRE)—as well as large-scale teleconnection indices (e.g., IOD, ENSO, PDO, and NAO) on annual and seasonal scales. The key findings are as follows: (1) mean annual TEMP exceeding 30 °C and RH less than 30% were concentrated in arid regions of the Sahelian–Sudano belt in West Africa (WAF), Central Africa (CAF) and North East Africa (NEAF). Semi-arid regions in the Sahelian–Guinean belt recorded moderate TEMP (25–30 °C) and RH (30–60%), while the Guinean coastal belt and Congo Basin experienced cooler, more humid conditions (TEMP < 20 °C, RH (60–90%). (2) Trend analysis using Mann–Kendal and Sen slope estimator analysis revealed spatial heterogeneity, with increasing TEMP and deceasing RH trends varying by region and season. (3) The warming rate was higher in arid and semi-arid areas, with seasonal rates exceeding annual averages (0.18 °C decade⁻¹). Winter (0.27 °C decade⁻¹) and spring (0.20 °C decade⁻¹) exhibited the strongest warming, followed by autumn (0.18 °C decade⁻¹) and summer (0.10 °C decade⁻¹). (4) RH trends showed stronger seasonal decline compared to annual changes, with reduction ranging from 5 to 10% per decade in certain seasons, and about 2% per decade annually. (5) Pearson correlation analysis demonstrated a strong negative relationship between TEMP and RH with a correlation coefficient of r = − 0.60. (6) Significant associations were also observed between TEMP/RH and both climatic variables (ET, SM, PRE) and large scale-teleconnection indices (ENSO, IOD, PDO, NAO), indicating that surface conditions may reflect a combination of local response and remote climate influences. However, further analysis is needed to distinguish the extent to which local variability is independently driven versus being a response to large-scale forcing. Overall, this research highlights the physical mechanism linking TEMP and RH trends and their climatic drivers, offering insights into how these changes may impact different ecological and socio-economic sectors. Full article

(This article belongs to the Special Issue Precipitation in Africa (2nd Edition))

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19 pages, 6481 KiB

Open AccessArticle

Aerosol Composition in a Semi-Urban Environment in Central Mexico: Influence of Local and Regional Processes on Overall Composition and First Quantification of Nitroaromatics

by Sara E. Olivares-Salazar, Roya Bahreini, Ying-Hsuan Lin, Telma Castro, Harry Alvarez-Ospina and Dara Salcedo

Atmosphere 2025, 16(7), 827; https://doi.org/10.3390/atmos16070827 - 7 Jul 2025

Abstract

The Metropolitan Area of Queretaro (MAQ) is a significant industrial hub in central Mexico whose air quality, including high concentrations of particulate matter (PM), poses a risk to the population. However, there have not been many studies on the sources and processes that [...] Read more.

The Metropolitan Area of Queretaro (MAQ) is a significant industrial hub in central Mexico whose air quality, including high concentrations of particulate matter (PM), poses a risk to the population. However, there have not been many studies on the sources and processes that influence the concentration of atmospheric pollutants. We used aerosol chemical composition and meteorological data from 1 January to 15 May 2022, along with back-trajectory modeling, to investigate emission sources not previously described in the region and the impact of local and regional meteorology on the chemical composition of aerosols. Furthermore, this study presents the first quantitative analysis of nitroaromatic compounds (NACs) in particulate matter in the MAQ using ultra-performance liquid chromatography coupled with high-resolution mass spectrometry. The NAC concentrations ranged from 0.086 to 3.618 ng m⁻³, with the highest concentrations occurring during a period of atmospheric stability. The secondary inorganic and organic fractions of the PM were the most abundant (50%) of the PM concentration throughout the campaign. Local and regional meteorology played a significant role in the variability of PM chemical composition, as it influenced oxidation and transport processes. The results reveal that emissions from biomass burning are a recurrent PM source, and regional emissions significantly impact the organic fraction of the PM. These results underscore the importance of considering both local and regional sources in assessing air pollution in the region. Full article

(This article belongs to the Section Aerosols)

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11 pages, 4042 KiB

Open AccessArticle

Assessment of ERA5-Land Reanalysis Precipitation Data in the Qilian Mountains of China

by Lihui Qian and Peng Zhao

Atmosphere 2025, 16(7), 826; https://doi.org/10.3390/atmos16070826 - 7 Jul 2025

Abstract

Precipitation serves as a crucial indicator of climate change and a vital part of the water cycle in mountainous regions. ERA5-Land, a cutting-edge global reanalysis dataset designed for land applications, has been extensively utilized in climate-related studies. In this research, we assessed the [...] Read more.

Precipitation serves as a crucial indicator of climate change and a vital part of the water cycle in mountainous regions. ERA5-Land, a cutting-edge global reanalysis dataset designed for land applications, has been extensively utilized in climate-related studies. In this research, we assessed the reliability of ERA5-Land monthly averaged reanalysis precipitation data in the Qilian Mountains (QLM). We did this by comparing it with the observations from 17 meteorological stations spanning from 1979 to 2017. The findings indicated that, overall, the ERA5-Land reanalysis precipitation data tended to overestimate the observed precipitation in the Qilian Mountains. The determination coefficient (R²) of the linear regression between ERA5-Land reanalysis precipitation and the observations was 0.97. This value implies that ERA5-Land reanalysis precipitation generally has good applicability in the Qilian Mountains. However, the annual-scale root mean square error (RMSE) was 3.97. This suggests that ERA5-Land reanalysis precipitation data cannot be directly applied to studies at a single meteorological station. The deviation between the ERA5-Land reanalysis precipitation data and the observed precipitation data can be ascribed to the altitude difference between meteorological stations and ERA5-Land grid points. Generally, as the altitude difference between meteorological stations and ERA5-Land grid points increases, the precipitation deviation also rises. This research can furnish a reference for the application of ERA5-Land reanalysis precipitation data in the Qilian Mountains. Full article

(This article belongs to the Section Meteorology)

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13 pages, 2769 KiB

Open AccessArticle

Assessment of Vertical Redistribution of Electron Density in Ionosphere During an X-Class Solar Flare Using GNSS Data

by Susanna Bekker

Atmosphere 2025, 16(7), 825; https://doi.org/10.3390/atmos16070825 - 7 Jul 2025

Abstract

The impact of solar flares on the Earth’s ionosphere has been studied for many decades using both experimental and theoretical approaches. However, the accuracy of predicting ionospheric layer dynamics in response to variations in solar radiation remains limited. In particular, understanding the vertical [...] Read more.

The impact of solar flares on the Earth’s ionosphere has been studied for many decades using both experimental and theoretical approaches. However, the accuracy of predicting ionospheric layer dynamics in response to variations in solar radiation remains limited. In particular, understanding the vertical redistribution of charged particles in the ionosphere during flares with different spectral characteristics presents a significant challenge. In this study, a method is presented for reconstructing the temporal evolution of the vertical electron concentration (

N e

) profile based on GNSS (Global Navigation Satellite Systems) measurements of total electron content along partially illuminated satellite-receiver paths. Using this method, vertical profiles of

N e

were reconstructed during various phases of the X13.3-class solar flare that occurred on 6 September 2017. The resulting profiles correctly respond to the observed variations in solar extreme ultraviolet and X-ray radiation. This indicates that the method can be effectively applied to analyse other powerful solar events. Full article

(This article belongs to the Special Issue Feature Papers in Upper Atmosphere (2nd Edition))

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12 pages, 1858 KiB

Open AccessArticle

Botanical Studies Based on Textual Evidence in Eastern Asia and Its Implications for the Ancient Climate

by Haiming Liu, Huijia Song, Fei Duan and Liang Shen

Atmosphere 2025, 16(7), 824; https://doi.org/10.3390/atmos16070824 - 7 Jul 2025

Abstract

Understanding morphological descriptions of plants documented by ancient peoples over 1000 years ago and identifying the species they described are critical for reconstructing the natural geographic distribution of plant taxa, tracking taxonomic variations, and inferring historical climate dynamics. Analyzing shifts in plant communities [...] Read more.

Understanding morphological descriptions of plants documented by ancient peoples over 1000 years ago and identifying the species they described are critical for reconstructing the natural geographic distribution of plant taxa, tracking taxonomic variations, and inferring historical climate dynamics. Analyzing shifts in plant communities and climatic conditions during this period is essential to unravel the interplay among floristic composition, climate fluctuations, and anthropogenic impacts. However, research in this field remains limited, with greater emphasis placed on plant taxa from hundreds of millions of years ago. Investigations into flora and climate during the last two millennia are sparse, and pre-millennial climatic conditions remain poorly characterized. In this study, a historical text written 1475 years ago was analyzed to compile plant names and morphological features, followed by taxonomic identification. The research identified three gymnosperm species (one in Pinaceae, two in Cupressaceae), 1 Tamaricaceae species (dicotyledon), and 19 dicotyledon species. However, three plant groups could only be identified at the genus level. Using textual analysis and woody plant coexistence methods, the climate of 1475 years ago in western Henan Province, located in the middle-lower Yellow River basin in East Asia, was reconstructed. Results indicate that the mean temperature of the coldest month (MTCM) was approximately 1.3 °C higher than modern values. In comparison, the mean temperature of the warmest month (MTWM) and mean annual temperature (MAT) were lower than present-day levels. This suggests slightly cooler overall conditions with milder seasonal extremes in ancient Luoyang—a finding supported by contemporaneous studies. Furthermore, annual precipitation (AP), precipitation of the warmest quarter (PWQ), and precipitation of the coldest quarter (PCQ) in the Luoyang region 1475 years ago exceeded modern measurements, despite the area’s monsoonal climate. This suggests significantly higher atmospheric moisture content in ancient air masses compared to today. This study provides floristic and climatic baseline data for advancing our understanding of global climate variability at millennial scales. Full article

(This article belongs to the Section Climatology)

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18 pages, 939 KiB

Open AccessArticle

Estimates of Isotope Ratios in the Magnetosphere and Implications for Implantation of Atmosphere in Lunar Regolith

by James R. Lyons and Sarah Uddin

Atmosphere 2025, 16(7), 823; https://doi.org/10.3390/atmos16070823 - 7 Jul 2025

Abstract

The plasma in Earth’s magnetosphere is comprised of ions from the solar wind and from Earth’s polar wind, with the orientation of the interplanetary magnetic field (IMF) acting to modulate the relative contributions from these two sources. Although ion composition and charge state [...] Read more.

The plasma in Earth’s magnetosphere is comprised of ions from the solar wind and from Earth’s polar wind, with the orientation of the interplanetary magnetic field (IMF) acting to modulate the relative contributions from these two sources. Although ion composition and charge state are strong indicators of ion provenance, here we consider isotope ratios as a possible additional method for tracing plasma provenance. Solar wind isotope ratios have been well characterized, but isotope ratios have not been measured for magnetospheric plasma, and only a few measurements have been made for Earth’s ionosphere. Accounting for diffusive separation in the ionosphere, and using a magnetospheric source flux model, we estimate isotope ratios for several light ions (H⁺, He⁺, N⁺ and O⁺) in the magnetosphere. The primary source of N and O magnetospheric ions is the polar wind, and He ions come primarily from the solar wind. H ions come from both polar and solar winds. The extreme diffusive separation of O⁺ isotopes argues against the polar wind as a significant source of O to the lunar regolith during the passage of the Moon through the magnetotail. Full article

(This article belongs to the Special Issue Research and Space-Based Exploration on Space Plasma)

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17 pages, 4778 KiB

Open AccessArticle

Occurrence and Atmospheric Patterns Associated with Individual and Compound Heatwave–Ozone Events in São Paulo Megacity

by Vanessa Silveira Barreto Carvalho, Paola do Nascimento Silva, Aline Araújo de Freitas, Vitor Lucas dos Santos Rosa Tenório, Michelle Simões Reboita, Taciana Toledo de Almeida Albuquerque and Leila Droprinchinski Martins

Atmosphere 2025, 16(7), 822; https://doi.org/10.3390/atmos16070822 - 6 Jul 2025

Abstract

High ozone (O₃) concentrations are frequently recorded in São Paulo Megacity, with extreme O₃ levels often linked to high temperatures and heatwaves, phenomena expected to intensify with climate change. The co-occurrence of extreme O₃ and heatwaves poses amplified risks [...] Read more.

High ozone (O₃) concentrations are frequently recorded in São Paulo Megacity, with extreme O₃ levels often linked to high temperatures and heatwaves, phenomena expected to intensify with climate change. The co-occurrence of extreme O₃ and heatwaves poses amplified risks to environmental and human health. Hence, this study aims to analyze individual and compound extreme O₃ and heatwave events and assess the associated atmospheric patterns. Hourly O₃ and temperature (T) data from 20 sites (1998–2023) were used to calculate the maximum daily 8 h average O₃ (MD8A-O₃) and maximum daily temperature (Tmax). The Mann–Kendall test identified trends for these variables. The 90th percentile of data from September to March defined thresholds for extreme events. Events were classified as extreme when MD8A-O₃ and Tmax exceeded their thresholds for at least six consecutive days. ERA5 data were used to evaluate atmospheric patterns during these events. The results show positive trends in MD8A-O₃ in 62% of sites, with values exceeding WHO Air Quality Guidelines, alongside positive Tmax trends in 90% of sites. Over the study period, four compound events, seven heatwaves, and four extreme O₃ events were identified. Compound and individual events were associated with the South America Subtropical Anticyclone and positive temperature anomalies. Individual O₃ events were linked to cold anomalies south of 30° S and positive geopotential height anomalies at 850 hPa. These findings highlight the increasing occurrence of extreme O₃ and heatwaves in São Paulo and their atmospheric drivers, offering insights to enhance awareness, forecasting, and policy responses to mitigate health and environmental impacts. Full article

(This article belongs to the Section Meteorology)

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23 pages, 31371 KiB

Open AccessArticle

Evaluations of GPM IMERG-Late Satellite Precipitation Product for Extreme Precipitation Events in Zhejiang Province

by Ruijin Zhu, Zhe Lv, Muzhi Li, Jiaxi Wu, Meiying Dong and Huiyan Xu

Atmosphere 2025, 16(7), 821; https://doi.org/10.3390/atmos16070821 - 6 Jul 2025

Abstract

In recent years, satellite products have played an increasingly significant role in monitoring and estimating global extreme weather events, owing to their advantages of an excellent spatiotemporal continuity and broad coverage. This study systematically evaluates the Global Precipitation Measurement (GPM) Integrated Multi-Satellite Retrievals [...] Read more.

In recent years, satellite products have played an increasingly significant role in monitoring and estimating global extreme weather events, owing to their advantages of an excellent spatiotemporal continuity and broad coverage. This study systematically evaluates the Global Precipitation Measurement (GPM) Integrated Multi-Satellite Retrievals for the GPM Late Run (IMERG-L) product for regional precipitation events based on the observations in Zhejiang Province from 2001 to 2020. In this study, seven typical precipitation indices with seven accuracy evaluation indexes are applied to analyze the performance of IMERG-L from multiple perspectives in terms of the precipitation intensity, frequency and spatial distribution dimensions. The results show that IMERG-L is capable of capturing the spatial distribution trends, especially in the frequency-based precipitation indices (CWD, R10mm and R20mm), which can depict the regional wetness and precipitation pattern. However, the product suffers from a systematic overestimation in capturing heavy precipitation and an extreme precipitation intensity, with a high false alarm rate and unstable accuracy, especially in heavy rainfall and above class events, where the Probability of Detection (POD) drops significantly, showing an obvious reduction in the recognition capability and risk of misclassification. Specifically, IMERG-L failed to reproduce the observed eastward-increasing trends in the annual maximum precipitation for both one-day (RX1day) and five-day (RX5day) durations, demonstrating its limitations in accurately capturing extreme precipitation patterns across Zhejiang Province. Overall, furthering the optimization and improvement of IMERG-L in reducing the intensity-dependent biases in heavy rainfall detection, increasing spatial inhomogeneity in trend representations and improving the false alarm suppression for extreme events are needed for the accurate monitoring and quantitative estimation of high-intensity extreme precipitation events. Full article

(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)

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24 pages, 17002 KiB

Open AccessArticle

The Role of Air Mass Advection and Solar Radiation in Modulating Air Temperature Anomalies in Poland

by Olga Zawadzka-Mańko and Krzysztof M. Markowicz

Atmosphere 2025, 16(7), 820; https://doi.org/10.3390/atmos16070820 - 5 Jul 2025

Abstract

This study examines the roles of air mass advection and solar radiation in shaping daily air temperature anomalies in Warsaw, Poland, from 2008 to 2023. It integrates solar radiation data, HYSPLIT back-trajectories, air temperature measurements, and machine learning methods, which are key atmospheric [...] Read more.

This study examines the roles of air mass advection and solar radiation in shaping daily air temperature anomalies in Warsaw, Poland, from 2008 to 2023. It integrates solar radiation data, HYSPLIT back-trajectories, air temperature measurements, and machine learning methods, which are key atmospheric factors contributing to temperature anomalies in different seasons. Radiation dominates during warm seasons, while advection-related geographic factors are more influential during winter. Increased solar radiation is observed across all seasons during high-positive temperature anomalies (exceeding two standard deviations). In contrast, cold anomalies in summer are accompanied by strong negative solar radiation anomalies (−136.3 W/m²), while winter cold events may still coincide with positive radiation anomalies (25.7 W/m²). Very slow circulation over Central Europe, which occurs twice as often in summer as in winter, leads to positive temperature (1.3 °C) and negative radiation (−2.1 W/m²) anomalies in summer and to negative temperature (−1.9 °C) anomalies and slightly positive radiation (0.3 W/m²) anomalies in winter. The seasonal variability in the spatial origin of air masses reflects shifts in synoptic-scale circulation patterns. These findings highlight the importance of considering the combined influence of radiative and advective processes in driving temperature extremes and their seasonal dynamics in mid-latitude climates. Full article

(This article belongs to the Section Meteorology)

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23 pages, 1622 KiB

Open AccessArticle

The Beneficial Spatial Spillover Effects of China’s Carbon Emissions Trading System on Air Quality

by Diwei Zheng and Daxin Dong

Atmosphere 2025, 16(7), 819; https://doi.org/10.3390/atmos16070819 - 5 Jul 2025

Abstract

Between 2013 and 2020, China had implemented a pilot cap-and-trade carbon emissions trading system (ETS) in some cities. Previous research has reported that this policy significantly reduces air pollution in the policy-implementing districts. However, whether and to what extent there are spatial spillover [...] Read more.

Between 2013 and 2020, China had implemented a pilot cap-and-trade carbon emissions trading system (ETS) in some cities. Previous research has reported that this policy significantly reduces air pollution in the policy-implementing districts. However, whether and to what extent there are spatial spillover effects of this policy on air pollution in other regions has not been sufficiently analyzed. The research objective of this study is to quantitatively assess the spatial spillover effects of China’s carbon ETS on air pollution. Based on data from 288 Chinese cities between 2005 and 2020, this study employs a multiple linear regression approach to estimate the policy effects. Our study finds that the policy significantly reduces the concentrations of black carbon (BC), nitrogen dioxide (NO₂), organic carbon (OC), particulate matter less than 1 micron in size (PM₁), fine particulate matter (PM_2.5), and particulate matter less than 10 microns in size (PM₁₀) in non-ETS regions. This indicates that the carbon ETS has beneficial impacts on air quality beyond the areas where the policy was implemented. The heterogeneity tests reveal that the beneficial spatial spillover effects of the ETS can be observed across cities with different levels of industrialization, population density, economic development, resource endowments, and geographical locations. Further mechanism analyses show that although the policy does not affect the degree of environmental regulation in other regions, it promotes green innovation, low-carbon energy transition, and industrial structure upgrading there, which explains the observed spatial spillover effects. Full article

(This article belongs to the Special Issue Air Pollution in China (4th Edition))

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19 pages, 3093 KiB

Open AccessArticle

Developing a Composite Drought Indicator Using PCA Integration of CHIRPS Rainfall, Temperature, and Vegetation Health Products for Agricultural Drought Monitoring in New Mexico

by Bishal Poudel, Dewasis Dahal, Sujan Shrestha, Roshan Sewa and Ajay Kalra

Atmosphere 2025, 16(7), 818; https://doi.org/10.3390/atmos16070818 - 4 Jul 2025

Abstract

Drought indices are important resources for monitoring and warning of drought impacts. However, regions like New Mexico, which are highly vulnerable to drought, as identified by the United States Drought Monitor (USDM), lack a comprehensive drought monitoring system that integrates multiple agrometeorological variables [...] Read more.

Drought indices are important resources for monitoring and warning of drought impacts. However, regions like New Mexico, which are highly vulnerable to drought, as identified by the United States Drought Monitor (USDM), lack a comprehensive drought monitoring system that integrates multiple agrometeorological variables into a single indicator. The purpose of this study is to create a Combined Drought Indicator for New Mexico (CDI-NM) as an indicator tool for use in monitoring historical drought events and measuring its extent across the New Mexico. The CDI-NM was constructed using four key variables: the Vegetation Condition Index (VCI), temperature, Smoothed Normalized Difference Vegetation Index (SMN), and gridded rainfall data. A quantitative approach was used to assign weights to these variables employing Principal Component Analysis (PCA) to produce the CDI-NM. Unlike conventional indices, CDI-NM assigns weights to each variable based on their statistical contributions, allowing the index to adapt to local spatial and temporal drought dynamics. The performance of CDI-NM was evaluated against gridded rainfall data using the 3-month Standardized Precipitation Index (SPI3) over a 17-year period (2003–2019). The results revealed that CDI-NM reliably detected moderate and severe droughts with a strong correlation (R² > 0.8 and RMSE = 0.10) between both indices for the entire period of analysis. CDI-NM showed negative correlation (r < 0) with crop yield. While promising, the method assumes linear relationships among variables and consistent spatial resolution in the input datasets, which may affect its accuracy under certain local conditions. Based on the results, the CDI-NM stands out as a promising instrument that brings us closer to improved decision-making by stakeholders in the fight against agricultural droughts throughout New Mexico. Full article

(This article belongs to the Special Issue Environmental Footprints of Drought: Focusing on Emerging Issues and Their Underlying Mechanisms (2nd Edition))

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26 pages, 23518 KiB

Open AccessArticle

Avalanche Hazard Dynamics and Causal Analysis Along China’s G219 Corridor: A Case Study of the Wenquan–Khorgas Section

by Xuekai Wang, Jie Liu, Qiang Guo, Bin Wang, Zhiwei Yang, Qiulian Cheng and Haiwei Xie

Atmosphere 2025, 16(7), 817; https://doi.org/10.3390/atmos16070817 - 4 Jul 2025

Abstract

Investigating avalanche hazards is a fundamental preliminary task in avalanche research. This work is critically important for establishing avalanche warning systems and designing mitigation measures. Primary research data originated from field investigations and UAV aerial surveys, with avalanche counts and timing identified through [...] Read more.

Investigating avalanche hazards is a fundamental preliminary task in avalanche research. This work is critically important for establishing avalanche warning systems and designing mitigation measures. Primary research data originated from field investigations and UAV aerial surveys, with avalanche counts and timing identified through image interpretation. Snowpack properties were primarily acquired via in situ field testing within the study area. Methodologically, statistical modeling and RAMMS::AVALANCHE simulations revealed spatiotemporal and dynamic characteristics of avalanches. Subsequent application of the Certainty Factor (CF) model and sensitivity analysis determined dominant controlling factors and quantified zonal influence intensity for each parameter. This study, utilizing field reconnaissance and drone aerial photography, identified 86 avalanche points in the study area. We used field tests and weather data to run the RAMMS::AVALANCHE model. Then, we categorized and summarized regional avalanche characteristics using both field surveys and simulation results. Furthermore, the Certainty Factor Model (CFM) and the parameter Sensitivity Index (Sa) were applied to assess the influence of elevation, slope gradient, aspect, and maximum snow depth on the severity of avalanche disasters. The results indicate the following: (1) Avalanches exhibit pronounced spatiotemporal concentration: temporally, they cluster between February and March and during 13:00–18:00 daily; spatially, they concentrate within the 2100–3000 m elevation zone. Chute-confined avalanches dominate the region, comprising 73.26% of total events; most chute-confined avalanches feature multiple release areas; therefore the number of release areas exceeds avalanche points; in terms of scale, medium-to-large-scale avalanches dominate, accounting for 86.5% of total avalanches. (2) RAMMS::AVALANCHE simulations yielded the following maximum values for the region: flow height = 15.43 m, flow velocity = 47.6 m/s, flow pressure = 679.79 kPa, and deposition height = 10.3 m. Compared to chute-confined avalanches, unconfined slope avalanches exhibit higher flow velocities and pressures, posing greater hazard potential. (3) The Certainty Factor Model and Sensitivity Index identify elevation, slope gradient, and maximum snow depth as the key drivers of avalanches in the study area. Their relative impact ranks as follows: maximum snow depth > elevation > slope gradient > aspect. The sensitivity index values were 1.536, 1.476, 1.362, and 0.996, respectively. The findings of this study provide a scientific basis for further research on avalanche hazards, the development of avalanche warning systems, and the design of avalanche mitigation projects in the study area. Full article

(This article belongs to the Special Issue Climate Change in the Cryosphere and Its Impacts)

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15 pages, 2934 KiB

Open AccessArticle

Assessment of the Area of Heavy Metals and Radionuclides Deposition on the Environment of the Household Waste Landfill on the 9th km of Vilyuisky Tract in Yakutsk City

by Sargylana Mamaeva, Marina Frontasyeva, Kristina Petrova, Vassiliy Kolodeznikov, Galina Ignatyeva, Eugenii Zakharov and Vladlen Kononov

Atmosphere 2025, 16(7), 816; https://doi.org/10.3390/atmos16070816 - 3 Jul 2025

Abstract

For the first time, the deposition area of heavy metals and other trace elements (Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, P, Pb, S, Sr, Sb, V, Zn, and Hg) on the territory surrounding a landfill of domestic (municipal) waste at [...] Read more.

For the first time, the deposition area of heavy metals and other trace elements (Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, P, Pb, S, Sr, Sb, V, Zn, and Hg) on the territory surrounding a landfill of domestic (municipal) waste at the 9th km of the Vilyuisky tract of Yakutsk within a radius of 51 km was assessed using the method of moss biomonitors and ICP-OES as an analytical technique. Mosses were analyzed for radionuclide content (⁴⁰K, ¹³⁷Cs, ²¹² Pb, ²¹⁴Pb, ²¹²Bi, ²¹⁴Bi, ²⁰⁸Tl, ⁷Be, and ²²⁸Ac) in a number of selected samples by semiconductor gamma spectrometry. The results of the examination of moss samples by ICP-OES indicate the presence of large amounts of toxic Ba and metal debris (Al, Co, Cr, Fe, S, and Pb) at the landfill. In addition, it is shown that the investigated samples contain elements such as Cd, Co, Cr, Cu, Cu, Mn, Ni, Pb, Sr, V, Zn, and Hg. The method of gamma spectrometry revealed that the studied samples contain such radioactive elements as ¹³⁷Cs, daughter products of ²³⁸U and ²³²Th. Detection of the same heavy metals and radionuclides in the atmospheric air of the city and in the vegetation near the landfill may indicate that one of the sources of environmental pollution may be products of incineration of the landfill contents at the 9th km of the Vilyuisky tract. Full article

(This article belongs to the Section Air Quality)

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22 pages, 5767 KiB

Open AccessArticle

Influence of Humidity on the Electric Field, Filtration Efficiency, and Flow Velocity in Electret Filter Media: Direct Numerical Simulation

by Daniel Stoll and Sergiy Antonyuk

Atmosphere 2025, 16(7), 815; https://doi.org/10.3390/atmos16070815 - 3 Jul 2025

Abstract

Electret filter media are electrostatically charged during the manufacturing process to activate effective electrical separation mechanisms. In order to investigate the influence of humidity on these mechanisms, the electric field, and filtration efficiency, a Direct Numerical Simulation (DNS) study of the aerosol deposition [...] Read more.

Electret filter media are electrostatically charged during the manufacturing process to activate effective electrical separation mechanisms. In order to investigate the influence of humidity on these mechanisms, the electric field, and filtration efficiency, a Direct Numerical Simulation (DNS) study of the aerosol deposition within wetted fibrous nonwoven filter media used in masks was carried out. Initial experimental investigations determined key properties of the filter material, including porosity, fiber diameter, and surface charge density. Using Micro-Computed Tomography (µCT), preferred locations for droplet deposition within the filter were identified. Additional experiments quantified the amount of water absorbed by the filter medium and assessed its impact on the existing electric field. Numerical simulations examined various models with differing porosity and fiber diameter, incorporating different levels of water content to analyze the changes in the electric field, flow velocity, and resulting filtration efficiency. The results provide valuable insights into the significant effects of fiber change on filtration performance, demonstrating the electret filter’s ability to partially compensate for the negative impacts of water. Full article

(This article belongs to the Special Issue Electrostatics of Atmospheric Aerosols (2nd Edition))

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26 pages, 5006 KiB

Open AccessArticle

Kilometer-Scale Regional Modeling of Precipitation Projections for Bulgaria Using HPC Discoverer

by Rilka Valcheva and Ivan Popov

Atmosphere 2025, 16(7), 814; https://doi.org/10.3390/atmos16070814 - 3 Jul 2025

Abstract

The main goal of this study is to present future changes in various precipitation indices at a kilometer-scale resolution for Bulgaria on an annual and seasonal basis. Numerical simulations were conducted using the Non-Hydrostatic Regional Climate Model version 4 (RegCM4-NH) following the Coordinated [...] Read more.

The main goal of this study is to present future changes in various precipitation indices at a kilometer-scale resolution for Bulgaria on an annual and seasonal basis. Numerical simulations were conducted using the Non-Hydrostatic Regional Climate Model version 4 (RegCM4-NH) following the Coordinated Regional Climate Downscaling Experiment Flagship Pilot Study protocol for three 10-year periods (1995–2004, 2041–2050, and 2090–2099), with horizontal grid resolutions of 15 km and 3 km, on the petascale supercomputer HPC Discoverer at Sofia Tech Park. Data from the Hadley Centre Global Environment Model version 2 (HadGEM2-ES), based on the Representative Concentration Pathway 8.5 (RCP8.5) scenario, were used as boundary conditions for the regional climate model (RCM) simulations, which were subsequently downscaled to the kilometer-scale (3 km) simulations using a one-way nesting approach. High-resolution model data were compared with high-resolution observational datasets as well as lower-resolution (15 km) data. Future changes in precipitation indices were analyzed on both annual and seasonal scales, including mean daily and hourly precipitation, the frequency and intensity of wet days (>1 mm/day) and wet hours (>0.1 mm/hour), extreme daily precipitation (99th percentile, p99), and extreme hourly precipitation (99.9th percentile, p99.9) for both future periods. Additionally, changes in near-surface (2 m) temperature and surface snow amount were also presented. There is no substantial difference in projected temperature change between the resolutions. A positive trend in annual mean precipitation is expected in the near future. Extreme precipitation (p99 and p99.9) is projected to increase in spring and winter, accompanied by a rise in daily and hourly precipitation intensity across both future periods. An increase in surface snow amount is observed in the central Danubian Plain, Thracian Lowland, and parts of the Rila and Pirin mountains for the near-future period. However, surface snow amount is expected to decrease by the end of the century. Full article

(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)

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21 pages, 11460 KiB

Open AccessArticle

Changes in the Intra-Annual Precipitation Regime in Poland from 1966 to 2024

by Joanna Wibig and Joanna Jędruszkiewicz

Atmosphere 2025, 16(7), 813; https://doi.org/10.3390/atmos16070813 - 3 Jul 2025

Abstract

Many studies relate to long-term changes in annual precipitation in Poland, yet most of them were statistically insignificant. The primary objective of this research was to investigate the precipitation regime during the year in the context of climate change, which is more crucial [...] Read more.

Many studies relate to long-term changes in annual precipitation in Poland, yet most of them were statistically insignificant. The primary objective of this research was to investigate the precipitation regime during the year in the context of climate change, which is more crucial than annual averages from the perspectives of agriculture and plant growth, as well as for the industrial sector and human access to clean water. For this reason, we used daily precipitation data from the Institute of Meteorology and Water Management—National Research Institute from 1966 to 2024. Each month of the study was examined for changes in monthly totals, the number of dry and wet days, precipitation intensities, and extremes. In the cold season, a considerable shift in precipitation patterns was found between November and December, which became drier, and January and February, which became wetter with more intense and extreme precipitation. Pronounced changes were also noticed in April and June, when not only the monthly totals but also the number of wet days and precipitation intensity decreased. These two months, together with winter, are essential for plant growth. On the contrary, July became slightly wetter. Interesting changes were also observed in September, including an increase in dry days and more intense rainfall. With the increase in temperature and changes in the advection of air masses, September became more similar to summer than to autumn months. The key factors driving shifts in precipitation regimes during the year were a warmer atmosphere and changes in circulation patterns. Full article

(This article belongs to the Section Climatology)

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20 pages, 3602 KiB

Open AccessArticle

Dust Aerosol Classification in Northwest China Using CALIPSO Data and an Enhanced 1D U-Net Network

by Xin Gong, Delong Xiu, Xiaoling Sun, Ruizhao Zhang, Jiandong Mao, Hu Zhao and Zhimin Rao

Atmosphere 2025, 16(7), 812; https://doi.org/10.3390/atmos16070812 - 2 Jul 2025

Abstract

Dust aerosols significantly affect climate and air quality in Northwest China (30–50° N, 70–110° E), where frequent dust storms complicate accurate aerosol classification when using CALIPSO satellite data. This study introduces an Enhanced 1D U-Net model to enhance dust aerosol retrieval, incorporating Inception [...] Read more.

Dust aerosols significantly affect climate and air quality in Northwest China (30–50° N, 70–110° E), where frequent dust storms complicate accurate aerosol classification when using CALIPSO satellite data. This study introduces an Enhanced 1D U-Net model to enhance dust aerosol retrieval, incorporating Inception modules for multi-scale feature extraction, Transformer blocks for global contextual modeling, CBAM attention mechanisms for improved feature selection, and residual connections for training stability. Using CALIPSO Level 1B and Level 2 Vertical Feature Mask (VFM) data from 2015 to 2020, the model processed backscatter coefficients, polarization characteristics, and color ratios at 532 nm and 1064 nm to classify aerosol types. The model achieved a precision of 94.11%, recall of 99.88%, and F1 score of 96.91% for dust aerosols, outperforming baseline models. Dust aerosols were predominantly detected between 0.44 and 4 km, consistent with observations from CALIPSO. These results highlight the model’s potential to improve climate modeling and air quality monitoring, providing a scalable framework for future atmospheric research. Full article

(This article belongs to the Section Aerosols)

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16 pages, 26026 KiB

Open AccessArticle

Computational Fluid Dynamics-Based Modeling of Methane Flows Around Oil and Gas Equipment

by Abhinav Anand, Stuart Riddick, Kira B. Shonkwiler, Aashish Upreti, Michael Moy, Elijah Kiplimo, Mercy Mbua and Daniel J. Zimmerle

Atmosphere 2025, 16(7), 811; https://doi.org/10.3390/atmos16070811 - 2 Jul 2025

Abstract

Recent studies estimate that emissions from oil and gas production facilities contribute between 20 and 50% of the total methane (

C H_{4}

) emitted in the US; therefore, quantifying and reducing these emissions are crucial for achieving climate goals. Methane quantification [...] Read more.

Recent studies estimate that emissions from oil and gas production facilities contribute between 20 and 50% of the total methane (

C H_{4}

) emitted in the US; therefore, quantifying and reducing these emissions are crucial for achieving climate goals. Methane quantification depends on both measuring methane concentrations and converting them to emissions through a modeling framework. Currently, simple atmospheric dispersion models are primarily used to quantify emissions and concentrations, but these estimates are highly uncertain when quantifying emissions from complex aerodynamic sources, such as oil and gas facilities. This investigation used a CFD modeling approach, which can account for aerodynamic complexity but has hitherto not been used to model methane concentrations downwind of a methane release of a known rate, and compared it against in situ measurements. High-time-resolution (1 Hz) methane concentration and meteorological data were measured during experiments conducted at the METEC on 21 March and 11 July 2024. The METEC site configuration, measured wind data, and controlled emission rates were used as input for the CONVERGE CFD model to model downwind

C H_{4}

concentration. The modeling was carried out between 20 and 70 m, from two different points of release in two separate controlled-release experiments, one from a separator and another from a wellhead. In these experiments, we found that the CFD model could predict the

C H_{4}

concentrations downwind of the release to a good degree. The model was evaluated on multiple metrics to assess its performance in estimating methane concentrations at typical fence line distances (∼30 m). These results help us to understand external flows and the ability of CFD models to predict downwind concentrations in aerodynamically complex environments. Full article

(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)

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17 pages, 5264 KiB

Open AccessCommunication

Some Interesting Observations of Cross-Mountain East-to-Southeasterly Flow at Hong Kong International Airport and Their Numerical Simulations

by Pak-Wai Chan, Ping Cheung, Kai-Kwong Lai, Jie-Lan Xie and Yan-Yu Leung

Atmosphere 2025, 16(7), 810; https://doi.org/10.3390/atmos16070810 - 1 Jul 2025

Abstract

With the availability of more ground-based remote-sensing meteorological equipment at Hong Kong International Airport, many more interesting features of terrain-disrupted airflow have been observed, such as the applications of short-range Doppler LIDAR. This paper documents a number of new features observed at the [...] Read more.

With the availability of more ground-based remote-sensing meteorological equipment at Hong Kong International Airport, many more interesting features of terrain-disrupted airflow have been observed, such as the applications of short-range Doppler LIDAR. This paper documents a number of new features observed at the airport area, such as the hydraulic jump-like feature, vortex, and extensive mountain wake/reverse flow. The technical feasibility of using a numerical resolution weather prediction model to simulate such features is also explored. It is found that the presently available input data and numerical model may not be able to capture the fine features of the atmospheric boundary layer, and thus they are not very successful in reproducing many small-scale terrain-disrupted airflow features downstream of an isolated hill. On the other hand, more larger-scale terrain-disrupted flow features may be better captured, but there are still limitations with the available turbulence parameterization schemes. This paper aims at documenting the newly observed flow features at the Hong Kong International Airport, enhancing the understanding of low-level windshear, and evaluating the outputs of numerical resolution simulations for reproducing such observed features and its technical feasibility on short-term forecasting. Full article

(This article belongs to the Section Atmospheric Techniques, Instruments, and Modeling)

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