Atmosphere

17 pages, 7131 KiB

Open AccessArticle

Analysis of the Causes of an O₃ Pollution Event in Suqian on 18–21 June 2020 Based on the WRF-CMAQ Model

by Ju Wang, Wei Zhang, Weihao Shi, Xinlong Li and Chunsheng Fang

Atmosphere 2024, 15(7), 831; https://doi.org/10.3390/atmos15070831 (registering DOI) - 11 Jul 2024

In recent years, O₃ pollution events have occurred frequently in Chinese cities. Utilizing the WRF-CMAQ model, this study analyzed the causes of an O₃ pollution event in Suqian on 18–21 June 2020, considering meteorological conditions, process analysis, and source analysis. It [...] Read more.

In recent years, O₃ pollution events have occurred frequently in Chinese cities. Utilizing the WRF-CMAQ model, this study analyzed the causes of an O₃ pollution event in Suqian on 18–21 June 2020, considering meteorological conditions, process analysis, and source analysis. It also designed 25 emission reduction scenarios to explore more effective O₃ emission reduction strategies. The results show that meteorological conditions such as temperature and wind field play an important role in the formation and accumulation of O₃. During the heavy pollution period, the contribution of vertical transport (VTRA) and horizontal transport (HTRA) to O₃ concentration is significantly enhanced. The photochemical reactions of precursors, such as NOx and VOCs transported from long distances and O₃ directly transported to Suqian from other regions, contribute greatly to O₃ pollution in Suqian; local sources contribute very little, between 12.22% and 18.33%. Based on the simulation of 25 emission reduction scenarios, it was found that excessive emission reduction of NOx is not conducive to the reduction of O₃ concentration, and it is best to control the emission reduction ratio at about 10%. Without affecting normal production and life, it is recommended to reduce VOCs as much as possible, particularly those generated by traffic sources. Full article

(This article belongs to the Special Issue Ozone Pollution and Effects in China)

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23 pages, 845 KiB

Open AccessArticle

Short Review of Current Numerical Developments in Meteorological Modelling

by Jürgen Steppeler

Atmosphere 2024, 15(7), 830; https://doi.org/10.3390/atmos15070830 (registering DOI) - 10 Jul 2024

Abstract

This paper reviews current numerical developments for atmospheric modelling. Numerical atmospheric modelling now looks back to a history of about 70 years after the first successful numerical prediction. Currently, we face new challenges, such as variable and adaptive resolution and ultra-highly resolving global [...] Read more.

This paper reviews current numerical developments for atmospheric modelling. Numerical atmospheric modelling now looks back to a history of about 70 years after the first successful numerical prediction. Currently, we face new challenges, such as variable and adaptive resolution and ultra-highly resolving global models of 1 km grid length. Large eddy simulation (LES), special applications like the numerical prediction of pollution and atmospheric contaminants belong to the current challenges of numerical developments. While pollution prediction is a standard part of numerical modelling in case of accidents, models currently being developed aim at modelling pollution at all scales from the global to the micro scale. The methods discussed in this paper are spectral elements and other versions of Local-Galerkin (L-Galerkin) methods. Classic numerical methods are also included in the presentation. For example, the rather popular second-order Arakawa C-grid method can be shown to result as a special case of an L-Galerkin method using low-order basis functions. Therefore, developments for Galerkin methods also apply to this classic C-grid method, and this is included in this paper. The new generation of highly parallel computers requires new numerical methods, as some of the classic methods are not well suited for a high degree of parallel computing. It will be shown that some numerical inaccuracies need to be resolved and this indicates a potential for improved results by going to a new generation of numerical methods. The methods considered here are mostly derived from basis functions. Such methods are known under the names of Galerkin, spectral, spectral element, finite element or L-Galerkin methods. Some of these new methods are already used in realistic models. The spectral method, though highly used in the 1990s, is currently replaced by the mentioned local L-Galerkin methods. All methods presented in this review have been tested in idealized numerical situations, the so-called toy models. Waypoints on the way to realistic models and their mathematical problems will be pointed out. Practical problems of informatics will be highlighted. Numerical error traps of some current numerical approaches will be pointed out. These are errors not occurring with highly idealized toy models. Such errors appear when the test situation becomes more realistic. For example, many tests are for regular resolution and results can become worse when the grid becomes irregular. On the sphere no regular grids exist, except for the five derived from Platonic solids. Practical problems beyond mathematics on the way to realistic applications will also be considered. A rather interesting and convenient development is the general availability of computer power. For example, the computational power available on a normal personal computer is comparable to that of a supercomputer in 2005. This means that interesting developments, such as the small sphere atmosphere with a resolution of 1 km and a spherical circumference between 180 and 360 km are available to the normal owner of a personal computer (PC). Besides the mathematical problems of new approaches, we will also consider the informatics challenges of using the new generation of models on mainframe computers and PCs. Full article

(This article belongs to the Special Issue Geometry in Meteorology and Climatology)

20 pages, 1473 KiB

Open AccessArticle

The Abrupt Change in Potential Evapotranspiration and Its Climatic Attribution over the Past 50 Years in the Sichuan–Chongqing Region, China

by Qingzhou Zheng, Xiaolin Huang, Tianxiong Zheng, Jun He, Ming Xiang, Mengsheng Qin and Kailun Jin

Atmosphere 2024, 15(7), 829; https://doi.org/10.3390/atmos15070829 (registering DOI) - 10 Jul 2024

Abstract

Potential evapotranspiration (PET), as an indicator of atmospheric evaporative demand, is a critical hydrological and meteorological factor to reflect regional and global hydrological cycles and environmental change. Understanding these nuanced responses of PET to environmental changes is important for agricultural production and water [...] Read more.

Potential evapotranspiration (PET), as an indicator of atmospheric evaporative demand, is a critical hydrological and meteorological factor to reflect regional and global hydrological cycles and environmental change. Understanding these nuanced responses of PET to environmental changes is important for agricultural production and water demand estimation. This study rigorously evaluated fluctuations in PET using the Penman–Monteith model over a 50-year span from 1970 to 2020 in the Sichuan–Chongqing region, an area notably susceptible to climate change. The changing characteristics of PET and local meteorological factors were detected by integrating the Mann–Kendall method and Pettitt test. Furthermore, the contribution and sensitivity of key meteorological variables to the observed variation in PET were also thoroughly investigated. Breakpoint analysis revealed that abrupt changes appeared in 1996 for annual PET. The detrending method indicated that substantial decreases in net radiation and wind speed (p < 0.01) were responsible for the decrease in annual PET from 1970 to 1996. Marked increases in minimum temperature and wind speed were the driving forces behind the uptick in annual PET in 1997–2020. At seasonal scales, wind speed and net radiation predominantly influenced PET in 1970–1996 in general. However, from 1997 to 2020, the factors controlling PET fluctuations displayed considerable seasonal variation. Sensitivity analysis showed that W_s and T_min were the second-most sensitive factors. By exploring the impacts of PET changes and shifts, attention must be paid when allocating water resources reasonably under the background of ongoing climate change and likelihood of future drought. Full article

(This article belongs to the Special Issue Observation and Modeling of Evapotranspiration)

29 pages, 858 KiB

Open AccessArticle

Α Hybrid Extended Kalman Filter Based on Parametrized ANNs for the Improvement of the Forecasts of Numerical Weather and Wave Prediction Models

by Athanasios Donas, George Galanis, Ioannis Pytharoulis and Ioannis Th. Famelis

Atmosphere 2024, 15(7), 828; https://doi.org/10.3390/atmos15070828 (registering DOI) - 10 Jul 2024

Abstract

A hybrid optimization filter for weather and wave numerical models is proposed and tested in this study. Parametrized Artificial Neural Networks are utilized in conjunction with Extended Kalman Filters to provide a novel postprocess strategy for 10 m wind speed, 2 m air [...] Read more.

A hybrid optimization filter for weather and wave numerical models is proposed and tested in this study. Parametrized Artificial Neural Networks are utilized in conjunction with Extended Kalman Filters to provide a novel postprocess strategy for 10 m wind speed, 2 m air temperature, and significant wave height simulations. The innovation of the developed model is the implementation of Feedforward Neural Networks and Radial Basis Function Neural Networks as estimators of an exogenous parameter that adjusts the covariance matrices of the Extended Kalman Filter process. This hybrid system is evaluated through a time window process leading to promising results, thus enabling a decrease in systematic errors alongside the restriction of the error variability and the corresponding forecast uncertainty. The obtained results showed that the average reduction of the systematic error exceeded 75%, while the corresponding nonsystematic part of that error decreased by 35%. Full article

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

19 pages, 2147 KiB

Open AccessArticle

Temporal and Spatial Variation Characteristics of the Ecosystem in the Inner Mongolia Section of the Yellow River Basin

by Junjie Yang, Laigen Jia, Jun Hao, Qiancheng Luo, Wenfeng Chi, Yuetian Wang, He Zheng, Ruiqiang Yuan and Ya Na

Atmosphere 2024, 15(7), 827; https://doi.org/10.3390/atmos15070827 (registering DOI) - 10 Jul 2024

Abstract

As one of the most vital ecological regions in China, the well-being of the Inner Mongolia section of the Yellow River Basin directly hinges upon comprehending the variations in its ecosystem. The current research puts emphasis on the analysis of single-factor ecological indicators [...] Read more.

As one of the most vital ecological regions in China, the well-being of the Inner Mongolia section of the Yellow River Basin directly hinges upon comprehending the variations in its ecosystem. The current research puts emphasis on the analysis of single-factor ecological indicators within the Mongolian section of the Yellow River and lacks summarization and analysis regarding the overall state of the ecosystem within the Mongolian section of the Yellow River. This study, using methods such as remote sensing interpretation and model simulation, combined with ground surveys, analyzes the macrostructure, quality status, service functions, and driving factors of the ecosystem in the Inner Mongolia section of the Yellow River Basin from 2000 to 2020. The results indicate that (1) in 2020, the ecosystem structure in the Inner Mongolia section of the Yellow River Basin was predominantly composed of forest, grassland, and other types of systems. (2) From 2000 to 2020, the Normalized Difference Vegetation Index (NDVI), Fractional Vegetation Cover (FVC), and net primary productivity (NPP) all showed increasing trends in the Inner Mongolia section of the Yellow River Basin, with NPP showing a slightly greater increase compared to the NDVI and FVC. (3) Over the past two decades, the overall rate of decrease in the wind erosion modulus per unit area was 1.675 t hm⁻². (4) An analysis of the drivers of ecosystem changes revealed that while climate change has exerted an influence, human activities have likewise had a substantial effect on the ecosystem over the past 20 years. This study contributes to a comprehensive understanding of the current status and changes in the ecosystem, providing a decision-making basis for subsequent ecological protection and management projects. Full article

(This article belongs to the Special Issue Response of Vegetation to Climatic and Anthropogenic Drivers in the Plateau)

34 pages, 23490 KiB

Open AccessArticle

Assessing the Impact of Lightning Data Assimilation in the WRF Model

by Vanderlei Vargas, Jr., Rute Costa Ferreira, Osmar Pinto, Jr. and Dirceu Luis Herdies

Atmosphere 2024, 15(7), 826; https://doi.org/10.3390/atmos15070826 (registering DOI) - 10 Jul 2024

Abstract

Recent advancements in computational technologies have enhanced the importance of meteorological modeling, driven by an increased reliance on weather-dependent systems. This research implemented a lightning data assimilation technique to improve short-term weather forecasts in South America, potentially refining initialization methods used in meteorological [...] Read more.

Recent advancements in computational technologies have enhanced the importance of meteorological modeling, driven by an increased reliance on weather-dependent systems. This research implemented a lightning data assimilation technique to improve short-term weather forecasts in South America, potentially refining initialization methods used in meteorological operation centers. The main goal was to implement and enhance a data assimilation algorithm integrating lightning data into the WRF model, assessing its impact on forecast accuracy. Focusing on southern Brazil, a region with extensive observational infrastructure and frequent meteorological activity, this research utilized several data sources: precipitation data from the National Institute of Meteorology (INMET), lightning data from the Brazilian Lightning Detection Network (BrasilDAT), GOES-16 satellite images, synoptic weather charts from the National Institute for Space Research (INPE), and initial conditions from the GFS model. Employing the WRF-ARW model version 3.9.1.1 and WRFDA system version 3.9.1 with 3DVAR methodology, the study conducted three experimental setups during two meteorological events to evaluate the assimilation algorithm. These included a control (CTRL) without assimilation, a lightning data assimilation (LIGHT), and an adaptive humidity threshold assimilation (ALIGHT). Results showed that the lightning data assimilation system enhanced forecasts for large-scale systems, especially with humidity threshold adjustments. While it improved squall line timing and positioning, it had mixed effects when convection was thermally driven. The lightning data assimilation methodology represents a significant contribution to the field, indicating that using such alternative data can markedly improve short-term forecasts, benefiting various societal sectors. Full article

(This article belongs to the Section Meteorology)

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17 pages, 3425 KiB

Open AccessArticle

Does Atmospheric Nitrogen Deposition Confer a Competitive Advantage to Invasive Bidens pilosa L. over Native Pterocypsela laciniata (Houtt.) Shih?

by Chuang Li, Yue Li, Yingsheng Liu, Shanshan Zhong, Huanshi Zhang, Zhelun Xu, Zhongyi Xu, Daolin Du and Congyan Wang

Atmosphere 2024, 15(7), 825; https://doi.org/10.3390/atmos15070825 (registering DOI) - 10 Jul 2024

Abstract

One of the key reasons for the success of invasive plants is the functional differences between invasive plants and native plants. However, atmospheric nitrogen deposition may disrupt the level of available nitrogen in soil and the functional differences between invasive plants and native [...] Read more.

One of the key reasons for the success of invasive plants is the functional differences between invasive plants and native plants. However, atmospheric nitrogen deposition may disrupt the level of available nitrogen in soil and the functional differences between invasive plants and native plants, which may alter the colonization of invasive plants. Thus, there is a pressing necessity to examine the effects of atmospheric nitrogen deposition containing different nitrogen components on the functional differences between invasive plants and native plants. However, the progress made thus far in this field is not sufficiently detailed. This study aimed to elucidate the effects of artificially simulated nitrogen deposition containing different nitrogen components (i.e., nitrate, ammonium, urea, and mixed nitrogen) on the functional differences between the Asteraceae invasive plant Bidens pilosa L. and the Asteraceae native plant Pterocypsela laciniata (Houtt.) Shih. The study was conducted over a four-month period using a pot-competitive co-culture experiment. The growth performance of P. laciniata, in particular with regard to the sunlight capture capacity (55.12% lower), plant supporting capacity (45.92% lower), leaf photosynthetic area (51.24% lower), and plant growth competitiveness (79.92% lower), may be significantly inhibited under co-cultivation condition in comparison to monoculture condition. Bidens pilosa exhibited a more pronounced competitive advantage over P. laciniata, particularly in terms of the sunlight capture capacity (129.43% higher), leaf photosynthetic capacity (40.06% higher), and enzymatic defense capacity under stress to oxidative stress (956.44% higher). The application of artificially simulated nitrogen deposition was found to facilitate the growth performance of monocultural P. laciniata, particularly in terms of the sunlight capture capacity and leaf photosynthetic area. Bidens pilosa exhibited a more pronounced competitive advantage (the average value of the relative dominance index of B. pilosa is ≈ 0.8995) than P. laciniata under artificially simulated nitrogen deposition containing different nitrogen components, especially when treated with ammonium (the relative dominance index of B. pilosa is ≈ 0.9363) and mixed nitrogen (the relative dominance index of B. pilosa is ≈ 0.9328). Consequently, atmospheric nitrogen deposition, especially the increased relative proportion of ammonium in atmospheric nitrogen deposition, may facilitate the colonization of B. pilosa via a stronger competitive advantage. Full article

(This article belongs to the Special Issue Urban and Regional Nitrogen Cycle and Risk Management)

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18 pages, 7123 KiB

Open AccessArticle

Characteristics of Atmospheric Rivers and the Impact of Urban Roof Roughness on Precipitation during the “23.7” Extreme Rainstorm against the Background of Climate Warming

by Yiguo Xu, Junhong Fan, Jun Zhang, Liqing Tian, Hui Zhang, Tingru Cui, Yating Wang and Rui Wang

Atmosphere 2024, 15(7), 824; https://doi.org/10.3390/atmos15070824 - 10 Jul 2024

Abstract

In July 2023, Baoding in Hebei Province experienced unprecedented torrential rainfall, breaking historical records and causing severe flooding. However, our understanding of the multi-scale circulation systems and physical mechanisms driving this extreme precipitation event remains incomplete. This study utilizes multi-source observational data and [...] Read more.

In July 2023, Baoding in Hebei Province experienced unprecedented torrential rainfall, breaking historical records and causing severe flooding. However, our understanding of the multi-scale circulation systems and physical mechanisms driving this extreme precipitation event remains incomplete. This study utilizes multi-source observational data and the Weather Research and Forecasting (WRF) numerical model to conduct a weather diagnosis and numerical simulation of this extreme rainfall event, focusing on the impact of atmospheric rivers (ARS) and urban rooftop roughness on the precipitation process against the background of climate warming. The study found that this extremely heavy rainstorm occurred in the circulation background formed by the factors of subtropical high ectopics, typhoon residual vortex retention, double typhoon water-vapor transmission, and stable high-level divergence. The ARS provided abundant moisture, with its vapor pathway significantly altered following the landfall of Typhoon Doksuri. The interaction between the ARS and the Taihang Mountains was crucial in triggering and intensifying the rainstorm in the foothills. Urbanization significantly affected the distribution of precipitation, with moderate urban roughness enhancing rainfall in and around the city, whereas excessive roughness suppressed it. These results contribute to a deeper understanding of the mechanisms behind extreme precipitation under climate change and provide a scientific basis for improving the forecasting and mitigation of such events. Full article

(This article belongs to the Special Issue Extreme Climate in Arid and Semi-arid Regions)

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18 pages, 4231 KiB

Open AccessArticle

The Development of a Hailstone Disdrometer and Its Preliminary Observation in Aksu, Xinjiang

by Yuanyuan Li, Xiaoxuan Mou, Juan Kang, Sihua Zhu, Yujiang Fan, Hongyun Fan, Xuhui Wei, Dan Chen, Shiqi Ren, Shengjie Jia, Jia Li, Na Li, Lingkun Ran, Kuo Zhou and Jinqiang Zhang

Atmosphere 2024, 15(7), 823; https://doi.org/10.3390/atmos15070823 - 9 Jul 2024

Abstract

Hailfall is a severe local weather event that can cause great economic losses as well as the loss of people’s property; however, it is still difficult for domestic meteorological stations to comprehensively observe hail, and domestic independently developed hail observation instruments are still [...] Read more.

Hailfall is a severe local weather event that can cause great economic losses as well as the loss of people’s property; however, it is still difficult for domestic meteorological stations to comprehensively observe hail, and domestic independently developed hail observation instruments are still scarce. To help enable better automatic hail observations, a new independently developed hailstone disdrometer based on the acoustic principle, which can be used to measure the hailstone number and particle size and to calculate the corresponding equivalent liquid precipitation of hailstones, is proposed in this paper. The characteristics of hailstones were preliminarily analyzed using observation data from two hailstone disdrometers installed in Aksu, Xinjiang, where three hail events were observed via the hailstone disdrometer in the summer of 2023. By analyzing the development of deep convection clouds using the Fengyun 4A satellite-based cloud-top brightness temperature, and synoptic conditions based on the fifth-generation global climate reanalysis dataset produced by the European Centre for Medium-Range Weather Forecasts (the ECMWF ERA5 dataset), the hail formation mechanism was investigated in detail for one hailfall event. Accurate hail observations are an important basis for understanding spatiotemporal hail variation. The hailstone disdrometer proposed in this study offers a useful approach for domestic hail observation to provide first-hand hail information for the inspection of weather modification effects and disaster prevention and reduction. Full article

(This article belongs to the Special Issue Weather and Climate Extremes: Observations, Modeling, and Impacts (2nd Edition))

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32 pages, 7993 KiB

Open AccessReview

Exploring the Complexities of Urban Forms and Urban Heat Islands: Insights from the Literature, Methodologies, and Current Status in Morocco

by Khaoula Benaomar and Abdelkader Outzourhit

Atmosphere 2024, 15(7), 822; https://doi.org/10.3390/atmos15070822 - 9 Jul 2024

Abstract

The Urban Heat Island phenomenon (UHI), characterized by elevated temperatures in urban areas compared to their rural surroundings, is highly exacerbated by urbanization and climate change. Understanding the complex relationship between UHI effect and urban form is crucial for effective urban planning and [...] Read more.

The Urban Heat Island phenomenon (UHI), characterized by elevated temperatures in urban areas compared to their rural surroundings, is highly exacerbated by urbanization and climate change. Understanding the complex relationship between UHI effect and urban form is crucial for effective urban planning and climate mitigation strategies. This paper examines the multifaceted connection between UHIs and urban forms, exploring various methods used to study this relationship. Through a review of the existing literature, we analyze the influence of various urban characteristics on the intensity and spatial distribution of UHIs. Furthermore, we discuss the key methods and technologies, such as remote sensing and modeling, used in advancing our understanding of UHI–urban form interactions. This study then delves into the literature on UHIs within the specific context of Morocco, identifying research gaps and emphasizing the need for more comprehensive research to address them. By translating study findings into actionable urban solutions, this paper suggests contextual mitigation strategies based on the research outcomes. Finally, by synthesizing current research findings and methodologies, this paper seeks to provide insights into the complexities of UHI dynamics and their implications for climate resilience, highlighting the potential of research for forging sustainable and climate-conscious planning strategies in Morocco and across the broader MENA region. Full article

(This article belongs to the Special Issue Urban Heat Islands and Global Warming (2nd Edition))

18 pages, 4291 KiB

Open AccessArticle

Distribution of Fine Particulate Matter Pollution in Winter over Eastern China Affected by Synoptic Conditions

by Xiaohui Liu, Huafeng Wu, Youjia Zou and Pinya Wang

Atmosphere 2024, 15(7), 821; https://doi.org/10.3390/atmos15070821 - 8 Jul 2024

Abstract

Based on the mean sea level pressure field and 10-meter wind field across eastern China, weather patterns were classified using principal component analysis in the T-model (T-PCA), and four weather conditions were identified. Weather conditions and meteorological factors affecting the winter PM_2.5 [...] Read more.

Based on the mean sea level pressure field and 10-meter wind field across eastern China, weather patterns were classified using principal component analysis in the T-model (T-PCA), and four weather conditions were identified. Weather conditions and meteorological factors affecting the winter PM_2.5 concentration in the Beijing–Tianjin–Hebei (BTH) region and the Yangtze River Delta (YRD) were also analyzed. The results showed that there were significant differences in the PM_2.5 distribution between BTH and the YRD under different weather conditions. The intensity and path of cold air played important roles in regulating the PM_2.5 concentration distribution in eastern China. For the BTH region, under type 2 and type 4 conditions, the weather was stable, and heavy pollution frequently occurred; however, under type 1 and type 3 conditions, cold air was active, and the air quality improved. For the YRD, both type 1 and type 4 conditions lead to high PM_2.5 concentrations in this region. Type 1 cold air flows southward along the northwestern path and is beneficial for transporting pollutants from BTH to the YRD, causing a high probability of PM_2.5 pollution. Conversely, the southward movement of type 3 cold air along the eastern path was beneficial for pollutant diffusion in the YRD. Full article

(This article belongs to the Section Air Quality)

20 pages, 4201 KiB

Open AccessArticle

Flood Forecasting through Spatiotemporal Rainfall in Hilly Watersheds

by Yuanyuan Liu, Yesen Liu, Yang Liu, Zhengfeng Liu, Weitao Yang and Kuang Li

Atmosphere 2024, 15(7), 820; https://doi.org/10.3390/atmos15070820 - 8 Jul 2024

Abstract

Flood prediction in hilly regions, characterized by rapid flow rates and high destructive potential, remains a significant challenge. This study addresses this problem by introducing a novel machine learning-based approach to enhance flood forecast accuracy and lead time in small watersheds within hilly [...] Read more.

Flood prediction in hilly regions, characterized by rapid flow rates and high destructive potential, remains a significant challenge. This study addresses this problem by introducing a novel machine learning-based approach to enhance flood forecast accuracy and lead time in small watersheds within hilly terrain. The study area encompasses small watersheds of approximately 600 km². The proposed method analyzes spatiotemporal characteristics in rainfall dynamics to identify historical rainfall–flood events that closely resemble current patterns, effectively “learning from the past to predict the present”. The approach demonstrates notable precision, with an average error of 8.33% for peak flow prediction, 14.27% for total volume prediction, and a lead time error of just 1 h for peak occurrence. These results meet the stringent accuracy requirements for flood forecasting, offering a targeted and effective solution for flood forecasting in challenging hilly terrains. This innovative methodology deviates from conventional techniques by adopting a holistic view of rainfall trends, representing a significant advancement in addressing the complexities of flood prediction in these regions. Full article

(This article belongs to the Topic Applications of Geodesy in Meteorological, Hydrological and Climatic Environments)

15 pages, 5638 KiB

Open AccessArticle

Northeast China Cold Vortex Amplifies Extreme Precipitation Events in the Middle and Lower Reaches Yangtze River Basin

by Hao Chen, Zuowei Xie, Xiaofeng He, Xiaodong Zhao, Zongting Gao, Biqiong Wu, Jun Zhang and Xiangxi Zou

Atmosphere 2024, 15(7), 819; https://doi.org/10.3390/atmos15070819 - 8 Jul 2024

Abstract

The middle and lower reaches of the Yangtze River (MLYR) frequently experience extreme precipitation events (EPEs) during June and July, the so-called Meiyu season. This study investigated EPEs in the MLYR during Meiyu seasons over 1961–2022, using rain gauge observations and ERA5 reanalysis [...] Read more.

The middle and lower reaches of the Yangtze River (MLYR) frequently experience extreme precipitation events (EPEs) during June and July, the so-called Meiyu season. This study investigated EPEs in the MLYR during Meiyu seasons over 1961–2022, using rain gauge observations and ERA5 reanalysis data. EPEs associated with the Northeast China cold vortex featured more undulating westerlies with a distinct wave train pattern from Europe to Northeast Asia. Due to robust Rossby wave energy, the trough deepened from Northeast China towards the MLYR and was confronted with a westward extension of the western Pacific subtropical high. Such a configuration enhanced the warm and moist monsoon conveyor belt and convergence of water vapor flux from southwestern China to the MLYR. The warm and moist air favored upward motion. The increased rainfall prevailed from southwestern China to the MLYR. In contrast, ordinary EPEs were characterized by zonal westerlies and weaker Rossby wave propagation. The Meiyu trough was comparatively shallow and confined to the MLYR with less westward expansion of the subtropical high. In response, the warm and moist monsoon conveyor belt was more localized, resulting in weaker EPEs in the MLYR. Full article

(This article belongs to the Special Issue Recent Advances in Air-Sea Interactions, Climate Variability, and Predictability)

16 pages, 13971 KiB

Open AccessArticle

Analysis of Flash Drought and Its Impact on Forest Normalized Difference Vegetation Index (NDVI) in Northeast China from 2000 to 2020

by Saraswoti Adhikari, Wanying Zhou, Zeyu Dou, Nazmus Sakib, Rong Ma, Bhavana Chaudhari and Binhui Liu

Atmosphere 2024, 15(7), 818; https://doi.org/10.3390/atmos15070818 - 8 Jul 2024

Abstract

Flash drought is characterized by rapid onset and short-duration drought conditions caused by a combination of factors, including high evaporation, high temperature, and prolonged periods of little to no precipitation, leading to a sudden and severe decrease in soil moisture levels. In comparison [...] Read more.

Flash drought is characterized by rapid onset and short-duration drought conditions caused by a combination of factors, including high evaporation, high temperature, and prolonged periods of little to no precipitation, leading to a sudden and severe decrease in soil moisture levels. In comparison to conventional drought, it is more susceptible to the effects of global warming and has the potential to become a common drought phenomenon in the coming years, necessitating further research. In this paper, we focused on flash drought events, specifically in forest parts of northeastern China that are included within the Greater Khingan Mountains (GKM), Lesser Khingan Mountains (LKM), and Changbai Mountains (CM), using daily soil moisture data as well as SPOT- VEGETATION NDVI satellite data from 2000 to 2020 and determined their impact on the forest NDVI. Our major findings are as follows. (1) The forest within GKM had the maximum area being affected by flash drought events. (2) The frequency ranged from 1 to 2 times, whereas the total duration varied between 20 and 55 days over the study area in a 21-year period. (3) Flash drought was most common in the plant-growing seasons. (4) The flash drought events had a negative influence on the forest NDVI. Our study contributes to a deeper understanding of the flash drought dynamics in forest areas of northeast China for flash drought monitoring, prediction, and management strategies in this region. Full article

(This article belongs to the Special Issue Vegetation and Climate Relationships (3rd Edition))

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17 pages, 14079 KiB

Open AccessArticle

Temporal and Spatial Variability of Ground Frost Indices in Northeast China

by Ting Wang, Gaohua Fan, Hui Zhang and Xiangjin Shen

Atmosphere 2024, 15(7), 817; https://doi.org/10.3390/atmos15070817 - 8 Jul 2024

Abstract

Frost is one of the most frequent, intense, and influential agrometeorological disasters that occurs frequently in Northeast China. The study of the spatiotemporal changes of ground frost is of great significance for farmers and policymakers in Northeast China, as it can inform decisions [...] Read more.

Frost is one of the most frequent, intense, and influential agrometeorological disasters that occurs frequently in Northeast China. The study of the spatiotemporal changes of ground frost is of great significance for farmers and policymakers in Northeast China, as it can inform decisions related to crop selection, planting schedules, and the development of regional climate adaptation plans. In this study, the spatiotemporal changes of frost indices (last spring frost (LSF), first fall frost (FFF), and frost-free period (FFP)) in Northeast China were analyzed from 1961 to 2020. Then, we investigated the mutation characteristics of the frost indices and their correlation with geographical factors. The results revealed that (1) the LSF, FFF, and FFP in Northeast China were concentrated at 120–140 DOY, 260–280 DOY, and 110–170 days, respectively. The spatial distribution of frost indices exhibited significant spatial heterogeneity. (2) The LSF, FFF, and FFP showed significant trends of advancement, delay, and extension, with trends of −1.94 days/10 a, 1.72 days/10 a, and 4.21 days/10 a, respectively. (3) More than 80% of the LSF, FFF, and FFP of the sites showed trends of advancement, delay, and extension, with greater variability in the central part of Heilongjiang Province. (4) The FFF and FFP experienced an abrupt change in the late 1990s. (5) The correlation between latitude and LSF, FFF, and FFP was the strongest, with correlation coefficients of 0.77, −0.79, and −0.78, respectively. This study provides a comprehensive understanding of the changing characteristics of ground frost indices that impact agricultural production in Northeast China against the backdrop of climate change. The findings hold significant scientific value in guiding the adaptation of agricultural production layouts in Northeast China to the evolving climatic conditions. Full article

(This article belongs to the Special Issue Vegetation and Climate Relationships (3rd Edition))

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12 pages, 10725 KiB

Open AccessArticle

Characterizing the Regional Differences in Carbon Dioxide Concentration Based on Satellite Observations in the Beijing-Tianjin-Hebei Region during 2015–2021

by Yanfang Hou, Wenliang Liu, Litao Wang, Futao Wang, Jinfeng Zhu and Shixin Wang

Atmosphere 2024, 15(7), 816; https://doi.org/10.3390/atmos15070816 - 8 Jul 2024

Abstract

The regional differences in carbon dioxide (CO₂) variations from the Orbiting Carbon Observatory-2 (OCO-2) over the Beijing-Tianjin-Hebei (Jing-Jin-Ji) region from 2015 to 2021 are analyzed in this study. This study shows an annual increase and a seasonal cycle; the CO₂ [...] Read more.

The regional differences in carbon dioxide (CO₂) variations from the Orbiting Carbon Observatory-2 (OCO-2) over the Beijing-Tianjin-Hebei (Jing-Jin-Ji) region from 2015 to 2021 are analyzed in this study. This study shows an annual increase and a seasonal cycle; the CO₂ annual growth rate was about 2.63 ppm year⁻¹, with the highest value being in spring and the lowest in summer. The spatial distribution is unbalanced, regional differences are prominent, and the CO₂ concentration is lower in the north of the Jing-Jin-Ji region (like Zhangjiakou, Chengde, and Qinhuangdao). Land-type structures and population economy distributions are the key factors affecting CO₂ concentration. By analyzing the land-type structures over Jing-Jin-Ji in 2020, we find that cropland, woodland, and grassland (CWG) are the main land cover types in Jing-Jin-Ji; the proportion of these three types is about 83.3%. The woodland areas in Zhangjiakou, Chengde, and Qinhuangdao account for about 65% of the total woodland areas in Jing-Jin-Ji; meanwhile, the grassland areas in these three regions account for 62% of the total grassland areas in Jing-Jin-Ji. CO₂ concentration variation shows a high negative correlation with CWG land areas (coefficient of determination (R²) > 0.76). The regions with lower population and GDP secondary industry (SI) density also have lower CO₂ concentration (like Zhangjiakou, Chengde, and Qinhuangdao), and the regions with higher population and GDP SI density also have higher CO₂ concentration (like the southeast of Jing-Jin-Jin). Full article

(This article belongs to the Special Issue Novel Insights into Air Pollution over East Asia)

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8 pages, 634 KiB

Open AccessArticle

Indoor Radon Measurement in Buildings of A.O.R.N Cardarelli, the Largest Hospital of National Relevance in Southern Italy

by Filomena Loffredo, Tiziana Capussela, Fortuna De Martino and Maria Quarto

Atmosphere 2024, 15(7), 815; https://doi.org/10.3390/atmos15070815 (registering DOI) - 7 Jul 2024

Abstract

Indoor radon concentrations constitute a major source of exposure to ionizing radiation for humans. It has been estimated that radon contributes about 10% of deaths from lung cancer in the USA and Europe. In Italy, current legislation establishes that the concentration of radon [...] Read more.

Indoor radon concentrations constitute a major source of exposure to ionizing radiation for humans. It has been estimated that radon contributes about 10% of deaths from lung cancer in the USA and Europe. In Italy, current legislation establishes that the concentration of radon must be monitored in all workplaces located in a basement and on the ground floor. In this study, the indoor radon concentration of 20 multi-floor buildings on the Cardarelli Hospital was measured during two consecutive semesters. The survey was carried out with CR-39 solid-state nuclear track detectors (SSNTDs). Radon concentrations were found to range from 4 Bq/m³ to 424 Bq/m³, with a median of 24 Bq/m³. The dependence of the radon concentrations on the measurement floor and the room-to-room spatial variation was also analyzed. Full article

(This article belongs to the Special Issue Air Pollution in Italy: Effects, Sources and Control)

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17 pages, 10295 KiB

Open AccessArticle

Interannual Fluctuations and Their Low-Frequency Modulation of Summertime Heavy Daily Rainfall Potential in Western Japan

by Takashi Mochizuki

Atmosphere 2024, 15(7), 814; https://doi.org/10.3390/atmos15070814 - 7 Jul 2024

Abstract

Heavy rainfall under the conditions of the changing climate has recently garnered considerable attention. The statistics on heavy daily rainfall offer vital information for assessing present and future extreme events and for clarifying the impacts of global climate variability and change, working to [...] Read more.

Heavy rainfall under the conditions of the changing climate has recently garnered considerable attention. The statistics on heavy daily rainfall offer vital information for assessing present and future extreme events and for clarifying the impacts of global climate variability and change, working to form a favorable background. By analyzing a set of large-ensemble simulations using a global atmospheric model, this study demonstrated that two different physical processes in global climate variability control the interannual fluctuations in the 99th- and 90th-percentile values of summertime daily rainfall (i.e., the potential amounts) on Kyushu Island in western Japan. The 90th-percentile values were closely related to large-scale horizontal moisture transport anomalies due to changes in the subtropical high in the northwestern Pacific, which was usually accompanied by basin-scale warming in the Indian Ocean subsequent to the wintertime El Niño events. The contributions of the sea surface temperatures over the northern Indian Ocean and the eastern tropical Pacific Ocean showed low-frequency modulations, mainly due to the influences of the global warming tendency and the interdecadal variability in the climate system, respectively. In contrast, tropical cyclone activity played a major role in changing the 99th-percentile value. The potentials of both the tropical cyclone intensity and the existence density fluctuated, largely owing to the summertime sea surface temperature over the tropical Pacific, which can be modulated by the El Niño diversity on interdecadal timescales. Full article

(This article belongs to the Special Issue Recent Advances in Air-Sea Interactions, Climate Variability, and Predictability)

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12 pages, 889 KiB

Open AccessArticle

Postfilament-Induced Two-Photon Fluorescence of Dyed Liquid Aerosol Enhanced by Structured Femtosecond Laser Pulse

by Dmitry V. Apeksimov, Pavel A. Babushkin, Yury E. Geints, Andrey M. Kabanov, Elena E. Khoroshaeva, Victor K. Oshlakov, Alexey V. Petrov and Alexander A. Zemlyanov

Atmosphere 2024, 15(7), 813; https://doi.org/10.3390/atmos15070813 - 6 Jul 2024

Abstract

Laser-induced fluorescence spectroscopy (LIFS) is actively used for remote sensing of atmospheric aerosols and is currently one of the most sensitive and selective techniques for determining small concentrations of substances inside particles. The use of high-power femtosecond laser sources for LIFS-based remote sensing [...] Read more.

Laser-induced fluorescence spectroscopy (LIFS) is actively used for remote sensing of atmospheric aerosols and is currently one of the most sensitive and selective techniques for determining small concentrations of substances inside particles. The use of high-power femtosecond laser sources for LIFS-based remote sensing of aerosols contributes to the development of new-generation fluorescence atmospheric lidars since it makes it possible to overcome the energy threshold for the nonlinear-optical effects of multiphoton absorption in particles and receive the emission signal at long distances in the atmosphere. Our study is aimed at the development and experimental demonstration of the technique of nonlinear laser-induced fluorescence spectroscopy (NLIFS) based on the remote excitation of aerosol fluorescent emission stimulated by a spatially structured high-power femtosecond laser pulse. Importantly, for the first time to our knowledge, we demonstrate the advances in using stochastically structured plasma-free intense light channels (postfilaments) specially formed by the propagation of femtosecond laser radiation through a turbulent air layer to improve NLIFS efficiency. A multiple increase in the received signal of two-photon-excited fluorescence of polydisperse-dyed aqueous aerosols by the structured postfilaments is reported. Full article

(This article belongs to the Special Issue New Methodological Aspects of Physics and Applications of Atmospheric Nonlinear Optics)

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