Atmospheric Science Letters最新文献

{"title":"Unprecedented September Heatwave in the Yangtze River Basin in 2024 and the Great Exposure Risk to School Students","authors":"Xie Tiejun,&nbsp;Ding Ting,&nbsp;Gao Hui,&nbsp;Wang Ji","doi":"10.1002/asl.1300","DOIUrl":"https://doi.org/10.1002/asl.1300","url":null,"abstract":"<p>In September 2024, the Yangtze River basin experienced a supremely extreme heatwave that broke historical records from at least 1961 and could have a severe impact on outdoor health of school children. This paper provides a timely analysis of the characteristics of the extreme heatwave in the Yangtze River basin in September 2024, its exposure to the population aged 14 years and below, and the causes that led to its occurrence, as well as its future projections. In September 2024, the regional average heatwave days in the Yangtze River basin reached 7.57 days, and the average daily maximum temperature (<i>T</i>_max) reached 31.53°C, both of which are much higher than the climatology and exceed the historical records. This supremely heatwave resulted in high exposure of the population aged 14 years and under, with the provinces of Sichuan, Chongqing, Hunan, and Jiangxi exposed to more than 100 million person-days. The extreme expansion of the South Asian High (SAH) and the Western Pacific Subtropical High (WPSH) may have directly contributed to this supremely heatwave. The CMIP6 projections show that the frequency of extreme heatwaves in September similar to that in 2024 will increase in the future.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1300","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143861640","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Two Arctic Wintertime Boundary Layer States: Disentangling the Role of Cloud and Wind Regimes in Reanalysis and Observations During MOSAiC","authors":"Sandro Dahlke,&nbsp;Annette Rinke,&nbsp;Matthew D. Shupe,&nbsp;Christopher J. Cox","doi":"10.1002/asl.1298","DOIUrl":"https://doi.org/10.1002/asl.1298","url":null,"abstract":"<p>The wintertime central Arctic atmosphere comprises a radiatively clear and a radiatively opaque state, which are linked to synoptic forcing and mixed-phase clouds. Weather and climate models often lack process representations surrounding these states, but prior work mostly treated the problem as an aggregate of synoptic conditions, resulting in partially overlapping biases. Here, we disaggregate the Arctic states and confront ERA5 reanalysis with observations from the MOSAiC campaign over the central Arctic sea ice during winter 2019/2020. Low-level winds and liquid water path (LWP) are combined to derive different synoptic classes. Results show that the clear state is primarily formed by weak/moderate winds and the absence of liquid-bearing clouds, while strong winds and enhanced LWP primarily form the radiatively opaque state. ERA5 struggles to reproduce these basic statistics, shows too weak sensitivity of thermal radiation to synoptic forcing, and overestimates thermal radiation for similar LWP amounts. The latter is caused by a warm bias, which has a pronounced inversion structure and is largest in clear and calm conditions. Under strong synoptic forcing, the warm bias is constant with height and discrepancies in mixed-phase cloud altitude appear. Separating synoptic conditions is regarded as useful for process-oriented evaluation of the Arctic troposphere in models.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 4","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1298","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"One-kilometer resolution forecasts of hourly precipitation over China using machine learning models","authors":"Bo Li,&nbsp;Zijian Zhu,&nbsp;Xiaohui Zhong,&nbsp;Ruxin Tan,&nbsp;Yegui Wang,&nbsp;Weiren Lan,&nbsp;Hao Li","doi":"10.1002/asl.1297","DOIUrl":"https://doi.org/10.1002/asl.1297","url":null,"abstract":"<p>Global numerical weather prediction (NWP) models often face challenges in providing the fine spatial resolution required for accurate prediction of localized phenomena and extreme precipitation events due to computational constraints and the chaotic nature of atmospheric dynamics. Downscaling models address this limitation by refining forecasts to higher resolutions for specific regions. Recently, machine learning (ML) based weather forecasting models demonstrate superior efficiency and accuracy compared to traditional NWP models. However, these ML models generally operate with a temporal resolution of 6 h and a spatial resolution of 0.25°. Furthermore, they predominantly rely on the fifth generation of the European Center for Medium-Range Weather Forecasts Reanalysis (ERA5) data, which is notorious for its precipitation biases. In this study, we utilize the High-Resolution China Meteorological Administration Land Data Assimilation System dataset, which provides more accurate precipitation data, as the target for downscaling and bias correction. This study pioneers the application of a transformer-based super-resolution model, SwinIR, to downscale and correct biases in precipitation forecasts generated by FuXi-2.0, a state-of-the-art ML weather forecasting model trained on ERA5 with a temporal resolution of 1 h. Our results demonstrate that the downscaled forecasts outperform the high-resolution forecasts from the ECMWF in terms of both accuracy and computational efficiency. However, the study also underscores the persistent challenge of underestimating high-intensity rainfall and extreme weather events, which remain critical areas for future improvement.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 3","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1297","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143689154","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sensitivity of European blocking to physical parameters in a large ensemble climate model experiment","authors":"Tim Woollings,&nbsp;Marie Drouard,&nbsp;David M. H. Sexton,&nbsp;Carol F. McSweeney","doi":"10.1002/asl.1295","DOIUrl":"https://doi.org/10.1002/asl.1295","url":null,"abstract":"<p>The occurrence of blocking weather patterns over Europe is analysed in a large ensemble of simulations of a climate model with perturbed physical parameters. The experiments were performed with HadGEM3-GC3 for the UK Climate Change Projections, and comprise a set of 15 coupled simulations supported by a larger suite of 505 atmosphere-only simulations. Despite the systematic perturbation of 47 different physical constants in the atmosphere-only experiments, only three were found to have any impact on European blocking frequencies. These reveal the sensitivity of European blocking to orographic drag in winter and to convective entrainment in summer. However, these sensitivities cannot be traced through to the coupled simulations, due to the smaller and more realistic range of perturbations used and likely also to coupled dynamical effects. Overall, we find that although physical sensitivity to the parameterisations exists, adjustment of the parameters is no replacement for further structural improvement in the representation of these processes in the model.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 3","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1295","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143554456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial structure of local winds “Rokko-oroshi”: A case study using Doppler lidar observation and WRF simulation","authors":"Hirotaka Abe,&nbsp;Hiroyuki Kusaka,&nbsp;Yasuhiko Azegami,&nbsp;Hideyuki Tanaka","doi":"10.1002/asl.1294","DOIUrl":"https://doi.org/10.1002/asl.1294","url":null,"abstract":"<p>Rokko-oroshi is a northerly local wind blowing in the mega-city Kobe, Japan. This wind blows from the Rokko Mountains. This study analyzed the three-dimensional structure of Rokko-oroshi observed with a near-surface anemometer and Doppler lidar on January 16, 2023. Furthermore, numerical simulations using the Weather Research and Forecasting (WRF) model revealed the factors responsible for the strong winds. The results showed that Rokko-oroshi on January 16, 2023 was a bora-type downslope windstorm. The Doppler lidar observed the strong winds of Rokko-oroshi and a stagnant layer immediately above them. Numerical simulation results indicated the stagnant layer was formed by mountain-wave breaking. Under this stagnant layer, the airflow transitioned from subcritical to supercritical, resulting in the strong winds of Rokko-oroshi. This Rokko-oroshi was accompanied by a hydraulic jump. The occurrence of the Rokko-oroshi was supported by an upper-level critical layer and a lower-level strong stable layer on the windward side of the Rokko Mountains.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1294","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143447062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How compound wind and precipitation extremes change over Southeast Asia: A comprehensive assessment from CMIP6 models","authors":"Yifei Jiang,&nbsp;Fei Ge,&nbsp;Quanliang Chen,&nbsp;Zhiye Lin,&nbsp;Klaus Fraedrich,&nbsp;Zhang Chen","doi":"10.1002/asl.1293","DOIUrl":"https://doi.org/10.1002/asl.1293","url":null,"abstract":"<p>Observational evidence has shown that Compound Wind and Precipitation Extremes (CWPEs) can cause substantial disruptions to natural and economic systems under climate change. This study conducts a historical assessment and future projection of CWPEs characteristics in the climate vulnerable region of Southeast Asia (SEA) based on two Shared Socioeconomic Pathways (SSPs) from Scenario Model Intercomparison Project (ScenarioMIP) in Coupled Model Intercomparison Project Phase 6 (CMIP6). Results reveal that the northern Philippines, the eastern and northwestern coastal areas of the Indochina Peninsula have experienced the most frequent, strongest CWPEs during the period of 1985–2014. SEA is projected to experience a frequency increase of 14.4% (22.5%) and intensity increase of 9.4% (19.5%) under the SSP2-4.5 (SSP5-8.5) scenario at the end of 21st century (2070–2099). Kalimantan appears to replace the Philippines as the most affected area, particularly under high emission scenario. In addition, the changes in CWPEs are primarily driven by the changes in precipitation, with the average contribution of precipitation changes across the whole region is 62.8% (70.4%) under the SSP2-4.5 (SSP5-8.5) scenario. For precipitation uncertainties, the contribution from model uncertainty decreases over time (from 73.9% to 42.7%), while scenario uncertainty increases (from 20.3% to 55.0%). In contrast, for wind projections, model uncertainty remains the dominant factor (from 81.3% to 87.6%) with little change. The present study reveals the high sensitivity of the CWPEs over SEA under global warming and highlighting the risks of future disaster impact in such vulnerable regions.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1293","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving vertical detail in simulated temperature and humidity data using machine learning","authors":"Joana D. da Silva Rodrigues,&nbsp;Cyril J. Morcrette","doi":"10.1002/asl.1288","DOIUrl":"https://doi.org/10.1002/asl.1288","url":null,"abstract":"<p>Atmospheric models used for weather forecasting and climate predictions discretise the atmosphere onto a vertical grid. There are however atmospheric phenomena that occur on scales smaller than the thickness of those model layers. The formation of low-level clouds due to temperature inversions is an example. This leads to atmospheric models underestimating, or even missing, these clouds and their radiative effects. Using radiosonde observations as training data, a machine learning model is used to improve the vertical detail of modelled profiles of temperature and specific humidity. In addition, a physics-informed machine learning model is developed and compared to the traditional approach; showing improvements in the cloud fraction profiles calculated from its predictions. The vertically enhanced profiles also improve the representation of layers of convective inhibition and anomalous refractivity gradients. This work facilitates targeted improvements to the representation of certain atmospheric processes without the burden of increased memory and computational cost from increasing vertical resolution throughout the whole model.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1288","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143248777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A generalized extreme value approach for the analysis of stationary climatic covariate in a Mediterranean city","authors":"Cherif Semia","doi":"10.1002/asl.1291","DOIUrl":"https://doi.org/10.1002/asl.1291","url":null,"abstract":"<p>Extreme value theory (EVT) is used as univariate extreme value analysis (EVA) in order to analyze and model the covariates temperature, relative humidity (RH) and the thermal comfort index (humidex) issued from a dataset of 38 years in Tunis. It is a South Mediterranean area known as a hotspot for climate change. The best approach is to reduce the data considerably by taking annual block maxima from mean monthly data. It will converge to a generalized extreme value distribution in order to estimate the return levels of the studied parameters. The stationarity of the series are checked by augmented Dickey-Fuller test. The modeling of the three parameters shows a Weibull distribution pattern. The extreme/maximum monthly means temperature of 30.2°C and humidex of 39.4 have a common return level between 300 and 350 years. The highest mean monthly RH of 86.0% is expected to be exceeded every 50 years. For the next 38 years, the maxima monthly mean temperatures are expected to be stable, and the maxima monthly mean RH values, as well as the humidex monthly mean maxima are expected to decrease. The percentile air temperature hot day (TX90p) and night (TN90p) indices show globally linear upward trends and the ones of cold days (TX10p) and cold nights (TN10p) have a downward trend. The diurnal yearly temperature range shows an almost flat trend for its evolution through the years of study.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1291","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143111766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Spatial and temporal dependence in distribution-based evaluation of CMIP6 daily maximum temperatures","authors":"Mala Virdee,&nbsp;Ieva Kazlauskaite,&nbsp;Emma J. D. Boland,&nbsp;Emily Shuckburgh,&nbsp;Alison Ming","doi":"10.1002/asl.1290","DOIUrl":"https://doi.org/10.1002/asl.1290","url":null,"abstract":"<p>Climate models are increasingly used to derive localised, specific information to guide adaptation to climate change. Model projections of future scenarios are conferred credibility by evaluating model skill in reproducing large-scale properties of the observed climate system. Model evaluation at fine spatial and temporal scales and for rare extreme events is critical for provision of reliable adaptation-relevant information, but may be challenging given significant internal variability and limited observed data in this setting. Comparing distributions of physical variables from historical simulations of Coupled Model Intercomparison Project models against observed distributions provides a comprehensive, concise and physically-justified skill measure. Calculating divergence between distributions requires aggregation of data spatially or temporally. The spatial and temporal scales at which a divergence measure converges to a consistent value can indicate the scales at which a well-defined climate signal emerges from internal variability. Below this threshold, there may be insufficient data for robust evaluation, particularly for rare extremes. Here, the behaviour of several divergence measures in response to spatial and temporal aggregation is analysed empirically to give a novel evaluation of CMIP6 daily maximum temperature simulations against reanalysis. Some key insights presented here can inform methodological choices made when deriving adaptation-relevant information. Convergence varies according to model, geographic region and divergence measure; selection of the level of precision at which models can provide reliable information therefore requires a context-specific understanding. For this purpose, an interactive tool provided alongside this study demonstrates scale-dependent evaluation across several geographic regions. Commonly applied measures are found to be only weakly sensitive to discrepancies in the tails of distributions.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1290","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143111765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Near-surface permafrost extent and active layer thickness characterized by reanalysis/assimilation data","authors":"Zequn Liu,&nbsp;Donglin Guo,&nbsp;Wei Hua,&nbsp;Yihui Chen","doi":"10.1002/asl.1289","DOIUrl":"https://doi.org/10.1002/asl.1289","url":null,"abstract":"<p>Whilst permafrost change is widely concerned in the context of global warming, lack of observations becomes one of major limitations for conducting large-scale and long-term permafrost change research. Reanalysis/assimilation data in theory can make up for the lack of observations, but how they characterize permafrost extent and active layer thickness remains unclear. Here, we investigate the near-surface permafrost extent and active layer thickness characterized by seven reanalysis/assimilation datasets (CFSR, MERRA-2, ERA5, ERA5-Land, GLDAS-CLSMv20, GLDAS-CLSMv21, and GLDAS-Noah). Results indicate that most of reanalysis/assimilation data have limited abilities in characterizing near-surface permafrost extent and active layer thickness. GLDAS-CLSMv20 is overall optimal in terms of comprehensive performance in characterizing both present-day near-surface permafrost extent and active layer thickness change. The GLDAS-CLSMv20 indicates that near-surface permafrost extent decreases by −0.69 × 10⁶ km² decade⁻¹ and active layer deepens by 0.06 m decade⁻¹ from 1979 to 2014. Change in active layer is significantly correlated to air temperature, precipitation, and downward longwave radiation in summer, but the correlations show regional differences. Our study implies an imperative to advance reanalysis/assimilation data's abilities to reproduce permafrost, especially for reanalysis data.</p>","PeriodicalId":50734,"journal":{"name":"Atmospheric Science Letters","volume":"26 1","pages":""},"PeriodicalIF":2.0,"publicationDate":"2025-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/asl.1289","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143120254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}