Atmospheric Research最新文献

{"title":"Impact of surface and entrainment heat fluxes on the thermodynamic structure of the convective boundary layer over the Tibetan Plateau: Observations and modeling analysis","authors":"Xiaolan Li ,&nbsp;Xiao-Ming Hu ,&nbsp;Wei Wei ,&nbsp;Lu Zhang ,&nbsp;Yan Ren ,&nbsp;Hongsheng Zhang","doi":"10.1016/j.atmosres.2025.108459","DOIUrl":"10.1016/j.atmosres.2025.108459","url":null,"abstract":"<div><div>Substantial uncertainties remain in numerical models incorporating different planetary boundary layer (PBL) schemes when it comes to reproducing the detailed thermodynamic structure of the convective boundary layer (CBL), particularly for the level of neutral stability (<em>z</em>_n), at which statically unstable lower CBL begins to transit into slightly stable upper CBL. Using multi-year radiosonde data from 12 stations and large-eddy simulation (LES), we examined the detailed CBL thermodynamic structure and processes over the Tibetan Plateau, particularly focusing on the impact of surface heating and entrainment on <em>z</em>_n. The results indicated that the values of <em>z</em>_n spatially ranged within 0.16–0.38<em>z</em>_i on the plateau, with <em>z</em>_i representing the CBL depth, and <em>z</em>_n was higher in the southwestern region and lower in the southeastern region. Surface−/entrainment-induced large-scale thermals (corresponding to nonlocal fluxes) tended to suppress/elevate <em>z</em>_n, due to warm air penetrating into the upper/lower CBL, whereas small-scale eddies (corresponding to local fluxes) exert the opposite effect on <em>z</em>_n. The LES results indicated that <em>z</em>_n increased before 08:00 Local Time (about 80 min after sunrise), as surface-induced small eddies dominated during the early stage of CBL development. After this time, <em>z</em>_n decreased as large-scale surface-induced thermals became more active. This improved understanding provides guidance for further improvement of PBL schemes.</div></div><div><h3>Plain language summary</h3><div>Convective boundary layer (CBL) over the Tibetan Plateau plays an important role in the climate system in East Asia. Nevertheless, detailed CBL structure and the impact factors over the plateau have not been fully examined yet. Combining the multi-year radiosonde fine-resolution profiles of potential temperature (<em>θ</em>) with the large eddy simulation (LES), we investigate the CBL structure, particularly the position of neutral point (<em>z</em>_n), a transition level separating the statically unstable lower CBL from the slightly statically stable upper CBL. We also examine the impacts of surface heating and entrainment process on detailed CBL structure. <em>θ</em> profiles exhibit a three-layer structure, with <em>z</em>_n spatially varying over the plateau. Different eddies with different sizes initiated from the surface and from the entrainment zone at the CBL top synergistically affect the evolution of the CBL and the altitude of <em>z</em>_n. This improved understanding of the detail CBL structure and the relevant physical processes provides a new angle to evaluate and calibrate numerical weather prediction (NWP) models with PBL schemes.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"329 ","pages":"Article 108459"},"PeriodicalIF":4.4,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lightning used to follow ship-tracks in Eastern Mediterranean winter thunderstorms","authors":"Yoav Yair ,&nbsp;Menahem Kozets ,&nbsp;Yanai Namia-Cohen ,&nbsp;Colin Price","doi":"10.1016/j.atmosres.2025.108453","DOIUrl":"10.1016/j.atmosres.2025.108453","url":null,"abstract":"<div><div>The interaction between aerosol particles and thunderstorm evolution and properties is complex and was studied by direct observational campaigns, remote sensing from space and through numerical simulations. Aerosols invigorate convection and can lead to enhanced charging manifested in more lightning, but they can also lead to a “Boomerang Effect” where too large concentrations of particles lead to diminished vertical development and weaker electrical activity. The effects of ship exhaust on ocean cloudiness have been studied intensively in recent years, following the discovery of prolonged ship tracks in oceanic regions where maritime transportation is most heavy, leading to large-scale changes in albedo and reduced precipitation. Recently it was shown that aerosols emitted by ships also tend to increase lightning activity, by modifying the dynamics and microphysics of clouds formed directly above the busiest shipping lanes. Here, we study the effects of ship-emitted aerosols on thunderstorms in one of the busiest shipping routes in the world: the Mediterranean Sea between the Suez Canal and the Gibraltar Straights. This region hosts hundreds of ships daily, and space observations show considerable enhancement of the Aerosol Optical Depth (AOD) and sulphate concentrations there, some from land sources and others directly related to maritime transportation. The research utilized 14 winter months of lightning detection networks data (ENTLN, from 2018 to 2022) and studied the properties of lightning with respect to sulphate concentrations and cloud properties. The results were divided between before and after the International Maritime Organization (IMO) regulation change in January 2020 that curbed sulphate emissions from 3.5 % to 0.5 %. We show a marked increase in winter lightning activity over the main east-west shipping lanes. That spatial enhancement is all but gone following the reduction in sulphate emissions from ships from February 2020, and on average, clouds became shallower with a thinner charging layer, testifying to the role of aerosol particles in convective invigoration and lightning generation.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"328 ","pages":"Article 108453"},"PeriodicalIF":4.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Response of thunderstorm activity to ENSO events in East Asia and the Western Pacific region","authors":"Ruiyang Ma ,&nbsp;Dong Zheng ,&nbsp;Yijun Zhang ,&nbsp;Wen Yao ,&nbsp;Wenjuan Zhang ,&nbsp;Biao Zhu","doi":"10.1016/j.atmosres.2025.108455","DOIUrl":"10.1016/j.atmosres.2025.108455","url":null,"abstract":"<div><div>This study utilized the Thunderstorm Feature Dataset (TFD), combined with the sea surface temperature (SST) anomalies over the NINO3.4 region (ENSO index) from the NOAA/ERSSTv5 dataset and ERA5 reanalysis data, to investigate the response of thunderstorm activity in East Asia and the Western Pacific region to ENSO events, an aspect that has been seldom addressed in previous studies. Results indicate ENSO events as the primary factors influencing the interannual variation of thunderstorm activity in the study area, with thunderstorm activity anomalies negatively correlated with the ENSO index, lagging by approximately 3 months. Regionally, thunderstorm activity anomalies and the ENSO index show a strong positive correlation in areas north of 20°N, encompassing Southeastern China land and adjacent sea area, but a negative correlation in areas south of 20°N, including the South China Sea, the Philippine Islands, and parts of the Western Pacific. Thunderstorm activity anomalies in these areas all lag the ENSO index by 1–3 months. The response of thunderstorm activity to ENSO events demonstrates a strong correlation with anomalies in convective parameters such as convective available potential energy (CAPE), K index, the mid-level (700–400 hPa) averaged relative humidity, and 500 hPa vertical velocity. During El Niño, warm SST in the central and eastern equatorial Pacific, along with enhanced upward motion, leads to anomalous downward motion and anticyclonic circulation in the Western Pacific region within the study area, resulting in a decrease in thunderstorm activity. Concurrently, the anomalous anticyclonic circulation in the Western Pacific region enhances the warm, moist southwest winds, which transport more water vapor to Southeastern China, thereby increasing thunderstorm activity. Conversely, during La Niña, the anomalous cyclonic circulation and moisture convergence in the Western Pacific region result in an increase in thunderstorm activity in the Western Pacific region within the study area. Additionally, the anomalous cyclonic circulation leads to a weakening of the warm and moist southwest winds and upward motion in the Southeastern China land area, consequently reducing thunderstorm activity.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"329 ","pages":"Article 108455"},"PeriodicalIF":4.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145027248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of reanalyzed surface air temperature over the western Tibetan Plateau","authors":"Jing Wang ,&nbsp;Xiao-Feng Li ,&nbsp;Jingzhi Wang ,&nbsp;Xin Lai ,&nbsp;Song Yang ,&nbsp;Nathan Forsythe ,&nbsp;Hayley J. Fowler","doi":"10.1016/j.atmosres.2025.108454","DOIUrl":"10.1016/j.atmosres.2025.108454","url":null,"abstract":"<div><div>Very few evaluation studies have focused on the western Tibetan Plateau (TP), despite considerable scientific interests from climatologists and glaciologists globally. This region exhibits anomalous glacial stability under climate warming, but the lack of long-term and high-density observational data poses a major research challenge. Evaluating and selecting reanalysis datasets with higher accuracy over the western TP is thereby vital for advancing climate research. Using ground-based 2-m air temperature (T_2m) observations from multiple neighboring countries across the western TP, we establish an integrated observational network to evaluate the performance of widely used reanalysis datasets, including NCEP1, NCEP2, ERA-Interim, JRA55, MERRA2, CRA-Land, CRA, and ERA5.</div><div>The results indicate that three reanalysis datasets (CRA-Land, CRA, and ERA5) generally outperform the others in capturing T_2m climatology and year-to-year variability across the western TP as a whole. However, over the Karakoram, the core glacial zone in the western TP, the above three datasets demonstrate the lowest skills in simulating T_2m climatology, although they still perform well in capturing year-to-year variability. For CRA-Land and CRA, the error sources are unclear, although their terrain elevation differences respectively explain ∼67.4 % and ∼69.1 % of their climatological T_2m errors. For ERA5, the terrain elevation differences (explaining ∼58.4 %) and collective radiative processes are the two primary error sources. Moreover, higher surface albedo in ERA5 is identified as the key contributor causing radiative errors. This study identifies the optimization of surface albedo in the Karakoram and its neighboring regions as a critical pathway to enhance ERA5 data quality in the future.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"329 ","pages":"Article 108454"},"PeriodicalIF":4.4,"publicationDate":"2025-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145010896","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of intraseasonal oscillation in the impact of western North Pacific warm pool on rainfall extremes in Yangtze River Basin","authors":"Xuchen Fan ,&nbsp;Fang Zhou ,&nbsp;Botao Zhou ,&nbsp;Jian Shi ,&nbsp;Zuxiang Yang ,&nbsp;Ting Yang ,&nbsp;Zhongkai Bo ,&nbsp;Na Wang","doi":"10.1016/j.atmosres.2025.108457","DOIUrl":"10.1016/j.atmosres.2025.108457","url":null,"abstract":"<div><div>The Yangtze River Basin (YRB), home to millions of people and vital farmlands, faces increasing flood risks due to extreme summer rainfall. This study demonstrated that the western North Pacific warm pool (WNPWP) can exert significant impacts on extreme precipitation in YRB through modulating atmospheric intraseasonal activities over the northwestern Pacific, which operates on 25–80-day timescales. Extreme precipitation occurs preferentially during warm WNPWP summers compared to cold WNPWP summers owing to that intraseasonal oscillation (ISO) over the northwestern Pacific is more likely to induce extreme rainfall over the YRB during warm WNPWP summers than cold WNPWP summers. The underlying mechanism involves enhanced southwesterly moisture transport by the anomalous anticyclone over the northwestern Pacific driven by the ISO in its specific phases. Crucially, this transport intensifies remarkably during warm WNPWP summers due to the strengthened anticyclonic background manifested as the westward extension of the Western Pacific Subtropical High (WPSH) in response to warm WNPWP conditions, which is statistically tied to preceding El Niño-Southern Oscillation (ENSO) events.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"328 ","pages":"Article 108457"},"PeriodicalIF":4.4,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144932623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unraveling the role of stratospheric intrusion and biomass burning in springtime tropospheric ozone enhancement in Yunnan, China","authors":"Yuheng Chen ,&nbsp;Fei Qiu ,&nbsp;Wen Chen ,&nbsp;Wenxuan Fan ,&nbsp;Anjie Yin ,&nbsp;Mingya Xie ,&nbsp;Puyu Lian ,&nbsp;Kaihui Zhao","doi":"10.1016/j.atmosres.2025.108458","DOIUrl":"10.1016/j.atmosres.2025.108458","url":null,"abstract":"<div><div>Ozone (O₃) pollution is particularly prevalent in spring and exhibits distinctive characteristics in southwestern China. Two significant natural sources contribute to O₃ pollution: stratospheric intrusion (SI) and cross-border transport of biomass burning (BB) emissions from Southeast Asia. However, the roles of SI and BB in tropospheric O₃ pollution in Southeast China remain insufficiently understood. This study investigated their distinct contributions during a typical SI event, using multi-source observations from AIRS satellite and surface samplers combined with the Goddard Earth Observing System coupled with chemistry (GEOS-Chem). SI and BB were identified as the key drivers of tropospheric O₃ enhancement. The upper-level jet stream facilitated SI, while low-level jets, the subtropical high, and low-level troughs created favorable dynamic conditions for the cross-border transport of BB. SI primarily influenced altitudes above 500 hPa, contributing 11.3–40.0 ppb of O₃. In comparison, BB transport reached as low as 850 hPa, with a positive contribution ranging from 8.5 to 11.6 ppb. Notably, O₃ precursor sensitivity (OPS) rapidly shifted to a VOC-limited regime under the influence of BB. This study highlights the importance of adopting a dynamic emission reduction strategy tailored to varying OPS conditions during different O₃ episodes. The findings provide valuable insights for policymakers in developing effective strategies to mitigate O₃ pollution, considering the impacts of SI and BB.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"328 ","pages":"Article 108458"},"PeriodicalIF":4.4,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996282","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Satellite based study on the role of Cloud Condensation Nuclei (CCN) and atmospheric thermodynamics in warm cloud evolution","authors":"Subin Jose ,&nbsp;Sijo Joseph ,&nbsp;N.B. Lakshmi","doi":"10.1016/j.atmosres.2025.108452","DOIUrl":"10.1016/j.atmosres.2025.108452","url":null,"abstract":"<div><div>The study presents observational evidence for the impact of Cloud Condensation Nuclei (CCN) concentration and atmospheric thermodynamic conditions on the diffusion growth and collision-coalescence processes in warm cloud evolution. We used multi-band optical data from the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (NPP) satellite (2013–2018) to identify the convective cloud clusters and examine the warm cloud evolution under different thermodynamic and pollution conditions based on cloud top temperature (T) - cloud drop effective radius (r_e) relationships. Analysis revealed that diffusion growth is predominant under polluted and stable (Estimated Inversion Strength (EIS) &gt; 1 K) atmospheric conditions. In the unstable regime (EIS &lt; 1 K), relative dispersion (ϵ) reaches its maximum (∼0.39) at a CCN concentration of around 1000 cm⁻³ and supersaturation remains higher at lower CCN concentrations and decreases rapidly beyond ∼1000 cm⁻³ which marks the transitional point between the aerosol-limited and updraft-limited regimes. However in the stable regime (EIS &gt; 1 K), ϵ remains relatively low (between 0.10 and 0.25) with low supersaturation. In unstable conditions the estimated cloud top entrainment index (ECTEI) is found to be −5.6 ± 1.5 indicating more favourable conditions for entrainment, while in stable conditions ECTEI is found to be −2 ± 3.3 reflecting entrainment suppression. Although the Twomey effect is found to be predominant under stable atmospheric conditions, a nonlinear relationship exists between droplet growth and CCN concentration. In the aerosol limited regime, an increase in growth rate ranging from ∼0.0026 <span><math><mi>μ</mi></math></span>m/s to 0.0032 <span><math><mi>μ</mi></math></span>m/s is observed while at high CCN concentrations (above ∼1000 cm⁻³) growth rates decreases to 0.0025 <span><math><mi>μ</mi></math></span>m/s. These observations can help refine aerosol–cloud interaction (ACI) parameterizations in climate models, thereby reducing uncertainties in the estimation of aerosol effective radiative forcing under a warming climate.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"328 ","pages":"Article 108452"},"PeriodicalIF":4.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144932625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differences in the raindrop size distributions of pre-monsoon thunderstorms and tropical cyclones observed over eastern India","authors":"Anuj Shrivastava ,&nbsp;Balaji Kumar Seela ,&nbsp;Bhishma Tyagi ,&nbsp;Pay-Liam Lin","doi":"10.1016/j.atmosres.2025.108456","DOIUrl":"10.1016/j.atmosres.2025.108456","url":null,"abstract":"<div><div>Investigations on the raindrop size distributions (RSDs) are essential for understanding the dynamical and microphysical processes contributing to precipitation. Empirical relationships derived from RSD parameters, like radar reflectivity–rainfall rate (<em>Z–R</em>), mass-weighted mean diameter–rainfall rate (<em>D</em>_<em>m</em><em>–R</em>), shape–slope (<em>μ–Ʌ</em>), and normalized intercept parameter–rainfall rate (<em>log</em>_<em>10</em><em>N</em>_<em>w</em><em>–R</em>) relationships, can enhance the rainfall estimation, and cloud modeling simulations. In the present study, four years (2018–2021) measurements of a Laser Precipitation Monitor (LPM; Thies) disdrometer installed at the National Institute of Technology Rourkela, India, are used to investigate the RSD characteristics of thunderstorms (TSs) and tropical cyclones (TCs) observed during pre-monsoon (March–May) season. Along with the disdrometer data, auxiliary parameters like convective available potential energy (CAPE), convective inhibition (CIN), total column water vapor (<em>WV</em>), vertical profiles of temperature (T) and relative humidity (RH) from reanalysis data sets of ECMWF (European Centre for Medium-Range Weather Forecasts) fifth-generation reanalysis (ERA5) are also used in this study. TCs have dominant small-sized raindrops, whereas moderate and large-sized raindrops predominate in TSs. Diurnal variation of RSD indicates that raindrop sizes during TCs are limited to 4.5 mm. The mean values of <em>R</em>, <em>Z</em>, <em>D</em>_<em>m</em>, <em>μ</em>, and liquid water content (<em>W</em>) are maximum during the TSs and the normalized intercept parameter (<em>log</em>_<em>10</em><em>N</em>_<em>w</em>) and slope parameter (<em>Ʌ)</em> are maximized during the TCs. The average RSD indicated significant variations between TSs and TCs precipitation with a significant difference in <em>Z–R</em>, <em>D</em>_<em>m</em><em>–R</em>, <em>μ–Ʌ</em>, <em>log</em>_<em>10</em><em>N</em>_<em>w</em>–<em>R</em> relationships. The <em>Z–R</em> relationships during the TSs and TCs are <em>Z</em> = 543.22<em>R</em>^1.46 and <em>Z</em> = 291.3<em>R</em>^1.31, respectively. The diurnal variations in <em>Z–R</em> coefficient ‘<em>A</em>' and exponent ‘b’ values are associated with sizeable diurnal variations of CAPE and CIN.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"329 ","pages":"Article 108456"},"PeriodicalIF":4.4,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145020625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The causes of the extreme precipitation event in the Sichuan Basin in August 2020: A perspective from anomalous inter-monthly climate differences and weather processes","authors":"Yilin Gong,&nbsp;Ke Fan,&nbsp;Hongqing Yang","doi":"10.1016/j.atmosres.2025.108450","DOIUrl":"10.1016/j.atmosres.2025.108450","url":null,"abstract":"<div><div>During August 2020, record-breaking precipitation occurred over the Sichuan Basin (SCB), the highest since 1979, exceeding both the historical August average and the rainfall of July 2020. This observed inter-month precipitation evolution contrasts with the typical climatological pattern, in which precipitation rises from July to August. During this period, two extreme rainfall episodes occurred—11 to 13 August (E1) and 15 to 18 August (E2)—and E2 exhibited a more northerly-located precipitation center and higher precipitation compared to E1. These two extreme precipitation episodes accounted for 60.1 % of the total rainfall in August 2020. This study investigates the causes of inter-monthly precipitation anomalies in the SCB during July–August 2020 from the perspective of the inter-monthly difference (August minus July) and further reveals the causes of two extreme precipitation episodes. Compared to July, the enhanced and eastward-shifted South Asian High (SAH) and the northeastward-shifted Western Pacific Subtropical High (WPSH) collectively contributed to the record-breaking precipitation over the SCB in August. The enhanced western Pacific convection and suppressed Indian Ocean convection influence precipitation through its effects on WPSH and SAH indirectly. During both extreme episodes (E1 and E2), abundant water vapor was transported from the tropical western Pacific to the SCB by the intensified WPSH. Concurrently, more moisture from the Indian Ocean resulted in more precipitation in E2. Moreover, non-adiabatic heating anomalies on the Tibetan Plateau facilitated the development of a southwest vortex, which enhanced upward motion over the SCB. All key processes can be validated by the Linear Baroclinic Model.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"328 ","pages":"Article 108450"},"PeriodicalIF":4.4,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertical structure of cloud macro- and microphysical properties under the Southwest Vortex systems in the warm season based on CloudSat","authors":"Xinyue Zhang ,&nbsp;Pengguo Zhao ,&nbsp;Dian Li ,&nbsp;Wen Zhao ,&nbsp;Hui Xiao ,&nbsp;Yunjun Zhou ,&nbsp;Zeneng He","doi":"10.1016/j.atmosres.2025.108443","DOIUrl":"10.1016/j.atmosres.2025.108443","url":null,"abstract":"<div><div>This study investigates the vertical structure of macro- and microphysical cloud properties associated with the Southwest Vortex (SWV) during the warm season, utilizing CloudSat satellite observations and Southwest Vortex Yearbooks (2012–2017). Results show that the SWV system's cloud top height exceeds 16 km, with a maximum average cloud cover of 35 %, approximately 17 % higher than the East Asian average. Single-layer clouds account for about 48 %, with frequency decreasing as cloud layer number increases. Altocumulus and high clouds are most frequent, while deep convective clouds and nimbostratus are least frequent. Cloud phase analysis under the SWV systems shows a balanced occurrence (37 %) of ice and liquid clouds, with mixed-phase clouds showing the lowest frequency (27 %). Radar reflectivity vertical profiles identify key layers at 2 km (raindrop evaporation) and 5 km (mixed-phase regions).The liquid cloud effective radius reaches a peak of 35 μm at 1.5 km, stabilizing to 15 μm above 2 km. The ice cloud effective radius is distributed between 25 and 95 μm, with a maximum value of 95 μm observed at 5 km. The ice water content exhibits a unimodal distribution, peaking at 0.3 g·m⁻³ at 8 km. As an α mesoscale convective system, the SWV's strong updraft drives airflow to the upper atmosphere, where low temperatures and supersaturated conditions facilitate the growth of ice crystals. These results clarify the SWV's unique cloud vertical structure and properties, reveal links between regional mesoscale convective systems and cloud-precipitation processes, and provide a basis for enhancing the accuracy of climate and weather forecasts.</div></div>","PeriodicalId":8600,"journal":{"name":"Atmospheric Research","volume":"328 ","pages":"Article 108443"},"PeriodicalIF":4.4,"publicationDate":"2025-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144932689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}