Journal of Geophysical Research: Atmospheres最新文献

{"title":"Removal Processes of the Stratospheric SO2 Volcanic Plume From the 2015 Calbuco Eruption","authors":"J.-L. Baray,&nbsp;F. Gheusi,&nbsp;V. Duflot,&nbsp;P. Tulet","doi":"10.1029/2025JD043850","DOIUrl":"https://doi.org/10.1029/2025JD043850","url":null,"abstract":"<p>We analyze the volcanic plume from the April 2015 Calbuco eruption over a 35-day period using simulations from Meso-NH, a non-hydrostatic mesoscale atmospheric model. A dedicated parameterization of the deep injection of the plume into the stratosphere ensures a realistic representation when compared to Infrared Atmospheric Sounding Interferometer satellite observations. During the first 12 hr of the eruption, on 22 April 2015, SO₂ mixing ratio reached 29 ppmv between 15 and 18 km for the first eruption pulse, and 38 ppmv between 12 and 16 km for the second. Most SO₂ was injected directly into the stratosphere, with a stratospheric load reaching 308 ktS (kilotons of atomic sulfur, i.e. 616 kilotons of SO₂) after the eruption. After 1 month, both stratospheric and tropospheric SO₂ loads returned to near-background levels. During analysis, the chemical conversion of SO₂ into H₂SO₄ removed a part of SO₂ from the stratosphere. During the long-range advection, the co-location between the subtropical jet stream and the Calbuco plume led to three significant stratospheric intrusions on 24, 26 and 28 April 2015. These events transferred stratospheric SO₂ into the troposphere, SO₂ mixing ratios in the upper troposphere reaching 15 ppmv, 26 and 15 ppbv, respectively. SO₂ is gradually oxidized into H₂SO₄, with up to 5 ktS of gaseous H₂SO₄ in the stratosphere on 30 April, but dynamical processes dominate the SO₂ atmospheric budget over chemical transformations. This study demonstrates that stratospheric intrusions can play a critical role in the removal of volcanic material from the stratosphere following a major eruption.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145223838","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":"Subseasonal Prediction Skill of Winter Quasi-Stationary Waves in the Northern Hemisphere","authors":"Lualawi Mareshet Admasu,&nbsp;Rachel H. White","doi":"10.1029/2025JD043337","DOIUrl":"https://doi.org/10.1029/2025JD043337","url":null,"abstract":"<p>Quasi-stationary Rossby waves modulate persistent (lasting days to weeks) atmospheric ridges and troughs, and can lead to extreme weather events, particularly in the midlatitudes. Due to their persistent nature, these quasi-stationary waves (QSWs) provide a unique opportunity to improve subseasonal forecasts of extreme events. Here, we evaluate the skill of the ECMWF dynamical subseasonal-to-seasonal (S2S) forecast model to forecast QSWs in Northern Hemisphere winter. The model shows spatially varying prediction skill, with the North Pacific region showing the highest skill across all lead times studied (7–35 days). We find very large interannual and intraseasonal variability in the subseasonal skill of this North Pacific region. The interannual variability is statistically consistent across different S2S models, indicating that physical conditions varying from year to year influence the prediction skill. Further investigation shows improvements in the S2S skill under certain phases of the Madden-Julian oscillation (MJO), under La Niña ocean conditions, during the westerly phase of the quasi-biennial oscillation (QBO), and following the onset of sudden stratospheric warmings (SSWs). These identified conditions may be windows of opportunity for better S2S QSW forecast skill. Our results indicate that although the S2S skill of QSWs is low, there is potential to utilize natural modes of variability to better capture uncertainty of model outputs and identify times when skill is likely to be higher.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JD043337","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Impacts of the Madden-Julian Oscillation on Widespread Heavy Rainfall Over the Western Region of the Maritime Continent: Sumatra","authors":"Clemente Lopez-Bravo,&nbsp;Claire L. Vincent,&nbsp;Yi Huang,&nbsp;Todd P. Lane","doi":"10.1029/2025JD043493","DOIUrl":"https://doi.org/10.1029/2025JD043493","url":null,"abstract":"<p>The Precipitation Severity Index (PSI) is used to examine the occurrence of and mechanisms behind widespread persistent rainfall events in Sumatra. Analysis of cloud properties from Himawari-8 is combined with data from IMERG and ERA5 to explore new results about changes in cloud properties relating to heavy rainfall and intraseasonal variability. This study brings a fresh angle to the challenge of understanding the Madden-Julian Oscillation (MJO) modulation of cloud and precipitation over Sumatra by examining changes in the total cloud area and, more importantly, changes in the cold cloud tops that indicate the deepest convection. Although widespread cold clouds are likely regardless of MJO phase, the enhanced prevalence of cold tops requires the support of the large-scale convective envelope. These results provide insight about how the MJO influences the nature as well as the amount of convection. Heavy rainfall is shown to make a larger percentage contribution to the total rainfall during the MJO-enhanced convection phases (2-3-4) over Sumatra. This contribution is suggested to be related to a higher prevalence of cold cloud core areas in phases 2 and 4. In phase 3, there is a remarkable increase in the percentage contribution of heavy rainfall in the cold cloud area but a relatively lower prevalence of the coldest cloud core area, suggesting large-scale environmental support for heavy rainfall but not necessarily the most intense convection. These results exemplify the role of mesoscale processes and cloud microphysics in modulating the MJO-scale modulation of rainfall.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JD043493","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145223864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 One-Dimensional Variational Precipitation Retrieval Algorithm Considering Cloud Types for Western North Pacific Tropical Cyclones Using FengYun-3E Microwave Sounders","authors":"Jintao Xu,&nbsp;Ziqiang Ma,&nbsp;Hao Hu,&nbsp;Xiaoqing Li,&nbsp;Xiang Fang","doi":"10.1029/2025JD044523","DOIUrl":"https://doi.org/10.1029/2025JD044523","url":null,"abstract":"<p>Accurate precipitation retrieval from passive microwave observations is essential for global meteorological and climatological studies particularly in tropical cyclone (TC) environments. Building upon the Global Scene-Dependent Atmospheric Retrieval Testbed (GSDART), this study develops an enhanced one-dimensional variational (1DVAR) precipitation retrieval algorithm specifically tailored for monitoring TCs based on Chinese FengYun-3E (FY-3E) passive microwave observations over the northwestern Pacific. The algorithm introduces a precipitation-type differentiation module into the 1DVAR framework (1DVARDPT), employs the Advanced Radiative Transfer Modeling System (ARMS) as the forward operator, and utilizes observations from the FY-3E microwave humidity and temperature sounders (MWTHS). A comprehensive comparative analysis from 19 TCs reveals that considering precipitation types significantly improves retrieval performances—reducing relative bias from −9.89% to 2.02% and mean absolute error (MAE) from 0.38 mm/hr to 0.32 mm/hr—while enhancing the detection of both light/moderate and heavy precipitation. Furthermore, using ARMS instead of the Community Radiative Transfer Model (CRTM) as the forward operator markedly reduces the systematic underestimation seen in conventional retrievals (bias improved from −23.50% to −9.89%), demonstrating ARMS's superiority in precipitation-sensitive radiative transfer modeling. The findings from this study underscore the importance of accounting for precipitation-type variability in 1DVAR retrievals and highlight the strong potential of FY-3E observations and ARMS for advancing microwave-based precipitation estimation.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145223862","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":"Linkages of Multiple Types of Compound Droughts and Hot Events at the Global Scale","authors":"Sifang Feng,&nbsp;Zengchao Hao,&nbsp;Yu Meng,&nbsp;Vijay P. Singh,&nbsp;Yitong Zhang,&nbsp;Xuan Zhang,&nbsp;Fanghua Hao","doi":"10.1029/2025JD043562","DOIUrl":"https://doi.org/10.1029/2025JD043562","url":null,"abstract":"<p>Precipitation deficits in the hydrologic cycle lead to various types of droughts, including meteorological, agricultural, and hydrological droughts. The concurrence of different types of droughts and high temperatures, commonly termed compound drought and hot events (CDHEs), including compound meteorological drought-hot events (CMDHEs), compound agricultural drought-hot events (CADHEs), and compound hydrological drought-hot events (CHDHEs), has received increasing attention due to their larger impacts than single events. Although different CDHEs have been evaluated separately, the linkages among them have seldom been quantified. Using monthly hydroclimatic variables, we evaluated spatial variations and temporal linkages of different CDHEs from 1952 to 2021. High frequencies of different CDHEs are observed in regions such as northeastern South America, central Africa, and southeastern China. The strong synchronous linkages among CDHEs, defined as the likelihood of simultaneous CADHEs/CHDHEs conditional on CMDHEs, are observed in low-latitude regions, which are related to drought propagations. Additionally, cascading linkages, defined as the empirical likelihood of subsequent CADHEs/CHDHEs conditional on CMDHEs, are also modulated by temperature persistence. For different climate types, the strongest linkages are observed in equatorial climates, while the weakest linkage is found in snow climates. These findings provide critical insights for developing cross-sectoral mitigation strategies to reduce CDHE-related risks and enhance predictive capabilities for such compound events by considering their temporal linkages under global warming.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145223863","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":"Fresh Cooking Organic Aerosol Particles Exist as Liquid in Most Urban Temperature Range","authors":"Suyi Hou,&nbsp;Wenli Liu,&nbsp;Mikinori Kuwata","doi":"10.1029/2025JD043825","DOIUrl":"https://doi.org/10.1029/2025JD043825","url":null,"abstract":"<p>Cooking organic aerosol (COA) is an important contributor to particulate matter. COA reacts with atmospheric oxidants such as ozone, as it contains unsaturated fatty acids such as oleic acid. Laboratory studies during the last decades suggested that the atmospheric chemical lifetime of oleic acid ranges from minutes, whereas atmospheric observations demonstrated that the corresponding value is several hours to half a day. To account for the disagreement, the phase state of COA particles has been hypothesized as (semi-)solid based on experimental studies for synthetic mixtures at room temperature. However, most of these studies employed substrate, which cannot fully represent the phase state of suspending aerosol particles. The phase state of suspending COA particles has rarely been measured, especially for the whole range of urban-environment relevant temperatures. By measuring the bounce behavior of suspending particles as a function of temperature, we examined the phase state of major fatty acids in COA (oleic, linoleic, pimelic, and stearic acids), in addition to laboratory-generated COA produced by heating canola oil, lard, and hotpot soup base. All types of fresh COA particles were liquid for the temperature range above −15°C. Comparison with recent laboratory kinetic study suggested that the phase transition may partially, but not fully, account for the reduced chemical reactivity at lower temperatures. As the temperature of most cities in the world is higher than −15°C, we suggest that fresh COA particles are mostly liquid on a global scale, though observational verification would still be needed.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224098","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":"All-Sky Assimilation of FY-4B AGRI Reflectance in the CMA-MESO Model With ARMS as a Forward Operator","authors":"Yuchen Xie,&nbsp;Fuzhong Weng,&nbsp;Chengzhi Ye,&nbsp;Ruixia Liu,&nbsp;Xiuzhen Han","doi":"10.1029/2025JD043600","DOIUrl":"https://doi.org/10.1029/2025JD043600","url":null,"abstract":"<p>All-sky assimilation of visible and near-infrared observations has attracted widespread attention. In the CMA-MESO model, this study proposes an optimized reflectance scheme based on the Ross-Li bidirectional reflectance distribution function (BRDF) model. Over land, the Ross-Li the BRDF model is coupled with the ARMS model using a method based on Fourier transform and Gaussian quadrature decomposition. Over ocean, a static reflectance lookup table is employed. For cloudy sky simulation, an effective cloud particle radius parameterization scheme consistent with cloud microphysical assumptions is introduced. For FY-4B AGRI data at visible and near-infrared bands, all-sky observation errors are analyzed for a dynamic update in the 3DVAR data assimilation system. Five assimilation experiments are conducted, including three single-channel experiments assimilating FY-4B AGRI channels 2, 4, and 5 individually, and two combined-channel experiments assimilating channels 2 + 4 and 4 + 5. Among the single-channel cases, channel 4 assimilation shows the greatest improvement in the representation of ice cloud coverage. In contrast, assimilating channel 2 or channel 5 alone led to confusion between liquid and ice cloud increments. The combined-channel assimilation experiments outperformed the single-channel ones, yielding a significant reduction in the standard deviation (STD) of the simulated reflectance. In summary, assimilating FY-4B AGRI observations holds a great potential for improving the accuracy of cloud cover representation.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2025JD043600","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Unexpected High Loading of Active Carbonyls and Terpenoids in Alpine Forest on Tibetan Plateau: Implication of Secondary Organic Aerosols and Ozone Formation","authors":"Yonggang Xue,&nbsp;Zhu La,&nbsp;Liqin Wang,&nbsp;Shan He,&nbsp;Long Chen,&nbsp;Long Cui,&nbsp;Kin Fai Ho,&nbsp;Qiyuan Wang,&nbsp;Wenting Dai,&nbsp;Yu Huang,&nbsp;Junji Cao","doi":"10.1029/2025JD043466","DOIUrl":"https://doi.org/10.1029/2025JD043466","url":null,"abstract":"<p>The reaction of volatile organic compounds (VOCs) can enhance the formation of secondary organic aerosols (SOA) and ozone, and further cause climate forcing on Tibetan Plateau (TP), while their origins are lack of clearly understanding. An atmospheric VOC monitoring campaign was performed for different altitudes in TP in this study. High concentrations of active carbonyls (up to 17.00 ppbv, 79% of the sum of VOCs measured) and terpenoids (up to 2.87 ppbv, 17% of the sum of VOCs measured) were observed in the alpine forest. Compositions of carbonyls and terpenoids varied synchronously among different tree species across the altitude gradient, and the potential sources of carbonyls and terpenoids in southeast Tibet were mainly distributed on the pathway of Asia monsoon in alpine forest, which imply that local air-ground exchange is the major contributing factor for the ambient VOCs. The carbonyls and terpenoids were estimated for the formation of SOA at approximately 1.78 μg m⁻³ and 0.54 μg m⁻³, respectively. The results confirmed the high impacts of air-ground exchange of active VOCs on formation of secondary organic aerosols and regional climate.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224362","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 Mixed-Phase Cloud Microphysics to Aerosol Perturbations at the Contrasting Sites of Limassol, Cyprus, and Punta Arenas, Chile","authors":"Yun He,&nbsp;Patric Seifert,&nbsp;Cristofer Jimenez,&nbsp;Martin Radenz,&nbsp;Albert Ansmann,&nbsp;Johannes Bühl,&nbsp;Rodanthi-Elisavet Mamouri,&nbsp;Boris Barja González","doi":"10.1029/2024JD043157","DOIUrl":"https://doi.org/10.1029/2024JD043157","url":null,"abstract":"&lt;p&gt;Ice crystal number concentrations (ICNC) of shallow stratiform mixed-phase clouds (MPCs) were contextualized with the ice nucleating particle concentrations (INPC) of the same airmass in which the cloud layers formed. Prerequisite are ground-based lidar and cloud radar observations from two sites with contrasting aerosol conditions: Limassol (34.67&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${}^{circ}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;N, 33.04&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${}^{circ}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;E), Cyprus, dominated by desert dust and continental aerosols, and Punta Arenas (53.13&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${}^{circ}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;S, 70.88&lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${}^{circ}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;W), Chile, where marine aerosol and a so far unquantified fraction of aerosol from other sources prevails. For each MPC case, cloud-level INPC is derived from lidar observations of the cloud-free surroundings. The ICNC nucleated within the MPC is derived 180 m below the liquid-dominated cloud-top layer based on the synergetic observations from lidar and radar. At Limassol, both ICNC and INPC in dust-embedded MPC range from 0.05 to 3 L&lt;sup&gt;−1&lt;/sup&gt; and show good correlation. At similar temperatures, INPC derived in the free troposphere above Punta Arenas are at least one order of magnitude lower than at Limassol. In contrast, an agreement between ICNC (0.02–2 L&lt;sup&gt;−1&lt;/sup&gt;) and INPC (0.01–0.1 L&lt;sup&gt;−1&lt;/sup&gt;) at temperatures below &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;27&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${-}27$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;°&lt;/mo&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${}^{circ}$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt;C is not observed at Punta Arenas. Given the previously demonstrated reliability of the ICNC retrieval, we suggest that current parameterizations of free-tropospheric INPC at temperatures below &lt;span&gt;&lt;/span&gt;&lt;math&gt;\u0000 &lt;semantics&gt;\u0000 &lt;mrow&gt;\u0000 &lt;mo&gt;−&lt;/mo&gt;\u0000 &lt;mn&gt;28&lt;/mn&gt;\u0000 &lt;/mrow&gt;\u0000 &lt;annotation&gt; ${-}28$&lt;/annotation&gt;\u0000 &lt;/semantics&gt;&lt;/math&gt; &lt;span&gt;&lt;/spa","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2024JD043157","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224164","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Deep Learning Based Statistical Downscaling for Enhanced Representation of Indian Monsoon Rainfall With Subseasonal Variability and Extremes","authors":"Vikram S. Chandel,&nbsp;Biplab Banerjee,&nbsp;Subhankar Karmakar,&nbsp;Subimal Ghosh","doi":"10.1029/2025JD044167","DOIUrl":"https://doi.org/10.1029/2025JD044167","url":null,"abstract":"<p>Indian summer monsoon rainfall (ISMR) accounts for 80% of India's annual rainfall and impacts 1.4 billion people, yet remains poorly simulated by climate models. Although super resolution deep learning models such as YNet show promise in global downscaling efforts, we found their performance on ISMR less effective, particularly for extreme rainfall and intraseasonal variability. The transferability of downscaling algorithms trained on reanalysis data to climate model simulations, as well as a comprehensive evaluation across key timescales of ISMR variability, remain unexplored. To address these limitations, we propose two variants of YNet: YNet_D, which incorporates atmospheric variables to enhance downscaling accuracy, and YNet_DE, which prioritizes extreme rainfall using a weighted loss function. YNet_D and YNet_DE outperform YNet, reducing root mean squared error from 12.41 to 12.25 mm and 11.97 mm, respectively. For extremes, they lower the R95p bias from 78.27 to 56.52 mm and 40.22 mm. Both models also show improved performance at intraseasonal and interannual timescales and demonstrate better transferability to General Circulation Models. Unlike conventional statistical approaches, the models proposed retain key physical dynamics, providing a robust solution that preserves the system's variability and complexity.</p>","PeriodicalId":15986,"journal":{"name":"Journal of Geophysical Research: Atmospheres","volume":"130 19","pages":""},"PeriodicalIF":3.4,"publicationDate":"2025-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224166","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}