{"title":"Driving factors and photochemical impacts of Cl2 in coastal atmosphere of Southeast China","authors":"Gaojie Chen, Xiaolong Fan, Ziyi Lin, Xiaoting Ji, Ziying Chen, Lingling Xu, Jinsheng Chen","doi":"10.1038/s41612-025-01022-y","DOIUrl":"https://doi.org/10.1038/s41612-025-01022-y","url":null,"abstract":"<p>The elevated levels of molecular chlorine (Cl<sub>2</sub>) have been observed both during the daytime or nighttime, yet the key drivers influencing Cl<sub>2</sub> formation remain unclear. In this study, we observed the distinct daytime and nighttime peaks of Cl<sub>2</sub> in coastal atmosphere of Southeast China. Field observations combined with machine learning revealed that daytime Cl<sub>2</sub> generation was driven by nitrate (especially ammonium nitrate) photolysis, and aerosol iron photochemistry, while the N<sub>2</sub>O<sub>5</sub> uptake on aerosols containing chloride contributed to nighttime Cl<sub>2</sub> formation. Around noon, alkane oxidation rates by Cl radicals generated from Cl<sub>2</sub> photolysis surpassed those of OH radicals, leading to a 44% increment in RO<sub>2</sub> radical levels and a 42% enhancement in net O<sub>3</sub> production rates. This study offers new insights into the production and loss processes of Cl<sub>2</sub> in the tropospheric atmosphere, emphasizing its significance in coastal photochemical pollution.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"15 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jesse Norris, Stefan Rahimi, Lei Huang, Benjamin Bass, Chad W. Thackeray, Alex Hall
{"title":"Uncertainty of 21st Century western U.S. snowfall loss derived from regional climate model large ensemble","authors":"Jesse Norris, Stefan Rahimi, Lei Huang, Benjamin Bass, Chad W. Thackeray, Alex Hall","doi":"10.1038/s41612-025-01002-2","DOIUrl":"https://doi.org/10.1038/s41612-025-01002-2","url":null,"abstract":"<p>The western United States is dependent on winter snowfall over its major mountain ranges, which gradually melts each year, serving as a natural reservoir for water resources. In a future warmer climate, much of this snowfall could be replaced by rain, making it more challenging to capture and store water. In this study, we utilize an ensemble of dynamically downscaled simulations forced by 14 global climate models (GCMs). These GCMs project wildly different futures, in terms of both temperature and precipitation change, producing significant uncertainty in snowfall projections. Here we exploit the robust statistics of the downscaled ensemble, and diagose the sensitivity of end-of-century snowfall loss across the region to both warming and regional wetting/drying in the driving GCM. The windward slopes of the Sierra Nevada and Cascades are particularly sensitive to warming (losing ~ 15% annual snowfall per degree warming), with little influence of precipitation. By contrast, snowfall loss in the inter-mountain west is less sensitive to warming (~ 5% K<sup>−1</sup>), but is significantly offset/exacerbated by precipitation changes (~ 0.5% snow per 1% precipitation). Combining such sensitivities with the warming and regional precipitation signals in the full CMIP6 ensemble, we can fully quantify likely snowfall loss and its uncertainty at any location, for any emissions scenario. We find that the western U.S. as a whole will lose 34 ± 8% of its total volumetric snowfall by end-of-century under the high-emissions SSP3-7.0 scenario, but 25 ± 6% and 17 ± 6% under the lower-emissions SSP2-4.5 and SSP1-2.6 scenarios.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"22 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758307","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Diverse NPMM conditions deviate the 2023/24 El Niño from the 1997/1998 and 2015/2016 extreme El Niño events","authors":"Yong-Fu Lin, Mengyan Chen, Lingling Liu, Fei Zheng, Ruiqiang Ding, Xin Wang, Chau-Ron Wu, Min-Hui Lo, Huang-Hsiung Hsu, Jiepeng Chen, Ting-Hui Lee, Jin-Yi Yu","doi":"10.1038/s41612-025-01013-z","DOIUrl":"https://doi.org/10.1038/s41612-025-01013-z","url":null,"abstract":"<p>The 2023/24 El Niño commenced with an exceptionally large warm water volume in the equatorial western Pacific, comparable to the extreme 1997/98 and 2015/16 events, but did not develop into a super El Niño. This study highlights the critical role of contrasting Northern Pacific Meridional Mode (NPMM) conditions in this divergence. Warm NPMM conditions during the 1997/98 and 2015/16 events created a positive zonal sea surface temperature (SST) gradient in the equatorial western-central Pacific and enhanced Madden-Julian Oscillation (MJO) propagation, driving sustained westerly wind bursts (WWBs) and downwelling Kelvin waves that intensified both events. In contrast, the cold NPMM during 2023/24 induced a negative SST gradient and suppressed MJO activity, resulting in weaker WWBs and limited eastward wave activity, preventing the event from reaching super El Niño intensity. A 2,200-year CESM1 pre-industrial simulation corroborates these observational findings, underscoring the importance of NPMM interference in improving El Niño intensity predictions.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"1 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Mechanism driving stronger tropical cyclones in cooler autumn than the hottest summer","authors":"Vineet Kumar Singh, Hye-Ji Kim, Il-Ju Moon","doi":"10.1038/s41612-025-01008-w","DOIUrl":"https://doi.org/10.1038/s41612-025-01008-w","url":null,"abstract":"<p>Warmer sea surface temperatures (SSTs) increase evaporation, convection, and latent heat release in the atmosphere, which favors tropical cyclone (TC) intensification and ultimately leads to stronger storms. However, in this study, we find that the intensity of TCs in the western North Pacific, called typhoons, is on average higher in the colder autumn season than during the warmer summer season. The primary reason for this is that despite the decrease in SSTs during autumn, the deepening of the ocean mixed layer increase the TC heat potential and reduces storm-induced SST cooling. Atmospheric thermodynamic conditions also become more favorable to TC intensification in autumn than in summer due to higher heat and sensible heat fluxes in autumn resulting from the increased air-sea temperature/moist differences at the interface. Lastly, during autumn, the TC’s track shifts towards the equator as a result the TCs in this season travel over more favourable ocean condition which also contribute in the TC intensification. This finding will enhance the understanding of the mechanisms causing seasonal differences in TC intensity, which will aid in TC seasonal forecasting and risk assessment.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"23 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143737039","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuanwei Wang, Lingxiao Wang, Lei Wang, Ting Li, Jing Zhou, Xiaoyu Guo, Zhaoyan Xie, Sichen Lin, Ying Hong, Lin Zhao
{"title":"Divergent effects of temperature and precipitation on water flow into the largest lake on the Tibetan Plateau","authors":"Yuanwei Wang, Lingxiao Wang, Lei Wang, Ting Li, Jing Zhou, Xiaoyu Guo, Zhaoyan Xie, Sichen Lin, Ying Hong, Lin Zhao","doi":"10.1038/s41612-025-01017-9","DOIUrl":"https://doi.org/10.1038/s41612-025-01017-9","url":null,"abstract":"<p>The majority of lakes on the TP have expanded in an accelerated manner, changing the regulation of local water cycles and ecosystems. Here, spatiotemporal changes in inflow to Selin Co (the largest lake on the TP) from 1979 to 2022 were modeled, and the impacts of warming and wetting on water volume were explored. The modeled annual mean lake inflow was 2.27 km<sup>3</sup>, accompanied by a significant growth trend of 0.035 km<sup>3</sup>/yr (<i>p</i> < 0.01, the contributions of warming and wetting are −0.016 and 0.048 km<sup>3</sup>/yr respectively). Warming (+0.0386 K/yr) caused a decrease of 0.33 km<sup>3</sup> in lake inflow per year, accounting for 14.5% of the annual mean water volume, while wetting (+4.46 mm/yr) caused an increase of 0.91 km<sup>3</sup> in lake inflow per year, accounting for 40% of the annual mean value. These divergent effects of increasing temperature and precipitation on lake inflow makes it more difficult to predict the future water resources of basins such as Selin Co.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"52 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xin Wang, Feiyue Mao, Daniel Rosenfeld, Yannian Zhu, Zengxin Pan, Yang Cao, Lin Zang, Xin Lu, Wei Gong
{"title":"Volcanic aerosols lend causality to the indicated substantial susceptibility of clouds to aerosol over global oceans","authors":"Xin Wang, Feiyue Mao, Daniel Rosenfeld, Yannian Zhu, Zengxin Pan, Yang Cao, Lin Zang, Xin Lu, Wei Gong","doi":"10.1038/s41612-025-00974-5","DOIUrl":"https://doi.org/10.1038/s41612-025-00974-5","url":null,"abstract":"<p>The large indicated associations between aerosols and cloud radiative effects imply large negative radiative forcing, i.e., cooling incurred by the aerosols’ effects on clouds, if their relationships are causal. The alternative explanation is aerosol-meteorology co-variability. Here, we examine whether aerosols are the primary driver of aerosol-cloud co-variability, i.e., constituting susceptibility of the cloud properties to aerosols. It is done by domains affected by volcanic aerosols, where the aerosol-meteorology co-variability is expected to be minimized. We hypothesize that volcanic aerosols would reduce aerosol-meteorology co-variability under similar meteorology, thus diminishing aerosol-cloud co-variability. However, our findings in both volcanic and non-volcanic regions across the global oceans indicate a consistent pattern of aerosol-cloud co-variability. This does not prove definitively a causal link between aerosols and cloud properties, but mininimizes the probability that meteorological co-variability is a major cause.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"72 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jingchen Pu, Mu Mu, Jie Feng, Xiaohui Zhong, Hao Li
{"title":"A fast physics-based perturbation generator of machine learning weather model for efficient ensemble forecasts of tropical cyclone track","authors":"Jingchen Pu, Mu Mu, Jie Feng, Xiaohui Zhong, Hao Li","doi":"10.1038/s41612-025-01009-9","DOIUrl":"https://doi.org/10.1038/s41612-025-01009-9","url":null,"abstract":"<p>Traditional ensemble forecasting based on numerical weather prediction (NWP) models, is constrained by the need for massive computational resources, resulting in limited ensemble sizes. Although emerging artificial intelligence (AI)-based weather models offer high forecast accuracy and improved computational efficiency, they still face considerable challenges in ensemble forecasting applications, due to the unclear error growth dynamic and the lack of suitable ensemble methods in AI-based models. In this study, we propose a fast, physics-constrained perturbation scheme through the self-evolution dynamics of an AI-based weather model for ensemble forecasting of tropical cyclones (TCs). These initial perturbations are conditioned on specific amplitude and spatial characteristics, exhibiting physically reasonable dynamical growth and spatial covariance. Based on this perturbation scheme, the TC track ensemble forecasts within the AI-based model significantly outperform those from the European Centre for Medium-Range Weather Forecasts (ECMWF) for both deterministic and probabilistic metrics. Notably, we conduct TC track forecasts with 2000 members for the first time, achieving further enhanced forecast skills in probability distribution and extreme scenarios of TC movement.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"443 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734263","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Opposing trends in winter Atmospheric River over the Western and Eastern US during the past four decades","authors":"Wenhao Dong, Ming Zhao, Zhihong Tan, V. Ramaswamy","doi":"10.1038/s41612-025-00998-x","DOIUrl":"https://doi.org/10.1038/s41612-025-00998-x","url":null,"abstract":"<p>Winter atmospheric rivers (ARs) are crucial for water supply and extreme weather events over the western (WUS) and eastern US (EUS), yet their long-term trends and interplay remain unclear. Here we fill this gap by analyzing multiple observational AR products over the past four decades. Contrasting yet interrelated trends emerge in AR frequency, intensity, and associated mean precipitation. A decline in AR activity over WUS contributes to a drying trend, while notable increases over EUS foster a wetter climate. These trends are driven by large-scale atmospheric and oceanic variability in the Pacific, which strengthens anticyclonic circulation patterns near both coasts. These anticyclonic patterns, however, have opposing effects–impeding ARs from steering to WUS while facilitating their development over EUS. Our findings present a unified explanation for the observed AR trends and have co-beneficial implications for mitigating concerns related to AR-induced extreme events across both densely populated coastal regions.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"36 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734265","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Interdecadal variability of tropical cyclone intensification rates in the Western North Pacific","authors":"Han Wang, Chujin Liang, Feilong Lin, Weifang Jin","doi":"10.1038/s41612-025-01001-3","DOIUrl":"https://doi.org/10.1038/s41612-025-01001-3","url":null,"abstract":"<p>Intensification rates of tropical cyclones (TCs) are critical in determining their lifetime maximum intensity and destructive power. However, the interdecadal variability of TC intensification rates in the Western North Pacific (WNP) remains unclear. In this study, we focused on the changes in TC intensification rates during 1980-2022 and found an abrupt increase in TC intensification rates after 2002. This change was primarily attributed to TCs undergoing rapid intensification (RI-TC). Furthermore, our investigations revealed that the RI-TC intensification rates were strongly related to the proportions of intensification rates ≥10 knots/6 h (IR-10) (r = 0.88), and the frequency of IR-10 events was highly correlated to sea surface temperature anomalies (r = 0.79), modulated by El Niño-Southern Oscillation and Interdecadal Pacific Oscillation. Additionally, we found that the IR-10 occurrence frequency shows a northwestward shift during 1980–2022, and this shift was primarily driven by 500 hPa vertical velocity, followed by vertical wind shear. These findings provide crucial insights into the evolution of TC intensification rates in the WNP over the past four decades. The role of IR-10 should not be underestimated in TC development, which could serve as a crucial parameter for the TC intensity prediction.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"1 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Tracking regional CH4 emissions through collocated air pollution measurement: a pilot application and robustness analysis in China","authors":"Yifan Li, Bo Zheng","doi":"10.1038/s41612-025-01011-1","DOIUrl":"https://doi.org/10.1038/s41612-025-01011-1","url":null,"abstract":"<p>Accurate regional methane (CH<sub>4</sub>) emission monitoring is essential for effective climate mitigation but remains constrained by limited observational networks and challenged by diffuse emission sources. Here, we present an innovative regional CH<sub>4</sub> inversion system integrating satellite-based carbon monoxide (CO) observations with ground-based CH<sub>4</sub>-to-CO flux ratios. Our study estimates China’s CH<sub>4</sub> fluxes between 2000 and 2021, revealing an average of 48.4 ± 13.8 Tg yr<sup>−1</sup> and a significant increasing trend of 1.1 ± 0.2 Tg yr<sup>−2</sup>. Over the 22-year period, socio-economic development drove a 92.1 Tg increase in China’s CH<sub>4</sub> fluxes, partially offset by a 78.1 Tg reduction due to declining emission intensity; however, this mitigating effect weakened after 2015. Our results demonstrate comparability with independent estimates, and comprehensive sensitivity and uncertainty analyses confirm the robustness of our approach. This study highlights the potential of integrating air pollution monitoring into tracking regional greenhouse gas emissions.</p>","PeriodicalId":19438,"journal":{"name":"npj Climate and Atmospheric Science","volume":"2 1","pages":""},"PeriodicalIF":9.0,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}