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Bivariate attribution of the compound hot and dry summer of 2022 on the Tibetan Plateau

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Science China Earth Sciences 2024年第7期67卷 2122-2136页

作者： Baiquan ZHOU panmao ZHAI Zhen LIAO State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081China

The extraordinarily high temperatures experienced during the summer of 2022 on the Tibetan Plateau(TP)demand attention when compared with its typical climatic *** absence of precipitation alongside the elevated temperatures resulted in 2022 being the hottest and driest summer on record on the TP since at least *** the susceptibility of the TP to climate change,this study employed large-ensemble simulations from the HadGEM3-A-N21. attribution system,together with a copula-based joint probability distribution,to investigate the influence of anthropogenic forcing,primarily global greenhouse gas emissions,on this unprecedented compound hot and dry event(CHDE).Findings revealed that the return period for the 2022 CHDE on the TP exceeds 4000 years,as determined from the fitted joint distributions derived using observational data spanning *** CHDE was directly linked to large-scale circulation anomalies,including the control of equivalent-barotropic high-pressure anomalies and the northward displacement of the subtropical westerly jet ***,anthropogenic forcing has,to some extent,promoted the surface warming and increased variability in precipitation on the TP in summer,establishing conditions conducive for the 2022 CHDE from a long-term climate change *** return period for a 2022-like CHDE on the TP was estimated to be approximately 283 years(1.2-61. years)by the large ensemble forced by both anthropogenic activities and natural ***,ensemble simulations driven solely by natural forcing indicated that the likelihood of occurrence of a 2022-like CHDE was almost *** outcomes underscore that the contribution of anthropogenic forcing to the probability of a 2022-like CHDE was 1.0%,implying that without anthropogenically induced global warming,a comparable CHDE akin to that observed in 2022 on the TP would not be possible.

关键词： Compound hot and dry event Tibetan Plateau Bivariate event attribution Anthropogenic forcing

Uptrend of the Western North Pacific Tropical Cyclone Outflow Height during 1.59-2021

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Journal of Meteorological Research 2024年第2期38卷 339-350页

作者： Yuan SUN Zhihao FENG Wei ZHONG panmao ZHAI Yanluan LIN Shuo LYU College of Advanced Interdisciplinary Studies National University of Defense TechnologyNanjing 211100 College of Meteorology and Oceanography National University of Defense TechnologyChangsha 410073 State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 Ministry of Education Key Laboratory for Earth System Modeling Department of Earth System ScienceTsinghua UniversityBeijing 100084

Relatively little is known about the impact of global warming on the tropical cyclone(TC)outflow,despite its large contribution to TC *** this study,based on the International Best Track Archive for Climate Stewardship(IBTrACS)dataset and ERA5 reanalysis data,we show that the TC outflow height has risen significantly(48.20±22.1. m decades-1.in the past decades(1.59-2021.over the western North Pacific,and the rising trend tends to be sharper for stronger TCs(the uptrend of severe typhoon is 61.09±40.92 m decades-1..This rising trend of the outflow height explains the contradiction between the decrease trend of the TC outflow temperature and the increase trend of the atmospheric troposphere ***,possible contribution of the TC outflow height uptrend to TC intensity has also been *** results show that the rise of outflow height leads to the decrease of outflow temperature,and thus an increased difference between underlying sea surface temperature(SST)and TC outflow temperature,which eventually favors the increase of TC intensity.

关键词： tropical cyclone outflow height global warming western North Pacific

基于SOM的长江流域持续性强降水过程典型环流的客观分型

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气象学报 2024年第5期82卷 632-644页

作者：杨雅涵翟盘茂周佰铨中国气象科学研究院灾害天气国家重点实验室北京100081

利用1.61.2021.逐日降水格点化观测资料和ERA5再分析资料,基于无监督深度学习的自组织特征映射神经网络(SOM)方法,将与中国长江流域夏季持续性强降水过程对应的大尺度环流客观划分成4种典型环流型(P1.P4)。各环流型呈现出的关键环流... 详细信息

利用1.61.2021.逐日降水格点化观测资料和ERA5再分析资料,基于无监督深度学习的自组织特征映射神经网络(SOM)方法,将与中国长江流域夏季持续性强降水过程对应的大尺度环流客观划分成4种典型环流型(P1.P4)。各环流型呈现出的关键环流系统配置影响异常雨带的形成及落区。P1.P3中、高纬度分别为典型的单阻型和双阻型环流形势,且西太平洋副热带高压(简称副高)显著偏强并向西延伸。P2和P4表现出较为明显的低压异常,P2中的巴尔喀什湖到贝加尔湖以西为宽广低槽,贝加尔湖以东为脊区,形成入梅期间的稳定环流形势,长江流域受到低值系统的控制,副高位置靠南。P4在巴尔喀什湖以西和以东分别表现出位势高度异常偏低和偏高,长江流域表现为气旋性环流异常,同时副高位置偏北。P1.P2有来自高纬度冷空气的影响,P3和P4的冷空气较弱。以副高北跳为主要特征的东亚夏季风向北推进与4种环流型的出现以及相应的雨带位置有紧密联系,P1.P2主要对应6月至7月上旬持续性强降水,P3、P4则主要对应7月上旬至8月持续性强降水,导致P1.P2降水异常中心位于长江中下游的江南地区,P3和P4的降水异常中心分别位于长江流域和长江以北地区。P1.P3的水汽输送相比另外两类明显偏强,造成的降水强度也更强。此外,对典型环流型的稳定性分析表明,长江流域持续性强降水过程与上述4种典型环流型的稳定维持密不可分。持续性强降水过程中93.2%的环流表现出持续性的特征,P1.P2、P3和P4持续天数分别主要集中在5和3 d。从长期趋势来看,P1.P3环流型出现频次增多,P2和P4趋于减少。这意味着从有利环流的角度来说,持续性强降水倾向于在长江以南和长江中下游地区发生。

关键词：长江流域持续性强降水逐日环流型异常环流的稳定性自组织特征映射网络

Changes in Climate Regionalization Indices in China during 1.61.201.

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Advances in Atmospheric Sciences 2014年第2期31卷 374-384页

作者： LIU Jing ZHAI panmao State Key Laboratory of Severe Weather Chinese Academy of Meteorological Sciences

The regionalization of climate in China is based on a three-level classification in terms of lasting days for accumulated temperature （AT）,aridity index,and July mean *** on daily meteorological observational data from 756 stations,trends and interdecadal variation in indices for classifying temperature zones,moisture regions and climatic subregions in the period 1.61.201. are *** reveal that the nationwide AT ≥ 1.℃C （AT1.） and its lasting days are basically increasing,while aridity in northern Xinjiang is *** increasing trend of July mean temperature in North China is found to be notably larger than in South *** terms of their national averages,a marked step increase of AT1. and its lasting period,as well as July mean temperature occurred around 1.97,while the aridity index presents no such clear *** comparing regionalization areas for 1.98-201. with those for 1.61.97,it is found that the semi-humid,semi-dry and dry regions in the sub-temperate zone,as well as the humid region in the middle subtropical zone,have experienced substantial shrinkage in terms of *** contrast,the areas of semi-dry and dry regions in the warm temperate zone,as well as the humid region in the south subtropical zone,present drastically increasing *** to the influence of such step changes that took place in 1.97,that particular point in time should be given close attention in future studies regarding the regionalization of climate in China.

关键词： climate regionalization climate trends interdecadal variation

Impacts of Extreme Droughts on Ecosystem Water Use Efficiency Diverge between Forest and Grassland

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Journal of Meteorological Research 2023年第5期37卷 710-721页

作者： Mengtian HUANG panmao ZHAI State Key Laboratory of Severe Weather and Institute of Global Change and Polar Meteorology Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

Ecosystem-scale water use efficiency (WUE),as a quantification of the coupling between carbon and water cycle,determines whether vegetation could survive under severe drought ***,how extreme droughts affect ecosystem-scale WUE and its difference among regions and biomes are still poorly *** this study,using data-oriented gridded products of gross primary productivity (GPP) and evapotranspiration (ET),we assessed the ecosystem WUE change during extreme drought years over China,and further compared drought impacts on WUE between forest and grassland *** found a spatial heterogeneity of WUE change in response to extreme droughts across ***,grassland WUE was substantially reduced concurrent with suppressed photosynthesis,while most of forest exhibited slightly decreased or even increased WUE under extreme *** addition,we demonstrated that drought characteristics and environmental conditions modulated drought impacts on *** anomalies during droughts and leaf area were found to be the predominant factors driving WUE change for both forest and *** increasing occurrence of compound dry and hot extremes,our results,therefore,would be an insightful supplement to the current understanding of the influence of extreme events on terrestrial ecosystems.

关键词： extreme droughts water use efficiency terrestrial ecosystems forest grassland China

Changes in Summer Persistent Precipitation over the Middle–Lower Reaches of the Yangtze River and Associated Atmospheric Circulation Patterns

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Journal of Meteorological Research 2021年第3期35卷 393-401页

作者： Rong YU panmao ZHAI State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

Persistence is an important property of precipitation and its related impacts. However, changes in persistent precipitation and the possible underlying mechanisms in the context of global warming have not yet been discussed in sufficient depth. In this study, the changes in persistent precipitation in summer and related atmospheric circulation patterns over the middle–lower reaches of the Yangtze River(MLRYZR)—a typical monsoon region frequently hit by consecutive rainfall events—are analyzed based on observed daily precipitation and NCEP/NCAR reanalysis data from 1.61.to 201.. The results reveal that persistent precipitation events(PPs) tend to happen in a more persistent way, with increased frequency and intensity in the MLRYZR region. Mechanism analyses show that persistent precipitation has happened along with simultaneous enhancement of some large-scale atmospheric circulation patterns,including the Lake Baikal blocking(BB), the Okhotsk Sea blocking(OB), and the western Pacific subtropical high(WPSH). Such enhanced anomalous circulation patterns could persistently reinforce the convergence and supply of water vapor in the MLRYZR region, contributing to the increase in PPs in this region. Based on the above results, we are able to offer some new insights into the long-term changes in precipitation structure and the possible causes. This study is also expected to support attribution studies on regional precipitation changes in the future.

关键词： persistent precipitation precipitation change atmospheric circulation pattern

CMIP6 Projections of the“Warming–Wetting”Trend in Northwest China and Related Extreme Events Based on Observational Constraints

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Journal of Meteorological Research 2022年第2期36卷 239-250页

作者： Qian WANG panmao ZHAI State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081 University of Chinese Academy of Sciences Beijing 100049

This study presents the improved future projections of the climate“warming-wetting”trend and climate extremes with different return periods in Northwest China at different global warming *** projections are based on the Coupled Model Intercomparison Project phase 6(CMIP6)simulations constrained by the high-resolution observation dataset using the equidistant cumulative distribution functions(EDCDF)*** results indicate that the climate will experience continuous warming and wetting as reflected by average temperature and total precipitation over Northwest China,especially under the scenario of the shared socioeconomic pathway 5-representative concentration pathway 8.5(SSP5-8.5).Most parts of Northwest China will continue to warm in the future more than global ***,areas with prominent“warming-wetting”trends will be mainly distributed in western Northwest *** is worth noting that extreme heat and precipitation events will also increase with the climate warming and wetting over Northwest ***,frequencies of rarer extreme events will increase more apparently than weaker extreme events and frequency increase of extreme heat events responds to global warming faster than that of extreme precipitation *** global warming within 2℃relative to 1.50-1.00 would slowdown the increase in extreme heat events and considerably suppress the increase in frequencies of extreme precipitation events,especially the rare(i.e.,50-yr)extreme events.

关键词： Northwest China projection precipitation temperature extreme events

Changes in Persistent Precipitation in Northwest China and Related Large-Scale Circulation Features

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Journal of Meteorological Research 2023年第5期37卷 604-616页

作者： Jingjing GAO Baiquan ZHOU panmao ZHAI State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesChina Meteorological AdministrationBeijing 100081

Based on China's daily precipitation data of 241. stations and ERA5 hourly reanalysis data from 1.61.to 201., the station-based and regional precipitation events over Northwest China(NWC) are identified and sorted into persistent precipitation(PP, duration ≥ 2 days) events and non-persistent precipitation(NPP, duration = 1.day) events;and then changes in the persistence structure of the PP and NPP events over NWC and the long-term mean adjustment of the related large-scale circulation configuration are analyzed. The results show that PP and NPP both witness an increasing trend over most parts of NWC. In terms of the total precipitation at most stations and the regional mean, contributions from PP have been increasing, while those from NPP have been decreasing. This demonstrates that the wetting trend in NWC is mainly caused by the increase in PP. Through analyzing the large-scale circulation corresponding to regional PP events at several representative levels, we found that the westerly jet at 200 hPa, the ridge/trough systems at 500 hPa, and the Mongolian low at sea level are the key circulation systems responsible for regional PP events over NWC. As for long-term mean changes after and before 1.90(a shifting point recognized by previous studies), it is found that the extent of the South Asian high becomes larger and the westerly jet shifts northward by approximately 1.5 degrees in the upper troposphere. The ridge near the Ural Mountains and the ridge downstream of NWC strengthen by approximately 1.–30 hPa at 500 hPa. Furthermore, the difference between the Mongolian low trough and its surrounding high pressure increases by approximately 2 hPa at the sea level. The combinations of circulation changes from upper to lower levels facilitate the strengthening of ascending motions. These adjustments in circulations create more favorable conditions for PP to occur over NWC in the last three decades.

关键词： persistent precipitation large-scale circulation westerly jet South Asian high

Anomalous Features of Extreme Meiyu in 2020 over the Yangtze-Huai River Basin and Attribution to Large-Scale Circulations

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Journal of Meteorological Research 2021年第5期35卷 799-814页

作者： Ruoyun NIU panmao ZHAI Guirong TAN National Meteorological Center China Meteorological AdministrationBeijing 100081 Chinese Academy of Meteorological Sciences China Meteorological AdministrationBeijing 100081 Nanjing University of Information Science&Technology Nanjing 210044

Extremely anomalous features of Meiyu in 2020 over the Yangtze-Huai River basin(YHRB)and associated causes in perspective of the large-scale circulation are investigated in this study,based on the Meiyu operational monitoring information and daily data of precipitation,global atmospheric reanalysis,and sea surface temperature(SST).The main results are as follows.(1.The 2020 YHRB Meiyu exhibits extremely anomalous characteristics,which are the most prominent since the 1.80 *** 2020 Meiyu season features the fourth earliest onset,the third latest retreat,the longest duration,the maximum Meiyu rainfall,the strongest mean rainfall intensity,and the maximum number of stations/days with rainstorm.(2)The extremely long duration of the 2020 Meiyu season lies in the farily early onset and late retreat of Meiyu in this particular *** early onset of Meiyu is due to the earlier-than-normal first northward shift and migration of the key influential systems including the northwestern Pacific subtropical high(NWPSH)and the South Asian high(SAH)along with the East Asian summer monsoon,induced by weak cold air activities from late May to early ***,the extremely late retreat of Meiyu is because of later-than-normal second northward shift of the associated large-scale circulation systems accompanied with strong cold air activities,and extremely weak and southward located ITCZ over Northwest Pacific in July.(3)The extremely more than normal Meiyu rainfall is represented by its long duration and strong rainfall *** latter is likely attributed to extreme anomalies of water vapor convergence and vertical ascending motion over the YHRB,resulting from the compound effects of the westward extended and enlarged NWPSH,the eastward extended and expanded SAH,and the strong water vapor transport associated with the low-level southerly *** extremely warm SST in the tropical Indian Ocean seems to be the key factor to induce the above-mentioned anomalous large-scal

关键词： extreme Meiyu anomalous feature large-scale circulation cause