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Seasonal prediction of extreme high-temperature days over the Yangtze River basin

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Science China Earth Sciences 2024年第7期67卷 2137-2147页

作者： Shifeng PAN Zhicong YIN Mingkeng DUAN Tingting HAN Yi FAN Yangyang HUANG Huijun WANG Key laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment Change/Collaborative Innovation Center on Forecast and Evaluation of Meteorological DisastersNanjing University of Information Science and TechnologyNanjing 210044China Southern Marine Science and Engineering Guangdong laboratory(Zhuhai) Zhuhai 519080China

Extreme high temperatures occur frequently over the densely populated Yangtze River basin(YRB)in China during summer,significantly impacting the local economic development and ecological ***,accurate prediction of extreme high-temperature days in this region remains a ***,the Climate forecast System Version 2(CFSv2)exhibits poor performance in this ***,based on the interannual increment approach,we develop a hybrid seasonal prediction model over the YRB(HM_(YRB))to improve the prediction of extreme high-temperature days in *** HM_(YRB)relies on the following four predictors:the observed preceding April-May snowmelt in north western Europe;the snow depth in March over the central Siberian Plateau;the CFSv2-forecasted concurrent summer sea surface temperatures around the Maritime Continent;and the 200-hPa geopotential height over the Tibetan *** HM_(YRB)indicates good capabilities in predicting the interannual variability and trend of extreme high-temperature days,with a markable correlation coefficient of 0.58 and a percentage of the same sign(PSS)of 76% during 1983-2015 in the one-year-out ***,the HM_(YRB) maintains high PSS skill(86%)and robustness in the independent prediction period(2016-2022).Furthermore,the HM_(YRB) shows a good performance for years with high occurrence of extreme high-temperature days,with a hit ratio of 40%.These predictors used in HM_(YRB)are beneficial in terms of the prediction skill for the average daily maximum temperature in summer over the YRB,albeit with biases existing in the *** study provides promising insights into the prediction of 2022-like hot extremes over the YRB in China.

关键词： Hot extremes Yangtze River basin CFSv2 Seasonal prediction One-year-out cross-validation

Distinct Interannual Variability and Physical Mechanisms of Snowfall Frequency over the Eurasian Continent during Autumn and Winter

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Advances in Atmospheric Sciences 2024年第10期41卷 1969-1983+2101-2103页

作者： Siyu ZHOU Bo SUN Huijun WANG Yi ZHENG Jiarui CAI Huixin LI Botao ZHOU Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters/Key laboratory of Meteorological Disasters Ministry of Education/Joint International Research Laboratory of Climate and Environment Change Nanjing University of Information Science and Technology Southern Marine Science and Engineering Guangdong laboratory Nansen Zhu International research Centre Institute of Atmospheric PhysicsChinese Academy of Sciences

This study investigates the dominant modes of interannual variability of snowfall frequency over the Eurasian continent during autumn and winter, and explores the underlying physical mechanisms. The first EOF mode(EOF1) of snowfall frequency during autumn is mainly characterized by positive anomalies over the Central Siberian Plateau(CSP)and Europe, with opposite anomalies over Central Asia(CA). EOF1 during winter is characterized by positive anomalies in Siberia and negative anomalies in Europe and East Asia(EA). During autumn, EOF1 is associated with the anomalous sea ice in the Kara–Laptev seas(KLS) and sea surface temperature(SST) over the North Atlantic. Increased sea ice in the KLS may cause an increase in the meridional air temperature gradient, resulting in increased synoptic-scale wave activity,thereby inducing increased snowfall frequency over Europe and the CSP. Anomalous increases of both sea ice in the KLS and SST in the North Atlantic may stimulate downstream propagation of Rossby waves and induce an anomalous high in CA corresponding to decreased snowfall frequency. In contrast, EOF1 is mainly affected by the anomalous atmospheric circulation during winter. In the positive phase of the North Atlantic Oscillation(NAO), an anomalous deep cold low(warm high) occurs over Siberia(Europe) leading to increased(decreased) snowfall frequency over Siberia(Europe). The synoptic-scale wave activity excited by the positive NAO can induce downstream Rossby wave propagation and contribute to an anomalous high and descending motion over EA, which may inhibit snowfall. The NAO in winter may be modulated by the Indian Ocean dipole and sea ice in the Barents-Kara-Laptev Seas in autumn.

关键词： atmospheric circulation Eurasian continent Indian Ocean dipole interannual variability sea ice snowfall frequency

Changes in the Boreal Summer Intraseasonal Oscillation under Global Warming in CMIP6 Models

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Advances in Atmospheric Sciences 2024年第10期41卷 1984-1998页

作者： Zhefan GAO Chaoxia YUAN Key laboratory of Meteorological Disaster of Ministry of Education Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Institute for Climate and Application Research (ICAR) Nanjing University of Information Science & Technology Application laboratory Japan Agency of Marine-Earth Science and Technology

Changes in the activities of the Boreal Summer Intraseasonal Oscillation（BSISO） at the end of 21st century under the SSP5-8.5 scenario are assessed by adopting 17 CMIP6 models and the weak-temperature-gradient assumption. Results show that the intraseasonal variations become more structured. The BSISO-related precipitation anomaly shows a larger zonal scale and propagates further northward. However, there is no broad agreement among models on the changes in the eastward and northward propagation speeds and the frequency of individual phases. In the western North Pacific（WNP）, the BSISO precipitation variance is significantly increased, at 4.62% K-1, due to the significantly increased efficiency of vertical moisture transport per unit of BSISO apparent heating. The vertical velocity variance is significantly decreased, at -3.51% K-1, in the middle troposphere, due to the significantly increased mean-state static stability. Changes in the lower-level zonal wind variance are relatively complex, with a significant increase stretching from the northwestern to southeastern WNP, but the opposite in other regions. This is probably due to the combined impacts of the northeastward shift of the BSISO signals and the reduced BSISO vertical velocity variance under global warming. Changes in strong and normal BSISO events in the WNP are also compared. They show same-signed changes in precipitation and large-scale circulation anomalies but opposite changes in the vertical velocity anomalies. This is probably because the precipitation anomaly of strong（normal） events changes at a rate much larger（smaller） than that of the meanstate static stability, causing enhanced（reduced） vertical motion.

关键词： Boreal Summer Intraseasonal Oscillation CMIP6 global warming weak-temperature-gradient assumption

Traditional Meiyu-Baiu has been suspended by global warming

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National Science Review 2024年第7期11卷 126-134页

作者： Zhicong Yin Xiaolei Song Botao Zhou Wenhao Jiang Huopo Chen Huijun Wang Key laboratory of Meteorological Disaster Ministry of Education/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&Technology Nansen-Zhu International research Centre Institute of Atmospheric PhysicsChinese Academy of Sciences

More than 1000 years, the Meiyu–Baiu have shaped the uniqueness of natural resources, civilization and culture in the Yangtze River Basin of China and the main islands of Japan. In recent decades, frequent rainstorms and droughts have seemingly diminished the misty features of traditional Meiyu–Baiu ***, there is still no consensus on whether their traditional nature is suspended. In this study, we quantitatively demonstrate that the Meiyu–Baiu almost completely lost their traditional features during 1961–2023, ～80% of which can be attributed to anthropogenic warming. Furthermore, in a warmer future,the traditional Meiyu–Baiu will be more unlikely to appear. This study underscores the urgency in adapting to climate shift because destructive extremes are measurably taking the place of mild and maternal rains.

关键词： global warming Meiyu–Baiu extremes human activity culture and civilization

Different ENSO Impacts on Eastern China Precipitation Patterns in Early and Late Winter Associated with Seasonally-Varying Kuroshio Anticyclonic Anomalies

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Advances in Atmospheric Sciences 2024年第9期41卷 1691-1703页

作者： Jingrui YAN Wenjun ZHANG Suqiong HU Feng JIANG Key laboratory of Meteorological Disaster Ministry of Education(KLME)/Joint International Research Laboratory of Climate and Environment Change(ILCEC)/Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters(CIC-FEMD)Nanjing University of Information Science and TechnologyNanjing 210044China

Winter precipitation over eastern China displays remarkable interannual variability,which has been suggested to be closely related to El Niño-Southern Oscillation(ENSO).This study finds that ENSO impacts on eastern China precipitation patterns exhibit obvious differences in early(November-December)and late(January-February)*** early winter,precipitation anomalies associated with ENSO are characterized by a monopole spatial distribution over eastern *** contrast,the precipitation anomaly pattern in late winter remarkably changes,manifesting as a dipole spatial *** noteworthy change in precipitation responses from early to late winter can be largely attributed to the seasonally varying Kuroshio anticyclonic *** the early winter of El Niño years,anticyclonic circulation anomalies appear both over the Philippine Sea and Kuroshio region,enhancing water vapor transport to the entirety of eastern China,thus contributing to more precipitation *** the late winter of El Niño years,the anticyclone over the Philippine Sea is further strengthened,while the one over the Kuroshio dissipates,which could result in differing water vapor transport between northern and southern parts of eastern China and thus a dipole precipitation *** the opposite anomalies of circulation and precipitation are displayed during La Niña *** analysis suggests that the seasonally-varying Kuroshio anticyclonic anomalies are possibly related to the enhancement of ENSO-related tropical central-eastern Pacific convection from early to late *** results have important implications for the seasonal-tointerannual predictability of winter precipitation over eastern China.

关键词： precipitation eastern China ENSO early winter late winter Kuroshio anticyclone

A generalized nonlinear three-dimensional Hoek‒Brown failure criterion

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第8期16卷 3149-3164页

作者： Jiaxin Wang Shunchuan Wu Haiyong Cheng Junlong Sun Xiaolong Wang Yaxi Shen Faculty of Land Resource Engineering Kunming University of Science and TechnologyKunming650093China Key laboratory of Geohazard forecast and Geoecological Restoration in Plateau Mountainous Area Ministry of Natural ResourcesKunming650093China Yunnan Key laboratory of Geohazard forecast and Geoecological Restoration in Plateau Mountainous Area Kunming650093China

To understand the strengths of rocks under complex stress states,a generalized nonlinear threedimensional(3D)Hoek‒Brown failure(NGHB)criterion was proposed in this *** criterion shares the same parameters with the generalized HB(GHB)criterion and inherits the parameter advantages of *** new parameters,b,and n,were introduced into the NGHB criterion that primarily controls the deviatoric plane shape of the NGHB criterion under triaxial tension and compression,*** NGHB criterion can consider the influence of intermediate principal stress(IPS),where the deviatoric plane shape satisfies the smoothness requirements,while the HB criterion *** criterion can degenerate into the two modified 3D HB criteria,the Priest criterion under triaxial compression condition and the HB criterion under triaxial compression and tension *** criterion was verified using true triaxial test data for different parameters,six types of rocks,and two kinds of in situ rock *** comparison,three existing 3D HB criteria were selected for performance comparison *** result showed that the NGHB criterion gave better prediction performance than other *** prediction errors of the strength of six types of rocks and two kinds of in situ rock masses were in the range of 2.0724%-3.5091%and 1.0144%-3.2321%,*** proposed criterion lays a preliminary theoretical foundation for prediction of engineering rock mass strength under complex in situ stress conditions.

关键词： Rock mechanics HoekeBrown criterion Failure criterion Intermediate principal stress True triaxial test Smoothness and convexity

Record-breaking summer-autumn drought in southern China in 2022:Roles of tropical sea surface temperature and Eurasian warming

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Science China Earth Sciences 2024年第2期67卷 420-431页

作者： Yuepeng HU Botao ZHOU Huijun WANG Dapeng ZHANG Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters/Key laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment ChangeNanjing University of Information Science and TechnologyNanjing210044China School of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing210044China

From summer to autumn in 2022,a severe drought lasted in southern China,posing serious effects on economic growth and ecological *** study explored the atmospheric circulations accounting for this persistent drought *** shows that the drought in southern China during the summer of 2022 was strongly linked to the divergence of water vapor flux and descending motions,which were respectively caused by the anomalous anticyclone over the western North Pacific and the northward movement of the East Asian subtropical jet(EASJ).Differently,the atmospheric background responsible for the sustained drought in autumn is manly featured by a cyclonic circulation anomaly over the region from the Bay of Bengal to the South China Sea,which led to decreased moisture and descending motions in southern *** investigation suggests that the rarely strong surface warming over northern Eurasia and the extreme La Nina-like pattern over the tropical Pacific jointly resulted in the anomalous anticyclone over the western North Pacific and the northward shift of the EASJ in the summer of 2022,while the cyclonic circulation anomaly prevailing over the region from the Bay of Bengal to the South China Sea in autumn was largely attributed to the extremely negative anomalies of the tropical Indian Ocean sea surface temperature.

关键词： Summer-autumn drought Southern China Tropical sea surface temperature Eurasian warming

Interdecadal change and projection of the relationship between spring Arctic Oscillation and summer precipitation in the Yangtze River valley in CMIP6 models

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Atmospheric and Oceanic Science Letters 2024年第4期17卷 15-22页

作者： Weikai Jia Botao Zhou Ziyi Song Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters/Key laboratory of Meteorological Disaster Ministry of Education/Joint International Research Laboratory of Climate and Environment ChangeNanjing University of Information Science and TechnologyNanjingChina

评估了20个CMIP6模式对春季北极涛动(AO)与长江流域夏季降水(YRP)关系的模拟能力.结果表明, 4个模式(ACCESS-ESM1-5, CMC-CM2-SR5, MRI-ESM2-0, NorESM2-LM))能合理模拟出1990年代后期AO-YRP关系的减弱. 1980-1998年,当春季AO位于正位相时,夏季东亚急流北移,长江流域为异常下沉运动,同时西太平洋副热带高压减弱,减少向长江流域的水汽输送,结果导致降水减少. 1999-2014年,上述大气环流与春季AO的联系不显著,从而减弱AO-YRP的关系.利用这四个模式进一步预估了RCP4.5情景下2015-2100年期间AO-YRP的关系.两者在2015-2040年为显著负相关关系,随后再次减弱.

关键词：北极涛动降水长江流域年代际变化 CMIP6

Persistent greening against drying in northeast Asian semiarid grasslands:Asymmetrical responses of direct and legacy effects to intensified drought

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Advances in Climate Change research 2024年第1期15卷 9-20页

作者： Yu-Tong MA Hai-Shan CHEN Yao-Ming SONG Bo-Tao ZHOU Shan-Lei SUN Xin-Guan DU Yue SUN Key laboratory of Meteorological Disaster Ministry of Education/Joint International research laboratory of Climate and Environment Change/Collaborative Innovation Center on forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China School of Atmospheric Sciences Nanjing University of Information Science and TechnologyNanjing 210044China

Despite experiencing a decadal shift towards drought conditions at the end of the 2Oth century,semiarid grasslands in northeast Asia(NEA)exhibited an evident greening trend from 1982 to ***,the mechanism behind this phenomenon remains ***,we analysed the interdecadal changes in vegetation response to drought on the basis of the standardised precipitation evapotranspiration index(SPEI)and Global Inventory Modelling and Mapping Studies LAI4g datasets,with an emphasis on the differences between direct and legacy effects(as measured by resilience),to explore the mechanism of persistent grassland *** revealed that during the post-drought shift period(2000-2020),the sudden decrease in the water content of the intermediate soil layer triggered an intensified vegetation response to ***,although direct effects and resilience were amplified,they exhibited asymmetric *** was stronger than direct effects,and this difference increased with increasing drought(drought recovery)*** combined effects may account for persistent greening against intensified drying in the semiarid grasslands in *** the projected exacerbation of future droughts,this study holds notable importance for comprehending the long-term change dynamics of dryland ecosystems.

关键词： Semiarid grassland Drought decadal shift Direct effect Legacy effect(resilience) Northeast Asia