首页|Characteristics of super drought in Southwest China and the associated compounding effect of multiscalar anomalies

Characteristics of super drought in Southwest China and the associated compounding effect of multiscalar anomalies

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In recent decades,Southwest China(SWC)has suffered from frequent super droughts,leading to severe economic losses and ecological degradation.This study investigates the characteristics of super droughts in SWC during 1961-2022,reveals the compounding effect of multiscalar anomalies,and explores the plausible atmospheric circulation mechanisms re-sponsible.The nature of super drought is a compound drought caused by the superposition of extreme drought events across multiple time scales.By contrasting the typical drought cases in 2006 and 2022,the decisive role of multiscalar drought compounding is confirmed.Based on the Comprehensive Multiscalar Index(CMI),multiple super drought events in SWC were identified to be temporally clustered during 2006-2014.Among them,the decadal background of enhanced evaporation and precipitation deficit at long time scales is a necessary condition for shaping the overall pattern of super droughts,while the precipitation and evaporation anomalies at short time scales trigger the outbreak of super droughts,determining the exact timing of occurrence.These events include August-September 2006,November 2009 to May 2010,July-October 2011,April-May 2012,January-April 2013,etc.Statistical results suggest that the contribution of superposed precipitation anomalies to super drought is 2.4 times that of evaporation.As regards the circulation mechanisms affecting multiscalar precipitation,the anomalous spatial patterns at short-term and long-term scales are similar,featuring the cyclonic circulation over the South China Sea and the northeasterly wind anomalies together with the subsidence center over SWC.During 2006-2014,the possible causes for the cross-seasonal persistent precipitation reduction in SWC are the extreme negative phase of the Pacific Decadal Oscillation(PDO)in the North Pacific as well as the pronounced warming of the warm pool in the western Pacific.The key dynamic processes are outlined as follows.On the one hand,the negative PDO phase generates anomalous anticyclonic circulation in the North Pacific,with the northeasterly winds on its southwest flank extending to Southeast Asia,hindering moisture transport into SWC.On the other hand,the warming of the warm pool excites anomalous cyclonic circulation to its northwest,also giving rise to northeasterly wind anomalies over SWC.Meanwhile,the ascending motion over the warm pool region diverges at upper levels with outflows converging aloft over SWC,which further induces compensating downward motion there.The combined effect of the above two remote forcings establishes a climatic background state unfavorable for precipitation over SWC at long time scales,thus constituting a crucial prerequisite for the superimposition of short-term precipitation anomalies to develop into super droughts.

Super droughtMultiscalarCompounding effectMechanism analysisSouthwest China

Lin WANG、Wen CHEN、Gang HAUNG、Ting WANG、Qiulin WANG、Xiaoyun SU、Zixuan REN、Chakrit CHOTAMONSAK、Atsamon LIMSAKUL、Kritanai TORSRI

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CAS Key Laboratory of Regional Climate-Environment for Temperate East Asia,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China

Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province,Chengdu 610072,China

Department of Atmospheric Science,Yunnan University,Kunming 650500,China

State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China

Carbon Neutrality Research Center,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China

Hangzhou Meteorological Bureau,Hangzhou 310051,China

Center for Monsoon System Research,Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing 100029,China

Department of Geography,Faculty of Social Sciences,Chiang Mai University,Chiang Mai 50200,Thailand

Environmental Science Research Center,Faculty of Science,Chiang Mai University,Chiang Mai 50200,Thailand

Climate Change and Environmental Research Center Technopolis,Klong 5,Klong Luang,Pathumthani 12120,Thailand

Hydro-Informatics Innovation Division,Hydro-Informatics Institute,Ministry of Higher Education,Science,Research and Innovation,Bangkok 10900,Thailand

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National Natural Science Foundation of ChinaInternational Partnership Program of Chinese Academy of Sciences for Future NetworkYouth Program of the Institute of Atmospheric Physics,Chinese Academy of Sciences during the 14th Five-Year Plan PeriodOpen Research Fund of Heavy Rain and Drought-Flood Disasters in Plateau and Basin Key Laboratory of Sichuan Province

42175041 & 42230605060GJHZ2022104FNSZKT202204

2024

10.1007/s11430-023-1341-4

中国科学:地球科学(英文版)
中国科学院

中国科学:地球科学(英文版)

影响因子：1.002
ISSN：1674-7313
年,卷(期)：2024.67(7)