大气科学学报2025，Vol.48Issue(5)：804-817,14.DOI:10.13878/j.cnki.dqkxxb.20241008001
华北夏季极端降水日数和热带东太平洋-大西洋偶极型海温异常的联系及机理
Linkages and mechanisms between extreme summer precipitation in North China and the tropical eastern Pacific-Atlantic SST anomaly dipole
摘要
Abstract
In recent years,the frequency of extreme precipitation events in North China has exhibited a notable upward trend,highlighting the need to understand their spatiotemporal variability and driving mechanisms.Previous studies have identified an out-of-phase relationship between sea surface temperature(SST)anomalies in the tropical eastern Pacific and the tropical Atlantic.This study investigates the relationship between extreme sum-mer precipitation days in North China and the tropical eastern Pacific-Atlantic SST anomaly dipole,with the goal of elucidating its underlying physical mechanisms and contributing to improved disaster prevention and mitigation strategies.Using high-resolution daily precipitation data from CN05.1(1979-2021),monthly SST data from ERSST V5,and atmospheric reanalysis data from ERA5,extreme precipitation days are defined based on the 90th percentile threshold.Empirical orthogonal function(EOF)analysis reveals that the SST anomaly dipole is the leading mode of tropical eastern Pacific-Atlantic SST variability during boreal summer.In its positive(negative)phase,SSTs in the eastern tropical Pacific are anomalously cold(warm),while those in the tropical Atlantic are anomalously warm(cold),corresponding to an increase(decrease)in extreme summer precipitation days in North China.Mechanistically,the positive phase of the tropical eastern Pacific-Atlantic SST anomaly dipole is as-sociated with an intensified Walker circulation and enhanced SSTs in the tropical western Pacific,which in turn amplify the local Hadley circulation and induce an anomalous anticyclonic circulation over the Northwest Pacific.These anomalies strengthen the East Asian summer monsoon,promoting moisture transport and convergence over North China.Concurrently,warming in the tropical Atlantic enhances local convection,while upper-tropospheric convergence and positive vorticity anomalies over western Europe and the Mediterranean trigger a quasi-stationary wave train.This wave train propagates eastward,resulting in an upper-tropospheric anticyclonic anomaly over North China and Northeast Asia,further supporting sustained upward motion and extreme precipitation in the re-gion.These results demonstrate a robust strong linkage between the tropical eastern Pacific-Atlantic SST anomaly dipole and extreme summer precipitation days in North China.However,further investigation is required to deter-mine whether this dipole structure is modulated by ENSO development and to identify which tropical ocean basin plays a dominant role in this relationship.Additionally,a westward shift in the region of strongest correlation with tropical Atlantic SST anomalies is observed from the preceding winter to the following summer,raising questions about the drives of this migration.It also remains unclear whether this relationship exhibits decadal-scale variabili-ty.These open questions warrant further exploration in future research.关键词
华北/夏季极端降水日数/热带东太平洋-大西洋/偶极型/海温异常Key words
North China/extreme summer precipitation days/tropical eastern Pacific-Atlantic/dipole/SST anom-aly引用本文复制引用
毛金诺,金大超..华北夏季极端降水日数和热带东太平洋-大西洋偶极型海温异常的联系及机理[J].大气科学学报,2025,48(5):804-817,14.基金项目
国家自然科学基金项目(42030605 （）
42088101) （）
