大气科学学报2026，Vol.49Issue(2)：258-271,14.DOI:10.13878/j.cnki.dqkxxb.20250401002
影响ENSO与夏季西北太平洋异常环流跨季节联系的关键因子
Key factor controlling the trans-seasonal relationship between ENSO and the summer western North Pacific circulation
摘要
Abstract
The western North Pacific anomalous circulation(WNPAC),manifested as large-scale anticyclonic or cyclonic circulation anomalies over the western North Pacific during boreal summer,is a key component of the East Asian summer monsoon system.It exerts substantial influence on regional precipitation,flood-drought varia-bility,and tropical cyclone activity in East Asia.In particular,an anomalous anticyclonic circulation enhances southwesterly moisture transport into eastern China,increasing the likelihood of excessive rainfall over the Yangtze River basin,whereas an anomalous cyclonic circulation tends to suppress moisture transport and alter rainfall distributions.Consequently,understanding and predicting summer WNPAC variability is of both scientific and societal importance. A robust trans-seasonal linkage has long been recognized between the El Niño-Southern Oscillation(ENSO)in the winter and the WNPAC in the following summer.El Niño decay years are generally associated with an a-nomalous anticyclonic circulation over the western North Pacific,while La Niña decay years tend to be accompa-nied by an anomalous cyclonic circulation.This ENSO-WNPAC linkage constitutes a fundamental source of sea-sonal predictability for the East Asian summer climate.However,its strength exhibits pronounced decadal variabil-ity,and the key factors governing this nonstationary under internal climate variability remain insufficiently under-stood,partly due to the limited length of observational records. To address this issue,this study investigates the internally driven modulation of the ENSO-WNPAC relation-ship using two independent large-ensemble simulations:FGOALS-LE and CESM-LE.These ensembles,conducted under identical external forcing but with different initial conditions,allow robust isolation of internal variability.By examining inter-member differences in the correlation between preceding-winter ENSO and summer WNPAC,we identify the dominant factors controlling variations in the trans-seasonal linkage and diagnose the associated physi-cal mechanisms.Particular attention is paid to differences in ENSO evolution characteristics,especially the relative occurrence frequencies of distinct ENSO decay types,as well as the role of sea surface temperature(SST)anom-aly structures. Both large-ensemble datasets consistently show that variations in the relative frequencies of ENSO decay types are the primary determinant of the ENSO-WNPAC relationship strength.Ensemble members exhibiting a stronger ENSO-WNPAC correlation are characterized by a higher proportion of slowly decaying ENSO events and a lower proportion of persistent ENSO events,whereas members with a weaker correlation display the oppo-site pattern.In contrast,the frequency of rapidly decaying ENSO events does not differ significantly between strong-and weak-correlation members,indicating that this ENSO category plays a limited role in modulating the linkage.These results demonstrate that the statistical composition of ENSO decay pathways,rather than ENSO am-plitude alone,is central to shaping the stability of the winter ENSO-summer WNPAC connection. Further analyses suggest that differences in ENSO decay rate are closely linked to variations in the meridional scale of ENSO-related SST anomalies.Broader versus narrower meridional SST anomaly structures are associated with distinct ENSO decay behaviors,which influence the persistence of tropical ocean-atmosphere anomalies into the subsequent summer and modulate the circulation response over the western North Pacific.This mechanism provides a dynamical link between SST spatial structure,ENSO temporal evolution,and the strength of ENSO teleconnections. These findings advance understanding of why the ENSO-WNPAC relationship varies under identical external forcing and underscore the critical role of internal variability in modulating ENSO event-type composition and teleconnection strength.The results further imply that skillful seasonal prediction of East Asian summer climate de-pends not only on ENSO occurrence but also on accurate representation of ENSO decay pathway and SST anoma-ly structures,with important implications for operational climate prediction systems.关键词
西北太平洋反气旋/厄尔尼诺-南方涛动/内部变率/大样本集合模拟Key words
western North Pacific anticyclone/El Niño-Southern Oscillation/internal variability/large-ensemble simulations引用本文复制引用
赵妍,王璐,程一峰,孙明,陈晓龙,朱嬿..影响ENSO与夏季西北太平洋异常环流跨季节联系的关键因子[J].大气科学学报,2026,49(2):258-271,14.基金项目
国家重点研发计划项目(2020YFA0608904) （2020YFA0608904）
粤港澳大湾区气象科技协同攻关项目(GHMA2025Y01) （GHMA2025Y01）
国家自然科学基金项目(42505029) （42505029）
气象灾害教育部重点实验室&气象灾害预报预警与评估协同创新中心联合开放课题(KLME202501) （KLME202501）
