大气科学学报2026，Vol.49Issue(1)：109-120,12.DOI:10.13878/j.cnki.dqkxxb.20251105009
2024/2025年前冬北半球季风区严重干旱事件特征及机理
Characteristics and mechanisms of the severe drought over Northern Hem-isphere regions during the early winter of 2024/2025
摘要
Abstract
The frequency and intensity of extreme climate events have increased under global warming,rendering monsoon regions—critical to water resources and agriculture—particularly vulnerable.During the early winter of 2024/2025(1 December 2024 to 15 January 2025),an exceptionally severe and widespread drought affected monsoon regions across the Northern Hemisphere.Eastern China experienced its most severe drought since 1979,with the area classified as exceptional drought reaching approximately 696 000 km2.This event caused substantial agricultural losses,ecosystem stress,and socioeconomic impacts,underscoring the need for a comprehensive un-derstanding of its underlying mechanisms. Using the high-resolution ERA5 reanalysis dataset together with Hadley Centre sea surface temperature and sea ice concentration data,this study investigates the spatiotemporal characteristics and physical drivers of this ex-treme drought.The analysis covers the period 1979-2025,with early winter defined as 1 December to 15 January of the following year.Monsoon regions are defined according to the IPCC AR6 framework. Results indicate that during the early winter of 2024/2025,eastern China experienced an extreme drought concurrent with drought conditions of varying intensity across nearly all Northern Hemisphere monsoon regions.The drought over eastern China was directly associated with pronounced anomalous moisture divergence.Circula-tion diagnostics reveal that an anomalous cyclone over the North Pacific and an anomalous anticyclone over the southern Qinghai-Xizang Plateau jointly established persistent cold and dry northerly flow,substantially reducing moisture transport into eastern China. Further analysis identifies the circumglobal teleconnection(CGT),a dominant mode of internal atmospheric variability,as a key contributor to the formation of the North Pacific cyclonic anomaly.In addition,autumn snow cover over the Tibetan Plateau reached a record low in 2024,the lowest since 1979.This reduced snow cover low-ered surface albedo,enhanced shortwave radiation absorption,and induced sustained warming,leading to the de-velopment of a deep warm anticyclone over the plateau in early winter.This anomalous high-pressure system fur-ther strengthened the northerly circulation over eastern China. Moreover,weak La Niña-like sea surface temperature anomalies in the tropical Pacific enhanced the Walker circulation,contributing to anomalous cyclonic circulation over the South China Sea and further suppressing mois-ture transport toward eastern China.The strengthened winter monsoon,as indicated by monsoon indices,was evi-dent across multiple Northern Hemisphere monsoon regions,consistent with concurrent drought conditions ob-served in West Africa and North America. This study concludes that the extreme drought over eastern China during early the early winter of 2024/2025 resulted from the combined effects of the CGT,anomalously low autumn snow cover over the Qinghai-Xizang Plateau,and weak La Niña-like sea surface temperature anomalies.Together,these factors restructured large-scale atmospheric circulation,leading to persistent moisture divergence and suppressed precipitation. Notably,although previous studies have suggested that ENSO and Arctic sea ice can modulate the CGT,the mechanisms linking sea surface temperature and sea ice anomalies to the CGT in this event differ from established interpretations and warrant further investigation.In the context of ongoing global warming,an accelerated hydro-logical cycle may increase the likelihood and severity of such compound drought extremes in monsoon regions.These findings highlight the importance of accounting for tropical-subtropical interactions,land-atmosphere feed-backs,and internal climate variability in improving predictions of extreme events in global monsoon systems.关键词
干旱/季风区/遥相关/拉尼娜事件/水汽Key words
drought/monsoon region/teleconnection/La Niña event/water vapor引用本文复制引用
孙博,李驰,戴永玲,陈平,李万玲,周波涛,王会军..2024/2025年前冬北半球季风区严重干旱事件特征及机理[J].大气科学学报,2026,49(1):109-120,12.基金项目
国家自然科学基金项目(42522502) （42522502）
