- 郭如月;尹泽疆;赵俊虎;杨崧;魏维;
This study investigates the extreme compound cold-wet event in southern China during January–February 2024,which was the second most extreme event recorded since 1960. Two cold-wet processes occurred during this period. The first process, from 22 January to 23 January, exhibited a more intense cold surge, while the second, from 1 February to 7February, featured more extreme precipitation and longer duration. This extreme cold-wet event was attributed to the combined effects of El Ni?o and positive North Atlantic Oscillation(NAO) in winter, coupled with intense convection in the western tropical Indian Ocean associated with a positive Indian Ocean Dipole(IOD) from the preceding autumn. El Ni?o and the Indian Ocean Basin mode in winter are conductive to enhanced anticyclone over the western North Pacific.Over the western tropical Indian Ocean, the enhanced convection associated with the warm sea surface temperature in winter and the positive IOD in preceding autumn can trigger an anomalous upper-level anticyclone over the Arabian Sea,enhancing the subtropical jet and deepening the India-Myanmar trough. The deepened India-Myanmar trough and the strengthened subtropical anticyclone over the western North Pacific enhance water vapor transport and subsequent extreme precipitation in southern China. Moreover, positive NAO and strengthened westerly jet stream induce widespread cooling in subtropical Eurasia, including southern China. Analysis from the backward trajectories using the HYSPLIT model confirms that moisture from the west and cold air from northern China at the near surface favored the compound cold-wet event in southern China. The extreme conditions of ENSO and NAO in winter and IOD in autumn jointly contributed to this extreme compound event.
2025年03期 v.31 237-248页 [查看摘要][在线阅读][下载 4378K] [下载次数：0 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：1 ] - 杜梦雯;冯立成;刘飞;谭晶;隋翠娟;韩雪;
This research analyzes the variations of the South Asian Summer Monsoon Rainfall Anomaly(SASMRA)between the first development year(Y0) and the following year(Y1) of all multi-year La Ni?a events from 1958 to 2022.During Y0, monsoon precipitation surpasses climatological values, presenting a tripole spatial pattern, whereas Y1 is characterized by below-normal precipitation with a dipole pattern. In certain regions, the difference in precipitation between Y0 and Y1 reaches up to 3 mm day–1. This work provides further insight into the key tropical ocean regions driving the precipitation distinction, and elucidates their coupling mechanisms with large-scale atmospheric circulation anomalies. Influenced by the development of earlier ocean-atmosphere anomaly patterns, the Tropical Indian Ocean and Western Pacific(TIO-WP) warming(cooling) is significant during the summer of Y0(Y1). The elevated sea surface temperature(SST) in Y0 supports an anomalous Western North Pacific(WNP) anticyclone via a Kelvin-wave-induced Ekman divergence mechanism. This anomalous anticyclone intensifies the suppressed convection over the WNP, which results in increased divergence in the upper-level troposphere over the Indian Ocean and South Asian regions, thereby boosting convection. Simultaneously, the easterly winds associated with the strengthened equatorial latitude SST anomaly(SSTA) gradient and the anomalous anticyclone intensified, transporting a large amount of water vapor to the west. The combined moisture and dynamic conditions support the enhanced precipitation in the South Asian region.
2025年03期 v.31 249-256页 [查看摘要][在线阅读][下载 4297K] [下载次数：0 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：1 ] - 阚梓彤;赵亮;李清泉;沈新勇;丁一汇;柳艳菊;
This study explores the impact of winter sea surface temperature(SST) anomalies in the Southern Indian Ocean on summer precipitation patterns in China, utilizing data from reanalysis sources and Coupled Model Intercomparison Project Phase 6(CMIP6) models. The results reveal that the Southern Indian Ocean Dipole(SIOD), characterized by contrasting SST anomalies in the northeast and southwest regions, acts as a predictor for Chinese summer precipitation patterns, namely floods in the south and drought in the north. In a positive SIOD event, the southwestern Indian Ocean exhibits warmer SSTs, while the northeastern region remains cooler. A negative SIOD event shows the opposite pattern.During the positive phase of the SIOD, the winter SST distribution strengthens the 850-hPa cross-equatorial airflow,generating a robust low-level westerly jet that enhances water vapor transport to the Bay of Bengal(BoB). These air-sea interactions maintain lower SSTs in the northeastern region, which significantly increase the land-sea temperature contrast in the Northern Hemisphere during spring and summer. This strengthened thermal gradient intensifies the southwest monsoon, establishing a strong convergence zone near the South China Sea and amplifying monsoon-driven precipitation in South China. Additionally, CMIP6 models, such as NorESM2-LM and NorCPM1, which accurately simulate the SIOD pattern, effectively capture the seasonal response of cross-equatorial airflow driven by SST anomalies of Southern Indian Ocean. The result highlights the essential role of cross-equatorial airflow generated by the SIOD in forecasting crossseasonal precipitation patterns.
2025年03期 v.31 257-270页 [查看摘要][在线阅读][下载 9646K] [下载次数：0 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：1 ] - 过文箫;郝鑫;李建东;韩婷婷;
Using a reanalysis dataset and Coupled Model Intercomparison Project Phase 6(CMIP6) models, this study investigated the southern and northern modes of the East Asian winter monsoon(EAWM) and their respective relationships with the El Ni?o–Southern Oscillation(ENSO). The EAWM northern mode(EAWM＿N) exhibited a consistent and strong connection with the mid-and high-latitude atmospheric circulation during 1979–2013, resembling the Eurasian teleconnection pattern. The positive phase of this pattern enhanced the sea-land pressure gradient across the mid-latitude East Asia and strengthened northerly winds flowing from high latitudes to South China, resulting in a strong EAWM＿N. The relationship between the EAWM＿N and ENSO shifted from insignificant to significant in the late 1990s, coinciding with a westward transition of the Walker circulation. In contrast, the EAWM southern mode(EAWM＿S) was closely associated with an anomalous cyclone over the Philippine Sea and exhibited a stable, robust inverse correlation with ENSO.Projections from 12 CMIP6 models indicated that the unstable negative correlation of EAWM＿N with ENSO would intensify, while the robust linkage between EAWM＿S and ENSO was expected to persist under both the SSP1-2.6 and SSP5-8.5 scenarios. Additionally, increased future variability in the Ni?o 3.4 index, driven by external forcing, corresponded well to enhanced variability of EAWM＿S. These findings underscore the necessity for further research into the distinct behaviors of the northern and southern EAWM modes under the background of ongoing climate warming.
2025年03期 v.31 271-288页 [查看摘要][在线阅读][下载 7790K] [下载次数：0 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：1 ] - 郭晞;陈小宇;李超;马晨;吴海英;庄园;
Understanding the factors that control typhoon rainfall distribution is critical for improving rainfall forecasting,especially for landfall typhoons. This study investigated the impact of typhoon size on rainfall characteristics at landfall in eastern coast of China. Typhoons Ampil(2018) and Rumbia(2018), which had similar intensities, were investigated to explore the connection between storm size and rainfall. The larger cyclonic wind field in Typhoon Rumbia led to greater vorticity and broader convergence compared to Typhoon Ampil, along with an ascending region outside the eyewall, which promoted more vigorous rainbands. Rumbia′s larger size exhibited greater outer-core radial vorticity advection relative to Ampil. This maintained its extensive outer-core wind field and intensified outer rainband development. Consequently,Rumbia generated more extensive and prolonged rainfall post-landfall compared to Ampil. A composite analysis of typhoons making landfall in eastern China(2001-2021) further examines the statistical correlation between typhoon size and rainfall distribution. Results indicate that larger typhoons are more likely to generate heavier and more spatially extensive rainfall in regions beyond their eyewalls. These findings highlight that typhoon size significantly regulates rainfall evolution during landfall, underscoring the necessity of incorporating this parameter into operational rainfall forecasting models for landfalling typhoons.
2025年03期 v.31 297-308页 [查看摘要][在线阅读][下载 5403K] [下载次数：0 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：1 ] - 刘芷含;蒋益荃;杨犇;李芳;
In the context of global warming, the increasing wildfire frequency has become a critical climate research focus in North America. This study used the Community Earth System Model(CESM 1.2) to investigate the impacts of 20thcentury wildfires on North American climate and hydrology. Summer represents the peak wildfire season in North America, with the Gulf of Mexico and Midwest regions experiencing the most severe effects. Wildfires not only damage vegetation during the fire season but also extend prolonged impacts into non-fire periods, showing distinct seasonal variations. In spring, wildfires increase surface albedo, triggering a cooling effect through enhanced snow cover and delayed snowmelt. Conversely, summer and autumn surface warming stems primarily from wildfire-suppressed vegetation transpiration. Warming near the Gulf of Mexico enhances moisture transport and precipitation, particularly in summer and autumn. Reduced evaporation and increased precipitation from the Gulf of Mexico significantly altered the hydrological cycle across North America, leading to increased runoff continent-wide.
2025年03期 v.31 309-318页 [查看摘要][在线阅读][下载 801K] [下载次数：0 ] |[网刊下载次数：0 ] |[引用频次：0 ] |[阅读次数：1 ] 下载本期数据