南京信息工程大学陈海山课题组报道了，不同海温背景下陆-气耦合对欧亚大陆南部夏季极端湿热复合事件的影响。该研究于2024年6月20日发表于国际一流学术期刊《大气科学进展》杂志上。

研究人员基于ERA5再分析数据和CESM1.2.2模式，研究了不同海温背景下陆—气耦合对欧亚大陆南部夏季极端湿热事件的影响。结果显示，耦合导致近地表气温升高超过0.5℃。1961-2020年，EHHE出现的频率持续增加，并与印度半岛北部(IDP)和长江中下游(YRB)土壤湿度异常密切相关。数值模拟进一步表明，陆-气耦合使EHHE的风险增加了25.4%。在典型的EI Nino海温背景下，陆—气耦合的加剧往往会导致EHHE频率的显著增加。

陆—气耦合影响区域EHHE变化的主导过程存在明显差异。地表热异常在内陆带占主导地位，而湿润条件在YRB更为重要。当暖SST异常存在时，IDP中的干土壤异常是显著的，蒸发受到限制，感热通量增加。正位势高度异常显著，并伴有下降运动引起的绝热增温和近地面大气中明显的暖中心。西风急流的南移增强了YRB上空的辐散。西太平洋上空反气旋环流异常有利于引导水汽向YRB输送，为夏季EHHE的发展提供了有利的环流背景。

附：英文原文

Title: Impacts of land–atmosphere coupling on summer extreme hot-humid compound events over southern Eurasia under different sea surface temperature backgrounds

Author: Yajing Qi, Haishan Chen, Siguang Zhu

Issue&Volume: 2024-06-20

Abstract: Land–atmosphere coupling and sea surface temperature (SST) anomalies both have essential impacts on weather and climate extremes. Based on the ERA5 reanalysis dataset and the CESM1.2.2 model, this study investigated the influence of land–atmosphere coupling on summer extreme hot-humid events (EHHE) over southern Eurasia under different SST backgrounds. The results suggested that coupling causes the near-surface air temperature increases exceeding 0.5 ℃. From 1961 to 2020, the frequency of EHHE has continuously increased and is closely related to soil moisture anomalies in the northern Indian Peninsula (IDP) and the middle and lower reaches of the Yangtze River (YRB). Numerical simulations further demonstrate that land–atmosphere coupling raises the risk of EHHE by 25.4%. In the typical El Nio SST background, intensified land–atmosphere coupling tends to produce notable increases in the frequency of EHHE. The dominant processes that land–atmosphere coupling affects the EHHE variations are evidently different between these two regions. Land surface thermal anomalies predominate in the IDP, while moisture conditions are more critical in the YRB. When warm SST anomalies exist, dry soil anomalies in the IDP are prominent, and evaporation is constrained, increasing sensible heat flux. Positive geopotential height anomalies are significant, combined with adiabatic warming induced by descending motion and a noticeable warm center in the near-surface atmosphere. The southward shift of the westerly jet enhances divergence over YRB. The anticyclonic circulation anomalies over the western Pacific are conducive to guiding moisture transport to the YRB, providing a favorable circulation background for the development of summer EHHE.

DOI: 10.1007/s00376-024-4073-2

Source: http://www.iapjournals.ac.cn/aas/en/article/doi/10.1007/s00376-024-4073-2viewType=HTML