Samson Hagos, Chuan-Chieh (Jay) Chang, Po-Lun Ma, Sandro W. Lubis, Karthik Balaguru, Pengfei Shi, Oluwayemi Garuba, L. Ruby Leung
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引用次数: 0
摘要
近几十年来,东非 3 月-4 月-5 月(MAM,"长雨")降水量的减少仍然是一个谜,各种拟议的大尺度驱动因素都是其特征。本文利用全球模式模拟和观测数据研究了长雨的年际变化及其近期的干燥趋势。对照模拟与抑制了陆地表面反馈的重新初始化模拟的比较结果表明,1980 年至 2014 年间出现的长降雨赤字大部分与西北欧亚大陆的变暖同步。与模拟结果一致的是,多组观测数据显示,东非 MAM 平均降雨量与欧亚西北部地表温度之间存在很强的负相关。理想化模拟进一步表明,欧亚西北部的变暖削弱了区域哈德利细胞,并使季风水汽输送从东非转向欧洲和南部非洲,突出了遥远的陆地表面变暖对观测到的降水量下降的作用。
Synchronization of the Recent Decline of East African Long Rains and Northwestern Eurasian Warming
The East African March–April–May (MAM, “long rains”) precipitation decline in recent decades remains a puzzle marked by various proposed large-scale drivers. Here, the interannual variability of the long rains and their recent drying trend are examined using global model simulations and observations. Comparison of a control simulation and re-initialized simulations in which land-surface feedback is suppressed shows that much of the long rains deficit experienced between 1980 and 2014 is synchronized with the warming of the Northwestern Eurasian landmass. In agreement with the modeling results, multiple observational data sets reveal a strong negative correlation between MAM mean East African rainfall amount and the surface temperature over Northwestern Eurasia. Idealized simulations further indicate that warming in Northwestern Eurasia weakens the regional Hadley Cell and diverts the monsoonal transport of moisture away from Eastern Africa toward Europe and southern Africa, highlighting the role of remote land surface warming on the observed precipitation decline.
期刊介绍:
JGR: Atmospheres publishes articles that advance and improve understanding of atmospheric properties and processes, including the interaction of the atmosphere with other components of the Earth system.