Uncertainty in projections of the South Asian summer monsoon under global warming by CMIP6 models:Role of tropospheric meridional thermal contrast  

作　　者：Yunqi Kong Yuting Wu Xiaoming Hu Yana Li Song Yang 

机构地区：[1]School of Atmospheric Science,Sun Yat-sen University and Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai,China [2]State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,State Oceanic Administration,Hangzhou,China [3]Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies,Sun Yat-sen University,Zhuhai,China [4]School of Energy and Environment,City University of Hong Kong,Hong Kong,China

出　　处：《Atmospheric and Oceanic Science Letters》2022年第1期56-61,共6页大气和海洋科学快报（英文版）

基　　金：jointly supported by the National Natural Science Foundation of China [grant numbers 42088101;41911540470;42075028];the Guangdong Major Project of Basic and Applied Basic Research [grant number 2020B0301030004];the Natural Science Foundation of Guangdong Province of China [grant number 2018A0303130268];the Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies [grant number2020B1212060025]。

摘　　要：Driven by the increase in CO_(2)concentration,climate models reach a consensus that the large-scale circulation of the South Asian summer monsoon(SASM) becomes weakened but with different magnitudes.This study investigates the major uncertainty sources of the SASM response to an abrupt quadrupling of CO_(2)(abrupt-4×CO_(2))in 18 models of phase 6 of the Coupled Model Intercomparison Project.The projected weakening of the SASM indicated by both zonal and meridional monsoon circulation indices is closely linked to decreases in the meridional gradient of upper-tropospheric temperature between Eurasia and the Indian Ocean(EUTT-IUTT).A climate feedback-response analysis method is applied to linearly decompose the uncertainty of changes in EUTT-IUTT into the partial changes due to external forcing and internal processes of the earth-atmosphere column.Results show that the uncertainty of changes in EUTT-IUTT is contributed positively by the dominant atmospheric dynamic process,followed by the cloud shortwave radiative effect,and negatively by the surface latent heat flux and cloud longwave radiative effect.Contributions from CO_(2)forcing and other internal processes including albedo and water vapor feedbacks,oceanic heat storage,and sensible heat flux are found to be minor.本文基于第六次国际耦合模式比较计划共18个模式的工业革命前实验和CO_(2)浓度突然四倍实验,发现在CO_(2)四倍强迫下,南亚夏季风环流呈显著减弱趋势,但减弱强度存在较大模式间差异.利用Webster-Yang指数和经向哈得莱环流指数的下降趋势表征SASM减弱强度,发现该下降趋势与欧亚大陆-印度洋之间对流层上层经向温度梯度的变化值(EUTT-IUTT)高度相关.进一步利用气候反馈-响应分析方法进行分析,发现EUTT-IUTT变化的模式间差异主要来自于大气动力过程,其次是云的短波辐射效应的贡献.地表潜热通量和云的长波辐射效应缩小了EUTT-IUTT变化的模式间差异.

关 键 词：South Asian summer monsoon CMIP6 Uncertainty in model projection Meridional temperature gradient Climate Feedback-Response Analysis Method 

分 类 号：P425.42[天文地球—大气科学及气象学]