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ISSN 1006-9895

CN 11-1768/O4

海气相互作用在FGOALS-g3模拟东亚夏季风及其对前冬El Ni?o响应中的贡献
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中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室

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国家重点研发计划“关键模式参数不确定性对全球季风预估的影响


The Role of Air-sea Coupling in Simulating East Asian Summer Monsoon and responses to pre-winter El Ni?o - Based on FGOALS-g3
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State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics, Chinese Academy of Sciences

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    摘要:

    本文基于观测、再分析资料和中国科学院大气物理研究所LASG国家重点实验室最新版本气候系统模式FGOALS-g3,探究了海气相互作用在东亚夏季风及其对前冬El Ni?o响应模拟中的贡献。大气环流模式(AGCM)模拟的气候态夏季风雨带偏东,东亚季风区表现为干偏差,耦合模式(CGCM)虽模拟出了夏季风雨带的位置,但降水偏弱。AGCM由于缺乏海气耦合过程,夏季西北太平洋地区对流模拟过强,使得副高偏东、南中国海季风槽偏东,造成东亚夏季风雨雨带偏东;东亚陆地区域水汽偏少,也是降水干偏差的一个重要原因,此两项可以解释70%以上的干偏差。在考虑海气相互作用后,西北太平洋的降水正异常减弱了局地海表温度,因此CGCM显著改进了副高以及南中国海季风槽偏东等偏差,使得夏季风雨带位置得到改进,季风区降水干偏差减小了36%,但由于水汽偏少,水汽纬向输送偏少,东亚季风区仍维持着显著的干偏差。对于对前冬El Ni?o的响应,CGCM能够再现El Ni?o衰减年夏季印度-西太平洋电容器效应(IPOC机制)对西北太平洋异常反气旋(WNPAC)的维持作用及偶极型分布的降水异常。而AGCM中夏季西北太平洋以及孟加拉湾、印度半岛周围海域对流对于海温的响应过于敏感,一方面西北太平洋局地暖异常造成的对流质量输送一定程度上抑制了WNPAC的建立,另一方面孟加拉湾、印度半岛周围海域过强的上升异常,通过局地环流,抑制了其南侧印度洋的对流异常,导致无法模拟出IPOC机制对衰减年夏季WNPAC的维持作用。因此,缺乏海气耦合过程是AGCM不能模拟出东亚夏季风对前冬El Ni?o滞后响应的关键原因。

    Abstract:

    Based on the reanalysis data and FGOALS-g3, this study explores the contributions of air-sea interactions to the simulation of the East Asian Summer Monsoon (EASM). For climatological mean, the Eastward shift of the Summer Monsoon Rain Belt in atmospheric general circulation models (AGCM) results in dry bias over the East Asian monsoon region. While coupled general circulation models (CGCM) present a proper position of the Summer Monsoon Rain Belt, rain in the East Asian monsoon region is weak. Due to the absence of air-sea interaction, the fake convective responses over the Northwest Pacific region lead to an eastward shift of Subtropical High, which is the main reason for the bias of AGCM in simulating the EASM precipitation. The dry humidity over land is not negligible and contributes 70% of the dry error with the help of the circulation bias. The position bias of Subtropical High and Summer Monsoon Rain Belt is significantly reduced in CGCM which reduces the dry bias by 36%. Less evaporation and less zonal water vapor transport in CGCM simulation together contribute more than 70 % dry bias. For responses to pre-winter El Ni?o, CGCM can reproduce the Western North Pacific Anomalous Anticyclone (WNPAC) and the corresponding dipole precipitation anomaly distribution in the El Ni?o decaying summer. It can also reproduce the Indo-western Pacific Ocean capacitor (IPOC) maintaining WNPAC. In AGCM simulation, convection in the Northwest Pacific, the Bay of Bengal, and the oceans surrounding the Indian Peninsula is too sensitive to SST in the El Ni?o decaying summer. On one hand, this results in strong convective mass transport in the Northwest Pacific, which inhibits the establishment of WNPAC to some extent. For another hand, strong convection in the North Indian Ocean can inhabit convection in the Indian Ocean, resulting in the inability to simulate IPOC mode. Therefore, the lack of air-sea interaction is the main reason for why AGCM cannot reproduce the two-season lag response of EASM to major El Ni?o.

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  • 收稿日期:2022-04-08
  • 最后修改日期:2022-09-17
  • 录用日期:2022-10-18
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