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丁天, 郭准, 周天军, 等. 2022. 海气相互作用在模式FGOALS-g3模拟东亚夏季风及其对前冬El Niño响应中的贡献[J]. 大气科学, 48(X): 1−17. doi: 10.3878/j.issn.1006-9895.2209.22076
引用本文: 丁天, 郭准, 周天军, 等. 2022. 海气相互作用在模式FGOALS-g3模拟东亚夏季风及其对前冬El Niño响应中的贡献[J]. 大气科学, 48(X): 1−17. doi: 10.3878/j.issn.1006-9895.2209.22076
DING Tian, GUO Zhun, ZHOU Tianjun, et al. 2022. Role of Air–Sea Coupling for Simulating the East Asian Summer Monsoon and Responses to Prewinter El Niño Based on Model FGOALS-g3 [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(X): 1−17. doi: 10.3878/j.issn.1006-9895.2209.22076
Citation: DING Tian, GUO Zhun, ZHOU Tianjun, et al. 2022. Role of Air–Sea Coupling for Simulating the East Asian Summer Monsoon and Responses to Prewinter El Niño Based on Model FGOALS-g3 [J]. Chinese Journal of Atmospheric Sciences (in Chinese), 48(X): 1−17. doi: 10.3878/j.issn.1006-9895.2209.22076

海气相互作用在模式FGOALS-g3模拟东亚夏季风及其对前冬El Niño响应中的贡献

Role of Air–Sea Coupling for Simulating the East Asian Summer Monsoon and Responses to Prewinter El Niño Based on Model FGOALS-g3

  • 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大气科学和地球流体力学数值模拟国家重点实验室(LASG)最新版本气候系统模式FGOALS-g3,探究了海气相互作用在模拟东亚夏季风及其对前冬El Niño响应中的贡献。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,但降水仍偏弱。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,使得副热带高压(简称副高)偏东、南中国海季风槽偏东,造成东亚夏季风雨带偏东;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。另一方面,对前冬El Niño的响应,CGCM能够再现El Niño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 Niño滞后响应的关键原因。

     

    Abstract: In this study, the role of air–sea interactions in the simulation of the East Asian Summer Monsoon (EASM) was investigated based on reanalysis data and Model FGOALS-g3. For climatological mean, the eastward shift of the summer monsoon rain belt in AGCMs (atmospheric general circulation models) leads to dry bias over the East Asian monsoon region. While CGCMs (coupled general circulation models) present a proper position of the summer monsoon rain belt, rain in the East Asian monsoon region is still weak. Due to the absence of air–sea interaction, the fake convective responses over the Northwest Pacific region result in an eastward shift of the subtropical high. This is the main reason for the bias of AGCM in simulating the EASM precipitation. And also the deficient water vapor over land is not negligible. The two factors together contribute to over 70% of the dry error. The position bias of the subtropical high and summer monsoon rain belt is considerably reduced in CGCM, which reduces the dry bias by 36%. Less evaporation and zonal water vapor transport in CGCM simulation jointly contribute to more than 70% of dry bias. Regarding the responses to prewinter El Niño, CGCM can reproduce the Western North Pacific Anomalous Anticyclone (WNPAC) and the dipole–precipitation anomaly distribution in the El Niño decaying summer as well as the Indo-western Pacific Ocean capacitor (IPOC) which maintains the WNPAC. In the AGCM simulation, convection in the Northwest Pacific, the Bay of Bengal, and oceans surrounding the Indian Peninsula is observed to be too sensitive to sea surface temperature in the El Niño decaying summer. On the one hand, this leads to strong convective mass transport in the Northwest Pacific, inhibiting the establishment of WNPAC to some extent. On the other hand, strong convection in the North Indian Ocean can inhibit convection in the Indian Ocean, causing the inability to simulate the IPOC mode. Thus, the lack of air–sea interaction is the main reason for the inability of the AGCM to reproduce the two-season lag responses of the EASM to major El Niño.

     

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