CMIP6 Intermodel Spread in Interhemispheric Asymmetry of Tropical Climate Response to Greenhouse Warming: Extratropical Ocean Effects
CMIP6 Intermodel Spread in Interhemispheric Asymmetry of Tropical Climate Response to Greenhouse Warming: Extratropical Ocean Effects
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DOI：
10.1175/jcli-d-21-0541.1
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发表时间：
2022-07-15
影响因子：
4.9
通讯作者：
Song, Zi-Han
中科院分区：
文献类型：
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作者：
Geng, Yu-Fan;Xie, Shang-Ping;Song, Zi-Han
热带气候对温室变暖的响应在赤道上是一阶对称的，但气候模式在热带变化的纬度不对称程度上存在分歧。利用耦合模式比对项目（CMIP6）第6阶段的37个模式，研究了热带气候响应赤道不对称的模式间传播。在CO2以每年1%的速度增加但没有气溶胶强迫的简单模拟中，本研究发现热带不对称的模式间传播与与大西洋经向翻转环流（AMOC）和南大洋海冰浓度（SIC）相关的温带地表热通量变化有关。AMOC或南大洋SIC变化改变了一个半球大气顶部和海面的净能量通量，并可能引起半球间的大气能量输送。在热带地区存在经向浅翻转环流的负反馈和副热带地区存在低云的正反馈。研究结果表明，减少温带变化的模式间传播可以提高热带气候预估的可靠性。
Tropical climate response to greenhouse warming is to first order symmetric about the equator but climate models disagree on the degree of latitudinal asymmetry of the tropical change. Intermodel spread in equatorial asymmetry of tropical climate response is investigated by using 37 models from phase 6 of the Coupled Model Intercomparison Project (CMIP6). In the simple simulation with CO2 increase at 1% per year but without aerosol forcing, this study finds that intermodel spread in tropical asymmetry is tied to that in the extratropical surface heat flux change related to the Atlantic meridional overturning circulation (AMOC) and Southern Ocean sea ice concentration (SIC). AMOC or Southern Ocean SIC change alters net energy flux at the top of the atmosphere and sea surface in one hemisphere and may induce interhemispheric atmospheric energy transport. The negative feedback of the shallow meridional overturning circulation in the tropics and the positive low cloud feedback in the subtropics are also identified. Our results suggest that reducing the intermodel spread in extratropical change can improve the reliability of tropical climate projections.