This study assesses the capability of 12 models in the Phase 6 of the Coupled Models Intercomparison Project (CMIP6) in simulating the Southeast Indian Subantarctic mode water (SEISAMW) by comparing to Argo observations. The results show that all of the analyzed CMIP6 coupled models can reproduce the SEISAMW and its seasonal cycle, albeit with discrepancies of formation region and properties among the models. The SEISAMW subduction rate shows significant interannual variability, which is primarily induced by lateral induction in these models, in agreement with observations. Furthermore, the longterm trends of the SEISAMW show volume loss in accordance with the descending trend of the subduction rate, which are co-occurred with the ascending trend of the Southern Annular Mode (SAM) indices in most of the analyzed CMIP6 models, similar to those in the CMIP3 and CMIP5 coupled models. Meanwhile, the potential density of the SEISAMWs show decreasing trends in these volume loss models, which could be explained by the warming (SAM0-UNICON, CESM2-WACCM, CAS-ESM2-0 and CIESM), the freshening (IPSL-CM6A-LR, CAMS-CSM1-0, MRI-ESM2-0, and FGOALS-f3-L) or the both (FIO-ESM-2-0, E3SM-1-0, and CanESM5) trends of the SEISAMWs in different CMIP6 coupled models. Decreases in the projected subduction rate and volume of SEISAMW imply a slowdown of Southern Indian Ocean circulation in the future, reducing the heat and carbon transport from atmosphere to ocean interior contributed by SEISAMW.

中文翻译：

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CMIP6 耦合模型中的东南印度亚南极模式水

本研究通过与 Argo 观测进行比较，评估了耦合模型比对项目 (CMIP6) 第 6 阶段中 12 个模型在模拟东南印度亚南极模式水 (SEISAMW) 方面的能力。结果表明，所有分析的 CMIP6 耦合模型都可以再现 SEISAMW 及其季节性周期，尽管模型之间的形成区域和特性存在差异。SEISAMW 俯冲率显示出显着的年际变化，这主要是由这些模型中的横向感应引起的，与观察结果一致。此外，SEISAMW 的长期趋势显示体积损失与俯冲率下降趋势一致，在大多数分析的 CMIP6 模型中，这与南环模态 (SAM) 指数的上升趋势共同发生，类似于 CMIP3 和 CMIP5 耦合模型中的那些。同时，SEISAMWs 的潜在密度在这些体积损失模型中显示出下降趋势，这可以通过变暖（SAM0-UNICON、CESM2-WACCM、CAS-ESM2-0 和 CIESM）、清新（IPSL-CM6A-LR 、CAMS-CSM1-0、MRI-ESM2-0 和 FGOALS-f3-L）或两者（FIO-ESM-2-0、E3SM-1-0 和 CanESM5）在不同 CMIP6 耦合模型中的 SEISAMW 趋势. SEISAMW 预计的俯冲速度和体积的减少意味着未来南印度洋环流将放缓，从而减少 SEISAMW 从大气到海洋内部的热量和碳传输。CAS-ESM2-0 和 CIESM）、清新（IPSL-CM6A-LR、CAMS-CSM1-0、MRI-ESM2-0 和 FGOALS-f3-L）或两者（FIO-ESM-2-0、E3SM -1-0 和 CanESM5) 不同 CMIP6 耦合模型中 SEISAMW 的趋势。SEISAMW 预计的俯冲速度和体积的减少意味着未来南印度洋环流将放缓，从而减少 SEISAMW 从大气到海洋内部的热量和碳传输。CAS-ESM2-0 和 CIESM）、清新（IPSL-CM6A-LR、CAMS-CSM1-0、MRI-ESM2-0 和 FGOALS-f3-L）或两者（FIO-ESM-2-0、E3SM -1-0 和 CanESM5) 不同 CMIP6 耦合模型中 SEISAMW 的趋势。SEISAMW 预计的俯冲速度和体积的减少意味着未来南印度洋环流将放缓，从而减少 SEISAMW 从大气到海洋内部的热量和碳传输。