ABSTRACT: The El Niño-Southern Oscillation (ENSO) in the preceding winter (December-January-February) is one of the key factors affecting subsequent East Asian summer (June-July-August) rainfall (EASR). However, current models face great challenges in reproducing ENSO’s impact on the EASR. This study attempts to reveal the factors that determine whether a model in phase 6 of the Coupled Model Intercomparison Project (CMIP6) can successfully reproduce this relationship by analyzing the outputs of historical climate simulation in 20 CMIP6 models. The results show that most of the models that overestimated ENSO interannual variability reproduced significant ENSO-EASR relationships, whereas all models that underestimated ENSO variability failed to reproduce this relationship. Further analyses show that models with stronger ENSO variability tended to simulate more realistic physical processes linking ENSO and EASR, i.e. the connections between ENSO and the tropical Indian Ocean (TIO) sea surface temperature (SST), between TIO SST and the Philippine Sea convection (PSC), and between PSC and EASR. Moreover, among the models that overestimated ENSO variability, only those that successfully captured significant TIO SST-PSC connections reproduced the observed ENSO-EASR relationship, although all these models captured ENSO-TIO SST and PSC-EASR teleconnections well. Therefore, simulating stronger ENSO interannual variability is the first necessary precondition for a CMIP6 model to capture the delayed effect of ENSO on EASR; reproducing a realistic TIO SST-PSC teleconnection is the second necessary precondition. This study will help models to improve their skills in simulation and prediction of EASR.

中文翻译：

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CMIP6 模型再现冬季 ENSO 与随后东亚夏季降雨之间关系的前提条件

摘要：前一个冬季（12-1-2 月）的厄尔尼诺-南方涛动（ENSO）是影响随后东亚夏季（6-7-8 月）降雨（EASR）的关键因素之一。然而，当前模型在再现 ENSO 对 EASR 的影响方面面临巨大挑战。本研究试图通过分析 20 个 CMIP6 模型中历史气候模拟的输出，揭示决定耦合模型比对项目 (CMIP6) 第 6 阶段中的模型能否成功再现这种关系的因素。结果表明，大多数高估 ENSO 年际变率的模型再现了显着的 ENSO-EASR 关系，而所有低估 ENSO 变率的模型都未能再现这种关系。进一步的分析表明，具有更强 ENSO 变异性的模型倾向于模拟更现实的连接 ENSO 和 EASR 的物理过程，即 ENSO 与热带印度洋 (TIO) 海面温度 (SST) 之间的联系，TIO SST 与菲律宾海对流之间的联系。 PSC)，以及在 PSC 和 EASR 之间。此外，在高估 ENSO 变异性的模型中，只有那些成功捕捉到显着 TIO SST-PSC 连接的模型才能重现观察到的 ENSO-EASR 关系，尽管所有这些模型都很好地捕捉了 ENSO-TIO SST 和 PSC-EASR 遥相关。因此，模拟更强的 ENSO 年际变化是 CMIP6 模型捕捉 ENSO 对 EASR 延迟影响的第一个必要前提；再现真实的 TIO SST-PSC 遥相关是第二个必要的先决条件。