Department of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea.
Department of Atmospheric and Oceanic Sciences, University of Colorado Boulder, Boulder, CO 80309.
Proc Natl Acad Sci U S A. 2022 Aug 23;119(34):e2200514119. doi: 10.1073/pnas.2200514119. Epub 2022 Aug 15.
Excessive precipitation over the southeastern tropical Pacific is a major common bias that persists through generations of global climate models. While recent studies suggest an overly warm Southern Ocean as the cause, models disagree on the quantitative importance of this remote mechanism in light of ocean circulation feedback. Here, using a multimodel experiment in which the Southern Ocean is radiatively cooled, we show a teleconnection from the Southern Ocean to the tropical Pacific that is mediated by a shortwave subtropical cloud feedback. Cooling the Southern Ocean preferentially cools the southeastern tropical Pacific, thereby shifting the eastern tropical Pacific rainbelt northward with the reduced precipitation bias. Regional cloud locking experiments confirm that the teleconnection efficiency depends on subtropical stratocumulus cloud feedback. This subtropical cloud feedback is too weak in most climate models, suggesting that teleconnections from the Southern Ocean to the tropical Pacific are stronger than widely thought.
东南热带太平洋的过度降水是贯穿几代全球气候模型的一个主要常见偏差。尽管最近的研究表明，过于温暖的南大洋是造成这种情况的原因，但鉴于海洋环流反馈，模型对这种远程机制的定量重要性存在分歧。在这里，我们利用一个南大洋辐射冷却的多模式实验，展示了一种从南大洋到热带太平洋的遥相关，这种遥相关是由短波亚热带云反馈介导的。南大洋的冷却会优先冷却东南热带太平洋，从而使东热带太平洋雨带向北移动，减少降水偏差。区域云锁定实验证实，遥相关效率取决于亚热带平流层云反馈。在大多数气候模型中，这种亚热带云反馈太弱，这表明南大洋与热带太平洋之间的遥相关比人们普遍认为的要强。
