Origins of Southern Ocean warm sea surface temperature bias in CMIP6 models

• Published in: npj Climate and Atmospheric Science
• Main Authors: Fengyun Luo, Jun Ying, Tongya Liu, Dake Chen
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Portfolio 2023
• Subjects: Environmental sciences; GE1-350; Meteorology. Climatology; QC851-999; Antarctic; Southern Ocean; The Antarctic; Antarc*
• Online Access: https://doi.org/10.1038/s41612-023-00456-6; https://doaj.org/article/b071cab2000c4153b85a495b4506069a

Abstract The warm sea surface temperature (SST) bias in the Southern Ocean (SO) has persisted in several generations of Coupled Model Inter-comparison Project (CMIP) models, yet the origins of such a bias remain controversial. Using the latest CMIP6 models, here we find that the warm SST bias in the SO features a zonally oriented non-uniform pattern mainly located between the northern and southern fronts of the Antarctic Circumpolar Current. This common bias is not likely to be caused by the biases in the surface heat flux or the strength of the Atlantic meridional overturning circulation (AMOC) — the two previously suggested sources of the SO bias based on CMIP5 models. Instead, it is linked to the robust common warm bias in the Northern Atlantic deep ocean through the AMOC transport as an adiabatic process. Our findings indicate that remote oceanic biases that are dynamically connected to the SO should be taken into account to reduce the SO SST bias in climate models.