Purich Ariaan, Boschat Ghyslaine, Liguori Giovanni
ARC Centre of Excellence for Climate Extremes, Sydney, Australia.
Climate Change Research Centre, University of New South Wales, Sydney, NSW, Australia.
Sci Rep. 2021 Nov 11;11(1):22069. doi: 10.1038/s41598-021-01306-2.
The Southern Ocean exerts a strong influence on global climate, regulating the storage and transport of heat, freshwater and carbon throughout the world's oceans. While the majority of previous studies focus on how wind changes influence Southern Ocean circulation patterns, here we set out to explore potential feedbacks from the ocean to the atmosphere. To isolate the role of oceanic variability on Southern Hemisphere climate, we perform coupled climate model experiments in which Southern Ocean variability is suppressed by restoring sea surface temperatures (SST) over 40°-65°S to the model's monthly mean climatology. We find that suppressing Southern Ocean SST variability does not impact the Southern Annular Mode, suggesting air-sea feedbacks do not play an important role in the persistence of the Southern Annular Mode in our model. Suppressing Southern Ocean SST variability does lead to robust mean-state changes in SST and sea ice. Changes in mixed layer processes and convection associated with the SST restoring lead to SST warming and a sea ice decline in southern high latitudes, and SST cooling in midlatitudes. These results highlight the impact non-linear processes can have on a model's mean state, and the need to consider these when performing simulations of the Southern Ocean.
南大洋对全球气候有着强烈影响，调节着热量、淡水和碳在全球海洋中的储存和传输。虽然此前的大多数研究集中在风的变化如何影响南大洋环流模式，但在此我们着手探索海洋对大气的潜在反馈。为了分离海洋变率对南半球气候的作用，我们进行了耦合气候模式实验，其中通过将40°-65°S的海表面温度（SST）恢复到模式的月平均气候态来抑制南大洋变率。我们发现抑制南大洋SST变率不会影响南半球环状模，这表明海气反馈在我们模式中对南半球环状模的持续性不起重要作用。抑制南大洋SST变率确实会导致SST和海冰出现显著的平均态变化。与SST恢复相关的混合层过程和对流变化导致南半球高纬度地区SST变暖、海冰减少，以及中纬度地区SST变冷。这些结果凸显了非线性过程对模式平均态的影响，以及在进行南大洋模拟时考虑这些过程的必要性。
