The Role of Ocean Dynamics in the Cross-equatorial Energy Transport under a Thermal Forcing in the Southern Ocean

• Published in: Advances in atmospheric sciences Vol. 38; no. 10; pp. 1737 - 1749
• Main Authors: Liu, Fukai, Luo, Yiyong, Lu, Jian, Wan, Xiuquan
• Format: Journal Article
• Language: English
• Published: Heidelberg Science Press 01.10.2021; Springer Nature B.V; Laboratory for Ocean Dynamics and Climate,Qingdao Pilot National Laboratory for Marine Science and Technology,Qingdao 266100,China; Frontier Science Center for Deep Ocean Multispheres and Earth System(FDOMES)and Physical Oceanography Laboratory,Ocean University of China,Qingdao 266100,China; College of Oceanic and Atmospheric Sciences,Ocean University of China,Qingdao 266100,China%Atmospheric Sciences and Global Change Division,Pacific Northwest National Laboratory,Richland,WA 99352,USA
• Subjects: Air-sea interaction; Atlantic Meridional Overturning Circulation (AMOC); Atmospheric models; Atmospheric Sciences; Cells; Circulation anomalies; Climate models; Convergence zones; Dynamics; Earth and Environmental Science; Earth Sciences; Energy; Energy transfer; Energy transport; Equator; Geophysics/Geodesy; Heat transport; Heating; Intertropical convergence zone; Meteorology; Ocean circulation; Ocean currents; Ocean dynamics; Ocean models; Oceans; Original Paper; Perturbation; Subtropical circulation; Water circulation; Wind; Wind stress; Southern Ocean; ocean dynamics; 大气热输运; atmospheric energy transport; Southern Ocean; 海洋热输运; oceanic energy transport; 南大洋; 海洋动力过程
• ISSN: 0256-1530; 1861-9533
• DOI: 10.1007/s00376-021-1099-6

Under external heating forcing in the Southern Ocean, climate models project anomalous northward atmosphere heat transport (AHT) across the equator, accompanied by a southward shift of the intertropical convergence zone (ITCZ). Comparison between a fully coupled and a slab ocean model shows that the inclusion of active ocean dynamics tends to partition the cross-equatorial energy transport and significantly reduce the ITCZ shift response by a factor of 10, a finding which supports previous studies. To understand how ocean dynamics damps the ITCZ’s response to an imposed thermal heating in the Southern Ocean, we examine the ocean heat transport (OHT) and ocean circulation responses in a set of fully coupled experiments. Results show that both the Indo-Pacific and the Atlantic contribute to transport energy across the equator mainly through its Eulerian-mean component. However, different from previous studies that linked the changes in OHT to the changes in the wind-driven subtropical cells or the Atlantic meridional overturning circulation (AMOC), our results show that the cross-equatorial OHT anomaly is due to a broad clockwise overturning circulation anomaly below the subtropical cells (approximately bounded by the 5°C to 20°C isotherms and 50°S to 10°N). Further elimination of the wind-driven component, conducted by prescribing the climatological wind stress in the Southern Ocean heat perturbation experiments, leads to little change in OHT, suggesting that the OHT response is predominantly thermohaline-driven by air-sea thermal interactions.