Effect of wind forcing on the meridional heat transport in a coupled climate model: equilibrium response

• Published in: Climate Dynamics
• Main Authors: Yang, Haijun, Dai, Haijin
• Other Authors: Yang, HJ (reprint author), Peking Univ, Lab Climate & Ocean Atmosphere Studies LaCOAS, Sch Phys, 209 Chengfu Rd, Beijing 100871, Peoples R China., Peking Univ, Lab Climate & Ocean Atmosphere Studies LaCOAS, Sch Phys, Beijing 100871, Peoples R China., Peking Univ, Sch Phys, Dept Atmospher & Ocean Sci, Beijing 100871, Peoples R China., Peking Univ, Lab Climate & Ocean Atmosphere Studies LaCOAS, Sch Phys, 209 Chengfu Rd, Beijing 100871, Peoples R China.
• Format: Journal/Newspaper
• Language: Chinese
• Published: CLIMATE DYNAMICS 2015
• Subjects: Coupled climate model; Atmospheric heat transport; Oceanic heat transport; Hadley cell; Atlantic meridional overturning circulation; Bjerknes compensation; MIXED-LAYER EDDIES; OVERTURNING CIRCULATION; ENERGY TRANSPORTS; THERMOHALINE CIRCULATION; OCEAN; ATMOSPHERE; PARAMETERIZATION; IMPACT; NORTH; CCSM4; Pacific; Southern Ocean; North Atlantic
• Online Access: https://hdl.handle.net/20.500.11897/416840; https://doi.org/10.1007/s00382-014-2393-0

The effect of the ocean surface winds on the meridional heat transports is studied in a coupled model. Shutting down the global surface winds causes significant reductions in both wind-driven and thermohaline ocean circulations, resulting in a remarkable decrease in the poleward oceanic heat transport (OHT). The sea surface temperature responds with significant warming in the equator and cooling off the equator, causing an enhancement and equatorward shift in the Hadley cell. This increases the poleward atmospheric heat transport (AHT), which in turn compensates the decrease in the OHT. This compensation implies a fundamental constraint in changes of ocean-atmosphere energy transports. Several other compensation changes are also identified. For the OHT components, the changes in the Eulerian mean and bolus OHT are compensated with each other in the Southern Ocean, since a stronger wind driven Ekman transport is associated with a stronger meridional density gradient (stronger bolus circulation) and vice versa. For the AHT components, the changes in the dry static energy (DSE) and latent energy transports are compensated within the tropics (30A degrees N/S), because a stronger Hadley cell causes a stronger equatorward convergence of moisture. In the extratropics, the changes in the mean and eddy DSE transports show perfect compensation, as a result of the equatorward shift of the Ferrell Cell and enhancement of atmospheric baroclinicity in mid-high latitudes, particularly over the North Atlantic. This work also shows how the Earth's climate is trying to maintain the balance between two hemispheres: the ocean in the Northern Hemisphere is colder than that in the Southern Hemisphere due to much reduced northward heat transports cross the Equator in the Atlantic, therefore, the atmosphere responds to the ocean with temperature colder in the Southern Hemisphere than in the Northern Hemisphere by transporting more heat northward cross the equator over the Pacific, in association with a southward shift of the intertropical convergence zone. NSF of China [91337106, 41376007, 41176002, 40976007]; National Basic Research Program of China [2012CB955200]; Special Fund for Meteorological Scientific Research in the Public Interest of CMA [GYHY201006022]; Norwegian Research Council through the East Asian DecCen project [193690/S30] SCI(E) ARTICLE [e-mail] 5-6 1451-1470 45