Abstract
The meridional heat transport (MHT) in the climate system is investigated using a state-of-the-art coupled climate model (CESM1.0). This work decomposes the MHT and studies their physics in detail. The meridional ocean heat transport (OHT) can be decomposed into the contributions from the Euler mean circulation, bolus circulation, sub-mesoscale circulation and dissipation. The Euler mean heat transport dominates the total OHT in most latitudes, except that in the Southern Ocean (40–50°S) where the OHT is determined by the eddy-induced circulation and dissipation. In the Indo-Pacific the OHT is fulfilled by the wind-driven circulation, which dominates the total global OHT in the tropics. In the Atlantic the OHT is carried by both the wind-driven circulation and the thermohaline circulation, and the latter dominates the total OHT in the mid-high latitudes. The meridional atmosphere heat transport consists of the dry static energy (DSE) and latent energy (LE) transport. In the tropics the LE transport is equatorward and compensates partially the poleward DSE transport. In the extratropics, the LE and DSE are poleward and reinforce one another, both of which are dominated by the eddy components. The LE transport can be considered as the “joint air–sea mode” since the ocean controls the moisture supply. It can be also precisely obtained from the evaporation minus precipitation over the ocean and thus this work quantifies the individual ocean basin contributions to the LE transport.
Highlights
Assessing the meridional heat transport (MHT) in the climate system is a classical question
We investigate the contributions of physical processes with different spatial-scale to the MHT
1 3 (a) peaks in the HTEMP and AHTDSE divergences correspond to the location of Intertropical convergence zone (ITCZ), where the enormous latent energy (LE) convergence has to be balanced by dry air heat divergence
Summary
Assessing the meridional heat transport (MHT) in the climate system is a classical question. The indirect approach cannot distinguish the heat transport by mean circulations, eddies as well as dissipation It is inappropriate in studying the relationship between the changes in the AHT and OHT, since they are not obtained independently. This is clear over the ocean north of 40°N It has a zonal extension much smaller than the Pacific, the Atlantic provides the atmosphere more water vapour in the tropics, sustaining a poleward eddy LE transport in the extratropics that is stronger than the Pacific does. This is a benchmark work for our step studies on the MHT variability. The “Appendix” lists the detailed calculations of the MHT and its components
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have