Relative Roles Of Dynamic And Thermodynamic Processes In Causing Global Mean SST Trends During The Past 100 Years

Global mean surface temperature(GMST)during 1910-2012 experienced four alternated rapid warming and warming hiatus phases.Such a temporal variation is primarily determined by global mean sea surface temperature(SST)component.The relative roles of ocean dynamic and thermodynamic processes in causing such global mean SST variations are investigated,using two methods.The first method is ocean mixed layer heat budget analysis.The budget diagnosis result shows that the thermodynamic processes dominate in the rapid warming phases,while the ocean dynamics dominate during the hiatus phases.The second method relies on the diagnosis of a simple equilibrium state model.This model captures well the horizontal distribution of SST difference between two warmer and cooler equilibrium states during either the rapid warming or hiatus phases.It is found that the SST difference during the rapid warming phases is primarily controlled by the increase of downward longwave radiation as both column integrated water vapor and CO2 increase during the phases.During the hiatus phases,the water vapor induced greenhouse effect offsets the CO2 effect,and the SST cooling tendency is primarily determined by the ocean dynamics over the Southern Ocean and tropical Pacific.The SST pattern associated with the Interdecadal Pacific Oscillation(IPO)might be responsible for the remote and local ocean dynamic responses through induced wind change.