Coupling between climate feedbacks and large-scale circulation

Abstract:

Recent advances in analysis techniques have demonstrated how regional climate feedbacks can be used to decompose the spatial pattern of warming into components associated with feedbacks (i.e., water vapor, lapse rate, sea ice, clouds), atmosphere and ocean heat transport, and the radiative forcing due to increases in greenhouse gas concentrations. Since feedbacks represent the energetics of a dynamic climate system, local imbalances will affect meridional heat fluxes, which in the tropics are modulated by the structure and intensity of the Hadley circulation. A goal of this study is to understand the relationship between the spatial pattern of feedbacks and the large-scale circulations that both cause and respond to them. In a subset of CMIP5 models and for particular seasons, the tropical circulation increases in intensity in a warmer world, in contrast to the anticipated weakening. The feedback pattern shows striking differences depending on whether the circulation strengthens or weakens. By analyzing the coupled feedback-circulation system, the results offer insights into understanding both climate sensitivity and the response of the hydrological cycle under global warming.