On the link between Hadley circulation changes and radiative feedback processes

Abstract

Previous studies have demonstrated that meridional displacements of precipitation in the tropics and changes in the Hadley circulation accompany interhemispherically asymmetric surface temperature changes. In this study, an attempt is made to provide a different perspective by linking this dynamical response to radiative feedback processes. An idealized experiment is conducted in which solar irradiance is reduced in the northern hemisphere extratropics. Radiative feedback analysis indicates that the interhemispheric asymmetry of water vapor and lapse rate feedbacks play a key role in maintaining the simulated cross-equatorial heat transport and Hadley circulation change. On the other hand, cloud feedback plays a relatively minor role because of a large cancellation between shortwave and longwave components. While the experiment is idealized, the implications of the results apply widely from paleoclimate to future climate changes. Copyright 2009 by the American Geophysical Union.