Radiative Response to Poleward Storm Cloud Anomalies from ISCCP Retrievals

Abstract:

Midlatitude storm clouds have generally shifted poleward in the last 30 years. Resultant changes in cloud radiative effects (CREs) may feed back onto the climate system. Observations of how clouds, their radiative effects, and large-scale dynamics mutually covary on interannual time scales may help gain insight into the nature and mechanisms of that feedback. Using ISCCP cloud and radiation retrievals, we find that in the Southern Hemisphere, poleward shifts of high clouds yield a negative SW CRE. This radiative effect is attributed to increased cloud albedo at the poleward side of the storm track. In the Northern Hemisphere, poleward shifts of high cloud produce a positive SW CRE, attributed to cloud amount decreases at the equatoward side of the oceanic storm tracks. Hemispheric differences in CRE are associated with hemispheric differences in the underlying climatological cloud field.