Circulation responses to snow albedo feedback in climate change

Abstract

Climate change is expected to cause a reduction in the spatial extent of snow cover on land. Recent work suggests that this will exert a local influence on the atmosphere and the hydrology of snow-margin areas through the snowalbedo feedback (SAF) mechanism. A significant fraction of variability among IPCC AR4 general circulation model (GCM) predictions for future summertime climate change over these areas is related to the models' representation of springtime SAF. In this study, we demonstrate a nonlocal influence of SAF on the summertime circulation in the extratropical Northern Hemisphere. Increased land surface warming in models with stronger SAF is associated with large-scale sea-level pressure anomalies over the northern oceans and a poleward intensified subtropical jet. We find that up to 25-30% and, on average, 5-10% of the intermodel spread in projections of the circulation response to climate change is linearly related to SAF strength. Copyright 2009 by the American Geophysical Union.