The mutual interaction between continental-scale ice sheets and atmospheric stationary waves

The great continental ice sheets of the Pleistocene represented significant obstacles to the Northern Hemisphere midlatitude westerlies. They must the refore have forced large changes in the atmospheric circulation, and conseq uently also in the patterns of accumulation and melting over the ice sheets themselves. A simplified three-dimensional coupled ice sheet-stationary wa ve model is developed in order to understand the ice sheet's response to th e circulation changes that it induces. Consistent with ice age climate simu lations, the ice sheet topography induces an anticyclonic circulation over the ice sheet, causing a slight warming over the western slopes and a stron ger cooling over the remainder. The modeled feedbacks significantly affect the ice sheet configuration, with the most important influences being the p atterns of summer temperature, and the topographically induced precipitatio n field. The time evolution of the ice sheet is also changed by the atmosph eric feedbacks and the results suggest the possibility of multiple equilibr ium solutions.