The Effect of Variable Surface Albedo on the Atmospheric Circulation in Desert Regions

Abstract

A desert circulation model, which includes a vertically parameterized boundary layer, is used to investigate flow in the northern Negev, Israel. An equation is derived relating the vertical velocity at the top of the boundary layer to net radiative heating, convective heating and friction at the ground. Since the net radiative heating is a function of the surface albedo, it is possible to calculate the vertical velocity at the top of the boundary layer as a function of surface albedo, all other things being equal. Calculations using data for the northern Negev desert on 21 June and 21 December, 1974, show sinking motion for high albedos, with a gradual decrease and change toward rising motion for lower albedos. The implication of this result is that a lowering of the surface albedo in a desert region could lead to increased vertical velocity and possibly to increased rainfall.