Dynamics of deserts and drought in the Sahel

摘要: It is suggested that the high albedo of a desert contributes to net radiative heat loss relative its surroundings and resultant horizontal temperature gradients induce frictionally controlled circulation which imports aloft maintains thermal equilibrium through sinking motion adiabatic compression. In subtropics this superimposed on descending branch mean Hadley but more intense. Thus feeds back upon itself in an important manner. If one takes into account biosphere, feedback mechanism could conceivably lead instabilities or metastabilities border regions. argued reduction vegetation, with consequent increase albedo, Sahel region at southern margin Sahara would cause motion, additional drying, therefore perpetuate arid conditions. Numerical integrations general model NASA's Goddard Institute for Space Studies appear substantiate hypothesis. Increasing north ITCZ from 14% 35% had effect shifting several degrees latitude south decreasing rainfall about 40% during rainy season.