THE LIFE-CYCLE OF STRATOSPHERIC AEROSOL-PARTICLES

This paper describes the life cycle of the background (nonvolcanic) st ratospheric sulfate aerosol. The authors assume the particles are form ed by homogeneous nucleation near the tropical tropopause and are carr ied aloft into the stratosphere. The particles remain in the Tropics f or most of their life, and during this period of time a size distribut ion is developed by a combination of coagulation, growth by heteromole cular condensation, and mixing with air parcels containing preexisting sulfate particles. The aerosol eventually migrates to higher latitude s and descends across isentropic surfaces to the lower stratosphere. T he aerosol is removed from the stratosphere primarily at mid- and high latitudes through various processes, mainly by isentropic transport a cross the tropopause from the stratosphere into the troposphere.