Abstract
The global distribution of the Pinatubo aerosol in the stratosphere is constructed for optical thickness at 1μm by combining satellite data and lidar data for one year, from June 1991 to June 1992, following the eruption. The distribution, averaged for every two months, is composed of the data from Stratospheric Aerosol and Gas Experiment II between about 70°N and 70°S and the data from other satellites and lidar measurements at high latitudes and in the tropical lower stratosphere. Radiative heating rate due to the Pinatubo aerosol is calculated combining this distribution at 1μm with the radiatioe properties of observed sulfate aerosols.
Sulfate aerosol does not absorb substantially but only scatters solar radiation, thereby producing very weak warming of about 0.02Kday-1 in the upper stratosphere due to ozone absorption of aerosol-reflected radiation. Terrestrial radiation brings a warming of about 0.1Kday-1 to the aerosol layer in low and middle latitudes, and very weak cooling at high latitudes. The net effect is, then, brought about by terrestrial radiation.
Stratospheric temperature change is also calculated using a fixed dynamical heating model. In low latitudes, the middle stratospheric temperature rises rapidly by about 2K during the first 40 days, following which the warming slows down and its axis moves northward to about 15°N. The largest warming of 3K appears in the axis latitude after 10 months and the second largest warming of 2.9K at 5°S after 12 months.
