THE RADIATION BUDGET OF THE STRATOSPHERE

Abstract

The radiation budget of the northern-hemisphere stratosphere, as a function of the mean thermal structure and composition of the stratosphere, is determined for the months of January, April, July, and October. Emission of infrared radiation by carbon dioxide, water vapor, and ozone is calculated by means of a simple numerical method derived from the differential equations of radiative transfer. Absorption of solar radiation by ozone is taken from published results; absorption of solar energy by water vapor is computed with the aid of an empirical formula. It is found that, in general, radiative equilibrium is not obtained at any latitude. Low latitudes constitute a heat source and high latitudes a heat sink in the stratospheric energy budget. It is shown that carbon dioxide is more important than water vapor in cooling the stratosphere and that infrared transfer in the 9.6µ ozone band normally results in a convergence of energy in the stratosphere. Some features of the stratospheric temperature distribution and circulation pattern are inferred from the computed radiation budget and its seasonal variations.