The Influence of the Internal Structure of Particles on Optical Properties of Stratospheric Aerosol, Radiative Forcing, and Global Annual Average Temperature

Abstract

One- and two-phase aerosol particles of stratospheric aerosol are considered. The first ones include homogeneous particles that are liquid drops of a 75% sulfuric acid solution; the second ones, droplets of sulfuric acid with inorganic admixtures dissolved in it. Optical properties of two-phase particles are considered in the approximation of two-layer, enlightened, and quasi-homogeneous spheres. The influence of the internal structure of aerosol particles and parameters of their size distribution on the instantaneous radiative forcing and radiation temperature of the underlying surface for an aerosol layer with an optical depth equal to 0.05 in the visible range is studied. Particles constituting the layer can lead both to the greenhouse and to the antigreenhouse effect. It is shown that the antigreenhouse effect (on the order of 4–8 W/m²) is created by ensembles of two-layer particles: (i) with narrow size distributions and (ii) with wider distributions and average radii not exceeding 0.25–0.40 μm; the greenhouse effect (on the order of 2–6 W/m²) arises at larger average radii and wide distributions.