Parametric study of the effects of arctic soot on solar radiation

Abstract

A numerical radiative transfer model has been used to simulate the possible effects of carbonaceous aerosol on the Arctic climate. Because of uncertainties in aerosol properties in the Arctic, the sensitivity of modeled components of the solar radiation budget to ranges in aerosol parameters was determined. It was found that differences in assumed aerosol absorption, concentration and vertical distribution were more important than differences in aerosol size distribution. Aerosol absorption was parameterized through the index of refraction assuming an aerosol composed of soot and sulfates. Modeling the radiative effects of the springtime phenomena of Arctic soot leads to an increase in average heating rates of 0.01–0.06 K day −1 in the lowest 1–5 km of the atmosphere under cloud free conditions. The higher value is similar to estimated heating rates at northern latitudes that would result from doubling atmospheric CO 2 concentrations. The hemispheric average temperature change due to the Arctic soot is, however, estimated to be almost two orders of magnitude less than for doubling of CO 2 concentrations.