Elemental carbon in the atmosphere: Cycle and lifetime

Abstract

Particulate elemental carbon is found in the atmosphere in both urban and remote regions and is often responsible for much of the absorption of solar radiation by atmospheric aerosols. Its atmospheric lifetime is controlled by four factors: the initial size distribution, the concentration of ambient particles, the frequency and duration of precipitation, and the efficiencies of removal mechanisms. A model of the atmospheric cycle of particulate elemental carbon which includes these factors has been used to estimate the range of atmospheric lifetimes expected under various conditions. Calculated lifetimes range from under 40 hours in rainy climates to well over 1 week in clean, dry regions.