Elemental carbon in the atmosphere: cycle and lifetime

Abstract

Particulate elemental carbon is found in the atmosphere in both urban and remote regions and isoften responsible for much of the absorption of solar radiation by atmospheric aerosols. Itsatmospheric lifetime is controlled by four factors: the initial size distribution, the concentrationof ambient particles, the frequency and duration of precipitation, and the efficiencies of removalmechanisms. A model of the atmospheric cycle of particulate elemental carbon which includesthese factors has been used to estimate the range of atmospheric lifetimes expected under variousconditions. Calculated lifetimes range from under 40 hours in rainy climates to well over 1 weekin clean, dry regions.