Space-Borne Estimation of Volcanic Sulfate Aerosol Lifetime

Aerosols are an important component of the climate system affecting visibility, clouds, and climate. They are also transported over short and long distances with consequences for continental-scale nutrient availability. Processes that remove aerosols from the atmosphere are difficult to evaluate with observations in isolation from aerosol sources. As a result, a quantitative assessment of uncertainties in our understanding of aerosols is limited and narrowing of those uncertainties is difficult to demonstrate. In this study, we use satellite observations of sulfur dioxide (SO2) and aerosols downwind of the Kīlauea volcano during May–September 2008. We derive the SO2 emission rate, the loss rate of SO2 that is indicative of the production rate of sulfate aerosols, and the subsequent removal rate of the formed sulfate. The result is the first determination of volcanic sulfate aerosol lifetime, 40–64 h, directly from satellite observations. The derived sulfate lifetime is significantly lower than the global average (3– 5.5 days) and reflects the rapid wet scavenging of this plume.