Radiative forcing of the stratosphere by SO2 gas, silicate ash, and H2SO4 aerosols shortly after the 1982 eruptions of El Chichon

Abstract

The 1982 eruptions of the El Chichon volcano injected large quantities of sulfur dioxide gas and silicate ash into the stratosphere. Several studies have shown that the long-lived sulfuric acid aerosols derived from these volcanic effluents produced measurable changes in the radiative heating rates and the global circulation. The short-lived but more strongly absorbing sulfur dioxide and ash clouds have received much less attention. The authors therefore used an atmospheric radiative transfer model and observations collected by satellites, aircraft, and ground-based observers to estimate the amplitudes of the stratospheric radiative heating rate perturbations produced by each of these components during the first few weeks after the El Chichon eruption. The results suggest that the radiative forcing by the ash and the sulfur dioxide gas should be included in more comprehensive models of the plume evolution. They also suggest that particle size distributions inferred from ash fallout rates could be wrong if the upwelling associated with this radiative heating is not considered. -from Authors