Solar radiation anomalies caused by the El Chichon volcanic cloud: Measurements and model comparisons

Abstract

AbstractThe eruption of the volcano El Chichon (17.33°N 93.20°W) in southern Mexico over the period 28 March to 4 April 1982 introduced massive amounts of sulphur dioxide into the stratosphere. The resulting sulphuric acid particulate cloud has affected appreciably the received solar radiation at the surface; measurements made at several locations in the continental United States and Hawaii have indicated that the directly transmitted solar radiation was depleted by up to 25%; diffuse sky radiation was enhanced by factors of up to 3; and global radiation was lowered by up to 5%. These reported anomalies are compared with the results of radiative transfer computations in a realistic model of a cloud‐free, vertically inhomogeneous, plane‐parallel turbid atmosphere. The model yields the observed trends in the direct, diffusely transmitted and global solar radiation under normal and anomalous conditions.