Comparing stratospheric aerosols from El Chichón and Mount Pinatubo using AVHRR data

Abstract

One of the key factors in assessing the climatic impact of the Mount Pinatubo eruption of June 15, 1991, is the relative size of this eruption as it compares with other eruptions. As a first approximation, the climatic changes observed after those earlier eruptions can be used to predict the changes to be expected from the more recent eruption. Ideally this intercomparison should be done with a common measurement system. Data from the advanced very high resolution radiometer (AVHRR) onboard the NOAA polar orbiting environmental satellite can be used to compare the optical properties of the aerosol layer produced by the two most recent major volcanic eruptions, El Chichón, early‐April 1982, and Mount Pinatubo, mid‐June 1991. In this paper, we use the error introduced into the multi‐channel sea surface temperature (MCSST) fields by the volcanically‐produced stratospheric aerosol layer to make a relative comparison of the size of the two eruptions. We also use aerosol optical thickness (AOT) estimates from the visible reflectance channel of the AVHRR to verify that the MCSST errors are indeed related to aerosol particle concentration in the stratosphere. During the first three months following both eruptions, these comparisons reveal that Mount Pinatubo introduced slightly less than twice (1.6 to 1.9) the amount of aerosol into the stratosphere as El Chichón.