Changes in stratospheric aerosols and solar insolation due to Mt. Pinatubo eruption as observed over the western Pacific

Effects of the Mt. Pinatubo eruption on the stratospheric aerosols and the solar insolation over the Western Pacific were estimated by sunphotometer and pyranometer on board ships. The sunphotometer measurements showed that the columnar aerosol optical thickness increased by 0.3 at 500 nm over the latitude from 30°N to 30°S, while that without the influence of volcanic eruptions is less than 0.1. The aerosol optical thickness became minimum in the summer of 1992, and increased again after the summer. The shipboard pyranometer measurements showed that solar insolation decreased after the eruption by 1.4∼4.1% compared with that before the eruption. This value is larger than that calculated with radiative transfer code, based on the aerosol model estimated from the sunphotometry.