Pinatubo eruption effects on solar radiation at Almeria (36.83°N, 2.41°W)

Volcanic eruptions are responsible for the injection of SO2 into the stratosphere, and the subsequent production of stratospheric aerosol layer. In June 1991, Mount Pinatubo injected approximately 20 millions metric tons of SO2 into the stratosphere. The volcanic aerosol circled the earth in 21 days, covering an area of about 42% of the earth's surface. A few weeks after the Mount Pinatubo eruption, an abrupt change was detected on the solar radiation flux measurements registered in our radiometric station, located at a sea shore location (36.83°N, 2.41°W, 10 m a.s.l). The Mann-Kendall rank statistic confirms this abrupt change with a high confidence level. We have evaluated the quantitative effect over different terms of solar radiation flux. There is a significant reduction in direct solar radiation of about 10%, while global solar irradiance shows a reduction of about 4%, due to the compensation effect of increasing diffuse irradiance. As in similar analyses carried out in mid-latitude locations, we found a decay of the aerosol effects during the 1992 summer and an enhancement in late 1992.This work was supported by Dirección General de Ciencia y Tecnología fro the Education and Research Ministry of Spain through the project n. PB91-0711