Effect of the El Chichón Volcanic Cloud on the Surface Radiative Regime in Central Alaska

Abstract

Five years of detailed radiation measurements were taken at Fairbanks, Alaska. These data showed that the El Chichón volcanic cloud had a major impact on the surface radiative regime, the maximum of which was observed in winter 1982/83, about 9 months after the eruption. The direct beam of the solar radiation was reduced by as much as 38% (3-month mean value), the ratio of diffuse over global radiation was increased by 91%, and the global radiation was reduced by about 5%. These values show that the volcanic cloud was a strong forward scatterer, while relatively little energy was absorbed or reflected back to space. Further, the aerosol optical depth and Linke's turbidity factor were calculated, and both displayed substantial increases. Effects of the stratospheric dust cloud were seen all through 1983 and the spring of 1984. In summer 1984, however, the radiative values were back to ?normal.? Our values were compared to other observations at lower latitudes and, in general, a good agreement was found.