THE IMPACT OF MOUNT-PINATUBO ON WORLD-WIDE TEMPERATURES

We monitor and model the effects on world-wide temperatures of the Jun e 1991 volcanic eruption of Mount Pinatubo in the Philippines. Global mean air temperatures were reduced, by up to 0.5 degrees C at the surf ace and 0.6 degrees C in the troposphere, for some months in mid-1992, in approximate accord with model predictions. Differences from these predictions occurred in the Northern Hemisphere winters of 1991-1992 a nd 1992-1993, as a result of atmospheric circulation changes that yiel ded continental surface warmings not fully reproduced by the model. Th e effects of the eruption were less evident by 1994. A superposed-epoc h composite for five major tropical eruptions shows significant global post-eruption cooling at the surface when the effects of the El Nino- Southern Oscillation are removed from the data. Stratospheric warmth f ollowing Pinatubo lasted until early 1993 according to Microwave Sound ing Unit data.