STRATOSPHERIC TEMPERATURE-CHANGES AFTER THE PINATUBO ERUPTION

The stratosphere warmed due to the absorption of radiation by the new aerosols produced from the June 1991 eruptions of the volcano Pinatubo (15.1 N, 120.4 E) in the Philippines. One year of northern hemisphere stratospheric temperatures at 30 and 50 mb are compared, respectively with 20-yr (1965-1984) and 26-yr (1965-1989) monthly means. Significant temperature increases for latitudes between the equator and approximately 30-degrees-N are observed after the eruptions from July through December 1991, but also from March through June 1992. During these months, temperatures rose between two and three standard deviations above a long-term mean, while temperatures should stay one or two standard deviations below the long-term average with respect to the phase of the QBO (Quasi-Biennial Oscillation). Only during January and February 1992 did the tropical stratospheric temperatures drop to values near the long-term average-however, this cooling is connected with the high-latitude stratospheric warming.