Volcanic Effects in the Upper Atmosphere
Abstract
Large volcanic eruptions have a well observed impact on the lower atmosphere and climate. In the past forty years, two eruptions, El Chichon in 1982 and Pinatubo in 1991, released significant amounts of aerosols. The effects of these two volcanos have been studied in the stratosphere (10km - 50km), but not in the upper atmosphere. This project attempted to find traces of the two eruptions at altitudes of 250km to 500km through temperature trend studies of long-term observations of the upper atmosphere. An ion temperature trend model was refined and then used to subtract solar, geomagnetic, annual, semi-annual, and correlated effects from Millstone Hill Incoherent Scatter Radar (ISR) data, which span more than 3 solar cycles starting in 1970s. After subtraction, the ion temperature residuals were studied around the years 1982 and 1991 for anomalous dips. This modeling technique was then applied to the Sondrestrom (1990-) and St. Santin (1966-1987) ISR sites to validate temperature trends and volcanic effects at different locations., Effects of the 1982 El Chichon eruption appeared to exist with a visible ion temperature drop in Millstone Hill and St. Santin measurements. The 1991 Pinatubo eruption was not immediately present until up to 2 years later over Millstone Hill and Sondrestrom, but this result contains large uncertainty due to solar and magnetic activities. Further study is needed to understand the theoretical effects of volcanic activity at those altitudes and gauge the significance of the observed temperature residuals.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMSA51A2038C
- Keywords:
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- 1610 GLOBAL CHANGE Atmosphere;
- 8409 VOLCANOLOGY Atmospheric effects;
- 2400 IONOSPHERE