HR: 14:20h
AN: A43D-03    [Abstracts]
TI: The 1982 El Chichon Eruption: The Birth of Volcanic Sulfur Dioxide Monitoring From Space
AU: * Krueger, A J
EM: akrueger@umbc.edu
AF: JCET/UMBC, 1000 Hilltop Circle, Baltimore, MD 21250, United States
AU: Krotkov, N
EM: krotkov@chescat.gsfc.nasa.gov
AF: GEST/UMBC, 1000 Hilltop Circle, Baltimore, MD 21250, United States
AU: Carn, S
EM: scarn@umbc.edu
AF: JCET/UMBC, 1000 Hilltop Circle, Baltimore, MD 21250, United States
AB: The 1982 eruption of El Chichon inspired a new technique for monitoring volcanic clouds using satellites. Data from the Total Ozone Mapping Spectrometer (TOMS) instrument on the Nimbus-7 satellite were used to identify sulfur dioxide in the volcanic cloud and to map the extent of the cloud. For the first time the sulfur dioxide mass in even the largest explosive eruption plumes could be determined. The sizes of eruptions could be measured over 4 orders of magnitude. The position and area of volcanic clouds was determined as the clouds drifted globally with the winds over weeks of time after the eruption. The loss of sulfur dioxide by conversion to sulfate was observed. In addition, volcanic ash clouds were mapped using the TOMS aerosol data. Using sulfur dioxide as a tracer, magmatic eruptions could be discriminated from steam-driven, phreatic eruptions. The data from the El Chichon eruption are reanalyzed using the latest version of the TOMS instrument calibration (V8). They show the shearing of the eruption clouds in three weeks into a globe-circling band while still anchored over Mexico. The measured sulfur dioxide mass in the initial March 28 eruption was 1.6 Tg; a second eruption on April 3 produced 0.3 Tg more, and the climactic April 4 eruption added 5.6 Tg, for a cumulative total of 7.5 Tg, in substantial agreement with estimates from prior TOMS data versions. The TOMS derived sulfur dioxide mass is an order of magnitude higher than the petrologic estimate that is based on the lost sulfur in glass phases of the tephra. This "excess sulfur" brought rise to a reevaluation of the pre-eruptive magmatic processes in volcanoes and a better understanding of eruptions.
DE: 0370 Volcanic effects (8409)
DE: 8408 Volcano/climate interactions (1605, 3309)
DE: 8428 Explosive volcanism
DE: 8485 Remote sensing of volcanoes
DE: 8494 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly