A New Long-Term Record of Volcanic SO2 Generated From HIRS/2 Satellite Data

Associate Professor Gregg Bluth (GMES) received a new grant of $194,381 + 18,723 cost shar in October 2003 from the National Aeronautics and Space Administration for his project, "A New Long Term Record on Volcanic SO2 Generated from HIRS/2 Satellite Data."

The project supports a PhD student for 3 years, and an extended (several months) visit from Dr. Fred Prata as a Visiting Scholar. Dr. Prata is a distinguished scientist at Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO). Dr. Prata is a pioneer in the use of satellite instruments to detect and analyze volcanic clouds.


Volcanic eruptions that inject ash, sulfur dioxide and other gases into the atmosphere occur on average more than 50 times per year somewhere on Earth. Volcanic eruptions produce a variety of hazards, ranging from short term aircraft hazards, to longer term effects from climate perturbation. However, many important details regarding the magnitude and frequency of sulfur emissions, and chemical and physical processes within volcanic clouds remain unclear. Some key questions may be largely solved if more data were available: issues of excess sulfur from volcanic outgassing; the separation of ash-rich and gas-rich portions of the clouds; the conversion of H2S to SO2 in the atmosphere; and the removal rates of SO2 in the atmosphere.

The most practical means of monitoring large volcanic emissions of sulfur is through satellite remote sensing, and since 1979 the majority of SO2 measurements have been through NASA's Total Ozone Mapping Spectrometer (TOMS). These measurements rely on reflected ultraviolet radiation and consequently have poor diurnal sampling and low spatial resolution. Two new methods have been proposed which employ infrared channels of the Moderate Resolution Infrared Spectroradiometer (MODIS) sensor, each of which have the ability to quantitatively retrieve SO2 masses. Our previous analyses of MODIS 7.3 micron data for eruptions at Hekla (2000) and Cleveland (2001) volcanoes have demonstrated that it is possible to estimate upper tropospheric SO2 layer abundance using the anti-symmetric stretch of the SO2 molecule.

This proposal focuses on the High Resolution Infrared Radiation Sounder/2 (HIRS/2) sensor, which also includes a 7.3 micron channel, on board the NOAA polar orbiting satellites since 1978. We propose to analyze HIRS radiances within this channel to map and quantify volcanic SO2 emissions, and construct a long term dataset complementary to TOMS but with potentially improved spatial and temporal resolutions. This additional coverage will greatly enhance our ability to study the dozens of observable eruptions in the past 20 years, as well as provide an important link to data from new sensors. Specifically, we propose to:

(1) acquire and process datasets for volcanic eruptions from HIRS/2, to match with the TOMS and MODIS data we have already archived; (2) develop and refine our techniques for sulfur dioxide retrievals with the 7.3 micron channel using several key eruptions, under varying environmental and plume conditions; and (3) create a long-term volcanic SO2 database from HIRS/2, with MODIS overlap and TOMS data to compare and cross-validate the results.

This proposal responds to the NASA NRA in the following ways: to the Earth Science Enterprise goal of studying the changing Earth, it supports the creation of an independent long term database of global volcanic emissions; by developing this new volcanic record it complements and enhances the usefulness of the existing (TOMS) database funded by the SENH program; by generating more detailed erupted sulfur budgets it will foster many science applications for understanding magmatic processes and cloud fates; and the HIRS/2 methodology provides an additional means of monitoring and understanding global volcanic activity, and consequently, volcanic hazards.

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Department of Geological & Mining Engineering & Sciences
Michigan Technological University
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