HR: 17:50h
AN: V44A-07    [Abstracts]
TI: A Comparison of Ultraviolet and Thermal Infrared SO₂ Retrievals of a Near-Pure SO₂ Plume
AU: * Kearney, C
EM: c.kearney@bristol.ac.uk
AF: Department of Earth Sciences, University of Bristol, Wills Memorial Queens Rd, Bristol, United Kingdom
AU: Watson, I M
EM: matt.watson@bristol.ac.uk
AF: Department of Earth Sciences, University of Bristol, Wills Memorial Queens Rd, Bristol, United Kingdom
AU: Watson, I M
EM: matt.watson@bristol.ac.uk
AF: GMES, MTU, 1400 Townsend Drive, Houghton, MI , United States
AU: Bluth, G J
EM: gbluth@mtu.edu
AF: GMES, MTU, 1400 Townsend Drive, Houghton, MI , United States
AU: Carn, S
EM: scarn@umbc.edu
AF: JCET, UMBC, 1000 Hilltop Circle, Baltimore, MD , United States
AU: Realmuto, V J
EM: Vincent.J.Realmuto@jpl.nasa.gov
AF: JPL, 4800 Oak Grove Drive, Pasadena, CA , United States
AB: Volcanic plumes are composed of various amounts of silicate ash, ice, SO₄^2-, SO₂ and other gases, all of which vary in abundance and have specific transmission signatures within the TIR. Overlaps in their absorption and scattering features, specifically silicate ash, may lead to overestimates of SO₂ unless corrected. The 8.6 μ m SO₂ algorithm was developed for passive degassing plumes with little to no silicate ash. Prior to an ash-correction, the capabilities of the 8.6 μ m SO₂ algorithm for large SO₂ plumes need to be established by comparing it to a well documented technique. In this study, we compare near-coincidental data from the UV Earth Probe Total Ozone Mapping Spectrometer (EP TOMS) and TIR MODerate resolution Imaging Spectroradiometer (MODIS) of a near-pure SO₂ plume from the Al-Mishraq State sulfur plant fire on 29 June 2003 and provide an ash-free end member for future SO₂ ash-correction studies. On 24 June 2003 a fire started at the Al-Mishraq State sulfur plant near Mosul, Iraq and lasted for approximately one month. On 29 June, EP TOMS and MODIS images were acquired at 0752 and 1010 UTC respectively. A previous EP TOMS retrieval estimated the plume contained 102 kt SO₂ compared to the 138 kt detected by MODIS based on the 8.6 μ m retrieval. The resampling of the MODIS-based retrieval to the coarser spatial resolution of EP TOMS results in a decrease in the MODIS total mass by 9%. Overall, the agreement between the retrieval techniques on a pixel scale is minimal and ranges between 10% to greater than 90% with no discernable spatial pattern. The low agreement between the two retrievals is likely the result of differences in spatial resolution of the EP TOMS and MODIS measurements, sensitivity of the SO₂ estimates to atmospheric absorption and scattering and solar illumination, variations in plume height with distance from the fire and time of data acquisition.
DE: 8419 Volcano monitoring (7280)
DE: 8430 Volcanic gases
DE: 8485 Remote sensing of volcanoes
SC: Volcanology, Geochemistry, and Petrology [V]
MN: 2007 Joint Assembly