HR: 14:10h
AN: V12E-03    [PDF]
TI: The Critical Role of UV Satellite Data in Monitoring Volcanic Sulfur Dioxide Emissions in the Troposphere
AU: * Carn, S A
EM: scarn@umbc.edu
AF: Joint Center for Earth Systems Technology (UMBC/NASA GSFC), University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 United States
AU: Bluth, G J
EM: gbluth@mtu.edu
AF: Department of Geological Engineering and Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 United States
AU: Krueger, A J
EM: akrueger@umbc.edu
AF: Joint Center for Earth Systems Technology (UMBC/NASA GSFC), University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 United States
AB: From the Congo to the Gal\'{a}pagos Islands to Iceland, effusive eruptions of sulfur-rich basaltic magma often liberate prodigious quantities of SO$_{2}$ ($\sim$0.05-5 Tg) over days or weeks of continuous emissions. Much of this SO$_{2}$ (and hence derived sulfate aerosol) resides in the troposphere, although there is evidence that small amounts reach the stratosphere following larger eruptions. Measurements by the Total Ozone Mapping Spectrometer (TOMS) instruments since 1978 indicate that such emissions represent an important and persistent source of tropospheric SO$_{2}$, contributing $>$30% of the total volcanic SO$_{2}$ measured by TOMS to date. Continued monitoring of this SO$_{2}$ source is therefore critical to any assessment of global volcanic degassing and its potential environmental or climatic impacts. Detection of SO$_{2}$ emissions from space also acts as an important signature of eruptive activity in the absence of other observations, allowing eruptions from remote volcanoes to be monitored. The ultraviolet wavelengths used by TOMS are comparatively insensitive to the effects of atmospheric water vapor, which perturbs retrievals of SO$_{2}$ in the infrared. Since the most prolific sources of tropospheric SO$_{2}$, such as Nyamuragira (D.R. Congo) and the Gal\'{a}pagos volcanoes, are located in the tropics, TOMS has been the most suitable tool for measuring these emissions, which are also very difficult and hazardous to study using ground-based or airborne techniques. UV measurements at higher spatial and spectral resolution than TOMS will be continued in 2004 by the Ozone Monitoring Instrument (OMI) on the EOS/Aura satellite. The increased sensitivity of OMI will permit detection of smaller volcanic clouds, along with lower tropospheric and boundary layer SO$_{2}$ plumes and hence expand the capabilities of UV satellite data. Temporal resolution is the major constraint on polar-orbiting UV satellite data, with only one image per day available at low latitudes. This complicates attempts to estimate the mass of SO$_{2}$ produced by continuously-emitting effusive eruptions, and will also apply to observations of passive degassing using OMI. We are exploring several techniques to combat this, including derivation of SO$_{2}$ fluxes and loss rates from TOMS data and use of contemporaneous geostationary satellite imagery to constrain eruption timing. Several examples will be presented, including eruptions of Nyamuragira and Cerro Azul (Gal\'{a}pagos Is).
UR: http://skye.gsfc.nasa.gov
DE: 0370 Volcanic effects (8409)
DE: 8400 VOLCANOLOGY
DE: 8409 Atmospheric effects (0370)
DE: 8419 Eruption monitoring (7280)
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting