HR: 0830h
AN: A21D-1011    [PDF]
TI: The Role of TOMS in Understanding the Fates of Volcanic Emissions
AU: * Bluth, G J
EM: gbluth@mtu.edu
AF: Geology Dept, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 United States
AU: Rose, W I
EM: raman@mtu.edu
AF: Geology Dept, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 United States
AU: Guo, S
EM: sguo@mtu.edu
AF: Geology Dept, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931 United States
AU: Carn, S A
EM: scarn@umbc.edu
AF: JCET, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 United States
AB: The Total Ozone Mapping Spectrometer (TOMS) has observed over 100 eruption s during the past 25 years, from both explosive and effusive sources. The four TOMS instruments (Nimbus-7, Meteor, ADEOS, and Earth Probe) have gen erated an unprecedented archive of eruption data and allowed us to look at processes, in addition to describing individual events. The TOMS sensors are less affected by atmospheric water vapor and optical thickness than i nfrared techniques, and thus are able to return information on the cloud f rom it's early, most concentrated form, to dilute cloudmasses several days later. From the many observations and advances generated from TOMS data, here we document those which pertain to the first few days following emis sion into the atmosphere. Following discrete eruption events, we have observed that the mass of retr ieved SO2 often increases for 1-2 days, independent of any volcanic contri bution. Combining TOMS with other sensor data suggests that significant S O2 is sequestered by ice in the rising plume. Ablation of the ice slowly re-releases SO2, which results in the apparent increase. After 2-3 days, this process appears to be largely complete, and SO2 removal then follows an exponential decay rate. TOMS-derived removal rates of SO2 have ranged from approximately 25 days (e-folding time) for Pinatubo-sized eruptions, to less than one day for smaller or tropospheric eruptions. Within the sa me eruption this rate may vary, as SO2 removal is strongly affected by ads orption onto co-existing ash and ice particles. The removal processes can also be linked to an eruption height threshold, separating eruptions whic h are emplaced above the tropopause and produce potentially long-lasting a tmospheric impacts from those which are rapidly removed from the atmospher e. We have also observed that many eruptions produce a vertical separatio n of gas-rich and ash-rich phases. However, other events have produced no separation, suggesting that the separation may be linked to the eruption dynamics or an early, gas-enriched pulse rather than a post-eruption, grav itational process.
DE: 8409 Atmospheric effects (0370)
DE: 8414 Eruption mechanisms
DE: 8419 Eruption monitoring (7280)
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting