HR: 0830h
AN: V11C-0515    [PDF]
TI: Coupling a Lagrangian Dispersion Model and Remote Sensing Data for Quantification of Volcanic Ash Transport and Deposition
AU: * Peterson, R A
EM: ffrap1@aurora.ua.fedu
AF: Geophysical Institute University of Alaska, Fairbanks, 903 Koyukuk Dr. PO Box 757320, Fairbanks, AK 99775 United States
AU: Dean, K
EM: ken.dean@gi.alaska.edu
AF: Geophysical Institute University of Alaska, Fairbanks, 903 Koyukuk Dr. PO Box 757320, Fairbanks, AK 99775 United States
AB: Use of remote sensing techniques, particularly the band 4 (10.3-11.3 $\mu$m) minus band 5 (11.5-12.5 $\mu$m) "split-window", is the predominant method for monitoring the long-term movement of airborne volcanic emissions such as ash, water vapor, and other gases. The split-window technique works well for moderately concentrated clouds, and there are methods based on radiative transfer that may provide quantitative information about total mass and particle size (Wen and Rose, 1994). However atmospheric dispersion, sedimentation and wet deposition eventually lead to the loss of discernible signals in the split window. Fortunately, numerical dispersion models do not have a low-concentration limit and are capable of longer term tracking. Model simulations also provide relative concentration changes with time. Only after post-event analysis is it possible to obtain quantitative concentration information as a function of space and time. A new technique combining remote sensing data with model simulations which may help provide near real-time information of cloud concentrations has been developed. This technique uses information gathered from several relatively recent eruptions for which total eruption volume and fallout distributions have been determined. Using the fallout distribution measurements and model simulations, the deposition rates at a function of location and time can be calculated. Combining this information with net eruption volume, ash cloud concentrations can be quantified from the model simulations and further correlated with the remote sensing data. The low-concentration limit of the split-window technique can then be obtained. Using this information, cloud concentrations can be obtained from model simulations for cases when concentration levels are too low or remote sensing data is simply not available. Although the required data for this technique is somewhat scare, initial results are encouraging and will be discussed. The results from this technique will be compared with those based on radiative transfer models. Also, some of the new numerical modeling techniques implemented to provide more precise information about deposition rates will be presented.
DE: 0370 Volcanic effects (8409)
DE: 3337 Numerical modeling and data assimilation
DE: 8404 Ash deposits
DE: 8419 Eruption monitoring (7280)
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting