HR: 09:45h
AN: V21E-08    [Abstracts]
TI: An interdisciplinary effort to identify source parameters for models that predict eruption cloud transport and dispersion for aviation safety
AU: * Mastin, L G
EM: lgmastin@usgs.gov
AF: U.S. Geological Survey, 1300 SE Cardinal Ct., Bldg. 10, Suite 100, Vancouver, WA 98683, United States
AU: Guffanti, M
EM: guffanti@usgs.gov
AF: U.S. Geological Survey, 12201 Sunrise Valley Drive, Reston, VA 20192, United States
AU: Servranckx, R
EM: rene.servranckx@ec.gc.ca
AF: Canadian Meteorological Centre, 2121 Trans-Canada Highway, Dorval, Québec, H9P 1J3, Canada
AB: During recent decades, dozens of commercial and military jets have inadvertently flown through volcanic ash clouds downwind from eruptions. These encounters have caused up to tens of millions of dollars (U.S.) in damage to each jet; a few nearly crashed when ceramitized deposits of ingested ash caused engines to fail. In order to avoid such encounters, the International Civil Aviation Organization (ICAO) has established Volcano Ash Advisory Centers (VAACs) throughout the world to detect eruptions using satellite imagery and to notify aircraft. VAACs also predict the paths of ash clouds using atmospheric transport models, using information on volcanic plume height, the mass rate of tephra entering the atmosphere, the vertical distribution of tephra, eruption duration, and grain size distribution as input parameters. In some cases, these "source parameters" must be estimated during an ongoing eruption with few or no observational constraints. In other cases, satellite or ground-based observations obtained during an eruption constrain plume height, umbrella cloud dimensions or growth rate, and other properties, allowing VAACs to refine source parameters, re-run models, and improve predictions. ICAOs International Airways Volcano Watch Operations Group has recommended improving methods of estimating eruption source parameters as a key step towards improving predictions of volcanic ash transport and dispersion. In the spring of 2007, members of the USGS; NOAA; the Universities of Michigan, Alaska, Pisa, and South Florida; the Air Force Weather Agency; the Australian Bureau of Meteorology; and the Canadian Meteorological Centre began an interagency effort to establish constraints on eruption source parameters. This effort has involved (1) assigning default parameters to volcanoes based on magma and eruption type; (2) improving characterization of total grain-size distribution and the size distribution in distal ash clouds; (3) refining empirical and model-based relationships between plume height and mass eruption rate to better constrain the latter from observations of the former; and (4) evaluating the sensitivity of models to source parameters using selected, well-characterized eruptions. Work thus far has found that ash-cloud trajectories can be highly sensitive to atmospheric temperature, humidity, and the three-dimensional wind field in the region, as well as to plume height, eruption rate, and height distribution of tephra. The fallout of fine tephra over a period of days cannot be accurately predicted without incorporating processes such as flocculation and scavenging by rain, which are not considered in current operational ash-cloud prediction models.
DE: 7280 Volcano seismology (8419)
DE: 8419 Volcano monitoring (7280)
DE: 8485 Remote sensing of volcanoes
DE: 8488 Volcanic hazards and risks
DE: 8494 Instruments and techniques
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2007 Fall Meeting