HR: 1340h
AN: A33A-0837    [Abstracts]
TI: Documenting PyroCb Development on High-Intensity Boreal Fires: Implications for the Arctic Atmosphere
AU: * Stocks, B J
EM: brianstocks@sympatico.ca
AF: B.J. Stocks Wildfire Investigations Ltd., 128 Chambers Avenue, Sault Ste. Marie, ON P6A4V4, Canada
AU: Fromm, M D
EM: mike.fromm@nrl.navy.mil
AF: Naval Research Laboratory, 4555 Overlook Avenue,SW, Washington, DC 20375, United States
AU: Servranckx, R
EM: rene.servranckx@ec.gc.ca
AF: Canadian Meteorological Centre, 2121 North Service Road, Dorval, QC H9P 1J3, Canada
AU: Lindsey, D
EM: lindsey@cira.colostate.edu
AF: Colorado State University, Cooperative Institute for Research in the Atmosphere, Fort Collins, CO 80523, United States
AB: The recent confirmation that smoke from high-intensity boreal forest fires can reach the Upper Troposphere/Lower Stratosphere (UTLS) through pyroconvection and be transported long distances has raised concern over the wider-scale environmental impact of boreal fire smoke. This concern is further elevated as climate change projections indicate a significant increase in the frequency and severity of boreal forest fires over the next century. Smoke in the UTLS is frequently transported to the Arctic and may have important implications for the radiative energy budget in the polar region. Soot deposition from fires may lead to enhanced melting of sea ice and glaciers, and the chemical impact of fire emissions at high altitudes is largely unknown. This knowledge gap will be addressed during the International Polar Year (IPY), as boreal fire emissions will be tracked and documented in detail through aerial, satellite and ground-based measurements, as a key component of the POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols, and Transport) and ARCTAS (Arctic Research of the Composition of the Troposphere from Aircraft and Satellites) projects to be conducted in 2008. A large fire in the Canadian Northwest Territories burned throughout the month of June 2007, in a remote region where forest fires are not actively suppressed, eventually reaching 90,000 hectares in size. This fire was monitored for blowup one week in advance; it erupted into pyroconvection on June 25, 2007. We present an analysis of this event combining satellite data with ground-based measurements to document the development and impact of this classic pyroCb event. Under extreme fire danger conditions, the fire burned close to 20,000 hectares on that day. Fire behavior was consistent with predictions using the Canadian Fire Behavior Prediction System, with the fire spreading at 2.7 km/hr, consuming 33,000 kg of fuel hourly, generating an energy release rate of ~45,000 kW/m. This constitutes a typical high-intensity boreal crown fire, common across northern Canada every summer, and often capable of producing independent pyroconvection. The June 25 blowup was monitored using OMI AI, CALIPSO, Aqua MODIS, AVHRR and GOES satellite imagery, and these measurements validated the predicted fire behavior, including the development of a convection column that rose 10-11 km and injected smoke within the UTLS. Over subsequent days this smoke spread to Arctic latitudes (70-80 degrees N).
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0320 Cloud physics and chemistry
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting