Smoke Management: Toward a Data Base to Validate PB-Piedmont - Numerical Simulation of Smoke on the Ground at Night, 1999 Environmental Conference Proceedings

Gary L. Achtemeier

USDA Forestry Sciences Laboratory

The use of fire for controlled burning to meet objectives for silviculture or for ecosystem management carries the risk of liability for smoke. Near-ground smoke can degrade air quality, reduce visibility, aggravate health problems, and create a general nuisance. At night, smoke can locally limit visibility over roadways creating serious hazards to transportation.

PB-Piedmont, a numerical model designed to simulate smoke movement at night over irregular terrain similar to that of the Piedmont of the Southeastern United States, is becoming available for use by land managers. PB-Piedmont has the potential to significantly influence management decisions and therefore must be subject to thorough validation. Decisions based on an incompletely validated model can be worse than decisions made with no model at all.

This paper summarizes a project designed to acquire the necessary validation data - remote measurements of smoke on the ground taken from the air with an intensified multi-spectral video camera capable of amplifying light up to 15,000 times. The project tested the hypothesis that smoke trapped near ground at night scatters sufficient moonlight to be observed from an aircraft. Smoke movement was recorded on Super VHS tape for two nighttime prescribed fires timed to coincide with moonlight and clear sky and near calm weather conditions. Selected images for the first night, 20 March 1997, demonstrate the complexity of near-ground smoke plumes. Image data were transferred to U.S. Geological Survey elevation maps. Small variations in elevation such as gaps in ridges are critical to smoke movement. PB-Piedmont must accurately simulate smoke movement at night on terrain scales that smoke "sees".