Document


Title

Smoke-column observations from two forest fires using Doppler lidar and Doppler radar
Document Type: Journal Article
Author(s): R. M. Banta; L. D. Olivier; E. T. Holloway; R. A. Kropfli; B. W. Bartram; R. E. Cupp; M. J. Post
Publication Year: 1992

Cataloging Information

Keyword(s):
  • ash
  • Canada
  • Colorado
  • convection
  • distribution
  • fire management
  • ignition
  • mountainous terrain
  • needles
  • Ontario
  • remote sensing
  • smoke behavior
  • vortices
  • wildfires
  • wind
Region(s):
Record Maintained By:
Record Last Modified: December 6, 2018
FRAMES Record Number: 35722
Tall Timbers Record Number: 10048
TTRS Location Status: In-file
TTRS Call Number: Fire File
TTRS Abstract Status: Fair use, Okay, Reproduced by permission

This bibliographic record was either created or modified by the Tall Timbers Research Station and Land Conservancy and is provided without charge to promote research and education in Fire Ecology. The E.V. Komarek Fire Ecology Database is the intellectual property of the Tall Timbers Research Station and Land Conservancy.

Description

To demonstrate the usefulness of active remote-sensing systems in observing forest fire behavior, we studied two fires, one using a 3.2-cm-wavelength Doppler radar, and one more extensively, using Doppler lidar. both instrumentS observed the kinematics of the convection column, induding the presence of two different types of rotation in the columns, and monitored the behavior of the smoke plume. The first fire, a forest fire that burned out of control, was observed by the Doppler radar during late-morning and afternoon hours. Strong horizontal ambient winds produced a bent-over convection column, which the radar observed to have strong horizontal flow at its edges and weaker flow along the centerline of the plume This velocity pattern implies that the column consisted of a pair of counterrotating horizontal vortices (rolls) with rising motion along the centerline and sinking along the edges. The radar tracked the smoke plume for over 30 km. It also provided circular depolarization ratio measurements, which gave infommaion that the scattering particles were mostly flat or needle shaped as viewed by the radar, perhaps pine needles or possiblyflat ash platelets being viewed edge on. The second fire, observed over a 5-h period Doppler lidar, was- a prescribed forest fire ignited in the afternoon. During thc first hour of the fire the lidar observed many kinematic quantities of the convection column, including flow convergence and anticyclonic whole-column rotation of the nearly vertical column, with a vorticity of approximatdy 10 -2 s-1 and an estimated peak vertical velocity w of 15m s-1 . After the first hour ambient meteorological conditions changed, the whole-column rotation ceased, and the convection column and smoke plume bent over toward the lidar in stronger horizontal flow. At two times during tbis later stage, w was estimated to be 24 and 10 m s-1. Lidar observations show tbat the smoke plume of tbis second fire initially went straight up in the convection column to heights of over 2 km, so most of the smoke was injected into the atmosphere above the unstable, afternoon, convective boundary layer, or mixed layer. Later, as the horizontal winds increased, a larger fraction of tbe smoke remained in the mixed layer. Finally, very late in tbe afternoon, after ignitions had ceased and the fire was smoldering almost all of the smoke remained within the mixed layer. These analyses show that lidar and radar can provide valuable tbree-dimensional datasets on kinematic quantities and smoke distribution in the vicinity of fires. This kind of information should be of great value in understanding and modeling convection-column dynamics and smoke-plume behavior. Published by American Meteorological Society. Abstract reproduced by permission.

Online Link(s):
Citation:
Banta, R. M., L. D. Olivier, E. T. Holloway, R. A. Kropfli, B. W. Bartram, R. E. Cupp, and M. J. Post. 1992. Smoke-column observations from two forest fires using Doppler lidar and Doppler radar. Journal of Applied Meteorology, v. 31, p. 1328-1349.