Journal of Geophysical Research: Atmospheres
kinematic structure, wildland fire, doppler lidar
Atmospheric Sciences | Climate | Meteorology
Wildland fires present a challenging environment to make meteorological measurements. Observations in the vicinity of wildland fires are needed to better understand fire-atmosphere interactions and to provide data for the evaluation of coupled fire-atmosphere models. An observational study was conducted during a low-intensity prescribed fire in an area of complex terrain with grass fuels east of San José, California. A ground-based scanning Doppler lidar acquired radial wind velocities and backscatter intensity in and around the fire plume from multiple horizontal and vertical scans. The development of a convergence zone was consistently observed to exist downwind of the plume and was indicated by a decrease in radial velocity of 3–5 m s−1. Divergence calculations made from the lidar radial velocities showed that the magnitude of convergence ranged between −0.06 and −0.08 s−1 downwind of the plumes, while a maximum of −0.14 s−1 occurred within the plume near the fire front. Increased radial velocities were observed at the plume boundary, indicating fire-induced acceleration of the wind into the base of the convection column above the fire front. Thermodynamic measurements made with radiosondes showed the smoke plume had a potential temperature perturbation of 3.0 to 4.4 K and an increase in water vapor mixing ratio of 0.5 to 1.0 g kg−1. Plume heights determined from sequential range height indicator scans provided estimates of vertical velocity between 0.4 and 0.6 m s−1, representing the ambient background vertical velocity as the top of the plume likely reached equilibrium.
A. Charland and Craig Clements. "Kinematic structure of a wildland fire plume observed by Doppler lidar" Journal of Geophysical Research: Atmospheres (2013). https://doi.org/10.1002/jgrd.50308