The impact of a controlled burn on atmospheric and surface conditions on a tallgrass prairie

A controlled burn was conducted on a tallgrass prairie near the El Reno, Oklahoma Mesonet site on 8 March 2005 from approximately 2100-2300 UTC. The only noticeable meteorological changes occurred in the air temperature at 1.5 m and 9 m and relative humidity at 1.5 m. A sudden spike in temperature and drop in relative humidity began at approximately 2200 UTC and lasted nearly 10 minutes. Once the fire passed the site, the temperatures gradually decreased while the relative humidity quickly increased.

Observations were also obtained from 4 Portable Automated Research Micrometeorological Station (PARMS) sites that were placed across the property from 5 February 2005 to 19 April 2005; The PARMS were removed during the fire and replaced soon afterwards. For days with adequate sunshine (at least 75% of the possible solar radiation reaching the surface), an “afternoon” average (from 1700-2100 UTC) of the observed variables was obtained. The analyses revealed that significant meteorological changes occurred in the albedo, net radiation, and sensible heat flux. Immediately following the burn, the albedo dropped drastically, but it steadily rose back to near its initial value by the end of the study period. Conversely, net radiation and sensible heat flux peaked a few days after the burn but began to decline soon after. Finally, a minor deviation was observed in the difference between surface skin temperature and the air temperature at 1.5 m, but it wasn't as pronounced as the changes observed in other variables.