Doppler Lidar Observations of the Wildfire Environment

Abstract

Extreme wildfire activity is often associated with downslope windstorms which cause fires to spread rapidly. To limit the potential for a utility-caused ignition, Public Safety Power Shutoffs (PSPS) can be used preemptively during predicted wind events. The timing of when winds might mix down to the surface and impact the power grid infrastructure is difficult to predict due to the interaction of the atmosphere with complex terrain. To improve the spatial and temporal accuracy of wildfire mitigation during PSPS events, the deployment of a mobile Doppler LiDAR was used to monitor the vertical structure and evolution of two downslope wind events. During both events, a mobile Doppler LiDAR was positioned in Santa Clarita, CA to collect vertical wind profiles and boundary layer heights. In one of the two cases, stronger winds aloft were observed mixing down to the surface providing critical information for the timing of potential de-energizations in that region. The Doppler LiDAR was also deployed to Ft. Stewart, Georgia for three prescribed wildfire events in order to observe smoke plume behavior and development. It was found that plume organization was greatly influenced by variations in surface and transport wind intensity. This paper will describe the various case studies, the meteorological context of each event, and compare their evolution and significance relating to wildfire potential.