Assimilation of lidar observation: A case study

This study first investigates the extent to which a Raman lidar is able to capture key boundary layer processes necessary for the development of convection. The results of this preliminary study show that the Raman lidar is able to capture the small-scale water vapor variability that is necessary for the development of convection. These results are then used to investigate impacts of assimilating moisture profiles from the Howard University Raman Lidar (HURL) for a mesoscale convective case, August 1-4, 2006.

The data for this case is from the Water Vapor Validation Experiment- Satellite and Sondes (WAVES) field campaign located at the Howard University Beltsville Site (HUBS) in Beltsville, MD. Specifically, lidar-based water vapor mixing ratio profiles are assimilated into the Weather Research and Forecasting (WRF) regional model over a 4km grid resolution over Washington, DC. Model verification is conducted using the Meteorological Evaluation Tool (MET) and the results from the lidar run are then compared to a control (no assimilation) run.

Qualitative findings indicate that, the assimilation of the lidar observations improved the equivalent potential temperature, and water vapor distribution of the region. This difference changed location, strength and spatial coverage of the convective system over the HUBS region.