Central U.S. WRF Statistical Verification of Simulated Composite Radar

A continental-scale convection-allowing simulation was conducted by the National Center for Atmospheric Research (NCAR) using the regional Weather Research and Forecasting (WRF) model. This 13-year simulation was designed to have 4-km grid spacing covering the entire continental U.S. and the southern portion of Canada (up to 56ºN) and downscaled the ERA-Interim reanalysis for the period from October 2000 to September 2013. Previous studies have shown that the simulation can realistically capture the spatial pattern of sub-seasonal, seasonal, and annual precipitation and temperature in most of the contiguous United States. Furthermore, the simulation can also partially produce propagating mesoscale convective systems (MCSs), as well as their major climatological features.

Downscaling to a higher resolution of 4-km permits the model to simulate deep convection without parameterization. The primary objective of this study is to evaluate the WRF model’s capabilities in producing similar characteristics of observed warm-season convection in the central United States, with the emphasis on convective population, organized convective modes, and storm propagation. The simulated composite (column maximum) radar is validated by the Weather Surveillance Radar-1988 Dopplers (WSR-88Ds) national mosaic. The comparison focuses on the Central Plains of the U.S. for March through August. Specifically, the area of interest for this research is bounded by 30 and 45 degrees north, and 90 and 105 degrees west. Initial results show that the simulation can produce a similar distribution of intermediate and convective reflectivity values, but also tends to overestimate lower reflectivities, specifically less than 10 dBZ. This research project is ongoing, and will report more results in the future.