UCLA

Using the Weather Research and Forecasting (WRF) model, an intra-model physics ensemble was created for July 2005 in hopes of finding a physics configuration that could most accurately recreate the typical summertime conditions of Southern California. The ensemble consisted of twenty-four members that mixed different Land Surface Models (LSM) with various Planetary Boundary Layer (PBL) parameterizations currently offered in WRF. It was found that the Pleim-Xiu LSM coupled with either the asymmetric convective model version 2 or the Yonsei University PBL scheme created the most skillful ensemble member.

In addition to the physics ensemble, short integrations along with different initializations proved to be beneficial. Initializing the model off of the North American Regional Reanalysis (NARR) instead of the North American Mesoscale (NAM) model was, in this case, extremely useful. The most accurate simulation of July 2005 was found when taking integration methods, initializations, and model physics into consideration.