Performance assessment of the Pleim-Xiu LSM, Pleim surface-layer and ACM PBL physics in version 3.0 of WRF-ARW

The Pleim-Xiu land-surface model, Pleim surface-layer and Asymmetric Convective Model (Version 2) are now options in version 3.0 of the Weather Research and Forecasting (WRF) model. These physics options were developed for the MM5 mesoscale model and used extensively by the air quality modeling community, so there was a need to extend these physics to WRF. The new physics in WRF are compared to the MM5 counterpart and several other WRF configurations in this study with a focus on the replication of 2-m temperature, 2-m moisture and precipitation. The new physics implementation is recommended for retrospective air quality simulations, in particular, those used so simulate warm season meteorology. In the summer, the performance was similar to the MM5 counterpart and has a smaller 2-m temperature and 2-m moisture error than other WRF simulations. For cold season cases, the model simulation was not as accurate as the other simulations as a whole, but did comparatively well in terms of less 2-m temperature error in the western part of the model domain (Plains and Rockies) and parts of the northeast United States. Also, 2-m mixing ratio was well simulated by the new physics suite in WRF. Monthly precipitation was well simulated, especially in the winter. Summer precipitation was not as well simulated as winter because of the scattered and random nature of warm season convection, but difference among models was not large. It is expected that once more precise analyses are available for WRF, like the RAWINDS analyses used to drive MM5, the performance of the new physics will further improve.