P70     A comparison of MPAS and WRF meteorological models in California: 2013 winter and 2016 summer case studies.

Gürer, Kemal, Jeremy Avise, and John DaMassa, California air Resources Board, Air Quality Planning and Science Division

The Modeling Platform Across Scales - Atmosphere (MPAS-A) v6.0 and Weather Research and Forecast - Advanced Research WRF (WRF-ARW) v4.0 models were applied to simulate meteorological conditions over California for a wintertime (January 10-24, 2013) and summertime (July 18-30, 2016) episode during the Discover-AQ and CABOTS field campaigns, respectively. WRF was configured with three, two-way nested domains of 36, 12, and 4 km horizontal grid resolution while MPAS was configured with a variable horizontal grid resolution ranging from 3 km over California to 48 km over the rest of the globe. Both models utilized 55 vertical layers starting with 20 m deep first layer with a maximum layer depth of 750 m in upper levels. Physics parameterizations were chosen to be as consistent as possible between WRF and MPAS.

Model results were evaluated against surface measurements throughout California using the METSTAT and AMET modeling analysis packages, and were compared using horizontal and vertical cross sections of various meteorological parameters, temporal evolution at surface stations, as well as 3D Lagrangian transport analysis. While the results are preliminary, the initial evaluation shows that MPAS is able to reasonably reproduce the observed meteorology and its characteristics, and may even exhibit superior performance to WRF over some regions.  Future work will include additional simulations with higher vertical resolution and differing horizontal grid structures.