Assessment of WRF Sensitivity to Physical Parameterizations for a Heat Wave Simulation in Kansas City Metro Area

The 2012 U.S. summer heat wave was one of the most severe heat waves in modern North American history. The objective of this study is to examine the impact of various physical parameterizations on simulating this extreme weather event in Kansas City metro area using the high-resolution Weather Research and Forecasting (WRF) model. A series of sensitivity experiments were produced by different combinations of microphysics, radiation and planetary boundary layer (PBL) schemes. Simulated surface air temperature, relative humidity and precipitation are evaluated by comparing against Local Climatological Data (LCD) observations and Parameter-elevation Regressions on Independent Slopes Model (PRISM) gridded dataset. The results show that most of the configurations showed an overall slight warm bias, and MYNN3 PBL scheme presents better simulations of surface air temperature than MYJ PBL scheme. Most of the experiments overestimated the precipitation during the period. Overall, the combination of Thompson microphysics, RRTMG radiation and MYNN3 PBL schemes presents the best simulation of this heat wave event. This best-performing simulation also successfully reproduces the urban heat island (UHI) effects and diurnal temperature variability in Kansas City metro area. These sensitivity experiments are used as a benchmark test to present model's sensitivity to various physics options. Long term simulations to reconstruct present-day climate in Midwest and future change projections using dynamical downscaling are under way.