Simulation of Summer Monsoon Convection at the U.S. Army White Sand Missile Range Using NCAR RTFDDA-VLES

The NCAR WRF (Weather Research and Forecasting) Model based RTFDDA-VLES (real-time four-dimensional data assimilation and very large eddy simulation) model is employed to study a case of summer monsoon convection and a case of late spring severe wind at White Sands Missile Range (WSMR), NM. Both convection and high winds affect the planning and execution of missile tests at WSMR, and both are influenced by local complex terrain, including the steep San Andres Mountains. to the west and the broader Sacramento Mountains. to the east. Thus it is of great interest to study the capability of numerical weather prediction models for simulating such weather at very high resolutions, with which fine scale terrain can be reasonably represented. The RTFDDA-VLES model is configured with five nested-grid domains at grid intervals of 8.1, 2.7, 0.9, 0.3, and 0.1 km, respectively. For the two case studies, 4-D data assimilation was active on the three coarsest grids. Preliminary modeling results show that smaller grid intervals increase the model's ability to simulate the fine-scale structure and intensity of moist convection and high wind. Spurious noise and phase shifts of the simulated phenomena often occur on all domains. Sensitivity experiments reveal the impact of different sub-grid filters (diffusion schemes), terrain smoothing, and surface momentum fluxes and heat fluxes. The results will be discussed.