WRF and Vertical Nesting: Multi-Scale Resolution of T-REX Measurements

Staggered vertical nests have been developed, coupled with the WRF innermost nests. This methodology is applied to the high resolution simulations of field data from the T-REX Campaign of measurements (Terrain-induced Rotor Experiment), Owens Valley, CA, 2006. Our real case WRF simulations are based on initial and boundary conditions from both high resolution T799 L91 ECMWF analysis data and GFS data. Four nests are used: a parent domain with 9 km grid and two WRF nests with 3 km and 1 km grid spacing. 150 vertical levels are used with adjusted sigmapressure levels for an improved and more uniform resolution around the tropopause and in the lower stratosphere. The innermost WRF nest is coupled in a one way mode with a fourth domain nested both in the horizontal and the vertical (450 staggered vertical levels). For vertical nesting, both lateral and vertical boundary conditions are treated via relaxation zones where the velocity and temperature fields are relaxed to those obtained from the WRF inner nest. We resolve mountain wave breaking, temperature adiabatic layers, intense vertical velocity fluctuations and dynamics of countergradient flows around