A numerical study of the effects of diurnal heating, moisture, and downstream topography on downslope winds within a valley

Real-data numerical simulations with the Naval Research Laboratory's Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS) were performed for several cases from the Terrain-induced Rotor Experiment (T-REX) where westerly momentum at upper levels penetrated into Owens Valley. Based on analysis of radiosonde profiles, two T-REX IOPs were chosen to represent dominant dynamic forcing, two to represent dominant thermal forcing, and a hybrid case from the Sierra Rotors Project was also simulated. Sensitivity tests were performed by running simulations in which the White-Inyo range was removed and the radiation and moisture parameterizations were disabled. The removal of the leeside topography results in a moderate increase in the westerlies, while the absence of radiation results in a pronounced weakening; however, significant westerlies are still maintained in the dynamic cases. The absence of moisture can result in a strengthening, weakening, or no significant effect depending on the particular case. These results are related to observations and idealized simulations from a companion paper.