Assessment of the Simulation of Gravity Waves Generation by a Tropical Cyclone in the High-Resolution WACCM and the WRF

National Center for Atmospheric Research Whole Atmosphere Community Climate Model (WACCM) with quasi-uniform grid of similar to 25-km horizontal resolution can resolve gravity waves (GWs) with horizontal scales down to similar to 250 km. In this study, the scale interactions between the GWs resolved by WACCM and those with smaller scales, its potential impact on the resolved waves, and the dependence of wave characteristics on spatial resolution are examined. The Weather Research and Forecasting (WRF) simulations with five different spatial resolutions (25, 20, 15, 10, and 4 km) are performed, with the high-resolution WACCM wind and temperature fields as initial and boundary conditions. Semicircular GWs excited by a tropical cyclone (TC) resolved by WACCM and WRF (25-km resolution) are found at similar locations and have similar structures. In this study, the sensitivity of GW structure to the choice of model horizontal resolutions is examined. Although WRF is successful in generating semicircular GWs in each case, the simulation reveals more power at shorter horizontal wavelengths of GWs at finer resolutions. Furthermore, we evaluate the performance of all these simulations in resolving GWs induced by the tropical cyclone (TGWs). The magnitude of the zonal momentum flux calculated from the high-resolution WACCM is greater than the WRF-25 simulation, in addition, the magnitude is comparable to the results from the WRF-15 and WRF-10 simulations.