Kinetic Energy Spectrum Analysis and Budget Diagnosis of a Mei-yu Rainstorm

Using the WRF model and NCEP reanalysis data, the authors numerically simulated a real Mei-yu rainstorm. Based on the high-resolution simulation results, the authors calculated the HKE (horizontal kinetic energy), VKE (vortex kinetic energy), and DKE (divergence kinetic energy) spectra, and determined the kinetic energy budget. The results show that in the development of the rainstorm, the mesoscale kinetic energy increases with height, with significant increases starting at the lower end of the mesoscale, which leads to the spectral transition characteristics in the mesoscale band. However, the transition scales vary at different heights. In the troposphere, the VKE is greater than the DKE, and in the tropospheric layer the opposite is the case. Different precipitation stages, different heights, and different scales have different sources of kinetic energy. In the upper troposphere, the contributors to mesoscale kinetic energy tend to be nonlinear and pressure terms. In the lower stratosphere, the effect of pressure is more obvious.