Evolution characteristics of gravity-wave parameters in a simulated rainstorm process

A rainstorm process during July 4-5, 2003, in the Huaihe river basin, was simulated by the mesoscale model WRF. Then, the atmospheric gravity wave parameters, such as the frequency, period, horizontal wavelength, vertical wavelength, horizontal phase velocity and group velocity, as well as their evolution characteristics, over the rainstorm area were retrieved by use of the simulation output with higher spatial and temporal resolution. It was shown that the development of meso-alpha and meso-beta scale gravity waves contributed more to the intensified rainfall, and the period and horizontal wavelength exhibited decreasing features while the frequency varied inversely as the dispersion of the gravity waves after the end of the rainfall process. Furthermore, the wave parameters show different features for the rainfall area and rainfall-free area, and the development of rainstorm was closely related to that of the meso-alpha and meso-beta scale gravity waves with small amplitude in the atmosphere.