Research into wave energy distribution and propagation features during the rainstorm

Based on NCEP/NCAR reanalysis grid materials, wave-packet propagation diagnosis (WPD) method and wave-packet distribution features of the “7.17” heavy rain in Chongqing in 2007, the paper made research into the relationship between the energy propagation, accumulation and dispersion features and the rain process. The result shows that: (1) before regional heavy rain, the perturbation energy of the whole atmosphere is enhanced and is spread from higher layer to middle layer with generation of rain and the perturbation strength is reduced. Before basic end of rain, the atmosphere perturbation energy is reduced suddenly. It can be seen that the generation and end of rain is related with enhancement and reduction of perturbation energy. (2) as for this example, the perturbation energy changes most obviously at 600hPa~400hPa and the perturbation energy in the middle layer is always the strongest center of the whole atmosphere. The average perturbation energy of main rain region at 500hPa is enhanced before rain due to impact of propagation of perturbation energy in other regions and maintains in relatively strong phase and is obviously reduced before end of rain. (3) The wave-packet value distribution and propagation at 500hPa shows that the perturbation energy with impact on heavy rain in Chongqing mainly comes from high-latitude areas, Bay of Bengal region, plateau areas and eastern coastal areas. Propagation and accumulation of perturbation energy in Bay of Bengal region and plateau areas is very obvious before and during the rain while propagation and accumulation in southeast coastal areas and West Pacific areas is not completely simultaneous with that in other areas but is also a key link with impact on accumulation of perturbation energy in rain regions. The heavy rain center is basically corresponding to the strong perturbation energy area and the heavy rain always happens after accumulation of strong perturbation energy to a certain extent, which- - shows that propagation and accumulation diagnosed in wave-packet propagation diagnosis method is meaningful for predication, analysis and instruction of regional rain process.