Analysis on the Moist Potential Vorticity of the Heavy Rainstorm Process in Henan in July 16,2004

A process of heavy rain occurred on July,16th,2004 in henan province of moist potential vorticity(MPV) are analyzed.The relationship between MPV and this heavy rainstorm is discussed.The results show that there are favourable dist ributions of MPV in the heavy rainstorm occurred in Summer in Henan province.The change of MPV corresponds to the heavy rainstorm.When MPV_1 0 in the low tropospheric and MPV_2 ≥0,there are advantageous fields of heavy rainstorm.On the other hands when the dry and cold air from the high level interacts the warm and moist air from the low level,it is easy to store and release the convective instability energy,and it is useful for heavy rainstorm occurring.