A Study On Application Of The Entropy Flow Index In Analysis Of The Rainstorm Far From Typhoon

Typhoon is the strongest rainstorm weather system. A lot of extreme records of rainstorm arerelated to typhoon. Meteorologists of domestic and international have done a lot of researchesabout genesis and development mechanism of the storm rainfall far from typhoon, and have gotmost harvest.Rainstorm,far from typhoon,arosed by the interaction of typhoon and mid-atitudeweather system, often bring strongest rainstrom which is above 100ram in northeast and north ofChina, and lead to serious flood disasters.In this paper, we selected an example that the No.5 "haitang" typhoon aroused an extremelyheavy rainfall to henan province after landing on July 2005.Firstly, by using routine observationdatasets both suface and sounding ,we analysed the large-scale influence system of rainstorm farfrom typhoon. Based on it, by using NCAR/NCEP reanalysis data and the method of band-passfielter, we made the scale separation to the process,and discussed the impact of the interaction oftyphoon, circulation and mid-scale system on the development of the rainstorm far fromtyphoon. Thinking of some bugs such as the potential pscudo-equivalent temperature only partlyreflecting the action of moisture condensation process,ignoring the fact of a large amount dripsstaying in the air and so on. Based on the concept of generalized equivalent potentialtemperature, we constructs the entropy flow indexes, inclusive of atmospheric remove entropyindex, advantage moist entyopy differential advection and generalized equivalent potentialtemperature advection etc. Application of the theory of dissipation structure, we emphaticallydiscussed the evolution rule of entropy flow indexes in the storm rainfall far from typhoonprocess and the relation to the appearance area of rainfall. The results show that there is highentropy air assembling at the top of boundary layer before the produce of storm rainfall far fromtyphoon. The evolution of high to low of atmospheric remove entropy index is better to thedeveloping of convection, and lead to the heavy rainfall. The appearance areas of storm rainfall isalways in the central of negative atmospheric remove entropy index or near the axes of negative.The high entropy central always accord with the placement of rainfall. The remove direction ofhigh entropy at top of boundary layer often indicates the future remove direction of the heavyrainfall. Moreover, we also calculated the environment parameters such as moist geopotentialvorticity, helicity and Q vector etc.The case which studies "haitang" typhoon storm rainfallprocess showed that all the parameters are effective for prediction and development of the stormrainfall's occurrence, and worthly extending in our actual prediction work.