| Short-term heavy precipitation occurs frequently in Liaoning province. It have been received much attention because it has a great influence on the industry, agricultural and transportation. It has threatened the safety of life. While the service and forecast of heavy rain and torrential rain in short time is difficult and concerned. Therefore, forecasting and early warning should be fixed point, quantitative and time, which is the inevitable requirement of the high speed development of social economy to the meteorological service.In this paper, by using the data of hourly precipitation at 1510 regional automatic weather station automatic weather stations and 62 national automatic weather stations in Liaoning, the radiosonde data, NCEP reanalysis data and radar data duiring 2005-2014, the distribution characteristics of short-term heavy rain and torrential rain in Liaoning have been analysized. Classify examples and analysis the physical quantities to establish forecasting model combined the optimization method and test improvement of radar which is from macro to concrete, from concept to numerical. Research shows:(1) Short-term heavy rain from the northwest to the southeast gradually increased in Liaoning province, which happen in the eastern region is significantly more than the western region. The number of days in southeastern region(Dalian, Dandong, East Benxi) in Liaoning province is most and it in the middle and east and western areas in Liaoning province is less.(2) The year of short time heavy rain frequently and the torrential rain is frequent,too. These distribution characteristics of month are similar. The number is most at July and August.The short-term heavy rainfall is more obvious than the torrential rain.The short-term heavy rain did not appear in October to May of next year. The short-term heavy rain changes were evident in one day. There are two major periods of occurrence which is at 15 pm and 20 pm.(3) The large scale circulation background of short-term heavy rainfall is mainly divided into 5 categories, North China cyclone, Mongolia cyclone, cyclone of Yangtze River basin, left of high pressure, typhoon. The number of short-term heavy rainfall affected by cyclone of North China is the highest, the next is Mongolia cyclone.(4) Physical quantities associated with short-term heavy rainfall are different in a year, and K index’s difference is smaller; the whole layer specific humidity integral maximum and severe weather threat index value and the maximum value occurred in August. Whole layer specific humidity difference of scores, the short-time strong precipitation need larger whole humidity levels integral, which may be influenced by the monsoon and subtropical high, and the water vapor is abundant.(5)Because of the different radar location, its data products are affected by the clutter of ground and the effective coverage of station density is different.There are some different results in different regions. By means of TS and BS test, the dynamic zoning classification scheme has a certain improvement to the short-term forecasting. Because of the relatively small number of test sample, it may bring some statistical errors, which it has effect on improving the accuracy of short- term rainfall estimation.(6) Because of the complex terrain conditions in Liaoning, the Z-I relationship is different in different regions. So to test and error analyze the results of the radar quantitative precipitation. At the same time to research the dynamic precipitation of Z-I in the classification of the sub regions. Research the dynamic zoning classification scheme and according to the relationship between Z-I in different echo intensity and different underlying surface features(coastal, mountain, plain).The results of this paper can provide a reference for improving the accuracy of short-term heavy rainfall forecasting. |
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