The Study On Forewarning Indexes Of Hail At The Edge Of Desert In Shehezi Region In XingJiang

Shehezi Region in XingJiang is at the edge of desert which is the foreland for weather modification and hail suppression,locating the boundary between the oasis and desert.Due to the peculiar geographical entironment,the disaster weather frequent occur such as hail.In order to strengthen the ability to advance the hail forecasting early warning and artificial hail suppression.Based on conventional observation data,regional automatic station data and Shihezi Doppler weather radar data,by using the method of statistical,synoptic,radar meteorologic to analyze the hail at the edge of desert.Summarizing the distributing character of space-time,the type of weather patters,the physical parameter and Doppler radar product.Concluding the hail forecasting early warning to improve the weather forecast.The mainly conclusions as follows:1.The climate character shows that the most frequent date for forming hail is at the second period of five days in May,the fifth period of five days in June,the first period of five days in July,the ffirst period of five days in August.The most frequent time is from 16:00 to 22:00.2.There are four atmospheric circulation features for forming hail.(1)The Ural east low trough type.(2)The transverse trough type.(3)The forward trough type.(4)The pass ing through trough type.The most probability is the Ural east low trough type,more than 53%.3.The physical characters shows that ?se(850-500)?1.2?,T(850-500)?30?,index K is more than 26?,the stability index SI?1.2?,the foreboding precipitation,the vertical wind shear between 200 hPa to 850 hPa?1.3 m·s-1·?-1.In spring the height of 0? layer is 2700 m,the height of-20? layer is 5390 m.In summer the height of 0? layer is 3700 m,the height of-20? layer is 6596 m.4.The radar product characteristics for nowcasting indicators present that(1)the convection cloud in spring show that the radar echo center is more than 45 dBz,the height of strong echo has run up 7km,there is 40 dBZ radar echo in the upper limit of-20?.the convection cloud in summer show that the radar echo center is more than 50 dBz,the height of strong echo has run up 8km,there is 45 dBZ radar echo in the upper limit of-20?.(2)A guidance for hail nowcasting are the rebellious wind area of Doppler radar radial velocity and the couple positive and negative velocity.(3)the abruptly increasing for value of VIL,and center value of VIL is more than 15kg·m-2,the convection weather is possible to hail.The value of VIL is proportional to the diameter of the hail.The range of the big VIL is proportional to precipitation.(4)The radar product of mesoscale cyclone,hail index and 1 hour cumulating precipitation must be combined with the combined reflectivity factor and VIL which can provide a good guidance for hail forecasting.5.At last summing up the motion of hail cloud at the edge of desert in Shehezi Region.