Change of Low-level Jet in a Heavy Rainstorm Process of Xiangtan in July 2016
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摘要
Based on the previous research on the model of rainstorm weather with low-level jet in Xiangtan,using the classification result of radar echo characteristics,the wind profile data provided by new generation of weather radar in Changsha and hourly rainfall data,a thorough study of the heavy rainfall from 2 to 5 July 2016 in Xiangtan was conducted. It was concluded that heavy precipitation had the characteristics of the WPSH pattern of rainstorm with low-level jet at early stage,and then it converted to cold shear jet pattern in latter stage. When low-level southwest jet began to have momentum download,that is to say,there was more than 12 m/s of southwest jet below 1 km,and it rapidly strengthened and expanded downward,it was conducive to the occurrence of short-term rainstorm. The low-level jet would not immediately cause a strong precipitation when it reached the station,with a certain lag. A positive correlation existed between the increase of low-level jet index and precipitation intensity,and low-level jet index could predict the occurrence of heavy rainfall and rain intensity.
Based on the previous research on the model of rainstorm weather with low-level jet in Xiangtan,using the classification result of radar echo characteristics,the wind profile data provided by new generation of weather radar in Changsha and hourly rainfall data,a thorough study of the heavy rainfall from 2 to 5 July 2016 in Xiangtan was conducted. It was concluded that heavy precipitation had the characteristics of the WPSH pattern of rainstorm with low-level jet at early stage,and then it converted to cold shear jet pattern in latter stage. When low-level southwest jet began to have momentum download,that is to say,there was more than 12 m/s of southwest jet below 1 km,and it rapidly strengthened and expanded downward,it was conducive to the occurrence of short-term rainstorm. The low-level jet would not immediately cause a strong precipitation when it reached the station,with a certain lag. A positive correlation existed between the increase of low-level jet index and precipitation intensity,and low-level jet index could predict the occurrence of heavy rainfall and rain intensity.
Based on the previous research on the model of rainstorm weather with low-level jet in Xiangtan,using the classification result of radar echo characteristics,the wind profile data provided by new generation of weather radar in Changsha and hourly rainfall data,a thorough study of the heavy rainfall from 2 to 5 July 2016 in Xiangtan was conducted. It was concluded that heavy precipitation had the characteristics of the WPSH pattern of rainstorm with low-level jet at early stage,and then it converted to cold shear jet pattern in latter stage. When low-level southwest jet began to have momentum download,that is to say,there was more than 12 m/s of southwest jet below 1 km,and it rapidly strengthened and expanded downward,it was conducive to the occurrence of short-term rainstorm. The low-level jet would not immediately cause a strong precipitation when it reached the station,with a certain lag. A positive correlation existed between the increase of low-level jet index and precipitation intensity,and low-level jet index could predict the occurrence of heavy rainfall and rain intensity.
引文
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[9]DAI J,HE N,YUAN HS,et al. Classification and radar echo features of low level jet rainstorms in Xiangtan City[J]. Ecology and Environmental Monitoring of Three Gorges,2018,3(1):47-52.(in Chinese).
[2]CAO CY,JIANG Y,SUN XM. Relationship between low heavy precipitation in a altitude jet stream and heavy rainfall event[J].Meteorological Monthly,2006,32(6):102-106.(in Chinese).
[3]ZHANG JY,QI LB,WANG QH. Analysis of relationship between heavy rain and jet stream with radar VWP product[J]. Meteorological Monthly,31(12):41-44.(in Chinese).
[4]SAI H,MIAO JF. A review of low-level jet research in China[J].Meteorological Science and Technology,2012,40(5):766-771.(in Chinese).
[5]YUAN XX. Synoptic analysis of southwester low-level jet formation in Jiangnan of China[J]. Acta Meteorologica Sinica,1981,39(2):245-251.(in Chinese).
[6]REN M,DING TS. Low-level jet and rainstorm in middle and low reaches of the Yangtze River[J]. Torrential Rain and Disasters,1997(1):130-137.(in Chinese).
[7]SUN SQ. Triggering mechanism of rainstorm by low-level jet[J].Meteorological Monthly,1979,7(4):8-10.(in Chinese).
[8]MIAO AM,WU J,ZHAO HY,et al. Statistical relation and flow pattern of low-level jet and heavy rainstorm in Shanxi[J]. Plateau Meteorology,2010,29(4):939-946.(in Chinese).
[9]DAI J,HE N,YUAN HS,et al. Classification and radar echo features of low level jet rainstorms in Xiangtan City[J]. Ecology and Environmental Monitoring of Three Gorges,2018,3(1):47-52.(in Chinese).