Research On The Characteristics And Influencing Factors Of Thunderstorms At Shuangliu Airport

Using the hourly meteorological observation data of Shuangliu International Airport's from 2013 to 2018,ECMWF ERA-interim and ERA5 reanalysis data,MICAPS conventional meteorological observation data and airport Doppler weather radar product data,the spatiotemporal characteristics and classification characteristics of thunderstorm weather at Shuangliu Airport are analyzed and studied.And the discrepancy of different types of thunderstorms in the background fields,dynamic and thermal characteristics also be discussed.In addition,the physical factors and radar parameters that affect the airport thunderstorm weather are used to establish the potential prediction equation based on the two-level logistic regression method,and the emptying process is carried out.Eventually,the thunderstorm weather forecast model for Shuangliu Airport is provided,which provide technical support for air traffic control of thunderstorm weather at Shuangliu Airport.(1)From 2013 to 2018,77.03% of thunderstorms at Shuangliu Airport were accompanied by precipitation.Spring and summer are the seasons with frequent thunderstorms,of which the number of thunderstorm from July to August in summer occurrences for more than half of the total number of the year.The number of thunderstorm events began to increase gradually in the afternoon,and the highest proportion of thunderstorms occurrence occurs from 21:00 pm to06:00 am the next day was characterized by "more night thunder and less day thunder".There were 82.7% of the thunderstorms have a duration within 3 hours.Thunderstorms are more active in the zenith,west and east directions,which has a certain relationship with the geographical location and topographic characteristics of Shuangliu Airport.(2)According to the difference in baroclinic frontogenesis and thermal conditions of the environmental field where the thunderstorm is located,thunderstorms that occur at Shuangliu Airport are divided into cold advection forced type,warm advection forced type,baroclinic frontogenesis type and weak advection type.The high-altitude northwest cold air plays a leading role in the occurrence of cold advection forced thunderstorms.When a thunderstorm occurs,Shuangliu Airport is mostly located behind the 500 h Pa trough,and the wind direction of the upper and middle troposphere rotates counterclockwise with height.The atmosphere has strong unstable energy,so the thunderstorms formed are often accompanied by thunderstorm gale,hail,or local short-term heavy precipitation.The radar echo map shows mixed precipitation echoes of cumuliform clouds and stratiform clouds.The strong southerly warm and humid air plays a leading role in the occurrence of warm advection forced thunderstorms.When a thunderstorm occurs,Shuangliu Airport is mostly located in front of the 500 h Pa trough,and the wind direction of the middle and lower troposphere rotates clockwise with height.Although the unstable energy of the atmospheric layer is relatively weak,the atmosphere is generally humid,so it is easy to form a thunderstorm with short-term heavy precipitation.The radar echo map shows the precipitation echo mainly with stratiform clouds.Baroclinic frontogenesis thunderstorms occur in the background of the strong intersection of cold air and warm air in the middle and lower layers,and the function of frontogenesis is significant.When a thunderstorm occurs,the atmospheric baroclinicity is strong,and the dynamic condition is good,so it is easy to form strong convection weather mixed with various weather phenomena.The radar echo map shows a radar bow-shaped echo band(squall line)near the Shuangliu Airport that is arranged laterally by many thunderstorm cells in a northeast-southwest direction.Weak advection thunderstorms occur in the background of weak baroclinic pressure.When a thunderstorm occurs,the atmosphere is approximately quasi-barotropic with a small frontogenesis function and insignificant temperature advection.The horizontal distribution of atmospheric water vapor is relatively uniform.The near-surface environment is characterized by high temperature and high humidity,and unstable energy is accumulated in the lower layers.When combined with some appropriate trigger mechanisms,thunderstorms accompanied by thundershower and gusty winds will be formed due to the ability to overcome convection.The radar echo map shows many echoes with small range and weak intensity scattered around the Shuangliu Airport,and the echoes have no obvious typical characteristics as a whole.(3)According to the basic conditions of thunderstorm occurrence,the following impact factors are selected by correlation analysis: CAPE index,K index,850 h Pa specific humidity,the potential pseudo-equivalent temperature difference between 850 h Pa and 500 h Pa,echo top,1.5(?) elevation angle basic reflectance,3.4(?)elevation angle basic reflectance,and vertically integrated liquid.The thresholds for these impact factors to produce thunderstorm weather in the corresponding season are calculated.And based on the idea of two-level logistic regression,the selected physical factors and radar factors are used to establish the prediction equation and the elimination equation respectively,and the sample data from April to August 2018 are used for the return inspection.The forecast model of established has indicative significance for forecasting the weather of thunderstorm in Shuangliu Airport,and the effect of forecast is better in summer.