| Hail is a natural disaster appears in many places around the world,therefore it’s very important to get to know the occurring,developing and evolution rules and structure characteristics of hail for improving the hail weather distinguishing forecast ability and artificial hail suppression work effect.This article combine the data of a new generation of doppler radar,satellite and L band air sounding,MICAPS surface data,NCEP,analyse deeply into a typical super cell hailstorm in Guangdong,17th, April,2011and a hail convective process in Beijing,11tn,June,2011,reveal different develop and evolve rules and its cloud structure,we can get main conclusions below:1)Super cell emerges in the typical atmospheric vertical structure’dry and cold upper layer,warm and wet in lower layer, atmospheric stratification is unstable and accumulate much energe,vertical wind shear is very big’.The move direction of storm is in the right of wind shear orientation,therefore this storm is a typical moving right storm.the cloud life experienced four stages, which contained primary period, evolution period, maturation period and extinction period. The cloud moved more than600km from primary to extinction, and lasted for more than10hours, which caused hail in six districts of Guangdong with extent reaching200km.In the maturation period, cloud kept a isolated elliptic moving to the southeast direction. The coverage area was very great with over300km length and100km width, and the part Tb b is lower than-75℃. All these characteristics indicated that the cloud system was a typical supercell severe hailstorm..In the mature stage,there appears super cell characteristics in radar picture,such as typical’bow’echo,’v’shape gap,bounded weak echo area(vault) and the strong echo overhang beyond it,and the echo wall in the left of bounded weak echo area.There exsit the structure of vault during all the time of super cell mature period, the POH value stays around100%when the vault emerges,and last for4hours,it has very important leading meaning for short time near forecast of super cell storm hailshooting and artificial hail suppression work. There is a strong west wind in the west lower layer of super cell,the east part is weak east wind,convergence strong,the cloud moving towards east,this is a kind of fast speed moving,keep absorption the severe convection of unstable air ahead,this convection can last for very long time,but passing by and cause convective weather to each place is very short.Optical thickness has no direct correspondence with hail,and the cloud water center which is reflected by optical thickness can reflect the precipitation information which is get from radar echo better than the cloud top informatin report from Tb b.we find that there are large quantity of ice particles in cloud, the size of ice particles exceed the threshold value of hailshooting, which applies that this convective cloud has much probability to emerge hail.2)The Beijing severe convective hail storm is consists of the combination of small convective cloud cluster,the life time of the storm is only several hours,the mature stage only last for1hour;but the life time of Guangdong super cell can reach more than10hours,and the mature stage last for4hours.The Tb b low value of severe convective hail storm keeps around-50℃in mature stage;the super cell keeps around-70℃in mature stage.From the radar picture,we can see that hail severe convective storm is combined by scattered echo,mature stage is a ribbon echo,the ribbon echo starts to crack only after lasting for one hour;the super cell keeps maintain bow echo.Through the comparison,we can find out that super cell is a stable convective cell,with a long life time, convection develops vigorous,get more damage to part area.The analysis and research of this article is very helpful for the comprehensive understanding of super cell,and the improving of hail forecast ability and the identification of artificial hail suppression work ability. |
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