Analysis of Lightening Characteristics with Severe Tropical Storm Ma war(1716)
In order to understand the characteristics of cloud-to-ground(C-G)lightning during the landfall of tropical cyclones,this paper analyzed the severe tropical cyclone Mawar that made landfall in Guangdong on September 3,2017 by employing lightning locations and weather radar mosaics for the prov-ince,the infrared brightness temperatures(TBB)from the FY-2E weather satellite and radiosonde data at Dongyuan.The results are shown as follows.During the visit of Mawar,a total of 45 010 flashes of C-G lightning were detected,of which 4 749 flashes were positive lightning.After landfall,the C-G lightning de-creased by about 40％,possibly related with the persistent weakening of Mawar.The C-G lightning was most active on the left side of the storm's moving direction and showed a significantly asymmetric structure.In the time both before and after the landfall,lightning mainly occurred in the outer rain band and took up a domi-nant role.After landfall,lightning tended to shrink inwards to the eye.For the whole cycle of landfall,the C-G lightning peaked in frequency two hours before landfall.It decreased rapidly after it,but the proportion of positive flashes rose significantly.It was found that the active lightning zone was much coincided with the strong echo zone across the landfall point of Mawar.The zone of low cloud-top TBB appeared in the outer rain band,corresponding well with the zone of active C-G lightning,with the flashes mainly taking place a-round the area where the cloud-top TBB was lower than 200 K.Below the level of 500 hPa,temperature pro-files were generally within the range of 5 ℃ where there was a thick and moist layer,being much unstable in stratification.Frequent C-G lightnings were accompanied by the presence of a severe vertical wind shear.
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