两次华南飑线卫星亮温特征与强对流天气分析

Characteristics of TBB for Two Southern China Squalls and Analysis of Intense Convective Weather

利用Himawari-8高时空分辨率红外亮温资料和ERA-Interim再分析资料,对比冷锋型和暖区型飑线个例("4·13"和"5·6")亮温特征与雷暴大风、地面强降水的关系,结果表明:(1)两次过程的云顶最低亮温、冷云区平均亮温差异小,但两次过程初生阶段云型不同,"4·13"与"5·6"相比,冷云顶面积较小、持续时间较短、移动速度较快;(2)"4·13"("5·6")的亮温梯度大值区主要位于冷云区东南侧(西南侧),与云团移动方向平行(垂直);两次过程雷暴大风与亮温梯度均具有较好的空间对应关系,亮温梯度增大超前于雷暴大风增强,可作为提前预警指标;(3)"4·13"地面强降水集中分布在低亮温区西侧,原因为风暴顶前移导致强降水与冷云区具有空间位置差异;"5·6"地面强降水则与云顶低亮温具有较好的对应关系。

Using Himawari-8 high spatiotemporal resolution infrared brightness temperature(TBB) data and ERA-Interim reanalysis data, this work compares the TBB, thunderstorm and intense surface precipitation with squalls between the type of cold fronts(which happened on April 13) and that of warm sectors(which took place on May 6). The result is shown as follows.(1) Differences are small in minimum cloud-top TBB and average cold-cloud zone TBB, though they differ in cloud type in the initial phase of their lifecycle. Compared to the May 6 case, the April 13 case shows a smaller cold-cloud top, a shorter duration and a faster moving speed.(2) In the April 13(May 6) case, large-value zones of TBB gradient are mainly on the southeast(southwest) side of the cold-cloud zone, move in direction parallel with(vertical to) the moving direction of cloud clusters. In both cases, thunderstorm and TBB gradient are well consistent spatially, with the latter increasing earlier than the former, which can be used as an indicator in pre-warning operation.(3) In the April 13 case, intense surface precipitation distributes mainly on the west side of a low-TBB area because the storm top moves ahead to cause the zone of intense precipitation to be spatially different from that of the cold-cloud zone. In the May 6 case, however, the intense surface precipitation corresponds well with the low cloud-top TBB.