沿海地区一次中尺度对流系统闪电活动及降水结构

利用TRMM卫星的测雨雷达,微波成像仪,闪电成像仪等探测数据,研究了2010年8月5日发生在江苏北部一次中尺度对流系统(MCS)的降水结构和闪电活动之间的关系.结果表明:MCS在发展阶段,对流云降水面积与层状云降水区相当;在减弱阶段,层状云降水区面积远大于对流云降水区.MCS的生命史中,大部分闪电发生在对流云区,仅有少数闪电发生在层状云区,在减弱阶段闪电多发生在对流云和层云的过渡区中.发生闪电的层云和对流云降水垂直廓线表明:在MCS的发展成熟和减弱中在4 km高度,层云降水率都达到最大值;在对流云降水区中发生闪电主要与对流云上空含丰富的冰相粒子和对流云发展厚度(顶高达17 km)有关.研究还表明闪电数目最大值一般回波强度在35～45 dBz之间,并非回波越强闪电越多.闪电主要发生在40～50 dBz之间,且明显向强回波区趋近,这对我们利用雷达回波预警闪电落区具有一定的参考意义.

Lightning activities and precipitation structure of mesoscale convective systems in Chinese coastal areas

Data from precipitation radar,passive microwave imager,lightning imager sensor on board and the Tropical Rainfall Measuring Mission (TRMM) satellite have been used to investigate relation between lightning activity and precipitation structure of mesoscale convective system (MCS) on August 5,2010 in the northern Jiangsu.The results show that when the MCS in the stage of development, convective precipitation area is equal to that of stratiform precipitation, while in the weakening stage, stratiform precipitation area is much larger than that of convective precipitation. In the whole life of MCS, the majority of lightning flashes happen in convective cloud area, only a few happen in the stratiform cloud area. In weakening stage, lightning occurrs in the transition zone between the convective and stratiform areas. Stratus occurrence of lightning and convective rainfall vertical profiles show that in the MCS maturing and weakening process at 4 km, stratiform rain rate reaches the maximum; the occurrence of lightning in convective precipitation areas is related with the plenty of ice particles and the development thickness of convective clouds (up to 17 km). Study also shows that echo intensity of lightning maximum number is generally related with 35-45 dBz and it is wrong that the stronger echo is, the more lightning happens. Statistics find that lightning occurs mainly between 40-50 dBz which significantly approaches to the strong echoes zone. It has a certain reference value to the use of radar echoes for warning lightning fall zone.