2019年马六甲地区红色精灵观测及母体雷暴分析

红色精灵是一种发生于闪电放电活跃的雷暴云上空的中高层大气瞬态发光现象, 它们通常由中尺度对流系统层状云降水区内的强地闪回击产生, 是对流层和中间层之间的一种能量耦合过程。目前, 有关中国南海及东南亚地区的红色精灵观测鲜有报道。为了进一步了解热带地区产生红色精灵事件的沿海性雷暴特征, 于2019年利用低光度光学观测系统和低频磁场天线在马来西亚马六甲地区开展了地基观测。实验于11月9日、12月11日和12月15日三次在沿海雷暴上空共捕捉到7例红色精灵事件, 其中包括4例圆柱型、2例胡萝卜型和1例舞蹈型。结合闪电定位、云顶亮温和低频磁场信号等同步数据, 分析表明所有事件均由正极性地闪回击产生, 且母体闪电回击位于雷暴对流区附近(云顶亮温≤210 K处), 这可能是该地区产生红色精灵的沿海性雷暴的共同特征。此外, 红色精灵生成期并不是闪电活动最强期, 而是发生于闪电频数短暂降低后, 这表明红色精灵的发生可能是该地区成熟雷暴中对流减弱的一个信号。 

OBSERVATIONS OF RED SPRITES IN MALACCA AREA IN 2019 AND ANALYSES OF PARENT THUNDERSTORMS

Red sprites are transient luminous events in the middle and upper atmosphere above thunderstorms with active lightning activity. As energy coupling processes between the troposphere and the mesosphere, they are usually generated by strong cloud-to-ground(CG) lightning return strokes in the stratiform cloud precipitation regions of mesoscale convective systems. At present, there are few reports on the observation of red sprites in the South China Sea and Southeast Asia. To further understand the characteristics of coastal thunderstorms that produce red sprite events in the tropics, we launched groundbased observations in Malacca, Malaysia in 2019 by using a low-light video camera system and a lowfrequency magnetic field antenna. The experiment captured a total of seven red sprites over three coastal thunderstorms on November 9, December 11, and December 15, including four column events, two carrot events and one dancing sprite. Combined with lightning location, cloud-top brightness temperature, lowfrequency magnetic field signal and other synchronous observational data, analysis shows that all events are induced by positive CG lightning strokes and parent lightning located near the convective regions of thunderstorms(cloud-top brightness temperature ≤210 K). This may be a common feature of coastal thunderstorms that produce red sprites in this region. Furthermore, red sprites did not appear during the period of strongest lightning activity, but rather after a brief decrease in lightning frequency, suggesting that the occurrence of red sprites is likely an indicator of weakening convection in mature thunderstorms in the region.