一种正地闪触发过程观测和分析  

Observation and Analyses on a Triggering Process of Positive Cloud-to-Ground

作　　者：甘泉[1] 张广庶[1] 李亚珺[1] 王彦辉[1] 张彤[1] 范祥鹏[1] 

机构地区：[1]中国科学院寒区旱区环境与工程研究所寒旱区陆面过程与气候变化重点实验室,甘肃兰州730000

出　　处：《高原气象》2010年第4期1005-1014,共10页Plateau Meteorology

基　　金：公益性行业(气象)科研专项(GYHY(QX)200706022);国家自然科学基金项目(40775004);中国科学院知识创新工程重要方向项目(KZCX2-YW-206-2)共同资助

摘　　要：利用2008年夏季在山东滨州获得的无线电窄带干涉仪及同步快慢电场资料,对发生于2008年6月29日的一次具有2次回击的正地闪进行了波形特征分析及定位处理。结果表明,正地闪预击穿过程起始于云中部负电荷区域,有持续时间长达163ms的预击穿过程,并在预击穿后期产生很多双极性脉冲。通过与负地闪的比较,发现云下部正电荷区的浓度对云中触发闪电的极性有一定的影响。正先导的触发和传输过程需要长时间的云内放电过程来提供能量,正流光传输是非阶梯型,结合同步观测的快电场三维定位结果的结合,得到正地闪首次先导速度约为4.1×105 m.s-1,首次回击的速度约为9×107 m.s-1,直窜先导的速度约为4.7×106 m.s-1,继后回击的速度约为9.6×107 m.s-1。正地闪的回击速度偏小,可能是由于干涉仪通道是二维的,且有一定的误差,还讨论了正地闪继后回击产生的原因是由于下部正电荷区很强,不同于一般的正地闪且只有1次回击过程。在该个例中还观测到正先导传输过程中的VHF辐射,这可能是由于雷暴过程下部正电荷区域很强。Using the observed data of interferometer and the electric field change detector,the waveform and locating of ＋CG with two RS occurred on 29 June 2008 were analyzed.The result shows that the pre-breakdown process of the flash is starting of the negative charge in central area of cloud area,there is very typical duration up to 163 ms of the pre-breakdown process and a lot of bipolar pulse in the latter part of the pre-breaddown.Comparing with the-CG,the concentration of positive charge in lower area of cloud has a certain influence on the polarity of flash.The trigger and transmission process of positive flash requires a large number of discharge within clouds to provide energy and its transmission is non-stepped-type,combination with the three dimensional positioning results obtained by the simultaneous observation of the fast electric field,some of the results are as follows： The speed of initial leading is 4.1×105 m·s-1,the speed of first return stroke is 9×107 m·s-1,the speed of dart lead and subsequent return-stroke is 4.7×106 m·s-1 and 9.6×107 m·s-1,the speed of the return stroke is low,probably due to the interferometer channel is two dimensional.The article also discusses the cause of subsequent return stroke is due to the strong lower positive charge region which is different from the general ＋CG that has only once strike;VHF radiation in the transmission of leading process have been observed in the case,due to the lower positive charge is very strong.

关 键 词：窄带干涉仪 正地闪 闪电 正先导 

分 类 号：P427.3[天文地球—大气科学及气象学]