闪电产生氮氧化物（LNOX）区域特征计算（I）：理论和计算方法

介绍了目前关于闪电产生氮氧化物（MOX）的研究概况，包括产生机理、特征、输运过程以及在全球气候变化中的作用。重点叙述了发生在区域性雷暴中闪电产生氮氧化物的机制、传输以及计算方法和可能误差，并对闪电产生氮氧化物区域特征计算方法和参数的选取作了简要介绍。     

脉冲电晕与地闪负先导梯级性机制模式探讨

根据新的观测事实，提出了地闪负先导明亮脉冲可能不是被－慢而弱的流光（引路流光）所此导，而是被一快而短暂的电晕（脉冲电晕）所引导的梯级性流光机制的不同观点。由此出发，对流光间歇时间、梯级长度等重要特征参数进行了新的分析；结合对梯级先导辐射特征脉冲产生机制的进一步分析，提出并论证了明亮脉冲的双向传输，通过一个简单的数值模式对梯级过程进行了计算模式，得到了一些与观测特征基本符合的结果。     

Thunderstorm and Lightning Activities over Western Pacific, Northern Indian Ocean and South China Sea Along with Their Adjacent Lands

The Lightning Imaging Sensor (LIS) and Radar Precipitation Feature (RPF) data are used to investigate the activities and properties of lightning and thunderstorms over a region including the Western Pacific, northern Indian Ocean and the South China Sea along with their adjacent lands. The lands feature significantly more frequent lightning flashes and thunderstorms than the oceans, especially the open oceans. The highest densities of lightning and thunderstorm occur over the Strait of Malacca and the southern foothills of the Himalayas. Over the ocean regions, the Bay of Bengal and the South China Sea are characterized by relatively frequent lightning and thunderstorm activities. Larger average spatiotemporal size and optical radiance of flashes can be found over the oceans; specifically, the offshore area features the most significant flash duration, and the open ocean area is characterized by the greatest flash length and optical radiance. The smallest average values of flash properties can be found over and around the Tibetan Plateau (TP). The oceanic thunderstorms tend to have a significantly larger horizontal extent than the continental thunderstorms, with the former and latter having the average area of the regions with radar reflectivity larger than 20 dBZ, generally over 7000 km2 and commonly below 6000 km2 , respectively. The TP thunderstorms show the smallest horizontal extent. Meanwhile, the oceanic thunderstorms exhibit greater 20 dBZ but smaller 40 dBZ top heights than the continental thunderstorms. The average flash frequency and density of the oceanic thunderstorms are typically less than 5 fl min–1 and 0.3 fl 100 km–2 min–1, respectively; in contrast, the corresponding values of continental thunderstorms are greater. It is explored that the regions associated with strong convective thunderstorms are more likely to feature small-horizontal-extent and low-radiance flashes.     

A review of advances in lightning observations during the past decade in Guangdong,China

This paper reviews recent advances in understanding the physical processes of artificially triggered lightning and natural lightning as well as the progress in testing lightning protection technologies, based on a series of lightning field campaigns jointly conducted by the Chinese Academy of Meteorological Sciences and Guangdong Meteorological Bureau since 2006. During the decade-long series of lightning field experiments, the technology of rocket-wire artificially triggered lightning has been improved, and has successfully triggered 94 lightning flashes. Through direct lightning current waveform measurements, an average return stroke peak current of 16 kA was obtained. The phenomenon that the downward leader connects to the lateral surface of the upward leader in the attachment process was discovered, and the speed of the upward leader during the connection process being significantly greater than that of the downward leader was revealed. The characteristics of several return strokes in cloud-to-ground lighting have also been unveiled, and the mechanism causing damage to lightning protection devices (i.e., ground potential rise within the rated current) was established. The performance of three lightning monitoring systems in Guangdong Province has also been quantitatively assessed.     

上升运动核心区与霰粒子非感应起电区关系的模拟研究北大核心CSCD

利用一个三维起电放电云分辨率模式,基于北京地区的一次探空数据,进行了孤立雷暴单体的模拟实验,并对模拟雷暴中上升运动较强阶段(最大上升速度W_(max)>5 m·s^(-1)),霰粒子发生非感应起电区域内的上升运动特点,及其与上升运动核心区(上升速度W>5 m·s^(-1))之间的空间关系进行了分析。结果表明,非感应起电区主要分布在上升运动核心区及其临近区域。出现在上升运动核心区内的非感应起电活动的起电效率通常较高(|非感应起电效率E_(n-charging|>0.1 nC·m^(-3))。上升运动中心也能够发生非感应起电。即使是在雷暴最大上升速度达到峰值时,在上升速度中心的霰粒子仍能发生非感应起电。但过强的上升速度不利于非感应起电效率的进一步提高。在该模拟雷暴中,效率较高的非感应起电活动多集中发生在W_(max)>5m·s^(-1)的时段内,区域则主要分布在-4~28m·s^(-1)的垂直速度区间内。对于具有更高效率的非感应起电活动(|E_(n-charging)|>0.5 nC·m^(-3)),尽管W_(max)越大,具有更高效率的非感应起电活动区范围就越大,起电效率中心也更靠近上升速度中心,但起电效率中心与上升速度中心并不重合。大部分具有更高效率的非感应起电活动都发生在W<20 m·s^(-1)的上升运动区内。此外,上升速度中心高度在闪电活动的多数时间里与反转温度高度基本一致,可以用来区分霰粒子非感应起电获得不同极性电荷的区域:在分析时段内(第12~23 min)的大部分时间里,霰粒子获得负电荷的区域都出现在该高度附近或以上高度中,而获得正电荷的区域则基本出现在该高度以下。     

云闪放电通道内的粒子密度及分布特征

依据在中国西藏高原地区得到的6幅云闪放电通道的光谱,由谱线波长、相对强度和跃迁几率等信息,结合等离子体理论,计算了云闪放电通道的温度和电子密度;进而,利用Saha方程、电荷守恒和粒子数守恒方程,得到了粒子处于各电离级上的数密度、通道质量密度、压强和平均电离度等参数,并对云闪通道内部粒子数分布特点进行了分析.结果表明,与地闪回击通道类似,云闪通道接近于完全电离,通道内部以单次电离的离子为主,且NII离子数密度最高.具有较高温度的通道位置处,中性和一次以上电离离子数密度的绝对值和相对值都较高,但是,不同温度下NII、OII、ArII粒子的相对浓度变化不大.与地闪回击通道不同,云闪同一放电通道内不同位置处粒子数密度差异较大,且沿通道没有显示规律性变化,通道压强从零点几到几兆帕.     

STUDY ON RAINFALL MEASUREMENT AND RAINDROP SPECTRA WITH THE DIFFERENTIAL REFLECTIVITY Z_(DR)TECHNIQUE OF A DUAL LINEAR POLARIZATION RADAR

In this paper,it is shown that the differential reflectivity Z_(DR) is related to drop sizedistribution(DSD)and the spectral shape variation of different truncated diameters.Z_(DR) is asensitive function to variation of DSD of the spectra.The effects of shape variation of DSD onrainfall can be deduced with a(Z_H,Z_(DR))dual-parameter technique,which is effective to improvethe accuracy of rainfall measurement and is of the priority of identifying large particles ofhydrometeors(especially hailstone)from the rain region.     

太阳、地磁、大气电扰动与天气、气候相关研究

从日际,年际及世纪尺度统计分析了太阳活动与大气电参数及气象参数之间的相关性及其可能机制,结果表明,太阳活动与全球气温,云量,ＡＶＩ、雷暴及平流层工之间有很好的相关性。     

北京地区雷暴的雷达回波特征与闪电活动的相关关系

基于雷达资料以及SFAIR 3000闪电定位资料分析了北京地区14次雷暴过程,研究了闪电活动与雷暴的雷达回波反射率体积的相关性。结果表明：反射率体积与总闪频次有着较好的相关性,其中-15℃层以上超过30 dBz的反射率体积与总闪频次的相关系数为0.89,其指数拟合优度为0.83。北京地区雷暴的单个闪电表征回波体积（VPF）在闪电活动开始时期有较高的水平,但在闪电活动结束时期较小。VPF还可作为闪电活动消亡的指示因子。