The charges that are deposited by cloud-to-ground lightning in Florida
The charges that are deposited by cloud-to-ground lightning in Florida
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佛罗里达州云对地闪电沉积的电荷
DOI：
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发表时间：
1986
期刊：
影响因子：
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通讯作者：
E. Krider
中科院分区：
文献类型：
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作者：
L. Maier;E. Krider
来自美国宇航局肯尼迪航天中心的电场磨网的数据已被计算机分析，以确定电荷模型的参数，该模型描述了由云对地闪电引起的云电荷分布的净变化的位置和大小。结果仅限于可以用点电荷模型描述的相对较大的事件，即在三个或更多地点产生至少1 kV m−1的场变化的放电，并且具有足够的空间对称性来拟合模型。努力的重点是确定不同但可比较的事件的高度和强度如何随闪电而变化，在风暴的整个演变过程中，以及从风暴到风暴。1976年、1977年和1978年7次中小型雷暴的结果表明，X、Y位置倾向于聚集在总尺寸为5km或更小的单元中，并且海拔高度在一天中的每闪之间都是惊人的恒定。不同风暴日产生的平均海拔在6.9 km（−14°C）到8.8 km（−26°C）之间，标准差通常小于平均值的20%。在不同的日子里沉积的电荷的平均值从11摄氏度到44摄氏度不等，标准偏差通常是平均值的50%。两个小风暴的电荷在5分钟内增加了80%或更多，并在闪电速率降低时达到峰值。假设闪电在网络上的不同位置沉积了扁平和水平的电荷盘，模拟了非球形电荷几何形状拟合点电荷模型可能导致的电荷参数误差。当圆盘半径小于等于5km时，不同圆盘位置X-Y位置误差的标准差小于2km。不同位置的盘电荷值和高度误差的标准差分别小于平均值的20%和10%；但是，当光盘离开网络时，电荷会有系统的增加，高度会降低。
Data from a network of electric field mills at the NASA Kennedy Space Center have been computer analyzed to determine the parameters of a charge model that describes the locations and magnitudes of the net changes in the cloud charge distribution that are caused by cloud-to-ground lightning. The results are limited to relatively large events that can be described by a point-charge model, i.e., discharges that produced field changes of at least 1 kV m−1 at three or more sites and that have enough spatial symmetry to fit the model. The focus of effort has been to determine how the altitudes and magnitudes of different but comparable events vary from flash to flash, throughout the evolution of a storm, and from storm to storm. The results for seven small to medium thunderstorms in 1976, 1977, and 1978 indicate that the X, Y locations tend to cluster in cells with an overall dimension of 5 km or less and that the altitudes are surprisingly constant from flash to flash and throughout the day. Different storm days produced mean altitudes that range from 6.9 km (−14°C) to 8.8 km (−26°C), and the standard deviations are usually less than 20% of the mean. The average values of the charges that are deposited on different days range from 11 C to 44 C, and the standard deviations are typically 50% of the mean. The charges in two small storms exhibited 5-min running means that increased by 80% or more and peaked as the lightning rate was decreasing. Errors in the charge parameters that might be caused by a nonspherical charge geometry fitting the point-charge model were simulated by assuming that the lightning deposited a flat and horizontal disc of charge at various locations over the network. For disc radii of 5 km or less the standard deviation of the X-Y position error at different disc locations was less than 2 km. The errors in the disc charge values and altitudes at different locations had standard deviations that were less than 20% and 10% of the means, respectively; but there was a systematic increase in the charge and a lowering of the height when the disc moved off the network.