Testing models of thunderstorm charge distributions with Coulomb's law
Testing models of thunderstorm charge distributions with Coulomb's law
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DOI：
10.1029/94jd02332
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发表时间：
1994-12
影响因子：
--
通讯作者：
M. Stolzenburg;T. Marshall
中科院分区：
文献类型：
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作者：
M. Stolzenburg;T. Marshall
通过将点电荷放置在200×200×100 m网格中，模拟了三维区域内的电荷分布，每侧10公里。电荷的位置是基于电场探测和高斯定律的一维近似。该模型利用库仑定律计算了所有点电荷及其对应的镜像电荷所产生的电场。该模型得到的垂直电场与观测场没有明显差别，也与无限大电荷层产生的电场基本相同。这些结果表明，一维高斯定律是近似有限层电荷密度的一种有效方法。对于x和y维从10公里降低到6公里的电荷区，模型的垂直电场几乎是相等的。因此，当使用典型的观察到的电荷密度时，在探测位置的两侧将电荷层延伸仅3公里就足以再现整个磁场。对于距离10×10 km模型区域边缘1公里的垂直路径，通过区域中心计算的垂直电场比其值减小了不到10%。这一发现意味着，观测到的电场分布可以远离电荷层的中心，并且仍然可以很好地近似它们的电荷密度和深度。在相对较短(小于2公里)的水平距离上，电荷密度需要相对较大的变化(约5倍)才能产生观测到的水平电场大小。
Charge distributions were modeled in a three-dimensional domain, 10 km on each side, by placing point charges in a 200 × 200 × 100 m grid. Charge locations were based on electric field soundings and the one-dimensional approximation to Gauss's law. The model calculates the electric field due to all the point charges and their corresponding image charges using Coulomb's law. Vertical electric fields from the model are not significantly different from the observed fields and are also nearly identical to fields resulting from infinitely extensive charge layers. These findings show that Gauss's law in one dimension is a valid method for approximating the charge density of finite layers. The model vertical electric fields are almost equivalent for charge regions that are reduced in x and y dimensions from 10 km to 6 km. Thus, extending charge layers for as little as 3 km on either side of the sounding location sufficiently reproduces the entire field when typical, observed charge densities are used. For a vertical path 1 km from the edge of the 10 × 10 km model domain, the calculated vertical electric field is reduced by less than 10% from its value through the center of the domain. This finding means that the observed electric field profile can be far from the center of the charge layers and still allow a good approximation of the their charge densities and depths. Relatively large changes (factor of about 5) in charge density over relatively short (less than about 2 km) horizontal distances are needed to produce observed magnitudes of horizontal electric fields.