Interaction of Lightning Electromagnetic Pulse with the Ionosphere

闪电对地面的影响是显而易见的，比如当一棵树被击中时。在另一个方向上，闪电也会对被称为电离层的高层大气层产生影响。电离层位于地球表面之上，受到太阳辐射的强烈影响。从人类的角度来看，电离层的实际影响之一是电离层在影响无线电波传播方面的作用。研究已经确定，闪电可以通过被称为精灵、光晕和精灵的扰动来影响电离层。由该奖项资助的研究将集中在闪电对降低电离层高度的影响上。该奖项将资助一名研究生，以促进下一代科学家的发展。研究人员建议在白天和夜间的条件下，检查单个闪电中电离层反射高度变化的不同模式。这将需要获取额外的数据（至少数百个事件），特别是在夜间。研究人员预计，许多观测到的效应受到闪电放电强度的影响。这项工作将包括对精灵建模的尝试，以解释反射高度的推断降低。还将研究许多其他问题：(1)反射高度的变化作为引起返回冲程峰值电流和前冲程间隔的函数，(2)第一个天波和地波的大小之间的相关性，以及(3)致密云内放电对电离层反射高度的影响（当它们成对发生时）。研究人员还将寻找E场频谱的差异，这可能归因于推断的有效反射高度的差异。

The effect of lightning at the ground is obvious, such as when a tree is struck. In the other direction, lightning also can have an impact on the layer of the upper atmosphere known as the ionosphere. The ionosphere is high above the Earth's surface and is strongly affected by solar radiation. One of the practical impacts of the ionosphere from the human perspective is the ionosphere's role in affecting the propagation of radio waves. Studies have determined that lightning can affect the ionosphere through perturbations known as elves, halos, and sprites. The research funded by this award will focus on the impact that lightning has on lowering the height of the ionosphere. A graduate student will be funded by this award, furthering the development of the next generation of scientists.The researchers propose to examine the occurrence of different patterns in ionospheric reflection height change within individual lightning flashes under both daytime and nighttime conditions. This will require acquisition of additional data (at least several hundreds of events), particularly at night. The researchers expect that many observed effects are influenced by lightning discharge intensity. The work will contain an attempt at modeling elves in order to explain the inferred lowering of the reflection height. A number of other issues will also be examined: (1) changes in reflection height as a function of causative-return-stroke peak current and preceding interstroke interval, (2) correlation between magnitudes of the first sky wave and ground wave, and (3) effect on ionospheric reflection height of compact intracloud discharges (in cases when they occur in pairs). The researchers will also search for differences in E field frequency spectra that could be attributed to the inferred differences in effective reflection heights.