Insolation and Magnetospheric-Ionospheric Coupling: Three Problems

国际和平研究所建议调查三个有理由怀疑电离层强烈影响以前被认为完全由磁层驱动的现象的具体问题。在每一种情况下，紫外线照射都会改变电离层(通过增加电导率，或通过增加极地风流)，这反过来可能会改变现象。这三个问题中的第一个问题是，强烈的极光是否像先前确定的那样，不仅受到当地电离层传导性的影响，而且还受到对半球传导性的影响。如果南半球的电导率确实影响了北半球强烈极光的形成，反之亦然，那么电离层电导率对空间天气的影响比之前认为的要大得多。第二个问题是与极地风有关的流出和从遥远的磁层(最终是太阳风)流入的极地雨之间可能存在耦合。在每一种情况下，电子的更大的迁移率都会导致产生与电子流相反的电场，但在相反的意义上。由于受紫外线辐射驱动的极地风通量远大于极地降水通量，很可能相互作用的主要方向是，当极地风较大时，极地雨将被驱动到较高的通量。这可以通过确定极地雨在紫外线照射越高时是否更强来相对容易地进行检查。第三个问题是电离层传导性是否影响扩散极光(和/或极光粒子总降水强度)。人们普遍认为，漫射极光代表了等离子体片的直接倾倒，没有明显的理由表明它会受到来自太阳辐射的电离层传导性的很大影响。然而，令空间物理界许多人惊讶的是，离散的极光受到阳光的抑制。最近的一些文献报告中有一些反常现象，这表明值得调查的是，等离子体片的“直接倾倒”是否真的独立于电离层的照射。

The PI's propose to investigate three specific problems for which there is reason to suspect that the ionosphere strongly influences phenomena previously thought to be driven solely by the magnetosphere. In each of these cases, UV insolation alters the ionosphere (through increasing conductivity, or through increasing polar wind outflows), which in turn may alter the phenomena. Each problem is expected to be solved in about one year with part time effort, yet yield worthwhile results.The first of the three problems is whether intense aurora are affected not only by local ionospheric conductivity, as previously determined, but also by conductivity in the opposite hemisphere. If it is true that southern hemisphere conductivity affects the formation of intense aurora in the northern hemisphere and vice versa, then the influence of ionospheric conductivity has a far more global influence on space weather than previously believed.A second problem is the possible coupling between the outflows associated with polar wind and the inflows from the distant magnetosphere (and ultimately solar wind) of the polar rain. In each case, the greater mobility of electrons leads to the creation of electric fields opposing electron flows, but in the opposite sense. Because the polar wind fluxes, driven by UV insolation, far exceed polar rain fluxes, it is likely the major direction of interaction is that when the polar wind is larger, the polar rain will be driven to higher fluxes. This can be relatively easily checked by determining whether polar rain is more intense when UV insolation is higher.The third problem is whether ionospheric conductivity affects the diffuse aurora (and/or total auroral particle precipitation intensity). It is widely assumed that the diffuse aurora represents a direct dumping of the plasma sheet, and there is no obvious reason why it should be much affected by ionospheric conductivity from insolation. However it surprised much of the space physics community to learn that discrete aurora are suppressed by sunlight. There are some anomalies in recent reports in the literature which suggest that it would be well worthwhile investigating whether the "direct dumping" of the plasma sheet really is indeed independent of the insolation of the ionosphere.