Insolation and Magnetospheric-Ionospheric Coupling: Three Problems

日照和磁层-电离层耦合：三个问题

• 批准号: 0222411
• 负责人: Patrick Newell
• 金额: $ 23.69万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-02-01 至 2007-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0222411&HistoricalAwards=false
• 关键词: Insolation; Magnetospheric; Ionospheric; Coupling; Three

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.

PI 提议调查三个具体问题，有理由怀疑电离层强烈影响以前认为仅由磁层驱动的现象。在每种情况下，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出），这反过来又可能改变现象。每个问题预计将在大约一年内通过业余时间得到解决，但会产生有价值的结果。三个问题中的第一个问题是，强烈的极光是否不仅受到先前确定的局部电离层电导率的影响，而且还受到相反半球电导率的影响。如果南半球电导率确实影响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全球影响比以前认为的要大得多。第二个问题是与极地风相关的流出与极地雨的遥远磁层（最终是太阳风）的流入之间可能存在耦合。在每种情况下，电子的更大迁移率都会导致产生与电子流相反的电场，但方向相反。由于紫外线照射驱动的极地风通量远远超过极地雨通量，因此相互作用的主要方向可能是当极地风较大时，极地雨将被驱动到更高的通量。这可以通过确定当紫外线照射较高时极地雨是否更强烈来相对容易地检查。第三个问题是电离层电导率是否影响漫射极光（和/或总极光粒子降水强度）。人们普遍认为，漫射极光代表等离子体片的直接倾倒，并且没有明显的理由说明为什么它会受到日照电离层电导率的很大影响。然而，当得知离散极光被阳光抑制时，空间物理学界的许多人都感到惊讶。文献中最近的报告中有一些异常情况，这表明非常值得研究等离子体片的“直接倾倒”是否确实独立于电离层的日照。