Insolation and Magnetospheric-Ionospheric Coupling: Three Problems

Johns Hopkins University, Baltimore MD

Investigators

Abstract

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.