GEM: Substorm Physics in the GEM Geospace General Circulation Model: Linking a Tail-Dynamics Module with the Rice Convection Model

这是一项为期三年的研究计划，旨在调查新发现的用于离子能量和传输的电离层来源的性质。离子激发是磁层物理学中最重要的话题之一，因为离子携带了大部分的粒子能量，因此在环境的形成中发挥了核心作用。拟议的计划直接解决了离子能化最令人困惑的问题之一--即重(O+)离子是如何在电离层的低海拔加速并大量向上输送到磁层的？这一问题至关重要，因为(1)在整个磁层中发现的O+离子的丰度需要某种方式将大量热离子从电离层向上输送，以及(2)在电离层低至400公里的高度观察到热离子上行和横向加速离子(TAI)。其他观测表明，至少存在一类TIU事件，其特征是没有离子摩擦加热和电子温度升高，这些特征不容易用已知的机制来解释。这些发现表明，负责向磁层输送大量陆地离子的过程尚未确定。我们最近描述了一种新的离子能源Tsunoda和Kagan，1995，它似乎是缺失的机制。新的源由洛伦兹力组成，这种力是由于扰动磁场的存在而产生的，例如，与大规模场对齐电流系统相关的扰动磁场。这种微扰磁场与纬度压力梯度或电流(相互垂直，横向于B)共同作用，在平行或反平行于B的方向上产生洛伦兹力。正如Tsunoda和Kagan 1995年所描述的那样，在这个提议中，这种机制能够解释在没有离子加热的情况下发生的一类TIU事件。然而，更令人兴奋的是，这些场排列的洛伦兹力有可能解释一些相关但仍然令人费解的观测结果，包括(1)离子加热产生的TIUS，(2)分子离子向磁层的输运，(3)离子回旋和离子声不稳定性的触发，(4)离子静电回旋波的横向加速，(5)离子声湍流和异常电阻率的发展，以及(6)向上场排列电流区的电子温度升高。鉴于场排列的洛伦兹力有可能解释各种与离子加速有关的现象，将对一个更大的非相干散射雷达数据数据库进行调查，以确定观测是否支持这一新理论的预测。

This is a three-year research program to investigate the nature of a newly discovered ionospheric source for ion energization and transport. The topic of ion energization is one of paramount importance in magnetospheric physics because ions carry the bulk of the particle energy and thereby play a central role in the molding of that environment. The proposed program directly addresses one of the most puzzling problems of ion energization - that is, how are heavy (O+) ions accelerated at low altitudes in the ionosphere and transported upward in large numbers to the magnetosphere? This question is crucial because (1) the abundance of O+ ions found throughout the magnetosphere requires some means by which large fluxes of thermal ions are transported upward from the ionosphere, and (2) thermal-ions upflows (TIU) and transversely accelerated ions (TAI) have been observed at altitudes as low as 400 km in the ionosphere. Other observations have demonstrated the existence of at least one class of TIU events that is characterized by the absence of ion frictional heating and the presence of elevated electron temperature, features that cannot be easily explained by known mechansims. These findings indicate that the process responsible for the transport of large fluxes of terrestrial ions to the magnetosphere has not yet been identified. We have recently described a new, ion energization source Tsunoda and Kagan, 1995 that appears to be the missing mechanism. The new source consists of Lorentz-type forces that arise because of the presence of a perturbation magnetic field, for example, that associated with a large-scale field-aligned current system. This perturbation magnetic field acts together with a latituinal pressure gradient or current (directed orthogonal to one another and transverse to B ) to produce a Lorentz-type force in a direction parallel or antiparallel to B . As described by Tsunoda and Kagan 1995 , and in this proposal, this mechanism is capable o f accounting for the class of TIU events that occur without ion heating. More exciting however, is the likelihood that these field-aligned Lorentz forces can account for a number of related but stil puzzling observations including (1) TIUs produced by ion heating, (2) the transport of molecular ions into the magnetosphere, (3) the triggering of the ion-cyclotron and ion- acoustic instabilities, (4) the transverse acceleration of ions by electrostatic ion-cyclotron waves, (5) the development of ion- acoustic turbulence and anomalous resistivity, and (6) elevated electron temperatures in upward field-aligned current regions. Given the potential of field-aligned Lorentz forces for explaining a variety of ion-acceleration-related phenomena, an investigation of a larger database of incoherent scatter radar data will be undertaken of determine if the observations support the predictions of this novel theory.