NSWP: Improving Quantitative Modeling of High-latitude Electrojet Conductivities during Magnetic Storm and Substorm Time

该项目旨在通过开发扰动条件下电喷流电导率的准确模型来提高空间天气预报能力。在强烈的地磁活动期间，沿磁力线的大电流会导致强电喷流、等离子体不稳定性和湍流的形成。这种湍流引起了强烈的反常电子加热和非线性输运，这对E区的电导率有很大影响。现有的电离层模型不包括这些影响。这限制了他们对空间天气预报所必需的磁暴和亚暴进行精确建模的能力。因此，该项目的目标是开发一个电离层电导模块，该模块将预测磁暴和亚暴期间的非线性电流和异常电子加热。该模块将由查找表和/或解析表达式组成，它将返回一系列海拔、纬度、驱动电场以及等离子体和中性大气条件的E区电导率矩阵。该项目将执行三项任务：(1)对异常电子加热和非线性电流进行定量建模；(2)建立一个考虑湍流效应的电导率数据库；(3)测试现有磁层和电离层模拟代码和模型中修改后的电导率。三维E区湍流的超级计算机模拟将与现代理论分析相结合，以确定加热和导热系数。电子加热的预测将使用非相干散射雷达和火箭数据进行验证，而预测的电离层磁场和电流将与磁强计和SuperDARN数据进行验证。为了使结果有用和可用，将把它们纳入Lyon-Fedder-Mobary(LFM)磁层模拟程序和磁层-电离层-热层模型(CMIT)，这是磁层/电离层社区广泛使用的两个程序。升级后的LFM和CMIT的结果将与未修改的代码和观测结果进行测试。需要解决的具体科学问题是：高纬度电离层对强对流电场的非线性反应是什么？为什么观测到的风暴时跨极帽位势往往比现有模型预测的要小？湍流引起的电导率变化是主要还是完全解释了模型未能解释观测的原因？

The project aims to improve space weather prediction capabilities by developing an accurate model of electrojet conductivity under disturbed conditions. During periods of intense geomagnetic activity, large currents along the magnetic field lines can induce the formation of strong electrojets, plasma instabilities, and turbulence. This turbulence gives rise to intense anomalous electron heating and nonlinear transport which significantly affects the E-region conductivity. Existing ionospheric models do not include these effects. This limits their ability to accurately model magnetic storms and substorms essential for space weather predictions. Accordingly, the objective of this project is to develop an ionospheric-conductance module which will predict nonlinear currents and anomalous electron heating during magnetic storms and substorms. This module will consist of a look-up table and/or analytic expressions which will return the E-region conductivity matrix for a range of altitudes, latitudes, driving electric fields, and plasma and neutral atmospheric conditions. The project will undertake three tasks: (1) quantitative modeling of anomalous electron heating and nonlinear currents; (2) creation of a conductivity database which accounts for turbulent effects; and (3) testing the modified conductivities in existing magnetosphere and ionosphere simulation codes and models. Supercomputer simulations of 3D E-region turbulence combined with modern theoretical analyses will be applied to determine the heating and conductivities. The predictions of electron heating will be validated using incoherent scatter radar and rocket data, while the predicted ionospheric fields and currents will be tested against magnetometer and SuperDarn data. In order to make the results useful and available, they will be incorporated into the Lyon-Fedder-Mobary (LFM) magnetosphere simulation code and the magnetosphere-ionosphere-thermosphere model (CMIT), two codes that are widely used by the magnetosphere/ionosphere community. The results of the upgraded LFM and CMIT will be tested against the unmodified codes and observations. Particular science questions to be addressed are: What is the nonlinear response of the high-latitude ionosphere to strong convection electric fields? Why is the observed storm-time cross-polar-cap potential often smaller than that predicted by existing models? Do the turbulence generated changes in conductivities mostly or fully account for the reason that models fail to account for observations?