Statistical Evaluation of the Solar Wind Control of the Large-scale Birkeland Currents

磁层及其与电离层的耦合非常复杂且动态。使用全球磁流体动力学（MHD）模型的全球尺度物理模拟是用于研究该系统的主要工具之一，建立模拟再现自然系统行为的程度对于评估我们的预测能力至关重要。全球的配置和能量传输率反映在电流流动沿着磁层和电离层之间的磁力线。这些电流，被称为伯克兰电流，可以使用铱通信卫星以及其他卫星（如国防气象卫星计划（DMSP），丹麦奥斯特卫星和德国CHAMP（CHAllenging Minisatellite Payload）卫星）观测到的磁扰动来观测。这个项目将定量地比较观测到的电流系统与MHD模拟的结果。 有两项主要任务。第一步是确定控制物理参数，如太阳风携带的行星际磁场和太阳极紫外线（EUV）辐射产生的电离层电导的Birkeland电流分布和强度的定量依赖关系。第二步将是评估仿真如何捕捉电流对系统驱动器的依赖性。自1999年2月以来，已从70多颗低空极轨道铱卫星星座获得了磁强计数据。在这段时间里，DMSP、Oersted和CHAMP卫星的磁场观测也是可用的。使用所有这些数据来推导全球Birkeland电流分布的方法已经到位。从1999年到现在，该项目将使用大约1000个具有稳定太阳风条件的间隔。在数据分析工作的同时，该项目将使用磁流体动力学模拟，其中包括内磁层中环电流的影响，以模拟电流。这些模拟将在社区协调建模中心使用密歇根大学和莱斯大学开发的空间气象建模框架进行。将统计模型与模拟进行比较，将有可能定量地确定模拟在多大程度上反映了太阳风-磁层-电离层相互作用对物理参数的依赖性。

The magnetosphere and its coupling to the ionosphere is very complex and dynamic. Global-scale physics-based simulations using global magnetohydrodynamic (MHD) models are one of the principal tools used to study the system, and establishing the extent to which the simulations reproduce the behavior of the natural system is essential to assessing the state of our predictive capabilities. The global configuration and energy transport rate are reflected in the electric currents flowing along the lines of magnetic force between the magnetosphere and the ionosphere. These currents, referred to as Birkeland currents, can be observed using the magnetic perturbations observed by the Iridium communications satellites as well as other satellites such as those of the Defense Meteorological Satellite Program (DMSP), the Danish Oersted satellite and the German CHAMP (CHAllenging Minisatellite Payload) satellite. This project will quantitatively compare the observed current systems with the results of MHD simulations. There are two primary tasks. The first step is to determine the quantitative dependencies of the Birkeland current distributions and intensities on the controlling physical parameters, such as the interplanetary magnetic field carried by the solar wind and the ionospheric conductance generated by solar Extreme Ultraviolet (EUV) radiation. The second step will be to evaluate how well the simulations capture the dependencies of the currents on the system drivers. Magnetometer data from the constellation of more than 70 low-altitude, polar-orbiting Iridium satellites has been acquired since February 1999. Magnetic field observations from the DMSP, Oersted, and CHAMP satellites are also available during this time. Proven techniques are in place to derive the global Birkeland current distributions using all of these data. The project will use approximately 1000 intervals from 1999 to the present having stable solar wind conditions. In parallel with the data analysis effort, the project will use MHD simulations that include the effects of the ring current in the inner magnetosphere to model the currents. These simulations will be run at the Community Coordinated Modeling Center (CCMC) using the Space Weather Modeling Framework developed at the University of Michigan and Rice University. The comparison of the statistical model with the simulations will make it possible to determine quantitatively how well the simulations capture the dependence of the solar wind-magnetosphere-ionosphere interaction on the physical parameters.