Space Weather: Reconstruction of the Transverse Solar Wind Profile at 1 AU Using Basic Data Assimilation Techniques

地磁暴和由于太阳风条件的突然变化而引起的磁层特性的突然变化影响着地球上和轨道上的各种系统。例如，大的地磁暴可能中断无线电通信;增加管道和电网电流，改变高空大气阻力，影响低空卫星轨道。行星际压力事件，如行星际冲击压缩磁层，导致突然的脉冲，可以有足够高的地面磁场变化率，在技术系统中产生不利的电流量。在了解如何准确预测地球磁层状态的过程中，太阳风等离子体和行星际磁场的测量结果可作为经验和理论模型的主要输入参数。目前，模型、预测和一般科学只从太阳风中获取单个航天器的输入，尽管已知太阳风输入可能是高度不对称的，而且通常有多个太阳风监测器。因此，作者建议使用所有现有的太阳风监测器的数据，重建一个更有代表性的太阳风剖面磁层横截面使用现代的，自洽的磁流体动力学（MHD）数据同化技术。此外，他们还提议比较根据由此开发的同化多点测量结果和目前采用的单点上游观测结果对真实的磁层事件的预测，并对改进进行量化。拟议的同化技术将有助于在更完整地描述太阳风和更准确的空间气象预测的基础上更好地了解日地相互作用。研究结果（方法和代码都将公开提供）将有可能提高空间气象预测的准确性，并有助于科学界进行太阳风-磁层相互作用研究，特别是在太阳风/国际货币基金组织输入条件不对称的情况下。计划为拟议的工作开展国际和多机构合作（美国航天局/地球科学基金会、美国海洋大气局/欧洲空间委员会和捷克共和国布拉格的查尔斯大学）。

Geomagnetic storms and sudden changes of magnetospheric properties due to sudden changes in solar wind conditions affect a wide variety of systems on Earth and in orbit. For example, large geomagnetic storms can interrupt radio communications; increase pipeline and power grid currents and change high-altitude atmospheric drag affecting low-altitude satellite orbits. Interplanetary pressure events, like interplanetary shocks compressing the magnetosphere, lead to sudden impulses that can have a high enough rate of ground magnetic field change producing an adverse amount of current in technological systems. In developing an understanding how to accurately forecast the state of the Earth's magnetosphere, solar wind plasma and interplanetary magnetic field measurements serve as the primary input parameters to empirical and theoretical models. Currently models, predictions and general science take only single-spacecraft input from the solar wind even though it is known that the solar wind input can be highly asymmetrical and multiple solar wind monitors are often available. Therefore, the authors propose to use data from all available solar wind monitors to reconstruct a more representative solar wind profile across the magnetospheric cross-section using modern, self-consistent magnetohydrodynamic (MHD) data assimilation techniques. Furthermore, they propose to compare predictions for real magnetospheric events based on the thus developed assimilated multi-point measurements and on the currently employed single-point upstream observations and quantify the improvements. The proposed assimilation technique will allow the development of better understanding of the Sun-Earth interactions based on a more complete description of the solar wind and more accurate space weather predictions. The results (both method and code will be made publicly available) will have the potential to improve the accuracy of space weather predictions, and also to assist the scientific community in solar wind-magnetosphere interaction studies, especially for the case of asymmetric solar wind/IMF input conditions. An international and multi-institutional collaboration (NASA/GSFC, NOAA/SEC, and Charles University in Prague, Czech Republic) is planned for the proposed work.