Collaborative Research: GEM--Impact of Solar Wind Dynamic Pressure Enhancement on the Cusp and Polar Cap Ion Source

电离层外流离子是地球空间环境的主要粒子源之一。它们在地球同步轨道内区域的动态在空间天气扰动中起着至关重要的作用，其影响包括卫星阻力、通信和导航系统中断以及破坏电网。该项目的重点是了解来自太阳的驱动因素之一，地球空间的太阳风压缩，如何产生这些流出离子及其传输的物理过程。压缩通常可以是强烈的和脉冲的，但我们目前对由此产生的流出离子的观测和模拟知之甚少。该项目将建立空间界迫切需要的这类知识，以提高我们对脉冲空间天气事件的预测能力。该项目通过提供平衡的任务来支持研究生的教育，以培养学生在模拟和数据分析方面的基本研究能力。该项目的科学目标是了解太阳风压缩如何影响流出离子。本文的主要目的和方法是：（1）研究星团卫星资料，以便更好地观测压缩引起的尖瓣和瓣叶离子通量的时间变化。(2)进行3D全局混合模拟，以评估由压缩引起的流出离子背后的物理过程。混合模拟是目前最合适的工具，考虑到这些流出离子的动力学过程。模拟的目的是与观测结果进行比较，以建立坚实的物理理解。这也将改善我们目前的外流离子模型规格，最终可以纳入空间天气建模，以实现更好的预测太阳风压缩的影响。这一奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Outflow ions from the ionosphere are one of the major particle sources for the Earth's space environment. Their dynamics in the region inside the geosynchronous orbits play a crucial role in space weather disturbances, whose effects include satellite drag, disruption in communication and navigation systems, and damaging electric power grids. This project is focused on understanding the physical processes of how one of the drivers from the Sun, solar wind compression of the geospace, generates these outflow ions and their transport. The compression can often be strong and impulsive, but we currently have little knowledge in both observations and simulations on the resulting outflow ions. This project will establish such knowledge, which is urgently needed in the space community to improve our forecast ability for impulsive space weather events. This project supports the education of a graduate student by providing balanced tasks for developing the student's essential research ability in both simulations and data analysis.The science goal of this project is to understand how solar wind compression impacts outflow ions. The two main objectives and methods are (1) Investigating Cluster satellite data to establish a better observational understanding of temporal variations of the ion fluxes in the cusp and lobes resulting from the compression. (2) Conduct 3D global hybrid simulations to evaluate the physical processes behind the outflow ions caused by the compression. The hybrid simulation is currently the most appropriate tool to take into account the kinetic processes of these outflow ions. The simulations are designed to be compared with the observation results to establish a solid physical understanding. It will also improve our current model specification of the outflow ions that can eventually be incorporated into space weather modeling to achieve a better forecast of the impact of solar wind compression.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.