EAGER: Transformative Modeling Studies of Magnetosphere-Ionosphere/Thermosphere System

EAGER：磁层-电离层/热层系统的转换模型研究

• 批准号: 1559717
• 负责人: Paul Song
• 金额: $ 29.67万
• 依托单位: University of Massachusetts Lowell
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-15 至 2017-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1559717&HistoricalAwards=false
• 关键词: EAGER; Transformative; Modeling; Studies; Magnetosphere

The space environment surrounding the Earth is extremely dynamic, responding rapidly to the changing plasma and electromagnetic fields arriving from the Sun. Storms in space can trigger explosively (like earthquakes and volcanoes), driving strong electric currents through the upper atmosphere, which induce currents in the solid earth that can disrupt power grids; redistributing the charged particles within the embedded layers of the ionosphere, which can interfere with GPS navigation systems; and heating the upper atmosphere, which increases drag degrading the orbits of satellites. Global models of the high-altitude geospace environment are electromagnetic in nature and can follow these rapid changes in the magnetic fields and currents surrounding Earth, not so models of the magnetically coupled lower altitude ionosphere/upper atmosphere, which are electrostatic in nature. This proposal is focused on the development of a first-of-its-kind global electromagnetic model of the ionosphere/upper atmosphere system that, if successful will ultimately be incorporated into next-generation space weather models. This project is appropriate for the EAGER program. It is high risk but the reward, if it succeeds, is a new generation of global magnetosphere-ionosphere models that could potentially change views on some of the most fundamental aspects of the coupling between space and the upper atmosphere during the rapid onset of disturbances and possibly trigger new discoveries by supplying predictions of other effects to search for in the observations. The results will ultimately improve capabilities for space weather prediction and are potentially of interest to the study of planetary atmospheres, accretion disks, nebula, and the interstellar medium. The training of a graduate student at the University of Massachusetts-Lowell on this grant is an excellent means of transferring knowledge about this complex numerical methodology to the next generation of space scientists and is a near-term broader impact.Present models of the ionosphere-thermosphere assume that the magnetic field close to Earth is constant. But fast time-scale processes like explosive auroral activity are not correctly represented unless the changes in the magnetic field produced by electric currents closing through the ionosphere are solved for self-consistently. A major impediment to developing such a model using present explicit numerical algorithms has been the intractably short time steps (as short as 1 millionth of a second at 100 kilometers altitude) required to maintain stability of the solution, which dictate unrealistically long computer run times in order to follow the evolution of the system. The PI is implementing new numerical technology not widely known in the geospace community based on implicit algorithms that enable the use of much longer time steps, and also optimizing the model to run on high-performance computers. The new electromagnetic model will then be used in a number of numerical experiments to explore controversial features of rapidly developing disturbances in the coupled geospace - upper atmosphere system.

地球周围的空间环境极其动态，对来自太阳的不断变化的等离子体和电磁场迅速作出反应。太空中的风暴可以爆炸性地触发（如地震和火山），通过高层大气驱动强电流，这会在固体地球中感应电流，从而破坏电网;重新分配电离层嵌入层内的带电粒子，这可能会干扰GPS导航系统;加热高层大气，这会增加阻力，降低卫星轨道。高空地球空间环境的全球模型是电磁性质的，可以跟踪地球周围磁场和电流的这些快速变化，而低空电离层/高层大气磁耦合模型则不然，后者是静电性质的。该建议侧重于开发第一个电离层/高层大气系统全球电磁模型，如果成功，该模型最终将被纳入下一代空间气象模型。该项目适合EAGER计划。 这是一项高风险的工作，但如果成功的话，其回报是新一代的全球磁层-电离层模型，这些模型有可能改变人们对空间与高层大气之间在扰动迅速发生期间相互作用的一些最基本方面的看法，并可能通过提供对观测中可寻找的其他效应的预测而引发新的发现。这些结果将最终提高空间天气预测的能力，并对行星大气、吸积盘、星云和星际介质的研究具有潜在的意义。 利用这一赠款在马萨诸塞州洛厄尔大学培训一名研究生是向下一代空间科学家传授关于这一复杂的数值方法的知识的一个极好的手段，并且是近期的一个更广泛的影响。 但是，快速的时间尺度的过程，如爆炸性极光活动是不正确的，除非通过电离层电流关闭所产生的磁场的变化是解决了自洽。使用目前的显式数值算法开发这样一个模型的一个主要障碍是难以处理的短时间步长（在100公里的高度短至百万分之一秒），以保持解决方案的稳定性，这决定了不切实际的长计算机运行时间，以遵循系统的演变。PI正在实施新的数值技术，该技术在地球空间社区中并不广为人知，它基于隐式算法，可以使用更长的时间步长，并优化模型以在高性能计算机上运行。 新的电磁模型将用于一些数值实验，以探索地球空间-高层大气耦合系统中快速发展的扰动的有争议的特征。