GEM: Evolution of Plasmasphere, Plumes and Fine Structure

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。该项目将收集来自5个不同卫星任务（OGO-5、ISEE-1、CRRES、Polar和IMAGE）的等离子层数量密度测量数据数据库。这些任务有互补的轨道，大约跨越4个太阳周期。等离子层侵蚀和恢复的周期取决于磁层强度的相对变化，也取决于上一次对流大变化的时间。因此，本项目将采用叠加历元时间分析。​该项目将创建一个等离子体密度的全球经验模型，包括羽流和精细结构，参数化由空间、选定的地磁指数、历元时间、太阳黑子数和季节。精细结构分析将通过从全球尺度分布中分离出那些尺寸低于预定义长度尺度的密度特征来完成。然后，精细结构将通过其对模型中使用的各种参数的依赖来表征。将模型结果与从LANL和DMSP航天器（两个未用于模型创建的任务）获得的数字密度进行比较，以验证模型。该模型将与来自5个任务数据库的具体案例研究一起使用，以检查等离子体羽流的随时间变化的形态，侵蚀等离子体的白天传输的细节，以及在传输过程中产生的精细尺度结构。等离子体羽流可以减缓白天的重联率（调节整个磁层的能量输入）。此外，整个等离子体层的密度分布和精细结构对散射高能粒子的波的生长、传播和有效性有重要影响。所有结果将公布并张贴在GEM Wiki网站上，以及西南研究院主办的镜像网站上。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This project will assemble a database of number density measurements in the plasmasphere from 5 different satellite missions (OGO-5, ISEE-1, CRRES, Polar, and IMAGE). The missions had complementary orbits and spanned roughly 4 solar cycles. The cycle of erosion and recovery of the plasmasphere depends on the relative changes of the strength of magnetospheric as well as on the time since the last major change in convection. Therefore, this project will employ a superposed epoch time analysis. Convection events ranging from mild to severely disturbed will be identified using an automated algorithm and epoch times will be assigned to all data. The project will create a global empirical model of plasmaspheric density that includes both plumes and fine-scale structure, parameterized by space, selected geomagnetic indices, epoch time, sunspot number, and season. Fine structure analysis will be done by isolating from the global-scale distribution those density features whose size falls below a pre-defined length scale. The fine structure will then be characterized by its dependences on the various parameters being used in the model. Comparisons of the model results with number densities obtained from LANL and DMSP spacecraft (two missions not used in the models creation) will be used to validate the model. This model will be used along with specific case studies from the 5-mission database to examine the time-dependent morphology of plasmaspheric plumes, the details of dayside transport of the eroded plasma, and the fine-scale structures that are created during the transport. Plasmaspheric plumes can slow down the dayside reconnection rate (modulating the energy input to the entire magnetosphere). In addition, the global density distribution, and the fine structure that prevails throughout the plasmasphere exert a significant influence upon the growth, propagation, and effectiveness of waves that scatter energetic particles. All results will be published and posted to the GEM Wiki website, and to a mirror site hosted by Southwest Research Institute.