磁尾等离子体片粒子注入与环电流形成关系的研究

Understanding the formation and development of the ring current in the terrestrial inner magnetosphere is crucial for studying magnetic storms. Particle injections from the magnetotail plasma sheet have been believed to be the main source of the ring current during storm times, and it has been one of the most focused topics in space physics research how plasma sheet particles are injected into the ring current. As two major mechanisms of plasma sheet injections,whether they are driven by the variations of solar-wind-driven convection electric field or by the magnetotail dynamics, e.g., substorms, Bursty Bulk Flows, and Dipolarization Fronts, is the key question. The simultaneous observations of the inner magnetosphere and the transient and localized tail dynamics provied by recent Radiation Belt and Storm Probes (RBSP) and magnetosphere probes such as THEMIS, Cluster, give us an unpercented opportunity to approach this question. This project plans to the near-Earth tail observations from THEMIS and Cluster and the inner magnetosphere observations from RBSP satellites to study: (1) the characteristics and physical mechanisms of particle injections caused by magnetotail dynamics; (2) the relative contribution to the ring current buildup from the large-scale convection electric fields and the transient inductive electric fields associated with particle injections; (3) the effects of particle injections to the ring current and the Dst index under various solar wind and IMF conditions. With the numerical study of the global magnetosphere model, OpenGGCM, we will be able to provide more insights to the physical processes of the formation and evolution of the ring current during magnetic storms.

地球内磁层环电流的形成和演化是研究磁暴的核心问题。暴时环电流的粒子主要来自磁尾等离子体片，但其进入环电流的物理机制是国际上争论的焦点之一。由太阳风驱动的磁层对流电场变化和磁尾动力学过程（如亚暴、BBF、DF）是环电流粒子注入的两个可能机制，而争论的焦点是哪类机制起主导作用。近期的辐射带双卫RBSP结合THEMIS、Cluster等磁尾探测项目可以实现对内磁层环电流和磁尾短时小尺度动力学过程的联合同步观测，为研究这一问题提供了良好的机会。本项目拟利用THEMIS、Cluster等磁尾卫星和内磁层RBSP卫星，研究（1）磁尾等离子体片动力学过程造成的粒子注入特征和机制；（2）与粒子注入相关的对流电场变化和小尺度感应电场对环电流影响的相对贡献；（3）不同条件下粒子注入影响环电流及Dst指数的物理机制。结合全球磁层模型OpenGGCM的数值模拟研究，我们可以较为全面地揭示暴时环电流形成和演化机制。