GEM: Solar Wind Triggering, Periodicity, and Evolution of Sawtooth Events During Magnetic Storms

GEM：磁暴期间太阳风的触发、周期性和锯齿事件的演化

• 批准号: 1003652
• 负责人: William Burke
• 金额: $ 27.6万
• 依托单位: Boston College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-15 至 2013-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1003652&HistoricalAwards=false
• 关键词: GEM; Solar; Wind; Triggering; Periodicity

Sawtooth events in the Earth?s magnetosphere are global, large-amplitude oscillations of energetic plasma particle fluxes at geosynchronous orbit. Sawtooth events are one of the primary magnetospheric modes during extreme solar wind driving periods cause large disturbances in the magnetosphere and ionosphere. It is thought that sawtooth events are periodic intense magnetospheric substorms. There are still a number of questions concerning sawtooth events that remain to be answered: (1) Under what magnetospheric condition can a solar wind change trigger substorm onset? (2) How does the magnetospheric convection near sawtooth onset vary with the solar wind? (3) What are the loading and unloading rates of the magnetotail magnetic flux during sawtooth oscillations? (4)? Can the effective scale length of the dayside magnetopause reconnection line be derived? (5) What determines the period of sawtooth oscillations? (6) Can the evolution of the magnetotail magnetic flux be calculated simply from the solar wind input? This project will use statistical analyses, as well as case studies, to examine these questions. The project will use a new method to determine the effective scale length of the dayside magnetopause reconnection line during sawtooth events and to determine how this scale length varies with the solar wind. The solar wind parameters will be used as input to calculate the evolution of the magnetotail/polar cap magnetic flux during sawtooth events. The new methods for determining the scale length of the reconnection line, and the evolution of magnetic flux in the magnetotail will provide guidance for similar studies of isolated substorms. The empirical formulas of the magnetospheric parameters have the potential to be useful in forecasting and nowcasting of space weather events.

地球上的锯齿事件？的磁层是全球性的，大振幅振荡的高能等离子体粒子通量在地球同步轨道。锯齿波事件是极端太阳风驱动期间磁层的主要模式之一，在磁层和电离层中引起大的扰动。磁层亚暴被认为是周期性的强磁层亚暴。关于亚暴事件，还有一些问题有待回答：（1）在什么样的磁层条件下太阳风的变化能够触发亚暴的发生？ (2)磁暴起始附近的磁层对流是如何随太阳风变化的？ (3)在磁尾振荡期间，磁尾磁通量的加载和卸载速率是多少？ (4)?向阳面磁层顶重联线的有效标度长度能导出吗？ (5)是什么决定了周期振荡的周期？ (6)磁尾磁通量的演化能简单地从太阳风输入计算出来吗？ 本项目将利用统计分析和个案研究来审查这些问题。 该项目将使用一种新的方法来确定太阳风事件期间昼侧磁层顶重联线的有效尺度长度，并确定这一尺度长度如何随太阳风而变化。太阳风参数将被用作计算磁尾/极帽磁通量在磁尾事件期间演变的输入。 确定重联线尺度长度和磁尾磁通量演化的新方法将为孤立亚暴的类似研究提供指导。磁层参数的经验公式在空间天气事件的预报和临近预报中具有潜在的实用价值。