Space Weather: Solar Wind/Magnetospheric Controls of Substorm Onset and Dynamics

本项目的主要目的是利用极光椭圆位置分析技术研究亚暴扩展阶段的触发机制和不同亚暴阶段的时间尺度。将要解决的问题是：(1)对流减少是否会引发亚暴（例如IMF向北转向）？(2)磁层压缩（例如风暴突然开始）是否会引发亚暴？(3)亚暴时间尺度的决定因素是什么？(4)生长阶段参数能否预测亚暴特征？这些问题对国家空间天气计划尤为重要。所采用的方法需要进行大量的统计研究。在ISTP任务期间，极地卫星上的紫外线成像仪（UVI）获得的大量（~数千万）全球极光图像将解决这些问题。除了图像之外，还汇编和分析了Geotail、wind和IMP-8航天器的太阳风等离子体和磁场观测数据，LANL系列地球同步卫星的高能粒子数据，GOES地球同步卫星和地面的磁力计数据，以建立具有统计意义的结果。这项为期三年的工作包括亚暴事件的识别和选择，极光特征提取（极帽和椭圆形位置以及极光功率），以及相关性分析。该项目将研究极地帽大小、椭圆边界位置（极地方向和赤道方向）以及极光发生前后的极光功率的时间变化，以确定导致膨胀期开始的条件。此外，它将把行星际冲击与极光爆发联系起来，并提供亚暴不同阶段的时间尺度分析。所有数据产品，包括开始列表和次风暴电影，以及已发表的结果（期刊重印），将应要求通过网络和cd - rom提供给一般社区。

The primary objectives of this project are to investigate triggering mechanisms of substorm expansion phase onset and time scales of different substorm phases by using the technique of auroral oval positional analysis. The questions that will be addressed are: (1) Can reductions in convection trigger substorms (e.g. northward turning of the IMF)? (2) Can magnetospheric compression (e.g. Storm Sudden Commencements) trigger substorms? (3) What determines substorm times scales? (4) Can growth phase parameters predict substorm characteristics? These issues are of particular importance to the National Space Weather Program. The method to be used involves a massive statistical study. A large number (~ tens of millions) of global auroral images acquired from the ultraviolet imager (UVI) aboard the Polar satellite during the ISTP mission will address these questions. In addition to the images, solar wind plasma and magnetic field observations from the Geotail, Wind, and IMP-8 spacecraft, energetic particle data from the LANL series of geosynchronous satellites, magnetometer data from the GOES geosynchronous satellites and from the ground are compiled and analyzed to establish statistically meaningful results. This three-year effort includes substorm event identification and selection, auroral feature extraction (polar cap and oval location and auroral power), and correlation analysis. This project will investigate the temporal variations of the polar cap size, the oval boundary locations (both poleward and equatorward), and auroral power before and after auroral onsets to determine conditions that lead to the expansion phase onset. In addition, it will correlate interplanetary shocks with auroral onsets and provide a time-scale analysis of the different phases of substorms. All data products, including an onset list and substorm movies, as well as published results (journal reprints), will be made available to the general community through the web and CD-ROMs upon request.