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

本项目的主要目标是利用极光椭圆位置分析技术研究亚暴扩展相开始的触发机制和不同亚暴相的时间尺度。将要解决的问题是：（1）对流的减少会触发亚暴（例如IMF的北转向）吗？(2)磁层压缩（例如风暴突然开始）能触发亚暴吗？(3)什么决定亚暴时间尺度？(4)生长相参数能预测亚暴特征吗？这些问题对国家空间气象方案特别重要。使用的方法涉及大量的统计研究。在ISTP使命期间，从极地卫星上的紫外成像仪获得的大量（约数千万）全球极光图像将解决这些问题。除了图像外，还对Geotail、Wind和IMP-8航天器的太阳风等离子体和磁场观测、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进行了汇编和分析，以确定有统计意义的结果。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（极帽和椭圆的位置和极光功率），和相关性分析。该项目将调查极帽大小、椭圆边界位置（向极和向赤道）以及极光爆发前后极光功率的时间变化，以确定导致扩张阶段开始的条件。此外，它还将把行星际冲击与极光爆发联系起来，并对亚暴的不同阶段进行时间尺度分析。所有数据产品，包括发病名单和亚风暴电影，以及已发表的结果（期刊重印），将通过网络和光盘应要求提供给广大社区。

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.