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太阳风热流异常(HotFlow Anomalies,简称HFAs)是在地球弓激波附近发生频率较高的现象.本文利用Cluster卫星2003～2009年的数据,找出7年中观测到的765个HFA事件.本文采用个例分析方法研究HFA事件中心前后5min,进而采用时间序列叠加分析方法研究HFA事件中心前后100s中等离子体和磁场参数的变化.研究结果表明HFA事件按照动压随时间的增加、减少变化趋势可以分为“?+”(减小-增加),“+?”(增加-减小),“M”(增加-减小-增加)和“W”(增加-减小-增加-减小-增加)四类,其中字母表示其形状与动压变化趋势类似.其他参数变化趋势与动压的变化趋势高度相关,也相应呈现明显分类规律.此外,统计结果显示,HFA事件发生数量在不同年份有所差别,通过与太阳风速度和太阳黑子数的对比发现,事件数量与太阳风速度呈正相关而与太阳黑子数代表的太阳活动性不存在显著的相关关系.本文的结果为我们深入研究HFA事件形成机制、结构演化等问题提供了参考依据.
The Hotspot Anomalies (HFAs) are a phenomenon of high frequency around the Earth’s bow shock.This paper uses the data of the Cluster satellite from 2003 to 2009 to find the 765 HFA events observed over the past 7 years.In this paper, The case analysis method was used to study the HFA event center before and after 5 min, and time series superposition analysis was used to study the change of plasma and magnetic field parameters before and after the HFA event in 100 s. The results show that HFA events can decrease with the increase of dynamic pressure over time, Divided into “+ +”, “+”, “M” and “W” (increase - decrease) Decrease-increase-decrease-increase), of which the letters indicate that the shape is similar to the change tendency of dynamic pressure, the change tendency of other parameters is highly related to the change tendency of dynamic pressure, and the corresponding classification rule is obvious. In addition, the statistical results show , The number of HFA events varies in different years. Comparing with the solar wind speed and sunspots, the number of events is positively correlated with the solar wind speed and has no significant correlation with the solar activity represented by sunspot numbers.In this paper, result Our in-depth study of the mechanism, structure, evolution and other issues HFA event form provides a reference.