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ACE飞船发射于1997年8月15日,将维持到2024年,位于日地连线重力平衡点L1。本文采用ACE飞船行星际磁场观测数据,基于GSE坐标系统,确定L1点的行星际磁场主体方位,进而将行星际磁场观测数据转换为极性符号序列。对于序列中的任一时间点,通过改变以它为中心的子序列探测行星际磁场的准27d重现周期和结构,再应用模板匹配方法识别重现结构,最后采用分段常值函数拟合获得分段稳定的周期和结构。得到的主要结果如下:(1)1999—2008年间,IMF重现周期绝大多数在(27±2)d范围内,只有1个例外,即2001年10月27日10:00—11月28日12:00时间内,重现周期为21d14h;(2)2001年1月8日12:00—2004年7月17日04:00,IMF为2扇瓣结构,2004年7月17日05:00—2007年6月30日23:00,IMF为4扇瓣结构,2007年7月1日00:00—2008年12月31日23:00,IMF为2扇瓣结构。
The ACE spacecraft was launched on August 15, 1997 and will be maintained until 2024 at the gravitational equilibrium point L1 connected to the Earth. In this paper, we use the data of interplanetary magnetic field of ACE spacecraft to determine the main azimuth of interplanetary magnetic field at L1 point based on the GSE coordinate system, and then convert the interplanetary magnetic field observation data into the polar symbol sequence. For any time point in the sequence, the quasi-27d reconstruction period and structure of the interplanetary magnetic field are probed by changing its sub-sequence, and the template matching method is used to identify the recurrence structure. Finally, the piecewise constant function fitting Obtain a stable, stable period and structure. The main results obtained are as follows: (1) During the period from 1999 to 2008, the majority of the IMF recurrence periods were within the range of (27 ± 2) d with only one exception, that is, October 27, 2001, from 10:00 to November 28 At 12:00 a.m., the recurrence period is 21d14h. (2) At 12:00 on January 8, 2001 - 04:00 on July 17, 2004, the IMF is a 2-flap structure, and on July 17, 2004, 05 : 00 - At 23:00 on June 30, 2007, the IMF is a 4-flap structure. At 00:00 on July 1, 2007 - 23:00 on December 31, 2008, the IMF is a 2-flap structure.