中低纬度Pc3-4地磁脉动特性研究——子午工程数据分析初步结果

Characters of the Pc3-4 Magnetic Pulsations at Middle and Low Latitudes:Preliminary Geomagnetic Results From Chinese Meridian Project

利用新建成的子午工程地磁台站数据,对比分析了地磁平静期间(2011年3月20—27日)和磁暴期间(2011年9月25日至10月1日)Pc3-4地磁脉动的时空分布特征及其对行星际条件的响应.数据分析结果表明,中低纬度(1.3<L<2.3,L为磁壳参数)的Pc3-4地磁脉动在这两个时期内的分布存在明显的晨昏不对称性,在昼侧前出现明显的Pc3-4地磁脉动并与行星际上游波动密切相关,其振幅增强可能与太阳风动压脉冲相关,高速太阳风更易导致Pc3-4地磁脉动;而对于近赤道低纬(L<1.3)区域,无论是在地磁平静期还是磁暴期均未能观测到Pc3-4地磁脉动,Pc3-4地磁脉动存在明显的纬度效应.

The characters of the Pc3-4 magnetic pulsations and their relationships to interplanetary conditions were studies during the periods of both the magnetic quite （March 20 to 2Y, 2011） and storm （September 25 to October 1, 2011）, using ground-based geomagnetic field measurements from the new-developed Chinese Meridia a Project. Preliminary results show there exist significant dawn- dusk asymmetric distribution of the Pc3-4 pulsations in the middle-low latitudes （1.3 〈L 〈 2.3）,with Pc3-4 pulsations activity are observed mainly in the pre-noon sector, during both time periods. They are closely related to the interplanetary conditions, with high-speed solar wind and solar wind dynamic pressure pulsation leading to enhancement of the Pc3-4. However, Pc3-4 pulsations activity is not observed near the equatorial low latitudes （L 〈 1.3） due to latitudinal effect.