2006年4月13～17日西太平洋地区电离层暴时特性研究

本文利用西太平洋地区的15个电离层台站的测高仪数据和国际GPS服务中心IGS 36个站提供的TEC数据，以及由美国喷气推进动力学实验室提供的Jason 1 TEC数据对2006年4月13～17日间一次由冕洞高速流所引发的磁暴所造成的电离层效应进行了分析.分析结果表明这次电离层暴呈现出显著的纬度效应，foF2和TEC等参量显示在磁暴主相期间对称分布的强正暴效应中心在磁纬±30°～±40°，且持续时间超过12 h.负暴效应被限制在中高纬地区，在磁暴进入恢复相时，开始向低纬渗透，且具有明显的地方时效应.TIMIED卫星测量的Σ［O/N2］显示磁暴发生后，暴时环流使得中低纬地区的Σ［O/N2］有大幅增加，而中高纬地区则显著下降.通过对hmF2的分析发现磁暴主相期间，有磁层电场向中低纬地区穿透，且持续时间较长为1～3 h.因此这次强正暴效应可能是由风场、电场和化学成分这三个因素的共同作用造成的.这次磁暴造成的电离层暴响应非常复杂，对造成各种正负暴的物理和化学机制还需要进一步的研究.

An investigation of ionospheric responses during the magnetic storm of 13～17 April 2006 at Western Pacific area

Based on a large data base from 15 ionosonde stations and 36 GPS stations combining with TEC data measured from the Oceanic satellite Jason 1, a casestudy is made on the ionospheric responses at Western Pacific area to the magnetic storm triggered by coronal hole high speed streams during 13～17 April 2006 The results show that the ionospheric storm has a clear latitudinal dependence. foF2 and TEC increased dramatically in the region where the magnetic latitude is between ±30° and ±40° and last more than 12 hours. Negative phase was confined at middle high latitude during the storm main phase and start to pervade to middle low latitudes as the Earth rotated to the nightside. TIMED satellite had shown that the Σ［O/N2］ decreased substantially at high middle latitude area and increased significantly at middle low latitudes. Through the analysis on the hmF2 variation, we had observed the magnetospheric electric fields penetrating to the low middle latitude ionosphere with long duration, 1～3 hours, during the storm main phase when IMF Bz remained southward. Therefore, the strong positive phase at this area might be caused by additional eastward electric fields, equatorward neutral winds as well as composition changes. Further study is needed to elucidate the effects of various physical and chemical processes on the plasma at this Western Pacific area.