An Investigation of Ionospheric Responses During the Magnetic Storm of 13~17 April 2006 at Western Pacific Area

Abstract

AbstractBased 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 case study 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. foF2 and TEC increased dramatically in the region where the magnetic latitude is between ±30°‐ and ±40°‐ and lasted more than 12 hours. Negative phase was confined at middle‐high latitude during the storm main phase and started to pervade to middle‐low latitudes as the earth rotated to the nightside. TIMED satellite shows that the Σ[O/N2] decreased substantially at high‐middle latitude area and increased significantly at middle‐low latitudes. Through the analysis on the hmF2 variation, we 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 Bz 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.