The study of zonal dynamo electric fields observed by the IPEI on board ROCSAT-1

Abstract:

The earth’s ionosphere is under direct and indirect influence from the sun. Electric currents, fields and other effects can penetrate into magnetosphere and high latitude ionosphere through magnetic field lines, and into the low latitudes by the disturbance dynamo mechansim, which can lasts for a few hours to a few days, with accumulation of positive charges at the low latitude ionosphere around the midnight. The directions of the corresponding disturbed electric fields are westward in the daytime and eastward in the nighttime, opposite to the normal quiet time condition. A comparison between model results and observed data from the IPEI on board ROCSAT-1 is carried out and presented. There were 23 storm cases with DST indexes lower than -140 from 2000 to 2003. The zonal electric fields, within ±30 degrees in magnetic latitude, are compared at periods one and two days before the storm onset and the time during the storm, which precisely shows the perturbed electric fields at different local times and different magnetic latitudes. Siganificant eastward perturbed electric fields at dawn were found in 17 out of the 23 events. The satellite orbit tracjectories are not suitable or nothing is found for the others.