Effect of the solar wind conditions on the ionospheric equivalent current systems

J J Zhang,C Wang,B B Tang,H Li

doi:10.5194/angeo-31-489-2013

Abstract

Abstract. We employ a global magnetohydrodynamics (MHD) model, namely the PPMLR-MHD model, to investigate the effect of the solar wind conditions, such as the interplanetary magnetic field (IMF) clock angle, southward IMF magnitude and solar wind speed, on the average pattern of the ionospheric equivalent current systems (ECS). A new method to derive ECS from the MHD model is proposed and applied, which takes account of the oblique magnetic field line effects. The model results indicate that when the IMF is due northward, the ECS are very weak while the current over polar region is stronger than the lower latitude; when the IMF rotates southward, the two-cell current system dominates, the eastward electrojet on the afternoon sector and the westward electrojet on the dawn sector increase rapidly while the westward electrojet is stronger than the eastward electrojet. Under southward IMF, the intensity of the westward electrojet and eastward electrojet both increase with the increase of the southward IMF magnitude and solar wind speed, and the increase is very sharp for the westward electrojet. Furthermore, we compare the geomagnetic perturbations on the ground represented by the simulated average ECS with the observation-based statistical results under similar solar wind conditions. It is found that the model results generally match with the observations, but the underestimation of the eastward equivalent current on the dusk sector is the main limitation of the present model.

Highlights

Discussions interplanetary magnetic field (IMF) clock angle, southward Ionospheric equivalent current systems (ECS) are a conve
We examine how the average ECS over the Northern Hemisphere vary with the change of the IMF clock angle, the southward IMF magnitude and the solar wind speed
In this study we investigated the effect of solar wind conditions such as the IMF clock angle, southward IMF magnitude and solar wind velocity on the average ECS by using the PPMLR-MHD model (Hu et al, 2007)

Summary

Introduction

Discussions interplanetary magnetic field (IMF) clock angle, southward Ionospheric equivalent current systems (ECS) are a conve-. IMF magnitude and solar wind speed, on the average pattern nient way to represent detailed features of global magnetic omalipfnepetthlhieeoefddifo,etncowtosdhs.eipcTrhhihvereetiacEmkCeeoqsSduaeifcvlrcoaromleeusnuntthlttcesouMfirnrtHedhnieDctaosmtybesolittdqehemualetsiswm(pEharCeogonnSpfeo)t.thtsihCAeecdeIfinlMaieemnlwPFdd aatsetacKincopttmei,vneaisptiytt,hyAieniEnclilfmuaondrimdtianatDgitoisiontn,ntewoonfhfsimiactyhap,naalyorretcigcaienutoitloemannradgagenendodeomttpoicfaadgtittennehCserdDcnteiirlic.sciicebmTPusleah,staeosaisyitnuotuslnceodysthvitnehaares-l is due northward, the ECS are very weak while the current band (Kamide et al, 1976). ECS over polar region is stronger than the lower latitude; when are a good approximation of the ionospheric currents shedtiwthnheeaestIwetMwse,asFtrthwdreoaeetrlaaedtsceettswrloesacjoretudrtotoehjnlewettcahitrserdos,djtetarhotwenongntwseterhocte-thcoaaerfnltilentcrhcunerroereoaeaEsnnsettsawrseaycrapstrtDiotdhderlmeyyalSnnewddcyoahttrmihsomlee--teicmsBdbthiaanesugitmcrluipjgeorhohhtcaooenrsnnisz,teoh1sne9ti9anspl3ta)iho.teinaiolosanpnohdseptrehicmercpeuoarrrlaetElhnvotaausrgyryhstDitnhetghmyeSbnsyDeiy(hadsUacosmuvnntsitoesioieirctomdonestfsqatunhadel jet. Under southward IMF, the intensity of the westward elec-. It is found that the model results generally match GICs are large enough to exceed the thresholDdisscoufssthioenssyswwtKaaitetiryhodwnteohoqrefudtiohsvb.easlIpeeorrnnevtsoacetsiunporthnrmeesrn,oetbd(oueEntll.etthhceteriducunfisdMekelrdseoesscdtaitnmoedralictsiuDoGtrnhreeeeonvmftoset;ashiMlneocoleipiedamemsnlti---teifnicttcPAteioiomtrrtnjreosome,lsafipsf,oeet1nscvt9ehos9rafef8vro)oeei,mllbelaecentatehdrdneiicgnEmagbCsaltadSpoceiwpMkhteoioultuoighnmte,dtehosceeedocweomullonlmtDutoGihlmmudeenaeihgcitvceaoeapeaoastnpmiilmdoeocaDnnisgpoie(sonofBcmceunmuiottasiatticelsetigiifloliengeionn,crasdsttsaaiuennncsddg-. Ing and forecasting) – Magnetospheric physics (Solar wind- or avoiding the harmful effects caused by GICs. Pulkkinen magnetosphere interactions).

Methods

Results

Conclusion