Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

S. Sharma,P. Galav,R. Pandey,N. Dashora

doi:10.5194/angeo-29-1063-2011

S. Sharma, P. Galav + Show 2 more

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https://doi.org/10.5194/angeo-29-1063-2011

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Journal: Annales Geophysicae	Publication Date: Jun 17, 2011
Citations: 39	License type: CC BY 3.0

Affiliation: National Atmospheric Research Laboratory

Abstract

Abstract. Response of low latitude ionosphere to the geomagnetic storm of 15 May 2005 has been studied using total electron content (TEC) data, obtained from three GPS stations namely, Yibal, Udaipur and Kunming situated near the northern crest of equatorial ionization anomaly at different longitudes. Solar wind parameters, north-south component of the interplanetary magnetic field (IMF Bz) and AE index data have been used to infer the strength of the geomagnetic storm. A large value of eastward interplanetary electric field at 06:15 UT, during the time of maximum southward IMF Bz has been used to infer the transmission of an eastward prompt penetration electric field (PPEF) which resulted in a peak in TEC at 07:45 UT due to the local uplift of plasma in the low latitudes near the anomaly crest over a wide range of longitudes. Wave-like modulations superposed over the second enhancement in TEC between 09:15 UT to 10:30 UT have been observed at all the three stations. The second enhancement in TEC along with the modulations of up to 5 TECU have been attributed to the combined effect of super plasma fountain and traveling atmospheric disturbances (TAD). Observed large enhancements in TEC are a cause of concern for satellite based navigation and ground positioning. Increased [O/N2] ratio between 09:15 UT to 10:15 UT when modulations in TEC have been also observed, confirms the presence of TADs over a wide range of longitudes.

Highlights

Studies of the geomagnetic storms and impacts thereof on Ionosphere-Thermosphere-Magnetosphere coupling processes are of great interest as such studies are covered under the ambit of space weather
We have investigated the response of low latitude ionosphere in terms of global positioning system (GPS) derived total electron content (TEC) at three stations located within 55◦ E to 105◦ E longitudes along with the variations in the thermospheric [O/N2] ratio
565In order to characterize the storm and to study effects thereof on the TEC, variations of solar wind velocity and pressure, 566IMF Bz, IEF Ey, AE, SYM-H and ASY-H indices have been plotted in Fig. 1 against the universal time, UT

Summary

Introduction

Studies of the geomagnetic storms and impacts thereof on Ionosphere-Thermosphere-Magnetosphere coupling processes are of great interest as such studies are covered under the ambit of space weather. Major geomagnetic storms are triggered by the earth directed coronal mass ejections (CMEs) from the sun when under the condition of a southward interplanetary magnetic field (IMF Bz), interaction between the solar wind and magnetosphere causes under shielding conditions and produces electric fields at the magnetospheric heights that may penetrate up to the equatorial latitudes. These fields are termed prompt penetration electric fields, PPEF (Nishida et al, 1966; Fejer et al, 1979; Fejer, 2002), which are eastward (westward) during the daytime (nighttime). Ionospheric manifestation of TADs is called the traveling ionospheric disturbances (TIDs)

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