Monitoring global traveling ionospheric disturbances using the worldwide GPS network during the October 2003 storms

Min Wang,Baiqi Ning,Feng Ding,Biqiang Zhao,Weixing Wan

doi:10.1186/bf03352702

Abstract

AbstractThe global traveling ionospheric disturbances (TIDs) during the drastic magnetic storms of October 29–31, 2003 were analyzed using the Global Position System (GPS) total electron content (TEC) data observed in the Asian-Australian, European and North American sectors. We collected the most comprehensive set of the TEC data from more than 900 GPS stations on the International GNSS Services (IGS) website and introduce here a strategy that combines polynomial fitting and multi-channel maximum entropy spectral analysis to obtain TID parameters. The results of our study are summarized as follows: (1) large-scale TIDs (LSTIDs) and medium-scale TIDs (MSTIDs) were detected in all three sectors after the sudden commencement (SC) of the magnetic storm, and their features showed longitudinal and latitudinal dependences. The duration of TIDs was longer at higher latitudes than at middle latitudes, with a maximum of about 16 h. The TEC variation amplitude of LSTIDs was larger in the North American sector than in the two other sectors. At the lower latitudes, the ionospheric perturbations were more complicated, and their duration and amplitude were relatively longer and larger. (2) The periods and phase speeds of TIDs were different in these three sectors. In Europe, the TIDs propagated southward; in North America and Asia, the TIDs propagated southwestward; in the near-equator region, the disturbances propagated with the azimuth (the angle of the propagation direction of the LSTIDs measured clockwise from due north with 0°) of 210° showing the influence of Coriolis force; in the Southern Hemisphere, the LSTIDs propagated conjugatedly northwestward. Both the southwestward and northeastward propagating LSTIDs are found in the equator region. These results mean that the Coriolis effect cannot be ignored for the wave propagation of LSTIDs and that the propagation direction is correlated with polar magnetic activity.

Highlights

Most traveling ionospheric disturbances (TIDs) observed in the ionosphere are the response of the ionosphere to acoustic gravity waves (AGWs) (Hines, 1960)
The follow statements are based on the Vph of TIDs, as is shown in Table 1 and Fig. 4: 1. In the North American region, the dominant Vph deduced from arrays 1, 2, 3, 5, and 6 during the first and second storms shows that both large-scale TIDs (LSTIDs) and mediumscale TIDs (MSTIDs) prevailed at mid-latitude
The Vph was dominated by MSTIDs with magnitudes of about 200±100 m/s

Summary

Introduction

Most traveling ionospheric disturbances (TIDs) observed in the ionosphere are the response of the ionosphere to acoustic gravity waves (AGWs) (Hines, 1960). When the gravity waves reach ionospheric height, the neutral wind perturbations interact with the plasma via collisions. Transportation along the field lines results in electron density enhancements in some places along the wave fronts (where the electrons have moved in from above and below) and depletions in others. The regular enhancements and depletions of plasma density show traveling wave’s properties, i.e. traveling ionospheric disturbances (Hooke and Schlegel, 1968; Tsugawa et al, 2003). The observation and research of ionospheric perturbation and gravity waves have been an important subfield of ionospheric dynamics studies; they constitute an important part of current research programs into space weather. The investigation of TIDs caused by storms provides data that furthers our understanding of the evolution

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Conclusion