Abstract

Abstract. This study presents a comprehensive observation of the large-scale traveling ionospheric disturbances (LSTIDs) in the eastern Asian sector during the 2015 St. Patrick's Day (17 March 2015) geomagnetic storm. For the first time, three dense networks of GPS receivers in China and Japan are combined together to obtain the two-dimensional (2-D) vertical total electron content (VTEC) perturbation maps in a wider longitudinal range than previous studies in this region. Results show that an LSTID spanning at least 60∘ in longitude (80–140∘ E) occurs as a result of possible atmospheric gravity waves (AGWs) propagating from high to lower latitudes at around 09:40–11:40 UT (universal time), and the crest of this LSTID shows a tendency of dissipation starting from the eastern side. The manifestation of the 2-D VTEC perturbation maps is in good agreement with the recordings from two high-frequency Doppler sounders and the iso-frequency lines from eight ionosondes. Then, the propagation parameters of the LSTIDs are estimated by applying least-square fitting methods to the distinct structures in the 2-D VTEC perturbation plots. In general, the propagation parameters are observably longitudinally dependent. For example, the propagation direction is almost due southward between 105 and 115∘ E, while it is slightly southwest and southeast in the western and eastern sides of this region. This feature is probably related to the regional geomagnetic declination. The mean values of the period, trough velocity (Vt), crest velocity (Vc), and wavelength of the LSTIDs in the studied longitudinal bands are 74.8±1.4 min, 578±16 m s−1, 617±23 m s−1, and 2691±80 km, respectively. Finally, using the VTEC map data from the Madrigal database of the MIT Haystack Observatory, the characteristics of the ionospheric disturbances over the European sector (30–70∘ N, 10–20∘ E) are also studied. The results are very different from those in the eastern Asian sector in parameters like the occurrence time, oscillation period, and propagation velocities.

Highlights

  • During the geomagnetic storm, the solar wind energy is impulsively or continually injected into the earth polar region, making the atmospheric and ionospheric states deviate greatly from their background levels (Fuller-Rowell et al, 1994; Mendillo and Narvaez, 2009)

  • It can be seen clearly that a geomagnetic storm occurred on 17 March 2015, with the sudden storm commencement (SSC) at ∼ 04:45 UT, which is characterized by a sharp increase in the solar wind speed, Bz, and SYM-H index

  • Using data from four GPS receiver networks (CMGN, Crustal Movement Observation Network of China (CMONOC), GPS Earth Observation Network (GEONET), and IGS), together with recordings of two HF Doppler sounders and eight ionosondes, we provide comprehensive and detailed observation results of the large-scale traveling ionospheric disturbances (LSTIDs) in the eastern Asian sector during the 2015 St

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Summary

Introduction

The solar wind energy is impulsively or continually injected into the earth polar region, making the atmospheric and ionospheric states deviate greatly from their background levels (Fuller-Rowell et al, 1994; Mendillo and Narvaez, 2009). The response of the ionosphere to the geomagnetic storm is classified by a variety of different features, one of which being the large-scale traveling ionospheric disturbance (LSTID) that is the wave-like perturbation mainly propagating equatorward from high latitudes. Traveling ionospheric disturbances (TIDs) are classified into LSTIDs and medium-scale TIDs, and they are considered to be the ionospheric manifestation of the presence of atmospheric gravity waves (AGWs) stimulated by different sources. LSTIDs are mainly caused by joule heating or Lorenz drag forcing in the auroral regions during a geomagnetic storm period (Hines, 1960; Richmond and Roble, 1979; Hocke and Schlegel, 1996). J. Liu et al.: A case study of the large-scale traveling ionospheric disturbances

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