Investigation of Daytime Total Electron Content Enhancements over the Asian-Australian Sector Observed from the Beidou Geostationary Satellite during 2016–2018

Oluwaseyi Jimoh,Jiuhou Lei,Fuqing Huang

doi:10.3390/rs12203406

Abstract

This study focused on the investigation of daytime positive ionospheric disturbances and the recurrence of total electron content (TEC) enhancements. TEC data derived from the Beidou geostationary satellite over the Asian-Australian sector were used to study the occurrence of TEC enhancements during 2016–2018. The occurrence of TEC enhancements under quiet geomagnetic condition was analyzed. Furthermore, the occurrence of TEC enhancements during different geomagnetic storm phases was considered to address the question that relates to the recurrence of TEC enhancements during the recovery phase of geomagnetic storms. The seasonal variation of TEC enhancements displayed equinoctial and solstitial peaks at the middle and low latitudes respectively. Besides, there was no evident systematic latitudinal dependence in the occurrence of TEC enhancements, albeit at the equatorial station, nearly no TEC enhancement was observed under Kp < 3. Meanwhile, the occurrences during the main phases of the geomagnetic storms were significantly above the TEC enhancement baselines except at HKWS. The prominence of TEC enhancements during the main phase in comparison with the initial and recovery phases could be attributed to the effects of prompt penetration electric fields and equator-ward neutral winds. Moreover, the pattern of TEC enhancements during the storm recovery indicates the effects of chemical composition changes, winds, and the possible modulation from the lower atmospheric forcing.

Highlights

The changes resulting from ionospheric disturbances are of importance in space physics research, spacecraft orbital design, and in the practical application of global navigation satellite systems (GNSS) and radio communication
This study aims to investigate the occurrence of total electron content (TEC) enhancements over the Asian-Australian sector and to ascertain the recurrence of TEC enhancements during the recovery phase of geomagnetic storms
We have presented the results of the daytime occurrence of TEC enhancements by using TEC observations from GEO-2 satellite over 5 ground-based GNSS receivers in the Asian-Australian sector from 2016 to 2018

Summary

Introduction

The changes resulting from ionospheric disturbances are of importance in space physics research, spacecraft orbital design, and in the practical application of global navigation satellite systems (GNSS) and radio communication. As a result of these consequences, it is of relevance to investigate the occurrence of these disturbances, especially at unexpected periods. Ionospheric F2-layer disturbances are driven by different sources, which are broadly classified into three categories, namely solar radiation, geomagnetic activity (S-disturbances), and meteorological activities (Q-disturbances) [1,2]. The occurrence of ionospheric Q-disturbance variations in the frequency of appearance and their correlations with geomagnetic storm phases have not been well understood and according to previous studies [3,4], these disturbances have been associated with meteorological events, quasi planetary oscillations in the ionosphere, and seismic events. It has been observed that the origin of the Q-disturbances is different from that of the regular F2 layer storm-time disturbances [2]. Positive disturbances caused by meteorological effects under quiet geomagnetic conditions can attain amplitude comparable to the amplitude of a moderate F2-layer storm [5]

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