The Feature of Ionospheric Mid-Latitude Trough during Geomagnetic Storms Derived from GPS Total Electron Content (TEC) Data

Na Yang,Guangliang Huang,Chunliang Xia,Yang-Yi Sun,Jin Wang,Huijun Le,Xiangxiang Yan,Libo Liu,Xiaomin Zuo,Tao Yu

doi:10.3390/rs14020369

Abstract

This study aims to investigate the features of the ionospheric mid-latitude trough over North America by using the MIT total electron content data obtained during three geomagnetic storms that occurred in August 2018, September 2017, and March 2015. The mid-latitude trough position sharply moves equatorward from the quiet-time subauroral latitude to mid-latitude with the decrease in SYM-H during geomagnetic storms. We find that the ionospheric behavior of TEC around the mid-latitude trough position displays three kinds of ionospheric storm effect: negative ionospheric storm effect, unchanged ionospheric behavior, and positive ionospheric storm effect. These ionospheric storm effects around the mid-latitude trough position are not always produced by the mid-latitude trough. The ionospheric storm effects produced by the mid-latitude trough are limited in the narrow mid-latitude trough regions, and are transmitted to other regions with the movement of the mid-latitude trough.

Highlights

The mid-latitude trough is a nighttime plasma density depletion structure in the subauroral ionospheric F region [1,2,3]
The main phase of the storm began at ~16:05 UT on 25 August, as the SYM-H (Figure 2d) began to decrease
The temporal variation of the trough position in the night sector during geomagnetic storms is mainly associated with the temporal variation of the geomagnetic activity

Summary

Introduction

The mid-latitude trough is a nighttime plasma density depletion structure in the subauroral ionospheric F region [1,2,3]. The depletion structure is typically close to 10 degrees wide in latitude, and appears at all longitudes in both the Northern and Southern. The mid-latitude trough most frequently occurs in the nighttime. The mid-latitude trough structure is composed of three parts: a polar boundary, a trough minimum, and an equatorward boundary. The trough position refers to the trough’s minimum position. The large density gradients on both boundaries of the mid-latitude trough can provoke severe amplitude and phase fluctuations of radio signals [3,6]; the fluctuations deteriorate the performance of navigation and positioning. The “trough” in this study refers to the mid-latitude trough

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Discussion

Conclusion