Abstract
The plasmasphere is located above the ionosphere with low-energy plasma, which is an important component of the solar-terrestrial space environment. As the link between the ionosphere and the magnetosphere, the plasmasphere plays an important role in the coupling process. Therefore, it is of great significance to study the electron content variation of the plasmasphere for the solar-terrestrial space environment. Nowadays, the topside global positioning system (GPS) observations on Low Earth Orbit (LEO) satellites provide a unique opportunity to estimate and study variations in the plasmasphere. In this paper, the plasmaspheric total electron content (PTEC) is estimated, and its long-term variations are studied from topside GPS observations onboard the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC). The PTEC in the daytime is higher than that in the nighttime, with the peak between 14:00 and 17:00 in the magnetic local time, while the minimum value of PTEC in the belt appears between 3:00 and 6:00 in the magnetic local time before sunrise. For seasonal variations, the PTEC is the highest in spring of the northern hemisphere and the lowest in summer of the northern hemisphere regardless of the state of the solar activity. The long-term variation in PTEC is further analyzed using 11-year COSMIC GPS observation data from 2007 to 2017. A high correlation between PTEC and the F10.7 indices is found. Particularly in the geomagnetic high-latitude region during the daytime, the correlation coefficient reaches 0.93. The worst case occurs during the nighttime in the geomagnetic middle-latitude region, but the correlation coefficient is still higher than 0.88. The long-term variations of plasmaspheric TEC are mainly related to the solar activity.
Highlights
IntroductionWith the continuous exploration into deep space and the increasing variety of electromagnetic applications, such as communication and navigation, monitoring and understanding of the solar-terrestrial space environment have become a hot field, including the Earth’s neutral atmosphere, ionosphere, plasmasphere, magnetosphere, and so on [1]
With the continuous exploration into deep space and the increasing variety of electromagnetic applications, such as communication and navigation, monitoring and understanding of the solar-terrestrial space environment have become a hot field, including the Earth’s neutral atmosphere, ionosphere, plasmasphere, magnetosphere, and so on [1].The plasmasphere is a part of magnetosphere, called the inner magnetosphere [2], which starts from the top of the ionosphere and ends at the plasmapause
Remote Sens. 2021, 13, 545 the ionospheric total electron content (TEC) simultaneously measured by Jason-1 satellite during the declining phase of solar cycle 23, and the results showed that the plasmaspheric density structures fundamentally followed the ionosphere, but there were still significant differences
Summary
With the continuous exploration into deep space and the increasing variety of electromagnetic applications, such as communication and navigation, monitoring and understanding of the solar-terrestrial space environment have become a hot field, including the Earth’s neutral atmosphere, ionosphere, plasmasphere, magnetosphere, and so on [1]. The plasmasphere is a part of magnetosphere, called the inner magnetosphere [2], which starts from the top of the ionosphere and ends at the plasmapause. It is currently believed that the charged particles in the plasmasphere mainly come from escape of the ionosphere and capture from the solar wind [4,5]. Richards et al [6] examined the relative importance of ionospheric and thermospheric densities and temperatures in producing the annual variation of the plasmaspheric electron density. Lee et al [7] compared the global plasmaspheric total electron content (TEC) with
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