Title: GNSS-derived data for the study of the ionosphere
Abstract: The objective of this chapter is to highlight the contribution of Global Navigation Satellite System (GNSS)–derived data to the monitoring and studying of the upper region of the Earth's atmosphere ionized mainly by solar radiation. GNSS signals travel across the ionosphere to reach receivers on the Earth or on low orbiting satellites (LEOs). The effect of the ionosphere plasma on such signals is to introduce a propagation delay that is proportional to the inverse of the squared frequency of the radio signal and to the total number of free electrons encountered by the signal along the ray path from the satellite to the receiver. This number is called "total electron content" or TEC and is very variable with time and location. When dual-frequency receivers are used to monitor GNSS signals for navigation and positioning purposes, first-order TEC effects can be removed and an estimate of TEC itself can be obtained. TEC represents a good indicator of ionosphere conditions and the availability of a very large number of GNSS receivers that provide TEC information makes it an essential contributor to ionosphere monitoring and science. An additional effect on GNSS signals is the presence of ionosphere plasma irregularities located particularly on high and low latitudes that induces rapid changes in amplitude and phase of the received signals called ionosphere scintillations. These rapid fluctuations of the GNSS signal degrade the system performance but at the same time give important information about ionospheric irregularities of different scales. This chapter starts with an outline about the ionosphere and the way TEC is estimated from GNSS signals. The way electron density profiles are obtained using radio occultation of signals between GNSS and LEO satellites is also mentioned. Finally, the main contribution of GNSS derived information to the ionosphere monitoring and science follows.
Publication Year: 2021
Publication Date: 2021-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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Cited By Count: 3
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