TEC and ROTI Measurements from a New GPS Receiver at BOWEN University, Nigeria

Abstract

Scintillation and total electron content (TEC) are the two major examples of the top-side ionospheric parameters that are recorded differently by most Global Positioning System (GPS) receivers. The new GPS sensor created by the Atmospheric and Space Technology Research Associates (ASTRA), Cornell University, and the University of Texas, Austin have capability to record scintillation and TEC fluctuations simultaneously. Hence, the Connected Autonomous Space Environment Sensor (CASES) from ASTRA is a software-defined GPS receiver with the dual frequency of L1 C/A and L2C codes for space-weather monitoring and can be remotely programmed via an internet source. The receiver employs numerous novel techniques that make it suitable for space-weather studies compared to other nearby GPS receivers, such as different methods for eliminating local clock effects, an advanced triggering mechanism for determining scintillation onset, data buffering to permit observation of the prelude to scintillation, and data-bit prediction and wipe-off for robust tracking. Moreover, the CASES hardware is made up of a custom-built dual frequency, a digital signal processor board, and a “single board computer” with an ARM microcontroller. We have used the CASES GPS receiver newly installed at Bowen University, Iwo, Nigeria, to investigate the TEC and the rate of the TEC index (ROTI) around the equatorial region. Measurements of the TEC and ROTI showed similar variation trends in monthly, seasonal, and annual periods when compared to TEC and ROTI measurements from a nearby station, BJCO at Cotonou, Benin Republic. The newly installed GPS receiver looks promising for scientific use as it is the only one operational in Nigeria at the moment.

Variability of Ionospheric Total Electron Content over some American, Asian and African Equatorial Stations

“…1. The presence and dynamic nature of the free charged particles in the upper atmosphere (that is, the ionosphere) can severely perturb and degrade ground-to-satellite and satellite-to-ground communications, and adversely affect satellite tracking and navigational control applications (Doherty, 2010;Bolaji et al, 2023). This is with resultant implication for the society and economy (NRC, 2008), hence the need for improved understanding of this highly variable medium through concerted investigative efforts.…”

“…The magnitude of the ionospheric impact on communication and navigation systems are directly related to the total electron content (TEC), de ned as a measure of the quantity of electrons in a unit area along the signal transmission path from the GPS satellite to a receiver on the earth's surface (Bagiya, 2009;Bhuyan, 2007). Among the most important parameters of the ionosphere that majorly in uence GPS signal and radio-wave propagations is TEC (Bolaji et al, 2023;Moses et al, 2020) due to its direct relation to the ionospheric electron density, which is the principal cause of degradation of trans-ionospheric radiowave communications signals (Olwendo et al, 2013;Bolaji et al, 2019;Aghogho, 2020). Ionospheric TEC values vary signi cantly with respect to the solar cycle, season, local time, altitude, latitude, longitude, and geomagnetic activity (Hamzah and Homam, 2015;Yan et al, 2022), because the main source of ionization (solar UV and x-ray intensity) depends on the position of the sun in the sky at a particular location on earth and on the sun's absolute output.…”