Abstract

Numerous raw data concerning the ionosphere exist almost everywhere in Africa. However, these data are underexploited due to the lack of simple methods to extract ionospheric parameters from the data. This paper presents a method for extracting vertical total electron content (VTEC) using Global Navigation Satellite System-Continuously Operating Reference Station (GNSS-CORS) raw data recorded between 01/01/2013 and 12/31/2021 at station BF01 (Latitude = 12.3714 N and Longitude = -1.5197 W) in Ouagadougou, Burkina Faso, located at the trough of ionization in the West African equatorial zone. This station is one of the stations in Burkina Faso that recorded data better continuously during the period of this study. This work involves the determination of VTEC using dual-frequency GPS measurements. Thus, the raw GNSS-CORS data in "T02" format were first converted into "Receiver INdependent Exchange Format" (RINEX) into time files in steps of 1 s. These files were then reorganized into daily files with 30 s steps, before being used for VTEC extraction. For this purpose, scripts were developed and run in Matlab. The extracted VTEC is saved in text and graphics files. With the result obtained, it is possible to dimension some fundamental characteristics of the ionosphere at low latitudes. It is also possible to produce spatio-temporal maps of TEC variations over Burkina Faso and even for the whole of West Africa at least if the CORS networks of neighboring countries are known.

Key words: Global navigation satellite system-continuously operating reference station (GNSS-CORS), vertical total electron content (VTEC), Receiver INdependent Exchange Format (RINEX), ionosphere.