The data was treated by SIMuRG \cite{Yasyukevich2020}. For provided GNSS data we acknowledge: The African Geodetic Reference Frame (AFREF) , INGV - Rete Integrata Nazionale GPS, REseau NAtional GPS permanent (RENAG), Institute of Geodynamics, National Observatory of Athens, Scripps Orbit and Permanent Array Center, UCSD\cite{Dow2009}, Austrian data center (BEV), Instituto Tecnológico Agrario de Castilla y León, Korea Astronomy and Space Institute\cite{Dow2009}, Dutch Permanent GNSS Array (DPGA), Royal Observatory of Belgium\cite{Bruyninx2012}, Pacific Northwest Geodetic Array (PANGA), The Western Canada Deformation Array (WCDA), Instituto Brasileiro de Geografia e Estatística, Système d'Observation du Niveau des Eaux Littorales (SONEL).

@article{Yasyukevich2020,	
author = {Yasyukevich, Yury and Kiselev, Alexander and Zhivetiev, Ilya and Edemskiy, Ilya and Syrovatskii, Semen and Maletckii, Boris and Vesnin, Artem},	
year = {2020},	
month = {07},	
pages = {},	
title = {SIMuRG: System for Ionosphere Monitoring and Research from GNSS},	
volume = {24},	
journal = {GPS Solutions},	
doi = {10.1007/s10291-020-00983-2}
}

@article{Dow2009,
	author = {Dow, John and Neilan, R.E. and Rizos, Chris},
	year = {2009},
	pages = {191-198},
	title = {The International GNSS Service in a Changing Landscape of Global Navigation Satellite Systems},
	volume = {83},
	journal = {Journal of Geodesy},
	doi = {10.1007/s00190-008-0300-3}
}
@inbook{Bruyninx2012,
	author = {Bruyninx, Carine and Habrich, H and Kenyeres, Ambrus and SГ¶hne, Wolfgang and Stangl, G. and VГ¶lksen, Christof},
	year = {2012},
	pages = {27-35},
	title = {Enhancement of the EUREF Permanent Network Services and Products},
	volume = {136},
	journal = {IAG Symp.},
	doi = {10.1007/978-3-642-20338-1_4}
}