Brazilian active GNSS networks as systems for monitoring the ionosphere

Abstract

This research shows the viability of using Global Navigation Satellite System (GNSS) stations from Brazilian active networks in monitoring the ionosphere. Various indexes of ionospheric irregularities and scintillation of GNSS signals, estimated in real-time and post-processed from GNSS data, are explored for this purpose. This way, an increase in the spatial resolution of ionospheric information is provided, allowing the generation of maps of scintillation and irregularities in observing the spatial and temporal behavior of the layer's activity cycle, since the number of ionosondes, imagers, and radars is insufficient for monitoring the irregularities in Brazil. Experiments to evaluate the estimates of the indexes are performed for periods of high and low variability of electrons. Three Brazilian networks are used: the Brazilian Network for Continuous Monitoring (RBMC), the GNSS Active Network of Sao Paulo State (GNSS-SP), and CIGALA/ CALIBRA. The results are compared with data from ionosondes and PolaRxS-PRO Septentrio receivers, proving compatible with moderate to high correlations. An analysis of the seasonal variation during the peak of solar cycle 24 is carried out. The maps allow identifying the displacement of ionospheric irregularities along the magnetic equator over Brazil, from northeast to southwest, starting at 7:00 pm and ending at 2:00 am local time. Realtime monitoring is carried out for the summer solstice in the southern hemisphere, and results are consistent with those from the post-processed mode. The indexes and maps can be applied to the analysis of GNSS positioning. Realtime ionospheric information can be used in important practical applications because the displacement monitoring of irregularities allows prior knowledge of whether there will be a deterioration of positioning accuracy in a certain region.

Evaluation of the GNSS Positioning Performance Under Influence of the Ionospheric Scintillation

“…The magnitude of the error due to the ionospheric effect on the GNSS signals depends directly on the Total Electron Content (TEC) present along the path traveled by the signal, which in turn is related to the ionization process in the ionosphere, and inversely proportional to the squared signal frequency (Matsuoka, 2007;Camargo, 1999;Pereira and Camargo, 2017). TEC and, consequently, the ionospheric error vary in time and space, and are subject to several influences (Davies, 1990).…”

Drift Velocity Estimation of Ionospheric Bubbles Using GNSS Observations

“…The panel in Figure 3c show the ROTI calculated for both satellites PRN 03 and PRN 32. The results reveal that from 00 UT to 04 UT the index attained values between about 0.05 and 0.2, which can be classified as moderate levels of changes in TEC caused by EPB irregularities (Pereira and Camargo, 2017). Once TEC depletions and ROTI indicated the presence of plasma bubbles in the ionosphere, the difference in the TEC levels between the reference stations of RIOD and ONRJ was computed.…”

A Retrospective of Global Navigation Satellite System Ionospheric Irregularities Monitoring Networks in Brazil

“…Part of this data can also be accessed through the ISMR Query Tool that will be described later in this paper. the ionosphere and its effects on GNSS under different perspectives, such as receiver design, performance and potential vulnerabilities (Moraes et al 2014;Salles et al 2021;Veettil et al 2011;, effects on GNSS positioning and mitigation (Marques et al 2016;2018;Park et al 2017;Vani et al 2019;Veettil et al 2020), climatology and monitoring the ionosphere (Pereira et al 2017;Spogli et al 2013;Vani et al 2021), among others.…”