The geomagnetic storm of 17–18 March 2015 was caused by the impacts of a coronal mass ejection and a high‐speed plasma stream from a coronal hole. The high‐latitude ionosphere dynamics is studied using arrays of ground‐based instruments including GPS receivers, HF radars, ionosondes, riometers, and magnetometers. The phase scintillation index is computed for signals sampled at a rate of up to 100 Hz by specialized GPS scintillation receivers supplemented by the phase scintillation proxy index obtained from geodetic‐quality GPS data sampled at 1 Hz. In the context of solar wind coupling to the magnetosphere‐ionosphere system, it is shown that GPS phase scintillation is primarily enhanced in the cusp, the tongue of ionization that is broken into patches drawn into the polar cap from the dayside storm‐enhanced plasma density, and in the auroral oval. In this paper we examine the relation between the scintillation and auroral electrojet currents observed by arrays of ground‐based magnetometers as well as energetic particle precipitation observed by the DMSP satellites. Equivalent ionospheric currents are obtained from ground magnetometer data using the spherical elementary currents systems technique that has been applied over the ground magnetometer networks in North America and North Europe. The GPS phase scintillation is mapped to the poleward side of strong westward electrojet and to the edge of the eastward electrojet region. Also, the scintillation was generally collocated with fluxes of energetic electron precipitation observed by DMSP satellites with the exception of a period of pulsating aurora when only very weak currents were observed.

Global navigation satellite systems (GNSS) underpin a number of modern life activities, including applications demanding positioning accuracy at the level of centimetres, such as precision agriculture, offshore operations and mining, to name a few. Precise point positioning (PPP) exploits the precision of the GNSS signal carrier phase measurements and may be used to provide the high accuracy positioning needed by these applications. The Earth’s ionosphere is critical in PPP due to its high variability and to disturbances such as scintillation, which can affect the satellite signals propagation and thereby degrade the positioning accuracy, especially at low latitudes, where severe scintillation frequently occurs. This manuscript presents results from a case study carried out at two low latitude stations in Brazil, where a dedicated technique is successfully applied to mitigate the scintillation effects on PPP. The proposed scintillation mitigation technique improves the least square stochastic model used for position computation by assigning satellite and epoch specific weights based on the signal tracking error variances. The study demonstrates that improvements in the 3D positioning error of around 62–75% can be achieved when applying this technique under strong scintillation conditions. The significance of the results lies in the fact that this technique can be incorporated in PPP to achieve the required high accuracy in real time and thus improve the reliability of GNSS positioning in support of high accuracy demanding applications.

GPS and GLONASS are currently the Global Navigation Satellite Systems (GNSS) with full operational capacity. The integration of GPS, GLONASS and future GNSS constellations can provide better accuracy and more reliability in geodetic positioning, in particular for kinematic Precise Point Positioning (PPP), where the satellite geometry is considered a limiting factor to achieve centimeter accuracy. The satellite geometry can change suddenly in kinematic positioning in urban areas or under conditions of strong atmospheric effects such as for instance ionospheric scintillation that may degrade satellite signal quality, causing cycle slips and even loss of lock. Scintillation is caused by small scale irregularities in the ionosphere and is characterized by rapid changes in amplitude and phase of the signal, which are more severe in equatorial and high latitudes geomagnetic regions. In this work, geodetic positioning through the PPP method was evaluated with integrated GPS and GLONASS data collected in the equatorial region under varied scintillation conditions. The GNSS data were processed in kinematic PPP mode and the analyses show accuracy improvements of up to 60% under conditions of strong scintillation when using multi-constellation data instead of GPS data alone. The concepts and analyses related to the ionospheric scintillation effects, the mathematical model involved in PPP with GPS and GLONASS data integration as well as accuracy assessment with data collected under ionospheric scintillation effects are presented.

It is well known that Global Navigation Satellite System (GNSS) signals suffer from a number of vulnerabilities, out of which a potential severe vulnerability is the effect of space weather. Space weather effects on the signals transmitted by GNSS include the effect of ionospheric perturbations and solar radio bursts. Intense solar radio bursts occurring in the L-band can impact the tracking performance of GNSS receivers located in the sunlit hemisphere of the Earth and are therefore a potential threat to safety-critical systems based on GNSS. Consequently monitoring these events is important for suitable warnings to be issued in support to related services and applications. On the other hand, the space weather effects leading to ionospheric perturbations on the GNSS signals are either due to dispersion or scintillation caused by plasma density irregularities. Scintillation can cause cycle slips and degrade the positioning accuracy in GNSS receivers. The high-latitude scintillation occurrence is known to correlate with changes in the solar and interplanetary conditions along with a consequential impact on GNSS receiver tracking performance. An assessment of the GNSS receiver tracking performance under scintillation can be analysed through the construction of receiver phase-locked loop (PLL) tracking jitter maps. These maps can offer a potentially useful tool to provide users with the prevailing tracking conditions under scintillation over a certain area and also be used to help mitigate the effects of scintillation on GNSS positioning. This paper reviews some of recent research results related to the impact and mitigation of space weather effects on GNSS receiver performance.

Ionospheric scintillation refers to rapid fluctuations in signal amplitude/phase when radio signals propagate through irregularities in the ionosphere. The occurrence of ionospheric scintillation can severely degrade the Global Navigation Satellite System (GNSS) receiver tracking loop performance, with consequential effects on positioning. Under strong scintillation conditions, receivers can even lose lock on satellites, which poses serious threats to safety–critical GNSS applications and precise positioning. The characteristics of intensity fading on Global Positioning System (GPS) L1 C/A signals during the peak of the last solar cycle at the low latitude station of Presidente Prudente (Lat. 22.12°S, Long. 51.41°W, Magnetic Lat. 12.74°S) are investigated. The results show that the occurrence of scintillation at this station is extremely frequent. An analysis of the fading events revealed an inverse relationship between fading depth and duration. Mathematical models are built to investigate and explain the statistical relationship between intensity fading and the commonly used amplitude scintillation index S4. Then the GPS receiver tracking loop performance is studied in relation to fading. A conclusion can be drawn that both fading depth and duration can affect the tracking loop performance, but the tracking error variance is more strongly related to fading speed, defined as the ratio of fading depth to fading duration. The proposed study is of great significance for better understanding the ionospheric scintillation intensity fading characteristics at low latitudes. It can also contribute to the research on the effects of scintillation on GNSS as well as support the design and development of scintillation robust GNSS receivers.