Considerations on mapping the GNSS ionospheric phase irregularities over Canada using kriging

Abstract:

Ionospheric irregularities over Canada, which are mostly driven by the coupling processes between the solar wind and Earth’s magnetic field, frequently result in phase scintillations over auroral oval and polar cap regions. Mapping of such irregularities can serve space weather nowcasting as well as positioning, navigation and timing (PNT) applications that are vulnerable to strong phase scintillation.

Kriging as one of the popular geo-statistical interpolation techniques relies on suitable spatial covariance functions or variograms. Variograms are used for deriving weights in ordinary kriging estimator. Kriging has been used in total electron content (TEC) interpolation for PNT applications, interpolation of intensity scintillation over equatorial regions, and to evaluate covariance functions of TEC variations over Canada.

In this paper, we examine kriging approach to map ionospheric phase irregularities over Canada using dual frequency phase rate variations from 1Hz GNSS observations. When combining different receiver types and constellations for mapping ionospheric phase irregularities over a region, receiver and constellation specific background phase noise deteriorate the precondition of stationarity of the phase irregularity indices, which is required for deriving variograms. Furthermore, reliability of experimental variograms, can be affected by several factors such as sample size, selected interval, trend, and anisotropy. GNSS phase irregularity maps are examined under different variogram estimation scenarios and corresponding results are evaluated using selected validation stations excluded from mapping experiments. In addition, the irregularity maps are investigated in the context of equivalent ionospheric currents derived from ground magnetometer network using the spherical elementary current system method.

NRCan contribution number: 20190353