Analysis of GPS phase rate variations in response to geomagnetic field perturbations over the Canadian auroral region

One year of high rate dual frequency GPS phase rate variation statistics at three Canadian auroral locations are compared with geomagnetic field variations observed at co-located magnetic observatories. The geomagnetic variations are characterized at the Canadian Space Weather Forecast Centre by the hourly range of magnetic field for northward, eastward and vertical downward directions. The hourly mean of GPS phase rate statistics are derived from 1-Hz GPS dual frequency phase measurements which are continuously being monitored at the Canadian Geodetic Survey of Natural Resources Canada. Analysis reveals correlation coefficients of about 0.7-0.8 between these two hourly indices. The highest correlation is found between hourly mean phase rate variations and hourly ranges of the magnetic field vertical component. This can be attributed to changes in the position of the auroral electrojet during rapid expansions of the auroral oval during periods of auroral substorms. Apart from allowing studies on local ionospheric irregularities, these results indicate that GPS phase rate measurements in the auroral zone are responding to the geomagnetic field variations which could be used as representative proxy measures for scintillation occurrence in the region. Analysis of GPS phase rate statistics also revealed station specific features due to non-ionospheric effects.