Ionosphere delay remote sensing during geomagnetic storms over Egypt using GPS phase observations

Abstract

Various factors can increase ionosphere activity, such as the geomagnetic latitude, altitude, and geomagnetic storms. These storms can result in a significant disruption of the Earth’s atmosphere due to the interchange of solar wind energy into the milieu encompassing the Earth. The principal reason for this research is investigating the geomagnetic activity effect on ionospheric delays over Egypt using GPS (Global Positioning System) multi-frequency (L2 and L1) measurements. In this contribution, a GPS network spread over Egypt was utilized to figure ionosphere errors over Egypt, utilizing two models that rely upon GPS observable linear combination and smoothed phase observables. An algorithm was coded in MATLAB® environment and was called the Ionosphere Error Estimation (IEE) program. GPS phase observables were considered in this investigation to avoid blunders from pseudo-range measurements. Data from six ground-based multi-frequency GPS receivers located over Egypt have been chosen to study the impact of geomagnetic storms on ionospheric blunders. This paper presents the consequences of ionospheric blunders during disturbed and quiet days throughout the years of 2013 and 2014. Results clarify that the applied models using unsmoothed and smoothed phase observables show a good agreement in estimating ionospheric blunders, especially in quiet days. Ionospheric blunder standard deviation of mean (SDM) results from using smoothed phase observables that ranges from 16 to 3 cm in quiet conditions and ranges from 21 to 8 cm in stormy conditions. While ionospheric blunder SDM ranges from 17 to 5 cm in quiet days and from 23 to 8 cm in stormy days using unsmoothed phase observables. In The maximum ionosphere delay estimated over stormy days using the unsmoothed phase observables, its magnitude was 13.19 m at ASWN while the highest ionosphere error at ASWN station in quiet days was 6.83 m. In the maximum ionosphere delay estimated over stormy days using the smoothed phase observables, its magnitude was 13.34 m at ALAM while the highest ionosphere error at ALAM station in quiet days was 4.94 m. Finally, geomagnetic storms represent a real problem in equatorial and high-latitude zones, which causes a significant influence on the ionosphere blunder, and they have the capability of upsetting the results.