GNSS-based analysis of high latitude ionospheric response on a sequence of geomagnetic storms performed with ROTI and a new relative STEC indicator

Abstract

This contribution presents a combined analysis of the occurrence of polar patches and development of auroral oval triggered by a sequence of geomagnetic storms in March 2012. The detection of the patches was realized with relative slant TEC (STEC) values extracted from geometry-free combination using novel, iterative algorithm of 4-degree polynomial fitting. The proposed approach allows sensing of large structures with high temporal resolution, since it provides epoch-wise information on STEC enhancement in respect to the specified background level. The comparative analysis of the novel indicator with well-known Rate of TEC Index (ROTI) has shown that the new one ensures the more detailed view on patch propagation. The applicability of relative STEC values was also preliminary confirmed by their validation with plasma density data obtained from SWARM mission. The evolution of auroral oval, involving its expansion as well as the intensity of TEC fluctuation, was performed with ROTI parameter. The results of patch occurrence and oval expansion for different geomagnetic conditions are consistent with previous works what proves the feasibility of comprehensive global navigation satellite system (GNSS)-based analyses with the proposed methodology.