Global and regional high resolution VTEC Representations using B-Splines and Kalman filtering

Knowledge about the variability of the Thermosphere – Ionosphere (TI) system is essential for many communication and navigation applications, especially during storm conditions, since the ionospheric storm disturbances will influence the propagation characteristics of radio waves. Ionosphere models and ionospheric observations help to analyse and understand the dynamics of ionospheric storms in the strongly interactive TI system. For that reason, this study will assess the performance of physics based and empirical models of the ionosphere. Within the assessment we compare the model results with observations, in order to demonstrate their capabilities. In this study we use two different models; the first model, the Coupled Thermosphere Ionosphere Plasmasphere electrodynamics (CTIPe), is a global 3D time-dependent physics based nonlinear, numerical code that consist of four distinct components running concurrently and fully coupled with respect to energy momentum and continuity. CTIPe will serve as a background model for a new assimilation scheme named Thermosphere Ionosphere Data Assimilation (TIDA). This new scheme is based on an Ensemble Kalman Filter approach as required by the strongly forced nature of the modeled system. The second model, , the high resolution empirical ionosphere model developed at DGFI-TUM is based on the combination of data from different space-geodetic observation techniques, namely GNSS, Satellite Altimetry, DORIS, Langmuir Probe (LP) and Ionospheric Radio Occultations (IRO). As an additional input data source and to stabilize the electron density key parameter estimation, the separation approach is applied to calculate electron density values on a 3D grid, from the combination of electron density profiles calculated by a given model such as IRI or NeQuick and 2D VTEC maps. As a first step of the data assimilation studies in the INSIGHT – II project, we will use the St. Patrick’s Day storm 2015 as case study, to validate the models against Total Electron Content (TEC) derived from ground based Global Navigation Satellite System (GNSS) measurements, as well as the critical frequency of the F2 layer and the maximum electron density height measured by different ionosondes around the globe.