Personal-computer-based system for real-time reconstruction of the three-dimensional ionosphere using data from diverse sources



[1] We present new capabilities of our system for monitoring the ionosphere over a fixed geographical area with dimensions of the order of several thousand kilometers. The system employs a nonlinear representation for electron density that ensures a nonnegative solution. The multidimensional nonlinear inverse problem is efficiently solved using a combination of the Newton-Kontorovich method and Tikhonov's regularization technique for ill-posed problems. The system is able to utilize a variety of types of ionospheric data, which are as follows: networks of ground- and space-based (satellite mounted) dual-frequency GPS receivers provide time series of oblique absolute total electron content (TEC) and/or relative TEC data (directly calculated from the raw dual-frequency group delays and phase delays, respectively), TEC data from ground- or space-based receivers operating with dual-frequency beacons mounted on low-Earth orbit (LEO) satellites, vertical TEC data from orbiting radio altimeters (such as Jason satellite), in situ electron density data from plasma probes on LEO satellites (such as Challenging Minisatellite Payload for Geophysical Research and Application), and electron density profiles from sounders. The resulting solution for the distribution of electron density is guaranteed to be smooth in space and time and to agree with all input data within errors of measurement. Real time performance is attained on a single personal computer with 5 min data refreshment period. Operation of the system is tested on real data with various data types simultaneously present. A new form of the stabilizing functional is developed to ensure reasonable assimilation of the in situ electron density data.