IONOSPHERIC IRREGULARITIES MEASURED BY GROUND-BASED AND SATELLITE-EMBEDDED RECEIVERS: ANALYSIS OF S4 INDEX IN A LOW LATITUDE REGION

The upper part of the atmosphere, the ionosphere, is partially ionized, and it is being crossed by many multi-frequency signals of the Global Navigation Satellite System (GNSS) satellites. This unique source of data can be acquired in real time from hundreds of permanent GNSS receivers. The real-time processing providing the distribution of the ionospheric free electrons (Global Ionospheric Maps) can be done as well in real time. We present their updated real-time assessment and combination.

This paper presents a data-driven model of the ionospheric electron density that has been developed for the EUMETSAT Polar System - Second Generation mission, with the main goal to improve the inversion of radio occultations for neutral atmospheric sounding. This model has been developed using occultation data from the COSMIC/FORMOSAT-3 satellite, which has been inverted using a LMS-based mechanization of the Abel inversion that implements the separability hypothesis.

We extend the kriging of the ionospheric electron density with slant total electron content (STEC) measurements based on a spatial covariance to kriging with a spatial–temporal covariance and develop a novel tomography approach by gradient-enhanced kriging assimilating STEC and F2 layer characteristics. The methods are cross-validated with independent measurements and point out the potential compensation for the often observed bias in the estimation of the F2 layer peak height.