Ground- and space-based GNSS data ingestion into the NeQuick model

BRUNINI C.; AZPILICUETA F.; GENDE M.; CAMILIÓN E.; ARAGÓN ANGEL A.; HERNANDEZ-PAJARES M.; JUAN M.; SANZ J.

Barcelona

Simposio; International Beacon Satellite Symposium 2010; 2010

Universitat Politecnica de Catalunya

This paper presents a technique for ingesting ground- and space-based dual-frequency GPS observations into a semi-empirical global electron density model. The NeQuick-2 model is used as the basis for describing the global electron density distribution. This model is mainly driven by the F2 ionosphere layer parameters (i.e. the electron density, m 2 N F , and the height, m 2 h F of the F2 peak), which, in absence of directly measured values, are computed from the ITU-R database (ITU-R, 1997). This database was established using observations collected from 1954 to 1958 by a network of around 150 ionospheric sounders with uneven global coverage. It allows computing monthly median values of m 2 N F and m 2 h F (intra-month variations are averaged), for low and high solar activity. For intermediate solar activity a linear interpolation must be performed. Ground-based GNSS observations from a global network of ~350 receivers are pre-processed in order to retrieve slant total electron content (sTEC) information, and space-based GPS observations (radio occultation data from the FORMOSAT-3/COSMIC constellation) are preprocessed to retrieve electron density (ED) information. Both, sTEC and ED are ingested into the NeQuick-2 model in order to adapt m 2 N F and m 2 h F , and reduce simultaneously both, the observed minus computed sTEC and ED differences. The first experimental results presented in this paper suggest that the data ingestion technique is self consistent and able to reduce the observed minus computed sTEC and ED differences to ~25 – 30% of the values computed from the ITU-R database.