M-Ingestion: Simultaneous Ingestion of Ionosonde and GNSS Data into the NeQuick Model

The steady increase in volume and quality of ionospheric measurements allows for potential improvements in the existing ionospheric models. In particular ionosonde and Global Navigation Satellite Systems (GNSS) data provide complementary information for original developments regarding the NeQuick model, a quick-run empirical model of the electron density supplying flexible solutions for various applications. Indeed NeQuick is often used to investigate radiowave propagation issues: among others it has been implemented within the Galileo Single Frequency Ionospheric Correction Algorithm.
The model is particularly suited to be used within an optimization procedure called ingestion. In this framework, an "effective ionization level" Az plays the role of solar activity input in order to fit a specific dataset eg of slant Total Electron Content (TEC). However larger discrepancies can then obviously be observed towards other parameters eg the F2-layer critical frequency foF2. This draws the interest for a multiple ingestion - or m-ingestion - scheme implying an adaptation towards several datasets by defining several effective parameters.
In our study, we perform m-ingestion of ionosonde and GNSS data providing us with slant TEC. In fact it allows us to constrain the electron density profile slab thickness. For the purpose, a high solar activity period (year 2002) was analysed based on collocated digisonde and EUREF GNSS observations at a mid-latitude site, Dourbes (50.1◦N, 4.6◦E). In this way, we can gather some clues on expected ionospheric effects on Galileo applications during the next solar activity maximum.