Performance Analysis of Global Empirical Ionospheric Models with GPS and Ionosonde Recordings over Lower-Midlatitude Cyprus Region

The present study is about a detailed analysis of geomagnetically quiet- and disturbed-time variations of F2 layer critical parameters (foF2 and hmF2) from a digisonde and Total Electron Content (TEC) extracted from a collocated GPS receiver observables at a lower-mid latitude Mediterranean location Nicosia, Cyprus. The data covers a duration of eight years from 2009-2016 that falls in the 24^th solar cycle. The study adheres to a comparative analysis of estimates from global empirical standard International Reference Ionosphere (IRI-2016) and the Standard Plasmasphere Ionosphere Model (SPIM-2017/IRI Plas 2017) and interpolated parameter from the IGS-Global Ionospheric Maps (GIMs) with the digisonde/GPS observed parameters. Our results confirm a remarkable divergence of F2-layer parameters from models/maps from that of the collocated GPS/digisonde observables. This contradicts the general conception of an ideal behaviour of empirical ionosphere models over the middle latitude region inferring that the transient region between the low and middle latitude do suffer from radical uncertainties in the estimations from the global ionosphere models and maps and needs further investigations. Interestingly, an intentional ingestion of observed GPS-TEC into the SPIM model claims an excellent convergence of the parameters towards the local observations even during various levels of geomagnetic storm conditions. It claims the flexibility in the SPIM-2017 model towards possible improvements through ingestion of the optional inputs pertaining to the global efforts towards a reliable prediction of TEC. Such efforts are in line with ionospheric error mitigations in navigation, communication and satellite applications over the eastern Mediterranean region.