A new global empirical NmF2 model for operational use in radio systems

The ionospheric F2 region around the peak electron density height hmF2 of about 250–500 km causes the most pronounced impact on transionospheric radio wave propagation. Therefore, the peak electron density of the F2 layer NmF2 is a key parameter for characterizing the ionosphere. We present an empirical model approach that allows determining global NmF2 with a limited number of model coefficients. The nonlinear approach needs 13 coefficients and a few empirically fixed parameters for describing the NmF2 dependencies on local time, geographic/geomagnetic location and solar irradiance and activity. The model approach is applied to a vast quantity of global NmF2 data derived from GNSS radio occultation measurements by CHAMP, GRACE and COSMIC satellite missions and about 60 years of processed NmF2 data from 177 worldwide ionosonde stations. The model fits to these input data with the same standard and root mean squared (RMS) deviations of 2 X 10¹¹ m^−-3. The proposed Neustrelitz global NmF2 model (Neustrelitz Peak Density Model - NPDM) is climatological, i.e., the model describes the average behavior under quiet geomagnetic conditions. A preliminary comparison with the electron density NeQuick model reveals similar results for NmF2 with RMS deviations in the order of 2 X 10¹¹ m^−-3 and 5 X 10¹¹ m^−-3 for low and high solar activity conditions, respectively.