Comparisons of Ionospheric Peak Parameters from Radio Occultation Observations and IRI-2016 Model Outputs over China

NmF2 and hmF2 outputted by the latest International Reference Ionosphere (IRI-2016) model are compared with COSMIC (Constellation Observing System for Meteorology Ionosphere and Climate) radio occultation (RO) measurements during 2008-2014 over China. For both NmF2 and hmF2, the correlations between IRI-2016 model outputs and COSMIC RO measurements are higher during high solar activity years (2011-2014) than low solar activity years (2008-2010). During LT(local time) 12:00-14:00 of equinox months in low solar activity years, IRI-2016 model generally underestimates NmF2 and overestimates hmF2 at 30°N-55°N, while overestimates NmF2 and underestimates hmF2 at 15°N-30°N. Outputs based on IRI_CCIR and IRI_URSI model options both overestimate NmF2 and the overestimation is more distinct during low solar activity years than high solar activity years. As for hmF2, during low solar activity years, both IRI_CCIR and IRI_AMTB model outputs are higher than COSMIC RO observations for all the three seasons and the deviations of IRI_AMTB model outputs from RO measurements are the largest, especially in winter. It is recommended that IRI_CCIR model and IRI_Shubin model should be used for calculating NmF2 and hmF2 over China respectively.