Comparison of peak characteristics of the F2 ionospheric layer obtained from the Cyprus Digisonde and IRI-2012 model during low and high solar activity period

We investigate first the climatology expressed by diurnal and seasonal variations of the critical frequency (f(o)F(2)) and the peak height (h(m)F(2)) of the F-2-layer derived from digital ionosonde measurements at the low-middle latitude European station in Nicosia, Cyprus (geographical coordinates: 35 degrees N, 33 degrees E, geomagnetic lat. 29.38 degrees N, I = 51.7 degrees). Monthly median hourly values of the F-2-layer peak characteristics are obtained using manually scaled data during the 5-year period 2009-2013. The observational results are then compared with the International Reference Ionospheric Model (IRI-2012) predictions using both URSI and CCIR coefficients. It is shown that the semi-annual pattern of daytime f(o)F(2) characterized by higher values at equinoxes than either solstices as well as the winter anomaly phenomenon demonstrate strong solar activity dependence. An annual pattern of night-time f(o)F(2) is also detected with lower values in winter and higher in summer. The seasonal variation of daytime h(m)F(2) is evident and peaks of h(m)F(2) at pre-sunrise and post-sunset hours are identified during December. The IRI-2012 model is capable to capture the main diurnal and seasonal patterns of f(o)F(2) and h(m)F(2). The highest overestimation of daytime f(o)F(2) is noted at equinoxes and solstices except from March, October, December of 2011, and June of 2013. Significant f(o)F(2) underestimation is observed at evening and after midnight during February and March of 2009. Large positive discrepancies between the modeled and observed h(m)F(2) values are noticed during the deep solar minimum year 2009. Overall, IRI-model estimates are more accurate for h(m)F(2) than f(o)F(2) over Cyprus and for the examined period. (C) 2015 COSPAR. Published by Elsevier Ltd. All rights reserved.