Аңдатпа
The data recorded by the Alma-Ata ionosonde [43.25N, 76.92E] are used to compare the critical frequency (foF2) and the F peak height (hmF2), calculated by using the standard program POLAN, with the latest version of the International Reference Ionosphere (IRI) model (http://omniweb.gsfc.nasa.gov/vitmo/iri2012_vitmo.html) for the recent solar minimum, the years 2008-2010. Diurnal variations of the F peak parameters and those defined values from IRI model prediction were compared for representative months of winter (January), equinoxes (March, September), and summer (July) seasons. The URSI model was used as an IRI option. It was found that for the Alma-Ata (Kazakhstan) location the morphology of seasonal and diurnal variations of the foF2 and hmF2 monthly medians the new IRI model describes quite well but underestimates the F2-layer critical frequency (approximately 30%) during winter and equinox seasons especially for nighttime, pre-sunrise and post-sunset periods. The F-layer peak heights are usually underestimated in all seasons for daytime (approximately 10-30 km), except the daytime in summer (up to 100 km), and overestimated for nighttime (approximately 5-30 km). Modeled and “real” TEC values for the altitude range from 50 km to 2000 km were calculated correspondingly without and with using the optional true foF2 and hmF2 values in the IRI model. Deviations between the modeled and “real” TEC values are found to be in the range of 47-55%.