Climatology of ionosphere over low-latitude (Kolkata) using FORMOSAT-3/COSMIC satellite observation

We have analyzed the diurnal, monthly, and seasonal variation in NmF2, HmF2, and IECs parameters derived from the COSMIC-RO observation over the low-latitude (Kolkata) region during 2008–2012 and compared the result with the IRI-2007 model output. In general, during HSA period the seasonal averaged model outcome prominently overestimates the observed values throughout the day, except HmF2, while in LSA period it is confined to post-noon hours. The differences between diurnal-dip and diurnal-peak values of all these parameters are considerably higher in the model outcomes than those of observed values, especially during increasing solar activity. In addition, the monthly averaged NmF2, BIEC, and TIEC values at noon and midnight, obtained from the both options, exhibit semi-annual variation, which are in good agreement with some earlier studies, whereas HmF2 shows annual variability for all solar activity. Moreover, the similarities and dissimilarities observed in variation pattern, particularly during 2011 and 2012, can help the research community to understand the recent trends of ionospheric parameters and develop the IRI model with more efficiency to fit the observed profile in a better way.