foF2 variability at a southern low-latitude station and the performance of IRI-2016 model during ascending phase of solar cycle-24

Publication date: Available online 21 August 2019Source: Advances in Space ResearchAuthor(s): S.S. Rao, Monti Chakraborty, R. Pandey, A.K. SinghAbstractIn this research, we have analyzed the data of the critical frequency of the F2 region (foF2) ionosphere over the southern low-latitude station COCO (Keeling) Island (Geog. Lat. 12.20°S; Geomag. Lat. 22.83°S; Geog. Long. 96.80°E) for the period 2009–2013 and thereof have compared the results with those obtained with the IRI-2016 model. Our analysis shows a good correlation between variations in foF2 and solar flux at an F10.7 cm wavelength. With regard to geomagnetic activity during 2009–2013, it has been found that the variability in the monthly mean Ap index remained below 20 nT throughout the period 2009–2013. Concerning quiet time F2 region variability, our results explicated solar cycle, semiannual, and seasonal/annual variations in foF2. Similar oscillations in foF2 have been explored using the Lomb-Scargle periodogram technique. We have also observed the fundamental mode (27 days) and its overtones (9- and 13-day) in the geomagnetic activity parameter (Ap). Analysis of foF2 showed the consistent presence of the semiannual anomaly and absence of the winter anomaly during the ascending phase of solar cycle-24. The presence of an annual component in normalized foF2 has been examined using regression analysis. A comparative study of ionosonde-observed foF2 with IRI-2016-modeled foF2 showed that the general iono...
Source: Advances in Space Research - Category: Science Source Type: research
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