Abstract and keywords
Abstract (English):
The successful operation of communicational and navigational applications requires knowledgeof state and behaviour of ionosphere as well as spatial and temporal changes taking place init. With this view, we have studied the variability and changes in the low latitude ionosphereby considering a low latitude Indian station Hyderabad (17.41∘N, 78.55∘E). The variabilityis studied during the year 2014, by using the space borne Global Positioning System (GPS)observations. From GPS observations an important parameter; Total Electron Content (TEC)is obtained, which represents the integral electron density of the ionosphere and is widely usedin studies concerning ionospheric variability. We have studied how the ionospheric conditionsat Hyderabad change from hour to hour, day to day, month to month and season to season. Wefound that ionosphere over Hyderabad exhibits significant, interesting and regular variability.Although, the trends followed by the ionospheric changes are similar, but the magnitude ofpeak values differ on different time scales. Finally we have compared the variability of observedor actual values of TEC with the corresponding values predicted by International ReferenceIonosphere (IRI) model-2016 and found good agreement between hourly values, while IRImodel overestimates or underestimates the daily values.

Ionospheric variability, Total Electron Content, International Reference Ionosphere-2016 model

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