Seasonal and solar activity dependence of storm time TEC variations for a low latitude station Palehua

The enhancement and depletions of the total electron content (TEC) on storm days from the quiet day values are analysed for different seasons and solar activity conditions at Palehua, a low latitude station, during the period 1980–1991.Considering the dependence of enhancement in storm time TEC for positive storms with solar radio flux F10.7, a positive correlation is observed in winter and equinox. For negative storms, the correlation of depletion in storm time TEC with solar radio flux F10.7 is positive in equinox, but no such dependency is observed in summer. The intensity of storm (Ap) is found to be negatively correlated with enhancement in storm time TEC, in equinox, for positive storms. But no such dependency is shown in winter. For negative storms, the depletion in storm time TEC shows no dependency with Ap in equinox, but shows positive correlation in summer. Considering the dependence of enhancement of TEC on Dst max, a positive correlation is observed in winter and equinox for positive storms. For negative storms, the correlation between depletion in storm time TEC and Dst max is found to be positive for summer and equinox. A similar correlation study is carried out for time delay (τ) of occurrence of maximum enhancement and depletion of TEC. The maximum and minimum percentage probability range of ΔTEC and τ are also analysed by considering the data seasonally.

► TEC values for a low latitude station, Palehua for the period 1980–1991 are considered.
► The enhancement and depletions of TEC on storm days from quiet day values (ΔTEC) are analysed.
► The dependence of ΔTEC on solar radio flux F10.7, intensity of storm Ap and Dst max are studied.
► Correlation study is done for time delay (τ) of occurrence of maximum ΔTEC with F 10.7, Ap and Dst max.
► The maximum and minimum percentage probability range of ΔTEC and τ are also analysed.