Abstract
Abstract. The High-Intensity Long-Duration and Continuous AE Activities (HILDCAA) intervals are capable of causing a global disturbance in the terrestrial ionosphere. However, the ionospheric storms' behavior due to these intervals is still not widely understood. In the current study, we seek to comprise the HILDCAA disturbance time effects in the total electron content (TEC) values with respect to the quiet days' pattern by analyzing local time and seasonal dependences, and the influences of the solar wind velocity on a sample of 10 intervals that occurred in the years 2015 and 2016. The main results showed that the hourly distribution of the disturbance TEC may vary substantially between one HILDCAA interval and another. An equinoctial anomaly was found since the equinoxes represent more ionospheric TEC responses than the solstices. Regarding the solar wind velocities, although HILDCAA intervals are associated with high-speed streams, this association does not present a direct relation to TEC disturbance magnitudes at low and equatorial latitudes.
Highlights
To geomagnetic storms, High-Intensity LongDuration and Continuous AE Activities (HILDCAA) intervals can influence the ionosphere, leading to disturbances in the ionospheric F2 region
We will present the ionospheric total electron content (TEC) responses observed during 10 HILDCAA intervals focusing on local time dependence and seasonal features and the solar wind velocity influences
A common feature of ionospheric storms is being associated with dependence on local time, mainly when they are caused by geomagnetic storms (Titheridge and Buonsanto, 1988; Pedatella et al, 2010)
Summary
High-Intensity LongDuration and Continuous AE Activities (HILDCAA) intervals can influence the ionosphere, leading to disturbances in the ionospheric F2 region. Park (1974) pointed out that ionospheric storms can be understood in terms of the superposed effects of many substorms In view of this and considering that the development of ionospheric storms during HILDCAA intervals has not been dealt with in depth, in the current study we have focused on the TEC pattern during this kind of event. The continuous energy injection and energetic particle precipitation into the polar upper atmosphere during HILDCAA intervals could modify the dynamic and chemical coupling process of the thermosphere–ionosphere system, resulting in changes in the electron density These modifications, beyond changing the auroral electron density, can be mapped to low latitudes involving electric field disturbances, as prompt penetration electric fields (PPEF) and disturbance dynamos (DD) (Koga et al, 2011; Silva et al, 2017; Yeeram and Paratrasri, 2019).
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