Latitudinal Responses of F2 Peak Parameters to High-intensity Long-duration Continuous AE Activity (HILDCAA) Events

Abstract:

The ionospheric responses to geomagnetic storms form an important part of the space weather study. The ionospheric perturbations may be described as enhancements and depletions compared to the quiet time variations, known as positive and negative phases of the ionospheric storms, respectively. In spite of a significant volume of studies on the ionospheric responses to the geomagnetic storms, understanding of ionospheric storm has not reached a level where it is possible to predict it. Geomagnetic activity may be divided into three categories: substorms, storms of different intensity, and high-intensity long-duration continuous AE activity (HILDCAA) events. This work presents specifically the latitudinal responses of the noontime F region peak parameters (hmF2 and foF2) to HILDCAA events. For this, digisonde data from 51 stations around the world was selected from the Digital Ionogram Data Base (DIDbase) from 2004 to 2012. For the same period 19 HILDCAA events were detected. Preliminary results show a positive effect in the peak parameters of the southern hemisphere and a negative effect in those of the northern hemisphere, suggesting that there is a predominantly northward component of the meridional winds. Additionally, it seems that the events occurring around the summer solstice have meridional wind components that are exclusively northward, while two of the six winter time events have southward components. Wintertime events are also the only ones with a very prominent eastward component of the zonal winds.