A long term study on the variability of HILDCAA events and solar wind-magnetosphere coupling

Abstract

In the proposed project, case studies on the middle latitude ionospheric response during HILDCAA events will be conducted using various ionospheric parameters like F2 layer critical frequency (foF2), F layer virtual height (h/F), total electron content (TEC), etc. as well as magnetometer data. The foF2 and TEC data over a chain of observing stations extending from the magnetic equator to the anomaly crest locations will be utilized to assess the effects of HILDCAAs on the evolution of equatorial ionization anomaly (EIA). Case studies will also be conducted to compare the effects of geomagnetic storms and HILDCAAs on the EIA variability. For the present study, Incoherent Scatter Radar (ISR) measurements at the Arecibo Observatory of electron density, ion and electron temperatures, H+, He+ and O+ concentrations, and plasma drift velocity will be utilized. In addition, data obtained from local global positioning system (GPS) receivers, ionosonde, neutral wind and magnetometer observations will also be analyzed. The Arecibo's ISR may provide us with much more information about the ionosphere than any other equipment in the world. From the Arecibo's ISR data it is possible to study the topside ionosphere (region above the F2 layer peak), the region that is not seen by any other instrument (despite the satellites). So, there is a unique opportunity of investigating the responses of the topside and protonosphere regions above Arecibo Observatory (north hemisphere middle latitude). Through the analysis of the H+, He+ and O+ concentrations, for example, it is possible to identify the transition height between the topside ionosphere and the protonosphere. By adding the neutral wind and the vertical plasma drift velocity to this study it is possible to check if the responses are local or there is solar wind driver. (AU)