Long term ionospheric effects and their associated modeling during extreme space weather events over the African sector
Abstract
The study of ionospheric dynamics and electrodynamics over the African region is complicated due to two main factors. The first one is largely logistical due to the scarcity of ground-based instrumentation dedicated to provide vital observations for utilisation in different scientific investigations. The second challenge has to do with different Physics exhibited at different latitude regions given that the African sector comprises of mid-latitudes in both northern and southern hemispheres as well as low/equatorial regions. The first challenge prohibits the accurate handling of the second problem. As a result, the ionospheric behaviour over the African sector is less understood and there remain several outstanding questions. Thus, the comprehensive understanding of different phenomena over the African sector is only based on the physical process performed only through a combination of measurements with existing sparsely located ground-based and satellite-based instruments. On the other hand, the demand of precise ionospheric correction for communication and navigation application in the region has grown up dramatically. However, to precisely correct the impact of the ionosphere on the commination/navigation radio signals, understanding of the physics behind each ionospheric phenomenon in the region is essential. This requires continuous observations of ionospheric parameters and its internal (due to lower thermosphere-ionosphere coupling) and external (due to solar wind –magnetosphere – ionosphere coupling) drivers, which become complex during both quiet and extreme space weather events.
We propose to assemble a team of diverse expertise to systematically look at different ground-based and satellite datasets as well as model simulations to comprehensively perform analyses and interpretations of the long-term ionospheric effects during extreme space weather events over the African sector with a view of addressing issues related (but not limited) to; ？ What mainly controls the ionospheric dynamics in the African sector? ？ Is it the forcing from above (SW-magnetosphere-ionosphere coupling) or from below (lower thermosphere-ionosphere coupling such as the role of atmospheric gravity waves (AGWs), planetary waves and tides)? ？ What is the relative contribution of the SW-magnetosphere-ionosphere coupling during disturbed conditions (over the existing background conditions) on a long term scale?
To contribute to the above questions, a multi-instrumental approach is required. Therefore, the assembled team consists of the principal investigators (PIs) of different instrumentation deployed in the African continent. The instruments include: magnetometers, Fabry Perrot Interferometers (FPIs), Global Navigation Satellite Systems (GNSS) receivers, very high frequency (VHF) radar, ionosondes and Continuous Doppler Sounding Systems (CDSSs). The beauty of these different instruments is that they observe different parameters, and coordinating these measurements provides excellent opportunity for the working team to understand the physical process that control unique ionospheric dynamics and structure in the African sector during quiet and disturbed conditions. Considering the range of instruments and volume of scientific results from long-term observations, performed by individual PIs, require extended discussion time to coordinate and understand all the results, we propose to hold TWO one-week face-to-face team meetings at ISSI in Beijing, China. Provisionally, we propose to hold the meetings in the second half of 2021 and 2022. The step-by-step progress report of the team？s effort will be presented at different international conferences, and the final paper(s) will be published in peer reviewed journal.
