Benchmark event categorization for space weather effects on aviation over sub-Saharan Africa

Abstract

Space weather events pose a significant risk to aviation technologies in Sub-Saharan Africa. The question is, how would an extreme space weather event present itself in Sub-Saharan Africa and how would this affect aviation technologies and communications? The objective of this work is to formulate space weather benchmarks which address the expected impact of extreme space weather in Sub-Saharan Africa. Data sets concerning various solar emissions, magnetic field fluctuations and ionospheric variations will be used to investigate space weather in Sub-Saharan Africa. Extreme value theory and Kendall's return periods are the statistical methods which will be utilized to achieve the objectives. The central analysis in this region is constructed in such a way that it may be readily expanded upon when additional data, space weather manifestations and aviation technologies emerge. Solar radio bursts are shown to cause disruptions on various aviation frequencies. An interference threshold, as a function of frequency, is derived. This study highlighted a particularly useful technology, the radio altimeter, which is particularly vulnerable to extreme space weather in the form of large broad-band solar radio bursts. There is insufficient space weather literature on this aviation component, which is disconcerting considering the vulnerability and yet importance thereof to aviation, within the study region. The current work addresses this gap in the literature by publishing a simulation of the impact of solar radio burst interference on the radio altimeter. Solar Extreme Ultra-Violet emissions are shown to impact the number of visible satellites available for GPS position estimation. For the most extreme ultra-violet emissions (> 0.0007 W/m2), the number of visible satellites is greatly reduced to three. This impedes accurate position estimation. Solar flare X-ray emissions increase D-region absorption of high frequency (30 MHz-300 MHz) communications. For extreme X-ray emissions (> 0.0002 W/m2), ionosonde blackout is observed. Aviation communications are at great risk during such emissions. The largest magnetic fluctuation was given by a Dst index of −422 nT. During this extreme magnetic variation, the Kp index attained a value of 9. From the statistical analysis the most extreme space weather event (or worst case scenario) would be realized by the combination (−422 nT, 5.74×10−3 W/m2), which has a return period of 1 in 13 years. This realisation included a X17 solar flare alongside a Dst index of −422 nT, and an extreme ultra-violet enhancement of 0.0012 W/m2. This observation is discussed within the context of Big Flare Syndrome. Importantly, it was discussed that this most extreme event would generate a significant enhancement across the solar emission spectrum (extreme ultra-violet, solar X-ray, solar radio); even though it would not register the largest X-ray enhancement. The expected impact to the aviation industry in the study region, as predicted from the current thesis, is presented within secondary substrata of the space weather benchmark statements. Of greatest impact to aviation in this study region are ionospheric fluctuations and solar radio emissions.