Ionospheric Scintillation nowcasting for Africa T M Matamba

Ionospheric Scintillation now-casting for Africa T. M. Matamba ; P. J. Cilliers and D. W. Danskin 15 July 2019

Space Weather Effects • Space weather can influence the performance and reliability of numerous technological systems that society depends on daily. • Space weather describes events that happen in space, which can disrupt modern technologies such as GPS, power grids, avionics, navigation and communication systems.

Layers of the Atmosphere Credit: https: //www. vectorstock. com/royalty-free-vector/layers-of-the-atmosphere-vector-10500995

Ionospheric variability IONEX data from ftp: //cddis. gsfc. nasa. gov/gnss/products/ionex/

Ionosphere and GPS Delay Scintillation Perturbs the signal propagation speed proportional to total electron content tens of metres error at solar maximum Causes rapid changes in signal phase and signal strength – most severe in auroral/equatorial regions and storms Images: Credit University of Bath 5

Ionospheric scintillation Climatology Global occurrence characteristics of scintillation (P. Kintner et. al 2009).

Amplitude Scintillation proxies Measured S 4 Signal to noise ratio on L 1

Distribution of Scintillation monitors in and around Africa RT Gough Island RT

Novatel, GSV 4004 GISTM Antenna Hermanus GISTM Antenna Panoramic view from antenna

Hermanus, S 4 scintillation event 2 August 2011

GISTM receiver, Pwani, Kenya

Scintillation from CRI receiver at Pwani University, Kenya October 2015 Results • • Scintillation data from Chinese GISTM Receiver (made by the Chinese Research Institute (CRI)) The higher scintillation levels (S 4 ≥ 0. 5 and σφ ≥ 0. 4) were observed regularly in October 2015 over Pwani, Kenya (LT=UT+3).

Near Real-time (NRT) GISTM data processing • GISTM data is transferred from Source to SANSA server every hour, on the hour • GISTM data is retrieved from SANSA server via ftp at 10 minutes after the hour • Latest hour of data is concatenated to previous 23 hours of data • S 4 for Elevation >20º is selected • S 4 correction is applied • S 4 and σϕ are verticalized using the algorithm of Spogli et al. (Ann Geophys 2009). • The display is scheduled by crontab activated script to update every 10 minutes. • The crontab stores the outputs of the results of each script in logs/directory. • NRT display shows most recent 24 hours of GISTM data

Elevation threshold dependence, Hermanus, 2019 -01 -01 event PRN 6 Elev ≥ 0⁰ Elev ≥ 20⁰

Elevation threshold dependence, Hermanus Threshold: elevation≥ 0⁰ Threshold: elevation≥ 20⁰

ICAO requirements regarding ionospheric products Space Weather Aviation Final Products: GNSS Navigation and Surveillance 1. TEC Real Time Maps 2. TEC Error 3. TEC Rate 4. TEC-Gradients 5. TEC-Map prediction ( 1 h- 24 h) 6. TEC-Map Quality 7. 3 D Ionosphere reconstruction and modelling 8. Scintillation measurements [S 4 and σφ Index] (GISTM) 9. ROTI (Rate of Change of TEC index)

Thresholds specified by ICAO for scintillation occurrence analysis. Threshold Level S 4 index range σϕ index range Weak 0. 2 < S 4 ≤ 0. 5 0. 2 < σϕ≤ 0. 4 Moderate 0. 5 < S 4 ≤ 0. 8 0. 4 <σϕ≤ 0. 7 Strong 0. 8 < S 4 0. 7 < σϕ

Hermanus

Pwani-Kenya http: //dev 2. swc. sansa. org. za/products/gnss/scintillation/latest_video 2. mp 4

Thank you in service of humanity

References • Jakowski, N. , Hoque, M. M. and Mayer, C. , 2011. A new global TEC model for estimating trans-ionospheric radio wave propagation errors. Journal of Geodesy, 85(12), pp. 965 -974. • Olwendo, J. , Cilliers, P. , Weimin, Z. , Ming, O. and Yu, X. , 2018. Validation of ROTI index for ionospheric amplitude scintillation measurements in a low latitude region over Africa. Radio Science. • Kintner, P. M. , Humphreys, T. and Hinks, J. , 2009. GNSS and ionospheric scintillation. Inside GNSS, 4(4), pp. 22 -30. • Hargreaves, J. K. (1992). The Solar-Terrestrial Environment. Cambridge Atmospheric and Space Science Series, Cambridge University Press. • Spogli, L. , Alfonsi, L. , De Franceschi, G. , Romano, V. , Aquino, M. H. O. , and Dodson, A. : Climatology of GPS ionospheric scintillations over high and midlatitude European regions, Ann. Geophys. , 27, 3429 -3437, https: //doi. org/10. 5194/angeo-27 -3429 -2009, 2009.