An Investigation of the Effect of Mid - Latitude Magnetic Storms on the TEC over South Africa for Solar Cycle 23 and 24 3. Results and Discussion 3.1 TEC over South Africa during Post Solar Maximum for 2003 Reference Day 1. ABSTRACT The GNSS observables on dual frequencies (L 1 = 1575.42 MHz & L2 = 1227.6 MHz) used in a technique provide a unique approach for permanent monitoring of the temporal and spatial variations of the ionospheric parameters such Total Electron Content (TEC) on regional and global scale (e.g. Klobuchar, 1991; Mannucci et al., 1998). This approach is possible due to dispersive nature of ionospheric medium (Ratchlife, 1959). TEC can be considered as the ionosphere’s measure of ionisation and is defined as the total number of electrons present along a path from GPS satellite orbiting at altitude of ~22 ,2000 Km in space to ground receiver on Earth. It is expressed in units of electrons per square meter, where 10 16 electrons/m2 = 1 TEC unit (TECU). As a GPS navigation signal travels through the ionosphere at the L 1 and L 2 frequencies, it experiences a time delay due to interaction with free electron gas, which to a first approximation is directly proportional to TEC and inversely proportional to the square of its frequency (f) as follows: Due to the non linear variability of the ionospheric parameters due to complex processes occurring within the layers of the ionosphere, the distorted navigation signals can cause noteworthy changes in the performance of ground based and space borne technological systems e.g. satellite navigation communications. For this and other purposes, the MAGIC package, is applied using 30s data from South Africa’s IGS and GPS networks (see Figure 1), to investigate the effect of mid - latitude magnetic storms on TEC over South Africa for Solar Cycles 23 and 24 The development of regional ionospheric Total Electron Content (TEC) models has contributed to understanding the behavior of ionospheric parameters and the coupling of the ionosphere to space weather activities on both local and global scales. In the past several decades, the International Global Navigation Satellite Systems Service (GNSS) networks of dual frequency receiver data have been applied to develop global and regional models of ionospheric TEC. These models were mainly developed in the Northern Hemisphere where there are dense network of ground based GPS receivers for regional data coverage. Such efforts have been historically rare over the African region, and have only recently begun. This thesis reports the investigation of the effect of mid-latitude magnetic storms on TEC over South Africa for portions of Solar Cycles 23 and 24. The MAGIC package was used to estimate TEC over South Africa during Post Solar Maximum, Solar Minimum, and Post Solar Minimum periods. It is found that TEC is largely determined by the diurnal cycle of solar forcing and subsequent relaxation, but effects due to storms can be determined. 6. REFERENCES Angel, A., Carrano, C., Komjathy, A., Astilean, A., Letia, T. Kalman filter-based algorithms for monitoring the ionosphere and plasmasphere with GPS in near-real time. Journal of Atmospheric and Solar-Terrestrial Physics 71 (2009) 158–174 Araujo-Pradere, E.A., T.J. Fuller-Rowell, P.S.J. Spencer. Consistent features of the TEC changes during ionospheric storms. Submitted to J. Atmos. Sol. Terr. Phys. 2005. pp 1834-1842. Araujo-Pradere, E. A., T. J. Fuller-Rowell, P. S. J. Spencer, and C. F. Minter, Differential validation of the US TEC model, Radio Sci., 42, RS3016, 2007 Bilitza, D. International Reference Ionosphere – Status 1995/96, Advances in Space Research, Volume 20, Issue 9, 1997, pp 1751 - 1754 Klobuchar, J. A. Ionospheric effects on GPS. GPS World, 2, 48-51, 1991. Mannucci, A. J., Wilson, B. D., Yuan, D. N., Ho, C. M., Lindqwister, U. J., Runge, T. F. A global mapping Technique for GPS-derived ionospheric total electron content measurements, Radio Sci., 33, 565-582, 1998. Moeketsi, D.M., Combrinck, W.L., McKinnell, L.A., Fedrizzi, M. Mapping GPS-derived ionospheric Total Electron Content over Southern Africa during different epochs of solar cycle 23. Adv. Space Res. 39, 821 – 829, 2007. Minter C.F., D.S. Robertson, P.S.J. Spencer, A.R. Jacobsen, T.J. Fuller-Rowell, R.Moses, D.M. Susczynsky, and E.A. Araujo-Pradere. A Comparison of MAGIC and FORTE Ionospheric Measurements, Radio Sci. 2007. Ratcliffe, J. A. Magneto-ionic theory and its application to the ionosphere. Cambridge University Press, Cambridge, 1959. Spencer P.S.J., Robertson D.S., and Mader G.L. Ionospheric data assimilation methods for geodetic applications. Paper presented at IEEE PLANS 2004, Inst. Of Electron. And Electr. Eng., Montery, Calif., pp. 510 - 517., Apr. 2004. 2. INTRODUCTION 2 μm 2 40.3 TEC ion f d Figure 1: Geographical map that depicts the locations of South Africa’s GNSS network. Figure 2: Panels a) - d) show TEC density maps over the ionosphere of South Africa at times 04:45 UT and 10:30 UT. Panels 2a) and 2d) is RTEC maps for times 04:45 UT and 10:30 UT, respectively whereas Panels 2b) and 2d) is MAGIC TEC maps for times 04:45 UT and 10:30 UT. 4. Future Work For proposed future work using the MAGIC package as an applied research tool, the following topics can be addressed; Expansion of the MAGIC model over Africa, when the GNSS capacity increases over Africa in the near future; Investigating the effect of geomagnetic storms over South Africa and Africa for Solar Cycle 24 and subsequent solar cycles; Comparison of the MAGIC package versus other local ionospheric TEC models. *V.P. van de Heyde 1 , D. M. Moeketsi 2 , C.P. Price 3 1 Department of Physics, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa 2 Centre of High Performance Computing, CSIR Meraka Institute, Rosebank 7700, South Africa 3 Department of Physics, University of Alaska Fairbanks (UAF) *E - Mail: vvandeheyde@uwc.ac.za CHPC National Meeting 2013 CTICC, Cape Town, South Africa 02 - 06 December 2013 5. ACKNOWLEDGEMENTS The main author of the poster would like to acknowledge the support of he’s supervisors, Dr. Moeketsi, Prof C.P. Price and Prof. R. Lindsay for the helpful discussions and suggestions as well as CHPC for giving the author an opportunity to present the research. The author would also like to thank the UWC Physics Department Staff and postgraduate colleagues for their support, suggestions, motivation and guidance thus far. Dr. Eduardo Pradere of the NOAA Space Weather Prediction Centre, USA, for discussions and guidance, but most importantly granting the MAGIC application for academic research use. Author would also like to thank the NRF and Inkaba yeAfrica for financial assistance during this study. Figure 3: A graphical visualization that illustrates spatiotemporal maps of how TEC fluctuates over the ionosphere of South Africa for 2003 October Reference Day. The UT times for panels a) - d) are 03:45 UT (~ sunrise), 10:15 UT (~ solar noon), 16:30 UT (~sunset) and 22:00 UT (~ solar midnight), respectively. 3.2 TEC over South Africa during Post Solar Maximum for 2003 Storm Day Figure 4: Panels a) - d) show STEC density maps over the ionosphere of South Africa at times 03:45 UT, 10:15 UT, 16:30 UT and 22:00 UT, respectively for 2003 Storm Day. Figure 5: Graphical display showcasing the average Storm TEC Time Series for the 2003 Storm Day, where the x label represents the amount of storm days (29 - 31 October 2003) in hours. The average value is of the 66 values of TEC, where the error bars is just the RMS Deviation of the 66 values about the mean. 3.3 Difference & Similarity amid Post Solar Min - and Min Periods for SA RTEC Figure 6: Illustration of the average SA TEC Time Series for all eight Reference Days.