Development of Ionospheric Total Electron Content. Model over Southern Africa using GNSS network. (a) Department of Physics, University of the Western Cape ...
Development of Ionospheric Total Electron Content Model over Southern Africa using GNSS network
V.P. vd Heyde (a), Dr. D.M. Moeketsi (b), Prof. R. Lindsay (a)
(a) Department of Physics, University of the Western Cape, S.A. (b) Centre of High Performance Computing, CSIR Meraka Institute Slide 1
OUTLINE • Introduction • Space Weather • Solar Activity & Sunspots • Ionosphere & GNSS • Motivation for Study • Local Ionospheric Models • MAGIC1.2 • TEC • Future Work • Acknowledgements Slide 2
INTRODUCTION What is Space Weather? •Emerging field of space science •Sun incredible influence on Earth’s space environment
•Satellite, navigation, communication, power distribution systems, and injure or kill astronauts
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INTRODUCTION Solar Activity and Sunspots Solar Flares – Violent eruptions from Sun CME – Huge amounts of matter (plasma)
Figure 1: Sunspot Number Vs Time (Years) – Adapted from NASA Slide 4
Ionosphere • Partially - ionized region in the upper atmosphere
• 60 km to ≈ 1000 km • Electromagnetic radiation (Solar EUV + X-rays) • Propagation of radio waves • Positioning Error for GPS Figure 2: Illustration of a typical vertical profile of the ionosphere (after Davies [1990], Komjathhy [1997] & Moeketsi [2008]) Slide 5
GNSS • IGS community referring to the US GPS, Russian GLONASS, & European GALILEO satellite system
• GPS is a satellite-based system developed by the US Department of Defense (DoD) • Space segment consists of 24 satellites – 6 Orbital Planes, inclined at 55°
• 20, 200 km above the Earth’s surface • Satellite transmits a navigation signal composed of two carriers (dual frequency) L1=1.6 GHz & L2=1.2 GHz Slide 6
GPS & Ionosondes Sites
Figure 3: Geographic locations of South African GNSS network Slide 7
Motivation for Study • International Global Navigation Satellite Systems (GNNS) Service (IGS) & S.A. networks of dual frequency GPS receivers, provides unique opportunity • Total Electron Content (TEC) of the ionosphere over S.A. region • Past decade, the usage of GPS data • Study focus on Ionospheric TEC model using GPS data assimilation based on Kalmann filter approach over S.A.
• MAGIC code
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Motivation for Study (cont) • Validate – Ionosonde measurements, International Reference Ionosphere
• Local & International research community • Contribute to regional space weather initiative in S.A. • Improving our understanding of coupling between solar activity & ionospheric process over the African region
• Important applications in high-frequency radio communications
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Local Ionospheric Models • MIDAS (Cilliers, 2004) – Ionospheric tomographic inversion in 4D
• UNB - IMT SA (Moeketsi, 2007) – Kalman Filtering
• ASHA (Opperman, 2007) – Variable degree adjusted spherical harmonic
• Neural Networks (Bosco, 2009) – Information processing systems
• Magic1.2 (Development Phase of model) – Assimilation method based on Kalman Filtering Slide 10
MAGIC1.2 • Kalman filter based data assimilation algorithm for imaging the Earth’s ionosphere in 4-D using GPS data
• Research tool in order to study various approaches to the problem of obtaining an estimate of the ionosphere • gmagic and gplot - Commands on Matlab to launch GUI •
Currently working on the source code to launch the GUI’s, and from GUI’s choose different parameters
• Colloboration with NOAA SWPC, University of Colorado, Boulder, USA & Dr. D. Moeketsi Slide 11
Magic1.2 - gmagic
Figure 4: The gmagic GUI: MATLAB toolbox for ionospheric data assimilation, where the function gmagic provides a general interface for downloading, preprocessing and assimilating data into the filter. Slide 12
Magic1.2 - gplot The function gplot enables the visualization of ionospheric reconstructions generated using gmagic
Figure 5: The gplot graphical user interface Slide 13
Vertical TEC over World
•TEC measure of number of e-s along path from GPS satellite to receiver •TEC units (1 TECU = 1016 electrons/m2)
•TEC obtained from the ionospheric delay between L1 and L2 signals Slide 14
Vertical TEC over US
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Peak Electron Density
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Electron Density Cross Section (World)
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Future Work • Constructing & expanding the US_TEC Magic model, over Southern Africa region • Memory problem with model as simulations is memory intensive bound • Plan to use Matlab Parallel Computing Toolbox, to be installed on CHPC Cluster
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Acknowledgements • CHPC • UWC Physics Department
• Dr. D. Moeketsi • Prof R. Lindsay • Inkaba yeAfrica Slide 19
Thank You for your attention
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