solar cycle effects on gnss-derived ionospheric total electron content ...

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TABLE OF CONTENTSLIST OF FIGURES ........................................................................................................................... 5LIST OF TABLES ............................................................................................................................. 9INTRODUCTION............................................................................................................................ 101.1 Background ............................................................................................................................ 101.2 Aim and Structure of Thesis................................................................................................... 12THE SUN, EARTH`s IONOSPHERE AND SATELLITE MISSIONS...................................... 162.1 Introduction ............................................................................................................................ 162.2 The Sun, <strong>solar</strong> <strong>cycle</strong> and Earth`s magnetic field.................................................................... 162.3 The Earth’s Ionosphere .......................................................................................................... 192.3.1 The D layer.................................................................................................................... 222.3.2 The E layer .................................................................................................................... 222.4.3 The F layer .................................................................................................................... 232.3.4 Major geographic regions of the ionosphere................................................................. 232.3.4.1 The equatorial region ........................................................................................... 242.3.4.2 The mid-latitude region........................................................................................ 242.3.4.3 The high latitude region ....................................................................................... 252.4 Ionospheric perturbations....................................................................................................... 262.4.1 Ionospheric storms ........................................................................................................ 262.4.2 Geomagnetic storms...................................................................................................... 272.4.3 Ionospheric scintillations............................................................................................... 272.5 Solar Terrestrial Indices ......................................................................................................... 282.5.1 The DST index .............................................................................................................. 282.5.2 The Kp, and Ap indices................................................................................................. 292.6 Ionospheric <strong>effects</strong> on propagation of electromagnetic waves .............................................. 302.6.1 Phase refractive index ................................................................................................... 312.6.2 Group refractive index .................................................................................................. 331
2.6.3 Ionospheric group delay and phase advance ................................................................. 342.6.3.1 Phase and group velocity...................................................................................... 342.7. Ground based Ionosonde....................................................................................................... 352.8 Satellite Missions ................................................................................................................... 372.8.1 Global Navigation Satellite System .............................................................................. 372.8.2 SOHO CELIAS/SEM.................................................................................................... 392.8.3 GOES Satellite Solar Environment Monitor................................................................. 402.9 Summary ................................................................................................................................ 41THE IONOSPHERIC TOTAL ELECTRON CONTENT MODEL........................................... 423.1 Introduction ............................................................................................................................ 423.2 Overview of modelling ionospheric TEC using GNSS ......................................................... 423.3 The UNB ionospheric modelling technique........................................................................... 443.3.1 GNSS ionospheric observables ..................................................................................... 443.3.2 Estimating Strategy ....................................................................................................... 493.3.3 Ionospheric shell height and mapping function ............................................................ 503.3.4 Interpolation scheme to create TEC maps..................................................................... 513.4 Modification of UNB-IMT for application over southern African region............................. 523.5 International Reference Ionosphere ....................................................................................... 543.6 Summary ................................................................................................................................ 55VALIDATION OF UNB-IMT USING IONOSONDE TEC MEASUREMENTS OVERSOUTH AFRICA ............................................................................................................................. 564.1 Introduction ............................................................................................................................ 564.2 Observations and data analysis .............................................................................................. 584.2.1 Southern Africa GNSS networks .................................................................................. 594.2.3 Southern Africa Ionosondes.......................................................................................... 604.3 Comparison of GTEC with ITEC........................................................................................... 614.3.1 Comparison of midday GTEC with ITEC measurements near <strong>solar</strong> maximum........... 612
Page 1 and 2: SOLAR CYCLE EFFECTS ON GNSS-DERIVED
Page 3 and 4: ACKNOWLEDGEMENTSI would like to ack
Page 5: SOHOSXITECVLBIVTECVTMUNB-IMTULMCARU
Page 9 and 10: 7.2 Recommendation for future work
Page 11 and 12: Figure 4.4: The scatter plot of mid
Page 13 and 14: Figure 6.5: Panel (a) depicts the c
Page 15 and 16: Chapter 1INTRODUCTION1.1 Background
Page 17 and 18: station using stochastic parameters
Page 19 and 20: (GTEC) computed using UNB-IMT with
Page 21 and 22: Chapter 2THE SUN, EARTH`S IONOSPHER
Page 23 and 24: that the solar mat
Page 25 and 26: charged ion is created, and the neg
Page 27 and 28: 2.3.1 The D layerThe D layer is the
Page 29 and 30: Figure 2.4: Major geographic region
Page 31 and 32: latitude of 78 to 80 near local n
Page 33 and 34: with different propagation velociti
Page 35 and 36: 2.6 Ionospheric effects</st
Page 37 and 38: where ω (radian.cωCZ = ,(2.5)ω1s
Page 39 and 40: nwhich is the group refractive inde
Page 41 and 42: (e.g. McKinnell, 2002). The ionogra
Page 43 and 44: GPS is a satellite-based system for
Page 45 and 46: solar flux between
Page 47 and 48: Chapter 3THE IONOSPHERIC TOTAL ELEC
Page 49 and 50: although efforts are continuously i
Page 51 and 52: side of the equation, which is slow
Page 53 and 54: TECcombi= TEC −ϕin2∑nj=−2p
Page 55 and 56: this reference frame compared to th
Page 57 and 58:
1997). For more information about t
Page 59 and 60:
As first validation, Figure 3.2 ill
Page 61 and 62:
Chapter 4VALIDATION OF UNB-IMT USIN
Page 63 and 64:
esults using ITEC measurements as o
Page 65 and 66:
code described in Chapter 3 to comp
Page 67 and 68:
Figure 4.2: Comparison of daily mid
Page 69 and 70:
(b) Main phase: the TEC is expected
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(Fedrizzi, et al., 2005). Further i
Page 73 and 74:
Figure 4.5: Computed difference ∆
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The seasonal variation is difficult
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Figure 4.7 (a)-(c) depicts the midd
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5. Summary and ConclusionsThis work
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Chapter 5MAPPING GNSS-DERIVED TEC O
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A detailed description of CELIAS/SE
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30 ° W 0 ° 30 ° E 60 ° E 90 °
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latitudes is not associated with ge
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However, a further investigation wa
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Figure 5.6: The day 301, 2003 <stro
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who reported that the largest TEC e
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Figures 5.7 and 5.8 depict examples
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dramatically to the X - ray and Ext
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the X9 flare, (e) shows the TEC map
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solar cycl
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chapter demonstrated the capabiliti
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(Hobiger et al., 2006). The main pu
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(d) Based on (a), (b) and (c), VTEC
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Figure 6.3: Comparison of VTEC (dar
Page 111 and 112:
However, for days in which data wer
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1994) and the follow-up to CONT95 (
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6.4.2 CONT05 CampaignCONT05 was a t
Page 117 and 118:
To further investigate the capabili
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space geodetic techniques during th
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(2) Short-term variations of TEC (p
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conducted for the year 2002 (near <
Page 125 and 126:
REFERENCESBartels, J., Heck, N. H.,
Page 127 and 128:
Precision Geodesy using the Mark-II
Page 129 and 130:
Fuller-Rowell, T. J., Codrescu, M.
Page 131 and 132:
Jakowski, N., Heise, S., Wehrenpfen
Page 133 and 134:
Langley, R. B., The GPS observables
Page 135 and 136:
McNamara, L. F. Radio amateur guide
Page 137 and 138:
Prölss, G. W. On explaining the lo
Page 139 and 140:
Stubbe, P. The ionosphere as a Plas
Page 141:
Zhang, D. H., Xiao, Z. Study of ion
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