Spatio-Temporal Analysis of Equatorial Ionospheric Scintillations in the Frame of Absolute GNSS Positioning Algorithms

Transcription

1 Spatio-Temporal Analysis of Equatorial Ionospheric Scintillations in the Frame of Absolute GNSS Positioning Algorithms Matthieu Lonchay 1 Y. Cornet 1 - M. Aquino 3 - R. Warnant 1 1 University of Liège (Belgium) Geomatics Unit National Fund For Scientific Research (Belgium) FNRS 3 The University of Nottingham (United Kingdom) EGU 14, Vienna (Austria) 3 April 14

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3 Spatio-Temporal characteristics of Ionospheric Scintillations may be exploited to build a more effective Stochastic Model 3 5 Spatio-Temporal Analysis Space Time PPP 3D Error [m] 15 1 Stochastic Modeling n 5 h 3h 6h 9h 1h 15h 18h 1h 4h UTC

4 Introduction Ionosphere Positioning Analysis Conclusions

5 Ionosphere The Ionosphere is a Plasma ionised by Solar Radiations and characterised by an electron density highly variable in Space and Time UV X-Rays MeV protons CME s Solar Winds Solar Flares

6 Ionosphere The electron density of the Ionosphere is responsible for Refraction effects of GNSS radio signals s Ionospheric Delay r n I n I = c v 1 ± 4.3 f N e I ± 4.3 s f N e dl = ± 4.3 f stec r

7 Ionosphere Small-Scale Irregularities in the electron density of the Ionosphere are responsible for Diffraction effects of GNSS radio signals Fluctuation of the GNSS signal phase n I σ φ = θ θ Fluctuation of the GNSS signal amplitude S 4 = I I I

8 Ionosphere Ionospheric Scintillations are rapid fluctuations of the signal phase and amplitude due to small-scale irregularities in the electron density of the Ionosphere Fluctuation of the GNSS signal phase σ φ = θ θ Fluctuation of the GNSS signal amplitude S 4 = I I I

9 Introduction Ionosphere Positioning Analysis Conclusions

10 Positioning Our Research focuses on two main Absolute GNSS Positioning Algorithms: the Standard Point Positioning (SPP) and the Precise Point Positioning (PPP) s SPP = Standard Point Positioning P s r t = D s r + T s s r + I r,k,m + c t s s s t r + M r,k,m + ε r,k,m r PPP = Precise Point Positioning P s r t = D s r + T s s r + I r,k,m + c t s s s t r + M r,k,m + ε r,k,m φ s r t = D s r + T s s r I r,k,φ + c t s s t r + λ k N r,k s + M r,k,φ s + ε r,k,φ s P r,if t = D s r + T s r + c t s s s t r + M r,if,m + ε r,if,m s φ r,if t = D s r + T s r + c t s s s s t r + λ IF N r,if + M r,if,φ + ε r,if,φ

11 Positioning The Precise Point Positioning is very sensitive to Ionospheric Scintillations which may totally degrade its performances and reliability SPP 3D Error [m] SJCU 47/14 16-Feb-14 Code Pseudorange Noise Measurement Geometry 3 PPP 3D Error [m] 1 Carrier Phase Noise Measurement Cycle Slips Loss of lock Ambiguity Resolution h 3h 6h 9h 1h 15h 18h 1h 4h Ionospheric Scintillation UTC

12 Introduction Ionosphere Positioning Analysis Conclusions

13 Analysis GNSS signal scintillations show signs of Spatio-Temporal Dependence INCO 47/14 16-Feb-14 N 3 S4 [-] W E 1.8 Phi6 [rad].6.4 S. h 1h h 3h UTC

14 Analysis GNSS signal scintillations show signs of Spatio-Temporal Dependence INCO 47/14 16-Feb Time lag? N 3 S4 [-] W E 1.8 Phi6 [rad].6.4 S. h 1h h 3h UTC

15 Analysis GNSS signal scintillations show signs of Spatio-Temporal Dependence INCO 47/14 16-Feb-14 N 3 S4 [-] W E 1.8 Phi6 [rad].6.4 S. h 1h h 3h UTC

16 Analysis The Ionospheric Scintillation GNSS Survey needs to be densified in order to perform a proper Spatio-Temporal Analyse INCO 44/14 :':'' N 3 6 W E GPS S

17 Analysis The Ionospheric Scintillation GNSS Survey needs to be densified in order to perform a proper Spatio-Temporal Analyse INCO 44/14 :':'' N 3 6 W E Multi-GNSS S

18 Analysis The Ionospheric Scintillation GNSS Survey needs to be densified in order to perform a proper Spatio-Temporal Analyse 15 N 44/14 :':'' 6 W 75 W MAN 45 W 3 W FORT PALM UFBA 15 S PRU INCO SJCU MAC 3 S POAL Multi-GNSS Multi-ISMR 45 S

19 Analysis The Ionospheric Scintillation GNSS Survey needs to be densified in order to perform a proper Spatio-Temporal Analyse INCO 44/14 :':'' N 3 6 W E Multi-GNSS S Multi-ISMR

20 Analysis Spatial Autocorrelation can be detected and quantified by using specific SAC indices I N Moran s I w ( v v)( v v) vi S4i 1 wij d Geary s C ( N 1) i j ij i j i j ij i j C i jwij i ( vi v) w ( v v) i j ij i i ij w ( v v ) E[ I] V[ I] I C 1 E[ C] V[ C] I ~ I ~ 1 I I 1 Hypothesis Test H: The situation is the result of a stationnary point process, i.e. there is no significative spatial dependency.

21 Analysis Spatial Autocorrelation can be detected and quantified by using specific SAC indices I N Moran s I w ( v v)( v v) vi S4i 1 wij d Geary s C ( N 1) i j ij i j i j ij i j C i jwij i ( vi v) w ( v v) i j ij i i ij w ( v v ) E[ I] V[ I] E[ C] V[ C] Hypothesis Test H: The situation is the result of a stationnary point process, i.e. there is no significative spatial dependency.

22 Analysis Spatial Autocorrelation can be detected and quantified by using specific SAC indices I N Moran s I w ( v v)( v v) vi S4i 1 wij d Geary s C ( N 1) i j ij i j i j ij i j C i jwij i ( vi v) w ( v v) i j ij i i ij w ( v v ) E[ I] V[ I] 1. E[ C] V[ C] S4 [-]. Hypothesis Test H: The situation is the result of a stationnary point process, i.e. there is no significative spatial dependency.

23 Analysis The Global Spatial Autocorrelation inside the data set is Significative only during the occurrence of Ionospheric Scintillations <S4> [-] INCO 44/14 13-Feb-14 h 3h 6h 9h 1h 15h 18h 1h 4h UTC

24 Analysis The Global Spatial Autocorrelation inside the data set is Significative only during the occurrence of Ionospheric Scintillations <S4> [-] INCO 44/14 13-Feb-14 Moran's I h 3h 6h 9h 1h 15h 18h 1h 4h UTC

25 Analysis The Global Spatial Autocorrelation inside the data set is Significative only during the occurrence of Ionospheric Scintillations <S4> [-] INCO 44/14 13-Feb-14 Moran's I Geary's C h 3h 6h 9h 1h 15h 18h 1h 4h UTC

26 Analysis The Global Spatial Autocorrelation inside the data set is Significative only during the occurrence of Ionospheric Scintillations <S4> [-] INCO 44/14 13-Feb-14.5 SAC > Moran's I Geary's C SAC > H Boundaries h 3h 6h 9h 1h 15h 18h 1h 4h UTC

27 Analysis The Global Spatial Autocorrelation inside the data set is Significative only during the occurrence of Ionospheric Scintillations <S4> [-] SAC > INCO 44/14 13-Feb-14.5 Moran's I -.5 Geary's C 1 SAC > H Boundaries h 3h 6h 9h 1h 15h 18h 1h 4h UTC

28 Introduction Ionosphere Positioning Analysis Conclusions

29 Conclusions We developed a methodology in order to exploit the availability of Multi-GNSS observations from an ISMR Network for the Spatio-Temporal Analysis of Ionospheric Scintillations (based only on GNSS Measurements). By using this methodology, we lead a first analysis of the Spatial Dependency of Ionospheric Scintillation Observations. We measured the Spatial Autocorrelation of the S4 observable and showed it was clearly significative but only in the presence of (strong) Ionospheric Scintillations, supporting a possible spatial interpolation at these times. We will extend the Spatio-Temporal Analysis to other parameters. We will perform a Local Spatial Autocorrelation Test to locate and determine the scale of the detected «hot spots». We will implement specific Spatial Interpolation Techniques to produce a «Scintillation Sky Map». We will integrate the Spatio-Temporal Analysis in the PPP algorithm.

30 Acknowledgements The ISMR data used for part of the presented work have been kindly provided by the Nottingham Geospatial Institute (NGI) of the University of Nottingham (UoN), UK, the Faculty of Science and Technology (FST) of the Universidade Estadual Paulista (UNESP), Brazil, and the European GNSS Agency (GSA) in the frame of the CIGALA/CALIBRA project. The research is performed at the Geomatics Unit of the University of Liège (ULg), Belgium, under the supervision of Pr. René Warnant and with the collaboration of Dr.Yves Cornet. In the frame of this project, a collaboration was established with Pr. Marcio Aquino and Dr. Craig Hancock from the Nottingham Geospatial Institute (NGI) of the University of Nottingham (UoN), UK. This research is funded by the National Fund for Scientific Research of Belgium (F.R.S.-FNRS). SPP and PPP Positions were computed by using the glab software developped by the gage group of the Technical University of Catalonia (UPC).

31 Spatio-Temporal Analysis of Equatorial Ionospheric Scintillations in the Frame of Absolute GNSS Positioning Algorithms Matthieu Lonchay 1 M.Lonchay@ulg.ac.be Y. Cornet 1 - M. Aquino 3 - R. Warnant 1 1 University of Liège (Belgium) Geomatics Unit National Fund For Scientific Research (Belgium) FNRS 3 The University of Nottingham (United Kingdom) EGU 14, Vienna (Austria) 3 April 14