Real Time Ionosphere Maps from GNSS Active Networks

1. Real Time Ionosphere Maps from GNSS Active Networks Claudinei Rodrigues de Aguiar Federal University of Technology - Parana rodrigues.aguiar@gmail.com Paulo de Oliveira Camargo São Paulo State University - UNESP

2. Outline Introduction Real time ionospheric modeling and monitoring Data Processing in Real Time Experiments Summary LISN Workshop 2011

3. Introduction LISN Workshop 2011 GNSS has definitely been an important tool for observation of the atmosphere parameters, especially those from the ionosphere. Mod_Ion (Camargo, 1999) (1995 a 1999): for post processing applications was developed at FCT/UNESP; Kalman Filter was further implemented (Camargo, 2001);

4. Introduction LISN Workshop 2011 • Mod_Ion_FK (Aguiar, 2005) - (2003 a 2005): Mod_Ion+Kalman Filter – changes in the functional model, and quality control was implemented in the Kalman filter algorithm; • GNSS SP Network (2006): availability of real time data; • GI e GIVE: current;

5. Introduction • This work is part of a research project for atmospheric studies based on real time reference stations equipped with dual frequency GNSS receivers: • GNSS SP (GNSS Active Network of São Paulo State) • RBMC (Brazilian Network for Continuous Monitoring) LISN Workshop 2011

6. Real time ionospheric modeling and monitoring Analytical Models Two-dimensional Three-dimensional Empirical functions Analytical functions Grid Analytical functions Fourier series Spherical harmonics Taylor series LISN Workshop 2011

7. Real time ionospheric modeling and monitoring Analytical Models Bidimensional Tridimensional Empirical functions Analytical functions Grid Analytical functions Fourier series Spherical harmonics Taylor series LISN Workshop 2011

8. Real time ionospheric modeling and monitoring An ionospheric model has been developed for applications in real time; An algorithm based on a Kalman filter has been developed for ionosphere modeling at low latitudes and for the estimation of ionospheric parameters: absolute vertical TEC (VTEC); In this work we have utilized the two dimensional Fourier series for modeling the vertical ionospheric delay. However, other modeling functions are being implemented; LISN Workshop 2011

9. Real time ionospheric modeling and monitoring The ionospheric delay values have been estimated from the geometry free linear combination of GPS dual frequency code-phase pseudorange smoothed by carrier phase observables (PS): LISN Workshop 2011

10. Real time ionospheric modeling and monitoring The ionospheric delay values have been estimated from the geometry free linear combination of GPS dual frequency code-phase pseudorange smoothed by carrier phase observables (PS): LISN Workshop 2011

11. Real time ionospheric modeling and monitoring GIVE Calculation of ionospheric delay for each IPP: LISN Workshop 2011

12. Real time ionospheric modeling and monitoring The real time modeling of the ionosphere is performed using data collected by active GNSS reference stations in Brazil; GNSS SP Network (GNSS Active Network of São Paulo State), leaded by FCT/UNESP and financed by FAPESP (São Paulo Research Foundation); LISN Workshop 2011

13. Real time ionospheric modeling and monitoring GNSS SP Network: Currently, eleven GNSS active stations providing data in real time LISN Workshop 2011

14. Real time ionospheric modeling and monitoring RBMC-IP (Brazilian Network for Continuous Monitoring of GNSS), maintained by IBGE (Brazilian Institute of Geography and Statistics ); LISN Workshop 2011

15. Real time ionospheric modeling and monitoring RBMC-IP LISN Workshop 2011

16. Real time ionospheric modeling and monitoring These networks provide their data via the Internet using Internet Protocol (NTRIP); The availability of GNSS data via the NTRIP protocol brings new perspectives in research related to modeling and/or monitoring of the ionosphere in real time; LISN Workshop 2011

17. Real time ionospheric modeling and monitoring NTRIP was projected to disseminate differential data correction or other types of GNSS data to users, moving or still, by the Internet. LISN Workshop 2011

18. Data Processing in Real Time Data via FTP RBMC GNSS SP Network Kalman Filter Data via NTRIP RBMC-IP GNSS SP Network Post-processing Real Time GNSS Positioning Ionosphere GNSS Navigation IonosphereMonitoring LISN Workshop 2011

19. Data Processing in Real Time In Brazil some referenceestations are providing real time data (RBMC-IP and GNSS SP Network); Thesestations are equippedwith dual frequency GNSS receiversthat use NTRIP transportprotocol; The station receivers are directly connected to the Internet, and the collected data are sent to a central computer that manages and storages the data LISN Workshop 2011

20. Data Processing in Real Time BNC Using a NtripClientprogramwecan download these data into a computer (converted to RINEX); Wedeveloped a package ofalgorithms for reading RINEX files in real time andtheprocessingthese data ; LISN Workshop 2011

21. Data Processing in Real Time Kalman Filter ALDAR dss, drr IonosphereModel: Fourier Series IonosphereMonitoring a1, ..., a19, dssanddrr BNC VTEC, ROT, IPP Real time ionospheremaps GMT Graphicvisualizationmaps LISN Workshop 2011 ALDAR make possible process the data supplied by the reference stations in real time

22. Data Processing in Real Time Kalman Filter ALDAR dss, drr IonosphereModel: Fourier Series IonosphereMonitoring a1, ..., a19, dssanddrr BNC VTEC, ROT, IPP Real time ionospheremaps GMT Graphicvisualizationmaps LISN Workshop 2011

23. GridMaps - Brazil • November 22, 2009; • Real time processing; • 29 NTRIP stations. L1 Ionospheric Delay GIVE LISN Workshop 2011

24. GridMaps – South America • May 11, 2006; • Processing for Central and South America stations, simulating real time; • 52 stations. L1 Ionospheric Dealy GIVE LISN Workshop 2011

25. SurfaceMaps - Brazil VTEC and ROT Map generated near real time from Grid. L1 Ionospheric Delay GIVE VTEC Map ROT Map LISN Workshop 2011

26. SurfaceMaps – South America VTEC and ROT Map generated simulating real time. L1 Ionospheric Delay GIVE VTEC Map ROT Map LISN Workshop 2011

27. Output File LISN Workshop 2011

28. Output File GIVE map Grid Map LISN Workshop 2011

29. Grid Quality • Analyze of the quality of ionospheric grid: • IGI versus IREFERENCE • IGI- IREFERENCE < εGIVE LISN Workshop 2011

30. Grid Quality • IGI versus IREFERENCE LISN Workshop 2011

31. Impact of the density of reference stations • The results show a limitation of the use of GI for the period of high solar activity, due to low number of the reference stations wich, consequently, results in a low number of IPP available to the generation of GI; • When the GI degraded the results we observed that: • GIVE was’nt available; • GIVE was available but did’nt have a minimum of 3 IGPs; LISN Workshop 2011

32. Impact of the density of reference stations • Temporal availability varies from 10% (2.4 h) to 90%(21.6 h); • Average of 70% (16.8 h monitored / unmonitored 7.2 h); LISN Workshop 2011

33. Impact Analysis of the distribution of reference stations in GI • It was developed the algortihm GS (Grid Simulator); • GS is responsible for analyzing the distribution of reference stations. • It is a software package that have their own libraries and also uses the GMT  and ImageMagick libraries. LISN Workshop 2011

34. Impact Analysis of the distribution of reference stations in GI • 29 stations (GNSS SP, RBMC-IP) • 24 hours of data; • 5º:coverage of 95% (22.8 h) in most of Brazil, the region under the influence SP GNSS coverage reaches 98% (23.5 h). • 2,5º: 25% (6 hours) in the worst case, and 97% (23,3 h) in the best situation. • 1º:the cell with better coverage (67% - 16 h); in other cell the coverage varies from 3% (0.7 h) to 50% (12 h). LISN Workshop 2011

35. Impact Analysis of the distribution of reference stations in GI • Considering the current configuration of the available networks in Brazil, the best results are obtained when using grids with spatial resolution greater than 2.5 °. • In the modeling of the ionosphere in real time, the best results are to be expected in the southeast, because of the influence of GNSS SP network; LISN Workshop 2011

36. Impact Analysis of the distribution of reference stations in GI • Analysis of the average distance: • Resolution 5ºx5º  spacing of approx. 600 km • Resolution 2,5ºx2,5º  spacing of approx. 250 km • Resolution 1ºx1º  spacing of approx. 100 km LISN Workshop 2011

37. Summary • The development of real time ionospheric model is under progress. • Some problems of dynamic programming have to be solved. LISN Workshop 2011

38. Summary • The next step is to provide, near real time, the ionospheric model coefficients and an ionospheric grid to users. • Tests carried out in point positioning show that the corrections provided by the GI should be used only when the GIVE is available; • The software developed also use libraries of the GMT (Generic Map Tools) and Image Magick, both open source. LISN Workshop 2011

39. Thank you for your attention! LISN Workshop 2011