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, 22:47 | Cite as

Determination of near real-time GNSS satellite clocks for the FORMOSAT-7/COSMIC-2 satellite mission

  • Tzu-Pang Tseng
  • Shu-Ya Chen
  • Kun-Lin Chen
  • Cheng-Yung Huang
  • Wen-Hao Yeh
Original Article
  • 213 Downloads

Abstract

In this study, we determine the near real-time (NRT) clocks of the Global Positioning System (GPS) and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS) satellites in the Taiwan RO Process System (TROPS), which is mainly designed for the data processing in both the FORMOSAT-3/COSMIC (F3C) and FORMOSAT-7/COSMIC-2 (F7C2) satellite missions. The accuracy of GNSS clocks defines the quality of the atmospheric excess phase, which is used for the retrieval of bending angle profiles in GNSS radio occultation (RO) observations. The accuracy of the NRT GNSS clocks is assessed by comparing the clock rate, clock stability and clock-induced positioning error on receivers with the final solutions given by the European Space Agency (ESA). Overall, the standard deviations of the clock rates from TROPS agree with those from ESA within 0.05 mm/s over 2304 clock solutions. Additionally, we find that the clock stability of the GPS Block IIF type (3 × 10−13) is an order of magnitude better than that of IIR Block types (3 × 10−12) over a time interval of 30 s. In comparison, the stabilities of GLONASS clocks are approximately 3 × 10−12. We quantify the NRT clock error on the receiver positioning by using the precise point positioning technique obtained from the Bernese GNSS software. The 3-dimensional clock-induced positioning error is approximately 3.3, 3.2 and 0.9 cm for station AUCK and 6.9, 6.3 and 3.1 cm for station NRC1 for the GPS-only, GLONASS-only and GPS + GLONASS cases, respectively. For GNSS-RO applications, the bending angle profiles derived using TROPS GPS clocks agree with the COSMIC Data Analysis and Archive Center products to within 0.01–1.00 μrad. However, this is not the case for the GLONASS clock, because the GLONASS clock-induced errors on the RO profile are 10–100 times greater than those induced by the GPS clock. This suggests that different weightings should be used for RO applications, such as data assimilation, when different satellite clocks are involved in GNSS-RO retrievals. This study serves as a reference for assessing the impact of GNSS clocks on both GNSS-POD (precise orbit determination) and GNSS-RO in preparation for the F7C2 satellite mission.

Keywords

GPS GLONASS Near real-time Clock FORMOSAT/COSMIC FORMOSAT-7/COSMIC-2 Radio occultation 

Notes

Acknowledgements

This study is funded by projects under grant numbers NSPO-S-102024, NSPO-S-103039, NSPO-S-105049 and NSPO-S-105058. We thank the TACC team in Taiwan CWB for their contributions to the F3C and F7C2 projects. We thank UCAR/COSMIC for providing the CDAAC software for the RO result comparisons. We are also grateful to IGS, CODE and ESA for providing the GNSS-related products. We thank anonymous reviewers for their helpful comments that improved the quality of the paper.

References

  1. Allan DW (1987) Time and frequency (time-domain) characterization, estimation, and prediction of precision clock and oscillators. IEEE Trans Ultrason Ferroelectr Freq Control 34(6):647–654CrossRefGoogle Scholar
  2. Beyerle G, Schmidt T, Michalak G, Heise S, Wickert J, Reigber C (2005) GPS radio occultation with GRACE: atmospheric profiling utilizing the zero difference technique. Geophys Res Lett.  https://doi.org/10.1029/2005GL023109 Google Scholar
  3. Cai C, Gao Y (2013) Modeling and assessment of combined GPS/GLONASS precise point positioning. GPS Solut 17(2):223–236.  https://doi.org/10.1007/s10291-012-0273-9 CrossRefGoogle Scholar
  4. Chung YD, Yeh TK, Xu G, Chen CS, Hwang C, Shih HC (2016) GPS height variations affected by ocean tidal loading along the coast of Taiwan. IEEE Sens J.  https://doi.org/10.1109/JSEN.2016.2538325 Google Scholar
  5. Dach R, Bohm J, Lutz S, Steigenberger P, Beutler G (2010) Evaluation of the impact of atmospheric pressure loading modeling on GNSS data analysis. J Geod 85(2):75–91.  https://doi.org/10.1007/s00190-010-0417-z CrossRefGoogle Scholar
  6. Dach R, Lutz S, Walser P, Fridez P (2015) Bernese GNSS Software Version 5.2, Astronomical Institute. University of Bern, SwitzerlandGoogle Scholar
  7. Estey LH, Meerten CM (1999) TEQC: the multi-purpose toolkit for GPS/GLONASS data. GPS Solut 3(1):42–49CrossRefGoogle Scholar
  8. Griggs E, Kursinski E, Akos D (2015) Short-term GNSS satellite clock stability. Radio Sci 50:813–826.  https://doi.org/10.1002/2015RS005667 CrossRefGoogle Scholar
  9. Hauschild A, Montenbruck O, Steigenberger P (2013) Short-term analysis of GNSS clocks. GPS Solut 17(3):295–307.  https://doi.org/10.1007/s10291-012-0278-4 CrossRefGoogle Scholar
  10. Ho S et al (2012) Reproducibility of GPS radio occultation data for climate monitoring: profile-to-profile inter-comparison of CHAMP climate records 2002 to 2008 from six data centers. J Geophys Res 117:D18111.  https://doi.org/10.1029/2012JD017665 Google Scholar
  11. Hwang C, Tseng TP, Lin T, Švehla D, Schreiner B (2009) Precise orbit determination for the FORMOSAT-3/COSMIC satellite mission using GPS. J Geod 83(5):477–489.  https://doi.org/10.1007/s00190-008-0256-3 CrossRefGoogle Scholar
  12. Hwang C, Tseng TP, Lin TJ, Švehla D, Hugentobler U, Chao BF (2010) Quality assessment of FORMOSAT-3/COSMIC and GRACE GPS observables: analysis of multipath, ionospheric delay and phase residual in orbit determination. GPS Solut 14(1):121–131.  https://doi.org/10.1007/s10291-009-0145-0 CrossRefGoogle Scholar
  13. Li YS, Hwang C, Tseng TP, Huang CY, Bock H (2014) A near real-time, automatic orbit determination system for COSMIC and its follow-on satellite mission: analysis of orbit and clock errors on radio occultation. IEEE Trans Geosci Remote Sens 52(6):3192–3203.  https://doi.org/10.1109/TGRS.2013.2271547 CrossRefGoogle Scholar
  14. Li X, Ge M, Dai X, Ren X, Fritsche M, Wickert J, Schuh H (2015) Accuracy and reliability of multi-GNSS real-time precise positioning: GPS, GLONASS: BeiDou and Galileo. J Geod 89(6):607–635.  https://doi.org/10.1007/s00190-015-0802-8 CrossRefGoogle Scholar
  15. Montenbruck O, Andres Y, Bock H, van Helleputte T, van den IJssel J, Loiselet M, Marquardt C, Silvestrin P, Visser P, Yoon Y (2008) Tracking and orbit determination performance of the GRAS instrument on Metop-A. GPS Solut 12(4):289–299.  https://doi.org/10.1007/s10291-008-0091-2 CrossRefGoogle Scholar
  16. Montenbruck O, Hauschild A, Andres Y, von Engeln A, Marquardt C (2013) (Near-) real-time orbit determination for GNSS radio occultation processing. GPS Solut 17(2):199–209.  https://doi.org/10.1007/s1029-012-027 CrossRefGoogle Scholar
  17. Petit G, Luzum B (eds) (2010) IERS conventions (2010), IERS technical note 36. Verlag des Bundesamts für Kartographie und Geodäsie, Frankfurt am Main. http://tai.bipm.org/iers/conv2010/
  18. Rebischung P, Griffiths J, Ray J, Schmid R, Collilieux X, Garayt B (2012) IGS08: the IGS realization of ITRF2008. GPS Solut 16(4):483–494.  https://doi.org/10.1007/s10291-011-0248-2 CrossRefGoogle Scholar
  19. Schreiner W, Rocken C, Sokolovskiy S, Hunt D (2010) Quality assessment of COSMIC/FORMOSAT-3 GPS radio occultation data derived from single- and double-difference atmospheric excess phase processing. GPS Solut 14(1):13–22.  https://doi.org/10.1007/s10291-009-0132-5 CrossRefGoogle Scholar
  20. Shi C, Yi W, Song W, Lou Y, Yao Y, Zhang R (2013) GLONASS pseudorange inter-channel biases and their effects on combined GPS/GLONASS precise point positioning. GPS Solut 17(4):439–451.  https://doi.org/10.1007/s10291-013-0332-x CrossRefGoogle Scholar
  21. Sośnica K, Thaller D, Dach R, Steigenberger P, Beutler G, Arnold D, Jäggi A (2015) Satellite laser ranging to GPS and GLONASS. J Geod 89(7):725–743.  https://doi.org/10.1007/s00190-015-0810-8 CrossRefGoogle Scholar
  22. Tseng TP, Zhang K, Hwang C, Hugentobler U, Wang CS, Choy S, Li YS (2014) Assessing antenna field of view and receiver clocks of COSMIC and GRACE satellites: lesson for COSMIC-2. GPS Solut 18(2):219–230.  https://doi.org/10.1007/s10291-013-0323-y CrossRefGoogle Scholar
  23. Tseng TP, Hwang C, Sośnica K, Kuo CY, Liu YC, Yeh WH (2017) Geocenter motion estimated from GRACE orbits: the impact of F10.7 solar flux. Adv Space Res.  https://doi.org/10.1016/j.asr.2016.02.003 Google Scholar
  24. Weber G (2006) Streaming real time IGS data and products using NTRIP. Proc IGS Workshop 2006:105–109Google Scholar
  25. Yeh TK, Hwang C, Huang JF, Chao BF, Chang MH (2011) Vertical displacement due to ocean tidal loading around Taiwan based on GPS observations. Terr Atmos Ocean 22(4):373–382.  https://doi.org/10.3319/TAO.2011.01.27.01(T) CrossRefGoogle Scholar
  26. Yi W, Song W, Lou Y, Shi C, Yao Y (2016) A method of undifferenced ambiguity resolution for GPS+GLONASS precise point positioning. Sci Rep 6:26334.  https://doi.org/10.1038/srep26334 CrossRefGoogle Scholar

Copyright information

© Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  • Tzu-Pang Tseng
    • 1
    • 2
    • 3
  • Shu-Ya Chen
    • 1
  • Kun-Lin Chen
    • 4
  • Cheng-Yung Huang
    • 4
  • Wen-Hao Yeh
    • 4
  1. 1.GPS Science and Application Research CenterNational Central UniversityJhongli CityTaiwan
  2. 2.Cooperative Research Centre for Spatial InformationCarltonAustralia
  3. 3.Geoscience AustraliaSymonstonAustralia
  4. 4.National Space OrganizationHsinchuTaiwan

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