Precise GNSS analyses for troposphere monitoring by Geodetic Observatory Pecný analysis center

Transcription

1 Precise GNSS analyses for troposphere monitoring by Geodetic Observatory Pecný analysis center Douša Jan, Václavovic Pavel Research Institute of Geodesy, Topography and Cartography (RIGTC) CzechGeo/EPOS Workshop November 16, 2016, GFU, Prague, Czech Republic

2 Introduction 2 Introduction GOP developments in GNSS-meteorology Future tropospheric (high-resolution) products GNSS products for climate research?

3 GNSS data analysis error sources 3 GNSS: Global Navigation Satellite Systems GPS, GLONASS, Galileo, BeiDou Satellite orbit and clock products Satellite antenna models Phase wind-up correction Satellite hardware delays Satellite-specific effects Ionosphere delay Troposphere delay Atmospheric effects Multipath effect Receiver clock corrections Receiver antenna models Receiver hardware delays Site-specific effects

4 GNSS meteorology Monitoring signal path delays in the troposphere with GNSS analysis 4 GPS x NWP GNSS model (carrier-phase observations): L c c N sat sat sat sat rec rec rec rec ion tro Tropo model: Symmetric part Asymmetric part sin A tro STD mf H ZHD mfw ZWD mfg G N cos A GE

5 Developments in GNSS meteorology 5 GPS hourly data flow NWM operational assimilations Towards high spatio-temporal resolution IGS real-time data flow IGS RT Service IGS M-GEX multi-gnss IGS Ultra-rapid precise orbits EUREF homogeneous reprocessing

6 GOP tropospheric solutions (2001-present) 6 Software: Bernese GNSS software, network solution (double-difference observations) Near real-time (hourly) solutions: Regional (2000), Multi-GNSS (2008), Global hourly (2010) absolute PCV model relative PCV model Comparison to UK MetOffice global NWM ZTD ZTD/final Bias StdDev regional < ±1 mm < 5 mm global < ±3 mm < 8 mm real-time < ±5 mm < 10 mm Douša J, Václavovic P, Evaluation of ground-based GNSS tropospheric products at Geodetic Observatory Pecny, IAG Symposia, Springer, 2016 Dousa J, Bennitt GV, Estimation and evaluation of hourly updated global GPS zenith tropospheric delays over ten months, GPS Solut, 2013 Douša J, Towards an Operational Near-real Time Precipitable Water Vapor Estimation, Phys Chem Earth, Part A,

7 TropNET system developed/shared by GOP Developed by GOP for GNSS4SWEC supporting transfer-of-knowledge 7 TropNET info: Supporting new Analysis Center setup KTU Karadeniz Technical University in Trabzon, Turkey AUT Aristotle University in Thessaloniki, Greece BEU Bulent Ecevit University in Zonguldak, Turkey KNMI Royal Meteorological Institute of Netherlands IMO Icelandic Meteorological Institute, Iceland MUT Military university of Technology, Warsaw, Poland CSU Central South University in Changsha, China SUT Slovak University of Technology Processing data from new networks: Slovakia SKPOS Latvia LATPOS Contribution to E-GVAP:

8 GNSS meteorology 8 Developing since 1997: MAGIC, COST 716, TOUGH, E-GVAP I-III, GNSS4SWEC The EIG EUMETNET GNSS Water Vapour Programme, E-GVAP Phases I-III ( ) Project coordinating the near real-time delivery of data from ~2400 GPS sites delivering > 14M ZTDs pcm Focus is on GPS-only hourly processing, delivering only ZTD in 90mins. Operational assimilation at a few European National Met Services, many others under testing. Use of E-GVAP ZTDs has proven positive impact on NWP forecast skill. Surface T and P used for conversion to Integrated precipitable Water Vapour (IWV). Active Quality Control (AQC) in place. MoUs in place with EUREF and EUPOS.

9 Data set: May-June floods of Danube, Moldau, Elbe rivers GNSS: ~500 stations (AT, CZ, DE, PL) SYNOP: ~200 stations (AT, CZ, DE, PL) NWM: regional (Aladin-CZ), global (ERA-Interim, NCEP GFS) RAOBS: E-GVAP + two high-resolution (CZ) WVR: Potsdam, Lindenberg (DE) RADAR images: Brdy, Skalka (CZ) Reference products GNSS: Bernese (GOP) EPOS (GFZ) NWM: G-Nut/Shu (GOP) DNS (GFZ) GNSS4SWEC WG1 Benchmark campaign for developing advanced GNSS tropospheric products in COST ES1206 Action 9 Utilization Gradient estimates Real-time method ZTD2IWV conversion Tomography NWM assessment PPP tropo-corrections Douša J, Dick G, Kačmařík M, Brožková R, Zus F, Brenot H, Stoycheva A, Möller G, Kaplon: Benchmark campaign and case study episode in Central Europe for development and assessment of advanced GNSS tropospheric models and products, Atmosph Meas Tech, 92016

10 NWM assessment within Benchmark 10 May 1 June 30, GNSS4SWEC Benchmark Aladin-CZ - GOP ERA-Interim - GOP GFS - GOP

11 Troposphere horizontal 1 st order gradients Exploiting dense Benchmark campaign for monitoring horizontal anisotropy 11 11

12 Tropospheric gradients in dense network May 31, 2013[18UTC] of GNSS4SWEC Benchmark 12 GNSS GOP GNSS GFZ ERA Interim NCEP GFS

13 Troposphere slant total delays (STD) Methodology and assessment of STD retrievals from GNSS, NWM and WVR Impact of different configurations Comparisons Remarks on solution differences Bias [mm] SDEV [mm] TUW_3 TUW_7 elevation angle cut-off: 3 vs ± ± 0.45 ROB_G ROB_V mapping function: GMF vs. VMF ± ± 0.27 TUO_G TUO_R GNSS observations: GPS vs. GPS+GLO ± ± 0.47 ROB_V TUO_R ZTD/gradient resolution: 15min/1h vs. 1h/3h ± ± 0.40 GOP_F GOP_S processing strategy: Kalman filter vs. backward smoothing ± ± Evaluations of STD solutions: GNSS vs. GNSS (10) GNSS vs. NWM (4) GNSS vs. WVR (1) Dual-stations (3) Strategies: Without residuals With raw residuals With clean residuals M. Kačmařík, J. Douša, G. Dick, F. Zus, H. Brenot, G. Möller, E. Pottiaux, J. Kapłon, P. Hordyniec, P. Václavovic, L. Morel, Validation of tropospheric slant total delays from different techniques, Atmosph Meas Tech, 2016 (submitted) 13

14 Initial real-time ZTD assessment GOP half-year real-time demonstration GOP s G-Nut/Tefnut PPP software ZTD from static processing ZTD from pseudo-kinematic processing Impact of IGS RTS precise corrections delays Impact various RT precise corrections static Impact of delay/ prediction 14 kinematic GOP + Uni Luxembourgh: 2-month RT campaign (Global + Europe) Different software (BNC, PPP-wizard, G-Nut/Tefnut) Impact of phase ambiguity resolution (PPP-wizard) Douša J, Václavovic P, Real-time zenith tropospheric delays in support of numerical weather prediction applications, Adv Space Res, 2014 Ahmed F, Václavovic P, Teferle FN, Douša J, Bingley R, Laurichesse D, Comparative analysis of real-time precise point poisitioning zenith total delay estimates, GPS Solutions,

15 15 Real-time demonstration: GNSS, NWM Use of IGS Real-Time Service global products for PPP (GNSS satellite orbits & clocks) Developing and assessing new software and strategies RT Demo campaign Scope: Europe (15) + Globe (17) Start: April 1, 2015 Status: 2 March, 2016 Software: 6+1 types Contributions: 7+1 ACs Real-time monitoring: AC Software Start Update Solutions GOP G-Nut/Tefnut real-time GPS, GLO, gradients TUW TUW software real-time GPS ROB G-Nut/Tefnut real-time GPS, GLO, gradients ASI Gipsy-Oasis hourly GPS, gradients UL (PPP-wizard) real-time GPS ICS G-Nut/Shu (GOP) forecast WRF model (EU, CZ) TUO RTKLib real-time GPS BKG BNC real-time GPS, GLO

16 GNSS data in climate research? 16 ( ZTD ZHD) 0.16 IWV T ZWD IWV = Integrated Water Vapor [kg/m2] m T m = f(t s ) or NWM integrated IWV assessment and validations Product cleaning, modeling, detrending Pre-conditions: long-term time-series of GNSS homogeneously estimated tropo parameters highest quality achieved using up-to-date models Products: trends, seasonal and daily variability validation purposes, climate research,

17 17 GOP-TropDB: comparison of tropo parameters The 3 rd generation system driven by PostgreSQL Gyori G, Douša J, GOP-TropDB developments for tropospheric product evaluation and monitoring design, functionality and initial results, In: IAG Symposia Series, Rizos Ch. and Willis P. (eds), Springer Vol. 143, pp , 2016

18 GOP Repro2: tropo horizontal gradients 18 GRD assessed w.r.t. ERA-Interim... GNSS tropospheric horizontal gradients (GRD) are sensitive to an asymmetry of GNSS signal tracking at low-elevation angles GOP reprocessing GRDs are compared to ERA-Interim NWM reanalysis promising indicator for cleaning historical archive EPN CB: Before replacement Low elevation tracking degradation After replacement Douša J, Václavovic P, The GOP troposphere product from the 2nd European re-processing ( ), (manuscript prepared for AMT), 2016

19 Software development at GOP in support of activities for GNSS meteorology, precise GNSS data processing 19 G-Nut generic library for GNSS application developments --> G-Nut software, C++, object oriented, linux/windows G-Nut/Anubis multi-gnss quality-check tool (open-source) G-Nut/Apep time-series analysis tool, coordinates, velocities, troposphere G-Nut/Geb precise point positioning (PPP) - static/kinematic, real-time/offline G-Nut/Shu numerical weather model (NWM) based troposphere corrections G-Nut/Tefnut troposphere monitoring - real-time, near real-time, offline G-Nut/Sothis GNSS satellite clock estimation, real-time/offline Other software developments: GOP-TropDB PostgreSQL-driven tropospheric evaluation system Trop-NET distributed system for near real-time GNSS troposphere monitoring Václavovic P, Douša J, G-Nut/Anubis - open-source tool for multi-gnss data monitoring, IAG Symposia Series, Springer, Vol 143, 2016 Václavovic P, Douša J, Backward smoothing for precise GNSS applications, Adv Space Res, 2015 Václavovic P, Douša J, Gyori G, G-Nut software library - state of development and first results, Acta Geodyn Geomater,

20 Thank you for your attention Acknowledgements: IGS and EUREF for GNSS data, products and models ECMWF for ERA-Interim re-analysis CHMI for data/models provided for GNSS4SWEC Benchmark campaign EU COST Action ES1206 (GNSS4SWEC) for the coordination new developments Ministry of Education, Youth and Science of the Czech Republic for the financial support of large infrastructure (LM ) Ministry of Education, Youth and Science of the Czech Republic for the financial support for GOP contributions to COST 716 and COST ES1206 Actions Czech Grant Agency for funding several projects related to GNSS-meteorology and GPS and GLONASS precise products 20