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Benchmark Campaign of the COST Action GNSS4SWEC:
main goals and achievements J. Douša (1), G. Dick (2), M. Kačmařík (3), P. Václavovic (1), E. Pottiaux (4), F. Zus (2), H. Brenot (5), G. Möller (6), J. Kaplon (7), L. Morel (8), and P. Hordyniec (7) (1) Geodetic Observatory Pecny, RIGTC, Ondřejov, Czech Republic (2) GFZ German Research Centre for Geosciences, Potsdam, Germany (3) Technical University of Ostrava, Czech Republic (4) Royal Observatory of Belgium, Brussels, Belgium (5) Belgian Institute for Space Aeronomy, Brussels, Belgium (6) Vienna University of Technology, Austria (7) Institute of Geodesy and Geoinformatics, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland (8) GeF Laboratory, ESGT – CNAM, Le Mans, France AGU Fall Meeting, December 12-16, 2016, San Francisco, CA, USA COLAGE invited talk: When: April 2 (Friday) at Conference (Atibaia city): Subject: General information of CHAMP mission, Application of GPS occultation data to retrieve TEC, Temperature profile and water vapor, and CHAMP data bank. Audience: South America's Space geophysics community and Graduate students.
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EU COST Action GNSS4SWEC
„Advanced GNSS Tropospheric Products for Monitoring Severe Weather Events and Climate“ (Chair: J. Jones, UKMO) 25 European countries / 4 non-EU partners / more than 160 participants Advanced Tropospheric Products: Tropospheric gradients Slant Total Delays (STD) Multi-GNSS: GPS/GLONASS/Galileo/BeiDou/… Ultra-fast and real-time tropospheric products Three Working Groups: WG1: Advanced GNSS processing techniques (J. Dousa, G. Dick) WG2: GNSS for severe weather monitoring (S. de Haan, E. Pottiaux) WG3: GNSS for climate monitoring (O. Bock, R. Pacione)
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Selected time period May + June 2013
Different weather conditions: quiet and variable Includes a severe weather event (May 30 – June 2): floods of Danube/Vltava/Elbe rivers
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Benchmark area and collected data set
Central Europe: Austria, Czech Republic, Germany, Poland Data collection GNSS: ~500 stations (AT, CZ, DE, PL) SYNOP: ~600 stations (AT, CZ, DE, PL) NWM: regional ALADIN-CZ (CHMI) global ERA-Interim (ECMWF) GFS (NCEP) WVR: Potsdam, Lindenberg (DE) RS OBS: E-GVAP + two high-resolution (CZ) RADAR images: Brdy, Skalka (CZ) Reference products GNSS: Bernese (GOP), EPOS-8 (GFZ) NWM: 3 ray-tracing software packages (GOP, GFZ, BIRA) Douša et al., AMT, 2016
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NWM assessment ALADIN-CZ ERA-Interim GFS BIAS SDEV
GNSS-derived ZTD solution of GOP compared to NWM for the whole Benchmark time period
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GNSS GOP GFZ Model ERA GFS
Comparisons of horizontal gradients with NWM GNSS May 31, 2013 18:00 UTC Severe weather event GOP GFZ Model ERA GFS
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Slant total delays validation study
Dual/triple GNSS stations selected from the Benchmark time period (May-June, 2013) 10 stations: POTS + POTM LDB2 + LDB0 WTZR + WTZS + WTZZ GOPE KIBG SAAL Solutions GNSS: 11 contributions, 5 software packages, different strategies NWM: ALADIN-CZ (CHMI), ERA-Interim (ECMWF), GFS (NCEP), 3 ray-tracing software packages WVR: station Potsdam (ZTD and slants) GNSS analysis Processing strategy: 1) Precise Point Positioning (PPP); 2) Double-differences (DD) Adjustment: ) Least-square adjustment; 2) Kalman filtering & backward smoothing Slant reconstruction: 1) ZTD + gradients („nonRES” version) 2) ZTD + gradients + raw post-fit residuals („rawRES” version) 3) ZTD + gradients + cleaned post-fit residuals („clnRES” version) Θ Slant Total Delay
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Validation of slant delays: GNSS vs. GNSS
BIAS (mm) SDEV (mm) GFZ solution chosen as reference BIAS = +2 mm / -3 mm (except of station POTM) SDEV = 3 – 5 mm (except of GOP_F: Kalman filter without backward smoothing)
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Validation of slant delays: GNSS vs. NWM
BIAS (mm) SDEV (mm) ALA/BIRA BIAS = station/solution dependent SDEV = 7 – 12 mm, except for stations KIBG+SAAL ERA/GFZ GFS/GFZ
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Collocated GNSS stations: POTS/POTM
Validation of slant delays: GNSS vs. WVR BIAS (mm) SDEV (mm) GFZ Water Vapor Radiometer Collocated GNSS stations: POTS/POTM BIAS = mm (for station POTS) SDEV = mm SDEV nonRES < SDEV clnRES < SDEV rawRES
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Real-time ZTD Demonstration Campaign
Two ongoing activities: Offline simulation using Benchmark data set Online campaign start April 1, 2015 27 stations 7 contributions from 6 AC 5 different software packages
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Summary Benchmark Campaign Troposphere gradients
extensive GNSS + meteorological data set collected reference product prepared, assessed & published gradients estimated & compared (NWM, GNSS) slant delays retrieved & compared (NWM, GNSS, WVR) various activities going on, e.g. slant delays & gradients, RT simulation Troposphere gradients extreme gradients observed in a dense network (up to 7 mm) in some situations significant variations, new information for NWP now-casting
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Summary Validation of Slant Delays Real-time development
solutions: 11×GNSS (5 sw packages), 3×NWM (3 sw), 1×WVR good agreement between all GNSS solutions comparisons with NWM and WVR GNSS vs. NWM: mm SDEV GNSS vs. WVR: mm SDEV post-fit residuals do not change bias, but increase SDEV Θ Real-time development Demonstration Campaign: running and monitored RT ZTDs using PPP (7 contributions): SDEV = 5-9 mm for stable solutions BIAS < 5 mm
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Acknowledgements Benchmark data set
IGS for data and variety of GNSS products and models (RTS, MGEX, Final, PCO/PCVs, ...) EUREF for reference frame GNSS stations EPOSA, SAPOS, ASG-EUPOS, CZEPOS, VESOG, GEONAS, Trimble for GNSS data ECMWF for global ERA-Interim re-analysis numerical weather model NCEP for Global Forecast System (GFS) numerical weather model CHMI, IMGW-PIB, ZAMG for synop meteorological data CHMI for mesoscale Aladin-CZ numerical weather model, meteorological radar images, radiosonde profiles EU COST Action ES1206 for the financial support of this collaborative effort Ministry of Education, Youth and Science of the Czech Republic for the financial support
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Thank you for your attention!
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