1. 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.

2. 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)

3. 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

4. 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

5. NWM assessment ALADIN-CZ ERA-Interim GFS BIAS SDEV
GNSS-derived ZTD solution of GOP compared to NWM for the whole Benchmark time period

6. 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

7. 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

8. 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)

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. Thank you for your attention!