1. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 Yoke Yoon Yago Andres Christian Marquardt COSMIC GPS Data Processing Slide: 1

2. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 2 Introduction Overview of Precise Orbit Determination (POD) activities COSMIC GPS data processing Status of GPS-based POD for COSMIC Preliminary results Future activities/goals Reprocessing of COSMIC data (2006-current) for whole constellation (POD and RO) Data reprocessing of other RO missions (CHAMP, GRACE, OceanSat-2) NRT operational POD for future Metop-B (2012), Metop-C (2016/2017) NRT offline POD for Jason-3

3. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 3 Overview of GPS data processing activities (1/2) MetOp-A operational NRT Utilize NRT GPS orbit & clock products from GRAS Ground Support Network (operated by ESOC/ESA) Based on (batch) sequential estimation RO data processing MetOp-A offline POD Utilize Rapid GPS orbit & clock products from CODE Based on batch estimation

4. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 4 Overview of GPS data processing activities (2/2) Jason-2 offline NRT POD Utilize NRT GRAS GSN products Batch estimation COSMIC GPS data processing Final (Precise) GPS products from CODE/AIUB (POD) Batch estimation RO data processing

5. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 5 COSMIC GPS Data Processing GPS-based POD status Raw data assessment Investigate various processing options Orbit (internal & external) assessment Planned POD-related activities/analysis GPS RO (not yet started) Processing of GPS data from the RO antennas Derive bending angles and refractivity profiles Timeline of reprocessing activities COSMIC POD (from Level-0) commences after summer 2011 POD and RO product delivery to ECMWF by end of 2012 (GRAS, COSMIC, CHAMP, GRACE)

6. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 6 COSMIC GPS Data Processing Nominal flight direction

7. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 7 COSMIC GPS Data Processing Assessment of raw data GPS receiver tracking performance over time Easy identification of POD problems that arise from s/c tracking or data outages Planned to be included in the operational processing facility as part of the monitoring system for future missions COSMIC FM 6

8. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 8 COSMIC GPS Data Processing Assessment of raw data COSMIC FM 6 (IGOR) MetOp-A (GRAS)

9. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 9 COSMIC GPS Data Processing POD processing strategy Use of quaternion for s/c orientation knowledge GPS phase and pseudorange observations sampled at 1 min (no smoothing) Precise GPS orbit and (30s) clock product from CODE/AUIB Parameter settings in NAPEOS gear more toward s/c modelled dynamics  weight on phase data,  = 3 cm  weight on pseudorange,  = 6 m 30-hr arc (6-hr overlap between consecutive arcs) 7 consecutive days of COSMIC FM#6 GPS observation data ( 26 Nov – 2 Dec 2008 )

10. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 10 COSMIC GPS Data Processing Parameter estimates COSMIC state vector (position & velocity) and clock offset Step-wise constant drag coefficient (12/arc) SRP coefficient (1/arc) 1/rev sine and cosine along- and cross-track empirical accelerations (1/arc) Carrier phase bias (per pass)

11. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 11 COSMIC GPS Data Processing Dynamic Models Gravity field modelEIGEN-GL04C (100 x 100) 3 rd body perturbationJPL DE405 ephemerides Solid Earth, Pole & Ocean tidesApplied Relativistic correction & driftApplied IR & Albedo radiationApplied Atmospheric density & SRPConstant area Measurement models IonosphereLinear combination Phase wind-upApplied Antenna phase center corrections (offset & variation) Nominal values applied Corrections applied

12. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 12 COSMIC GPS Data Processing External orbit product for comparison UCAR (website) 27-hr arc (Day 1 00:00:00 – Day 2 03:00:00) JPL (special request) 30-hr arc (Day 0 21:00:00 – Day 2 03:00:00) Orbit overlap assessment Shows the median of 6 sets of overlap (RMS) statistics Position (cm)Velocity (mm/s) # pts (per set) RTN3DRTN EUMETSAT 1.64.02.55.20.030.020.030.04241 JPL 1.62.80.73.40.02 0.010.03241 UCAR 1.92.2 3.80.02 0.010.03121

13. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 13 COSMIC GPS Data Processing External orbit product for comparison UCAR (website) 27-hr arc (Day 1 00:00:00 – Day 2 03:00:00) JPL (special request) 30-hr arc (Day 0 21:00:00 – Day 2 03:00:00) Orbit overlap assessment Shows the median of 6 sets of overlap (RMS) statistics Position (cm)Velocity (mm/s) # pts (per set) RTN3DRTN EUMETSAT 1.64.02.55.20.030.020.030.04241 JPL 1.62.80.73.40.02 0.010.03241 UCAR 1.92.2 3.80.02 0.010.03121

14. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 14 COSMIC GPS Data Processing Inter-comparison time period EUM vs JPL (24-hrs) 00:00:00 - 24:00:00 EUM vs UCAR (23-hrs) 01:00:00 – 24:00:00 UCAR vs JPL (23-hrs) Shows the median of 7 sets of daily RMS statistics Position (cm)Velocity (mm/s) # pts (per set) RTN3DRTN EUM-JPL 5.416.73.918.20.140.060.050.171441 EUM-UCAR 5.810.64.913.10.110.060.070.141381 UCAR-JPL 5.911.8513.90.110.08 0.151381

15. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 15 COSMIC GPS Data Processing Planned activities Smoothing of the quaternion Quaternion derived from magnetometer, Earth (highest weight) & Sun sensors

16. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 16 COSMIC GPS Data Processing s/c orientation (Euler angles) COSMIC s/c tumbles constantly as it does not maintain a 3-axis stable attitude

17. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 17 COSMIC GPS Data Processing Planned activities Smoothing of the quaternion Simultaneous processing of GPS data from two antennas (same s/c) (JPL COSMIC POD is based on this) POD antenna #1 from COSMIC FM 6 POD antenna #2 from COSMIC FM 6 flight direction

18. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 18 COSMIC GPS Data Processing Preliminary assessment (overlap of DOY 332-333 of 2008) of FM2 Position (cm) RMSVelocity (mm/s) RMS # pts RTN3DRTN EUM (1 Ant) 2.35.22.16.00.030.02 0.05 241 EUM (2 Ant) 1.32.81.13.30.020.01 0.02 241 JPL0.51.30.51.50.010.0040.0050.01241 UCAR3.2 6.37.80.030.04 0.06121

19. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 19 COSMIC GPS Data Processing External assessment (average of DOY 332 & 333 of 2008) of FM2 Position (cm) RMSVelocity (mm/s) RMS RTN3DRTN EUM-JPL (1 Ant) 2.88.55.910.80.070.030.040.09 EUM-JPL (2 Ant) 2.311.54.512.60.110.030.040.12 EUM-UCAR (1 Ant) 6.912.57.416.20.120.070.100.18 UCAR-JPL6.88.56.812.90.080.070.100.15

20. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 20 COSMIC GPS Data Processing External assessment (average of DOY 332 & 333 of 2008) of FM2 Position (cm) RMSVelocity (mm/s) RMS RTN3DRTN EUM-JPL (1 Ant) 2.88.55.910.80.070.030.040.09 EUM-JPL (2 Ant) 2.311.54.512.60.110.030.040.12 EUM-UCAR (1 Ant) 6.912.57.416.20.120.070.100.18 UCAR-JPL6.88.56.812.90.080.070.100.15 Position along-track bias (cm) EUM (1 Ant) vs JPL EUM (1 Ant) vs UCAR UCAR vs JPL DOY 332-6.0-10.54.2

21. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 21 COSMIC GPS Data Processing External assessment (average of DOY 332 & 333 of 2008) of FM2 Position (cm) RMSVelocity (mm/s) RMS RTN3DRTN EUM-JPL (1 Ant) 2.88.55.910.80.070.030.040.09 EUM-JPL (2 Ant) 2.311.54.512.60.110.030.040.12 EUM-UCAR (1 Ant) 6.912.57.416.20.120.070.100.18 UCAR-JPL6.88.56.812.90.080.070.100.15 Position along-track bias (cm) EUM (1 Ant) vs JPL EUM (2 Ant) vs JPL EUM (1 Ant) vs UCAR EUM (2 Ant) vs UCAR UCAR vs JPL DOY 332-6.010.6-10.56.14.2

22. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 22 COSMIC GPS Data Processing Planned activities Smoothing of the quaternion Simultaneous processing of GPS data from two antennas Analyze the existence of an along-track bias in inter-agency orbit comparison POD parameter tuning (i.e. drag coefficient)

23. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 23 COSMIC GPS Data Processing Planned activities Smoothing of the quaternion Simultaneous processing of GPS data from two antennas (from same s/c) Analyze the existence of an along-track bias in inter-agency orbit comparison Automate reprocessing of 5-6 years of data for 6 s/c

24. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 24 COSMIC GPS Data Processing Planned activities Smoothing of the quaternion Simultaneous processing of GPS data from two antennas (from same s/c) Analyze the existence of an along-track bias in inter-agency orbit comparison Automate reprocessing of 5-6 years of data for 6 s/c Processing of COSMIC RO data to derive bending angle & refractivity profiles

25. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 25 COSMIC GPS Data Processing Planned activities Smoothing of the quaternion Simultaneous processing of GPS data from two antennas (from same s/c) Analyze the existence of an along-track bias in inter-agency orbit comparison Automate reprocessing of 5-6 years of data for 6 s/c Processing of COSMIC RO data to derive bending angle & refractivity profiles Challenges in automating COSMIC POD Handling of large data gaps (especially at the beginning of the mission) Handling of maneuvers FM2 and FM5 had attitude control & receiver anomalies in 2007

26. EUM/OPS/VWG/11 Issue 1.0 22/06/2011 End of Presentation Questions?