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

EUM/OPS/VWG/11Issue 1.022/06/2011

Yoke YoonYago AndresChristian Marquardt

COSMIC GPS Data Processing

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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


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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


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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


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• 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 ROantennas

• 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)


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Nominal flightdirection


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• 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 theoperational processing facility as part of the monitoring system for future missions

COSMIC FM 6


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• Assessment of raw data

COSMIC FM 6 (IGOR)MetOp-A (GRAS)


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• 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 )


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• 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)


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Dynamic Models

Gravity field model EIGEN-GL04C (100 x 100)

3rd body perturbation JPL DE405 ephemerides

Solid Earth, Pole & Ocean tides Applied

Relativistic correction & drift Applied

IR & Albedo radiation Applied

Atmospheric density & SRP Constant area

Measurement models

Ionosphere Linear combination

Phase wind-up Applied

Antenna phase center corrections (offset & variation)

Nominal values appliedCorrections applied


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• 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)

R T N 3D R T N 3D

EUMETSAT

1.6 4.0 2.5 5.2 0.03 0.02 0.03 0.04 241

JPL 1.6 2.8 0.7 3.4 0.02 0.02 0.01 0.03 241

UCAR 1.9 2.2 2.2 3.8 0.02 0.02 0.01 0.03 121


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• 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


R T N 3D R T N 3D

EUMETSAT

1.6 4.0 2.5 5.2 0.03 0.02 0.03 0.04 241

JPL 1.6 2.8 0.7 3.4 0.02 0.02 0.01 0.03 241

UCAR 1.9 2.2 2.2 3.8 0.02 0.02 0.01 0.03 121


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• 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


R T N 3D R T N 3D

EUM-JPL 5.4 16.7 3.9 18.2 0.14 0.06 0.05 0.17 1441

EUM-UCAR

5.8 10.6 4.9 13.1 0.11 0.06 0.07 0.14 1381

UCAR-JPL 5.9 11.8 5 13.9 0.11 0.08 0.08 0.15 1381


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• Planned activities• Smoothing of the quaternion

Quaternion derived frommagnetometer, Earth (highest weight) & Sun sensors


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• s/c orientation (Euler angles)

COSMIC s/c tumbles constantlyas it does not maintain a 3-axis stable attitude


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• 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

flightdirection


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• Preliminary assessment (overlap of DOY 332-333 of 2008) of FM2

Position (cm) RMS Velocity (mm/s) RMS# pts

R T N 3D R T N 3D

EUM (1 Ant)

2.3 5.2 2.1 6.0 0.03 0.02 0.02 0.05241

EUM(2 Ant)

1.3 2.8 1.1 3.3 0.02 0.01 0.01 0.02241

JPL 0.5 1.3 0.5 1.5 0.01 0.004 0.005 0.01 241

UCAR 3.2 3.2 6.3 7.8 0.03 0.04 0.04 0.06 121


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• External assessment (average of DOY 332 & 333 of 2008) of FM2Position (cm) RMS Velocity (mm/s) RMS

R T N 3D R T N 3D

EUM-JPL(1 Ant)

2.8 8.5 5.9 10.8 0.07 0.03 0.04 0.09

EUM-JPL(2 Ant)

2.3 11.5 4.5 12.6 0.11 0.03 0.04 0.12

EUM-UCAR

(1 Ant)6.9 12.5 7.4 16.2 0.12 0.07 0.10 0.18

UCAR-JPL 6.8 8.5 6.8 12.9 0.08 0.07 0.10 0.15


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R T N 3D R T N 3D

EUM-JPL(1 Ant)

2.8 8.5 5.9 10.8 0.07 0.03 0.04 0.09

EUM-JPL(2 Ant)

2.3 11.5 4.5 12.6 0.11 0.03 0.04 0.12

EUM-UCAR

(1 Ant)6.9 12.5 7.4 16.2 0.12 0.07 0.10 0.18

UCAR-JPL 6.8 8.5 6.8 12.9 0.08 0.07 0.10 0.15

Position along-track bias (cm)

EUM (1 Ant) vs JPL

EUM (1 Ant) vs UCAR

UCAR vs JPL

DOY 332 -6.0 -10.5 4.2


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R T N 3D R T N 3D

EUM-JPL(1 Ant)

2.8 8.5 5.9 10.8 0.07 0.03 0.04 0.09

EUM-JPL(2 Ant)

2.3 11.5 4.5 12.6 0.11 0.03 0.04 0.12

EUM-UCAR

(1 Ant)6.9 12.5 7.4 16.2 0.12 0.07 0.10 0.18

UCAR-JPL 6.8 8.5 6.8 12.9 0.08 0.07 0.10 0.15

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 -6.0 10.6 -10.5 6.1 4.2


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• 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)


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• 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


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comparison• Automate reprocessing of 5-6 years of data for 6 s/c• Processing of COSMIC RO data to derive bending angle & refractivity

profiles


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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


End of Presentation

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

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