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IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
M. Fritsche, R. Dietrich, A. RülkeInstitut für Planetare Geodäsie (IPG),Technische Universität Dresden, Germany
Reprocessing of a Global GPS Network
Experiences and Results
M. RothacherGeoForschungsZentrum Potsdam (GFZ), Germany
P. Steigenberger Institut für Astronomische und Physikalische Geodäsie,Technische Universität München, Germany
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Outline
Basic Facts: Database, Software, Resources
Observation Modeling and Adjustment
Results
Conclusions
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Basic Facts
Project funded DeutscheForschungsGemeinschaft, 2003-2006
Processed period January 1994 – December 2007
GPS data 202 nominal GPS stations
Software modiefied Bernese GPS Software Version 5.0
Strategy modified processing scheme adapted from CODE IGS Analysis Center
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
• Processing on Cluster of Linux PCs- 1-day solution ~ 2.5h from raw level- 1-day solution ~ 15min from screened DD-level- 7-day solution ~ 2h on NEQ level
• Labor input invested ~ 15000 man hours- 40% software development and processing setup- 40% data handling and screening- 20% analysis of results and publication
• Results- 3 complete processing runs - ~ 20 additional solutions based on 1-day solutions
Basic Facts
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Bernese GPS Software
frozen version from!May 2005!
- absolue PCVs (!w.r.t. IGb00!)
- 2nd & 3rd –order IONO
- IMF for TROPO
1-day Normal Equations(NEQs)
ZD-code observations: - ION,DCB,CLK
DD-phase observations: - XYZ, TRP - ORB, PCV - ERP
Modeling and Adjustment
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Higher-order ionospheric effects
mean coordinate residuals for the year 2002 (GRL, Fritsche et al. 2005)compared to standard solution
Modeling and Adjustment
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
mean NMF-IMFdifferences for 2002 at 5° elevation (GRL, Vey et al. 2006)
Modeling and Adjustment
A Priori Tropospheric Delay
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
1-day NEQs
weekly solution
3-day solution
coordinates,Earth rotation parameter
satellite orbits
long term solution Reference Frame
Modeling and Adjustment
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Orbit Accuracy
SLR residuals for IGS, CODE and Reprocessing GPS orbits
(JoG, Steigenberger et al. 2008)
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Equipment change at Horn Point (HNPT)
Coordinate Discontinuities
abs. PCVs
U= -0.5 mm
rel. PCVs
U= -15.8 mmAOAD/M_TA_NGS NONE
ASH700936E SNOW
U= 15.3 mm
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Altogether 134 discontinuities considered between
1 January 1994 and 31 December 2005
Type #
Antenna/Radome change 35
Receiver change 5
Antenna & Receiver change 29
Earthquakes 17
Other 5
Unknown 43
Coordinate Discontinuities
directly equipment related
further equipment changes not reported?
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
GPS TRF – PDR05
Terrestrial Reference System Realization
- absolute PCVs for satellites and receiver antennas (scale)
- preelimination of weekly satellite arcs (CM)
- station coordinates, velocities: NNR w.r.t. IGb00
- Xpol, Ypol: freely estimated
- spherical harmonics for a surface load redistribution
(JGR, Rülke et al. 2008)
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Degree-1 Surface Load Coefficients
GPS TRF – PDR05
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
TRS space geodetic observations + random erros
additional constaints
systematic modeling errors
TRF= „Estimate“
Comparison of TRFs:
instead of 14-parameter transformation weekly 7-parameter transformations
GPS TRF – PDR05
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Weekly 7-Parameter Transformations w.r.t. ITRF2000 / ITRF2005
ITRF2000
ITRF2005
GPS TRF – PDR05
yrmmITR00-ITR05
Z 0.2T
yrmmPDRITR05
Z 4.0T
yrppbITR00-ITR05 14.0S
yrppbPDRITR05 04.0S
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Conclusions
(1) Reprocessing results show improved quality and homogeneity of estimated parameter time series
(2) Reference system realization based on homogeneously reprocessed GPS observations
(3) Concept of simultaneous estimation of satellite orbits, station positions and large-scale surface load deformation in the CM frame
IGS Analysis Center Workshop, Miami Beach, 2-6 June 2008
Fritsche M., R. Dietrich, C. Knöfel, M. Rothacher, A. Rülke, S.Vey, P. Steigenberger, (2005), Impact of higher-order ionospheric terms on GPS-estimates;GRL, doi:10.1029/2005GL024342
Vey S., M. Fritsche, R. Dietrich, M. Rothacher, A. Rülke, P. Steigenberger, (2006), Influence of mapping function parameters on global GPS network analyses – comparison between NMF and IMF, GRL, doi:10.1029/2005GL024361
Steigenberger P., M. Rothacher, R. Dietrich, Fritsche, M., A. Rülke, and S. Vey, (2006), Reprocessing of a global GPS network, JGR, doi:10.1029/2005JB003747
References
Steigenberger P., M. Rothacher, M. Fritsche, A. Rülke and R. Dietrich (2008), Quality of Reproccessed GPS Satellite Orbits, Journal of Geodesy, doi:10.1007/s00190-008-0228-7 (accepted)
Rülke A., R. Dietrich, M. Fritsche, M. Rothacher, and P. Steigenberger (2008), Realization of the Terrestrial Reference System by a reprocessed global GPS network, J. Geophys. Res., doi:10.1029/2007JB005231 (accepted)