m. fritsche, r. dietrich, a. rülke institut für planetare geodäsie (ipg),

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


Outline

Basic Facts: Database, Software, Resources

Observation Modeling and Adjustment

Results

Conclusions


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


• 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


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


Higher-order ionospheric effects

mean coordinate residuals for the year 2002 (GRL, Fritsche et al. 2005)compared to standard solution



mean NMF-IMFdifferences for 2002 at 5° elevation (GRL, Vey et al. 2006)


A Priori Tropospheric Delay


1-day NEQs

weekly solution

3-day solution

coordinates,Earth rotation parameter

satellite orbits

long term solution Reference Frame



Orbit Accuracy

SLR residuals for IGS, CODE and Reprocessing GPS orbits

(JoG, Steigenberger et al. 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


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?


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)


Degree-1 Surface Load Coefficients

GPS TRF – PDR05


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


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


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


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)

m. fritsche, r. dietrich, a. rülke institut für planetare geodäsie (ipg),

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