Kein Folientitel

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Status and Future of the IERS Combination
Efforts Markus Rothacher GeoForschungsZentrum
Potsdam IERS Combination WG and CPP
Meeting April 27, 2004 Technical University of
Vienna Vienna, Austria
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Content

• Vision
• Four Sets of IERS Products
• Status of Call for Long Time Series
• Status of Routine SINEX Generation
• Future Goals

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Vision for a Rigorous Combination
Parameter space for a rigorous combination
Parameter Type
VLBI
GPS/
DORIS/
SLR
LLR
Alti-
GLON.
PRARE
metry
ICRF
Quasar
Coord. (ICRF)
X
(X)
(X)
Nutation
X
X
Earth Rotation
Polar Motion
X
X
X
X
X
UT1
X
Length of Day (LOD)
X
X
X
X
X
X
X
X
X
(X)
Coord.Veloc.(ITRF)
Geocenter
X
X
X
X
ITRF
Gravity Field
X
X
X
(X)
X
Orbits
X
X
X
X
X
Gravity Field
LEO Orbits
X
X
X
X
Ionosphere
X
X
X
X
Atmosphere
Troposphere
X
X
X
X
Time/Freq. Clocks
(X)
X
(X)
IERS CPP and ITRF2004/IERS200x at present red
rectangle
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Four Sets of IERS Combined Products (1)

• Yearly IERS200x Products
• Based on long time series of SINEX files from a
  yearly reprocessing and recombination by all
  techniques including the full time span of global
  data
• Most recent standards in modeling,
  parameterization, processing strategy to be used
  in the reprocessing
• Combination of the series into an product set
• IERS200x ITRF200xEOP200xICRF200x
• Combination should be based on combined weekly
  intra-technique SINEX file and not on combined
  weekly inter-technique SINEX files
• Routine Weekly IERS Products (IERS CPP)
• EOPs and station coordinates routinely generated
  on a weekly basis
• Comparable to the IGS Final Products, i.e., based
  on the final solutions of a technique
• Envisaged latency ca. 3 weeks
• Strategy to be discussed at this meeting (IERS
  CPP, April 27, 2005)

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Four Sets of IERS Combined Products (2)

• Daily Rapid IERS Products
• Combination of VLBI Intensive Sessions (e-VLBI)
  with GPS rapid products and SLR/DORIS rapid
  solutions
• Comparable to the IGS Rapid Products ca. 24 hour
  latency
• IGS Generation of combined SINEX files on a
  daily basis including station coordinates, EOPs,
  in the future troposphere parameters
• VLBI Rapid generation of VLBI Intensive
  solutions (1hour), available on a daily basis
• SLR/DORIS Rapid generation of daily solutions
• Complementarity
• VLBI UT1 (and scale)
• GPS Reference frame, polar motion, LOD
• SLR/DORIS geocenter (and scale)
• Predicted IERS Products
• Prediction of EOPs based on the combined IERS
  Rapid Products

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Yearly ITRF/IERS200x Products Present Status

• IERS Call for Long Time Series (December 2004)
• Long time series important for two purposes
• ITRF2004 the generation of a new ITRF solution
  by the ITRF Combination Centers under the
  responsibility of the ITRF Product Center
• IERS CPP complementation it has become evident,
  that long time series are essential for the
  rigorous combination of the space techniques
  based on weekly solutions

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Importance of an ITRF2004 Solution

• A few years of additional data available
• New sites joined the global network
• Processing strategies of the individual
  techniques improved
• Velocities of more recent sites are not available
  or poorly determined in ITRF2000, which leads to
  the point that the individual techniques start to
  use their own TRF realizations
• Some station positions are no longer valid
  because of events (earthquakes, equipment changes
  creating discontinuities in the time series,
  local tie updates, etc.).
• Combination of weekly SINEX files a much more
  rigorous combination possible. More consistent
  IERS products and time series analysis,
  especially through a better detection of
  discontinuous position changes.
• Make use of the experience gained in rigorous
  combination strategies through the IERS SINEX
  Combination Campaign and the IERS CPP.

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Importance for the IERS CPP IERS200x

• Weekly SINEX solutions routinely generated not
  sufficient to generate combined inter-technique
  solutions in a consistent way over many weeks
  (weighting, local ties, datum)
• A further step towards the ultimate goal, namely
  a future rigorously combined, consistent IERS
  product series IERS200x
• Integrated Earth orientation parameters, Radio
  sources,
• and Site coordinates 200x
• IERS200x ITRF200x EOP200x ICRF200x
• Long time series are additional material to test
  such approaches
• At present no quasar coordinates are available
  yet ICRF not included in the combination

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Status of Call for Long Time Series
Individual analysis center
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Status of Call for Long Time Series

• http//iers1.bkg.bund.de/info/listFileITRF2004.php
  
• For the first time
• Intra-technique combined solutions available from
  all techniques over long time spans (except
  DORIS)
• Homogeneously reprocessed over many years (except
  IGS)

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IERS Long Time Series ITRF2004 Schedule
April 27, 2005 IERS CPP Meeting in Vienna to
discuss next steps April 28, 2005 IERS DB
Meeting (ITRF2004, IERS CPP) May 15, 2005
Submission of ITRF solutions by the ITRF CCs,
start of comparison and validation
phase August 5, 2005 Final ITRF2004 solution
ready after comparisons and validations August
26, 2005 Presentation of the new ITRF2004 at
the IAG Scientific Assembly (Cairns,
Australia) October 2005 IERS Workshop 2005
Discussion of IERS2005 next level of
improvement in parameterization and modeling
consistency Discussions concerning the
transitions to new IERS products IERS
Directing Board Meeting for decisions. 200x
Yearly realization of a new IERS200x based on
latest standards and strategies, improvements
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Routine Weekly Products (IERS CPP)
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IERS CPP Proposals (1)
( Intra-technique combination)
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IERS CPP Proposals (2)
( Inter-technique combination)
15
IERS CPP Proposals (3)
( Validation)
16
IERS CPP Proposals (4)
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IERS CPP Submission Schedule

• Intra-technique combinations (weekly SINEX files)
  due 8 weeks after the observations
• Inter-technique combinations (weekly SINEX files)
  due 12 weeks after the observations
• Validation of inter-technique combinations
  (report) due 16 weeks after the observations
• Special combined products due 8 weeks after the
  observations

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Status of Routine Weekly SINEX Generation
Intra-technique combinations (March 30,
089/2005)
Individual analysis center

• http//iers1.bkg.bund.de/info/listFileCPP.php
• Intra-technique solutions in time and complete
• Inter-technique solutions not yet available
• No validation yet

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IERS CPP Conclusions so far

• It took some time for the technique services to
  start to compute combined routine intra-technique
  solutions.
• Very important to have technique services fully
  involved, taking their responsibility for the
  technique-specific products (SINEX)
• Intra-technique combinations now routinely
  available from all techniques (except DORIS) a
  big step forward.
• 13 months (56 weeks) of weekly solutions
  available from all techniques.
• Now complemented and supported by the long time
  series of weekly SINEX files.
• All material available to study different
  strategies for the routine generation of
  inter-technique combinations.
• Demonstration of routine generation by October
  IERS Workshop 2005

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IERS CPP Schedule
April 27, 2005 IERS CPP Meeting at the EGU
Meeting in Vienna Discussion of the next steps
(inter-technique combination and
validation) May-July 2005 Test of strategies
for weekly routine generation of products and
for their validation August 2005 Results to be
presented at the IAG Scientific Assembly
(Cairns, Australia) August-October 2005 Set up
routine generation of products and their
routine validation October 2005 IERS Workshop
2005 Evaluation of the CPP and discussions
concerning the transitions to new IERS products
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IERS CPP Future Goals

• Start with weekly generation of (accumulated)
  inter-technique solutions
• Start validation of weekly intra-technique and
  inter-technique combinations
• Reduce latency of intra-technique solutions (2
  months)
• ITRF2004/IERS2005 Studies of rigorous weekly and
  multi-year solutions
• Work towards the combination of daily solutions
  (Rapid IERS Product)
• CONT05 new continuous VLBI campaign coordinated
  with the IERS CPP and the other techniques
  allows detailed studies of combination strategies
  etc.
• Encourage combinations on the observation level
• Add new common parameters to the weekly
  combinations
• Quasar coordinates (ICRF)
• Troposphere zenith delays and gradients
• Nutation offsets and rates (to IAU2000)
• Subdaily ERPs ? Orbits ? Clocks ?

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CONT05 Campaign

• Very useful experiences with the CONT02 Campaign
• Possibility to study the details of a rigorous
  combination (troposphere, local ties, nutation,
  UT1/LOD, modeling aspects, parameterization, )
• Continuous VLBI observations during 2 weeks
• Inclusion of other observation techniques
• SLR observations to GPS/GLONASS satellites
• SLR observations to multi-technique satellites
  (JASON, CHAMP, )
• DORIS observations (local ties, troposphere, )
• Co-location of auxiliary instruments
• As many water vapor radiometers as possible
• Meteorological Information
• Clock synchronization ?
• Gravimeters ?

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IERS Combination Pilot Project
Parameter space for a rigorous combination
Parameter Type
VLBI
GPS/
DORIS/
SLR
LLR
Alti-
GLON.
PRARE
metry
ICRF
Quasar
Coord. (ICRF)
X
(X)
(X)
Nutation
X
X
Earth Rotation
Polar Motion
X
X
X
X
X
UT1
X
Length of Day (LOD)
X
X
X
X
X
X
X
X
X
(X)
Coord.Veloc.(ITRF)
Geocenter
X
X
X
X
ITRF
Gravity Field
X
X
X
(X)
X
Orbits
X
X
X
X
X
Gravity Field
LEO Orbits
X
X
X
X
Ionosphere
X
X
X
X
Atmosphere
Troposphere
X
X
X
X
Time/Freq. Clocks
(X)
X
(X)
IERS Combination Pilot Project sub-space (red
rectangle)