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dorismail               28-Sep-2012 14:38:20 Message No 0845
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Author: "Lemoine, Frank G. (GSFC-6980)" <frank.g.lemoine@nasa.gov>
Subject: Update of GSC Operational SINEX series to gscwd13



Dear Colleagues.

The GSC analysis center is now implementing an update to its standard DORIS
processing.  The purpose of this update is to prepare for the upcoming reprocessing
to be associated with the development of the next ITRF, and prepare our GSC
Analysis Center contribution for the new IDS Combination.

Thus the delivery we have made today of the gscwd12 series (files from April - June 2012) will be the last,
and the new series, gscwd13 will become the standard.

The updates in modelling are as follows:

1. Static Gravity:  GOCO2s   (instead of EIGEN-GL04S1)

2. Time-Variable Gravity:  
      Harmonic Fits to 4x4 Time Series of Coeffiicients derived from SLR-DORIS solutions, 1993-2012.
      C21, S21 represented according to IERS conventions.

3.  Troposphere Modelling and Correction.
      GMF (Mapping Function), Saastamoinen (Troposphere), GPT (met data).
      Previously the Niell Mapping Function with the Hopfield model was used.
      In addition, the troposphere adjustment is now done only on the wet component,
      rather than the combined dry+wet.

4.   Station coordinates:
       DPOD2008_v1.9  & SLRF2008 (used for validation of DORIS-only orbits with
        SLR+DORIS orbits).

5.  Ocean Tides & Ocean Loading.
        GOT4.8  

6.   SPOT5.  After Late January 2008, we now explicitly model the solar array pitch
      bias of -40 deg and apply a Cr=1.0, instead of scaling the Cr to 0.820 in the gscwd12 series.
      This improves the overall macromodel performance.

So far the SINEX files for 2006 to 2011.0 have been delivered to the IDS data centers. 
The SINEX's for 2011 and 2012 will be updated
in the coming weeks and reprocessing is  underway for the older data. Further tests are also being
conducted to ascertain if other improvements can be applied to the DORIS modelling as recommended
by the IDS AWG.


Best regards,

Frank Lemoine (NASA GSFC)
Douglas S. Chinn (SGT Inc)
Nikita P. Zelensky (SGT Inc)
Karine Le Bail  (NVI Inc)
       
                           

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