[IGSMAIL-5174]: Scope of planned IGS Reanalysis

[Gerd Gendt]

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IGS Electronic Mail      08 Jul 11:16:31 PDT 2005      Message Number 5174
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Author: Gerd Gendt, Peng Fang

Dear Users of IGS Products,

The IGS is considering a reanalysis of all continuous GPS data since 1994
to provide a fully homogeneous set of products for users.  Based on the
accumulated experience of the IGS Analysis Centers over the past 11 years,
it is clear that the new products will be superior to the original sets,
especially for the earlier years.

This effort will probably begin later this year and will adopt the absolute
PCVs for satellite and tracking station antennas that are currently under
evaluation.  We expect that the project will require at least one year to
complete.

We ask your help in defining the scope of this effort by commenting on the
usefulness of various product choices below.  Any background information or
other explanations would be especially helpful.

* Daily GPS orbits & SV clocks in sp3c format
  + as currently provided
  + are GLONASS satellites also needed ?

* Regular terrestrial frames & daily ERPs in SINEX format
  + ERPs as currently provided (polar motion, polar motion rates, LOD)
  + weekly terrestrial frames (as currently provided) or daily ?
    [Note that moving to daily frames is a considerably greater effort but
     might be justified for certain research objectives.]

* Daily station & satellite clock files in .clk format
  + is this product needed ?
  + 5-minute intervals as currently provided
  + aligned to IGS internal timescale (steered to GPS Time) ?
  + perhaps omit internal/crystal clocks ?

* Daily station zenith tropospheric delays
  + is this product needed ?
  + should the sampling interval be decreased from 2 hr ?

* Daily global ionospheric maps
  + is this product needed ?
  + should the sampling interval be decreased from 2 hr ?

* Network coverage
  + should all official IGS stations be included ?
  + how many ACs should contribute for each station ?

* Other products or specs
  + please comment on any other aspect of this project


Responses should be sent to us.  Thanks very much for your help,

Gerd Gendt (gendt at gfz-potsdam.de)
Peng Fang  (pfang at ucsd.edu)
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