Subject: [IGSMAIL-1822] IGS Tropospheric Combination
From: Gerd Gendt
Date: Tue, 3 Mar 1998 0:29:45 PST

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IGS Electronic Mail      Tue Mar  3  0:29:45 PST 1998      Message Number 1822
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Author: Gerd Gendt
Subject: IGS Tropospheric Combination

Dear colleagues,

In January 1997 a pilot experiment on the combination of tropospheric
estimates was started. On a weekly basis the zenith path delay (ZPD)
estimates from the individual Analysis Centers are combined to form the
IGS tropospheric product. This product consist of weekly ZPD files for
about 100 globally distributed sites. The sampling rate is 2 hours.  

At the IGS workshop, 9-11  February 1998 in Darmstadt, it was
recommended that the pilot experiment will be finished and the combined
ZPD estimates will become an official product. The conversion into
precipitable water vapor will be postponed until a sufficient number of
surface met packages is available. At the moment it is up to the
customer to convert the ZPD by relying on the existing RINEX met files
as well as on interpolation within global or regional meteorological
fields.

The combination will be performed on a weekly basis and will start as
soon as all Analysis Centers have submitted their ZPD estimates and
their corresponding SINEX files. At the moment there is no strict
deadline for this product, however, all Analysis Centers are asked to
avoid unnecessary delays.  A weekly summary report on the combination
will be distributed.  The product will be archived at the global Data
Centers, e.g. 
       CDDIS directory GPS3:[PRODUCTS.www.TROP]
and at GFZ   ftp.gfz-potsdam.de directory /pub/igstrop/prod.

Any comments, hints, recommendations on this product are very much
appreciated.

Best regards

Gerd Gendt

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[Mailed From: Gerd Gendt <[email-masked]>]