[IGSMAIL-4085]: Ultra-Rapid tropospheric products available

[Gerd Gendt]

******************************************************************************
IGS Electronic Mail      18 Sep 04:59:02 PDT 2002      Message Number 4085
******************************************************************************

Author: Gerd Gendt

Dear colleagues,

In December 2000 the IGS Governing Board decided to explore the
use of its global hourly network for generation of Ultra-Rapid
tropospheric products. It was started a Pilot Experiment
to establish all the software components and to assess the quality
of the product, which was planned to be generated every three hours
at the beginning.

After some preparations, since summer 2001 Ultra-Rapid tropospheric
products are generated every three hours. It is a combination of
submissions from 7 Analysis Centers (ACs). Each product contains the
Zenith Path Delay (ZPD) values for the last 12 hours and has a sampling
rate of 1 hour.
The product submissions of the ACs have a delay from 0 to 2.5 hours,
in average 1.5 hours. Presently, the combination starts if all centers
have contributed.
If more frequent and/or faster products are needed by the user community
then IGS will try to change the schedule accordingly.

The quality of the product was assessed during the Pilot Experiment and
is (compared to IGS Final Tropospheric Product)
        5 to 6 mm ZPD for the standard deviation and
       -1 to 1 mm ZPD for the bias.
The internal consistency between the ACs (comparisons to hourly
combination itself) is checked each time and amount to
        3 to 5 mm ZPD for the standard deviation and
       -4 to 4 mm ZPD for the bias.
The bias-scatter from site to site is 3 to 6 mm ZPD.
The product includes ~100 sites, where ~50 are contributed by two or more
ACs.

The ftp-address and some information on products and statistics
are summarized in the appendix.

Any comments, remarks on this new product are very much appreciated.

Best regards

Gerd Gendt


-------------------------------------------------------------------------
Appendix:

Address for Ultra-Rapid tropospheric Products:

     ftp.gfz-potsdam.de/pub/transfer/kg_igs/nrtigstrop/prod

Files:
1. igs60_wwwwd_hh.tro   (e.g.igs60_11840_02.tro ):
   Product file in the SINEX-TRO-format, containing the solutions from
   all submitted sites for the last 12 hours with a sampling rate of 60
   minutes.


2. TROPSUM_wwwwd.ovw    (e.g. TROPSUM_11840.ovw):
   Contains for each hour a block with statistics on the comparison of the
   Individuals ACs to the combined product, e.g.
   Summary for 11840_23
   11840_23  +Center:         EMR             ESA             GFZ
   11840_23 .        | bias sdev nv d| bias sdev nv d| bias sdev nv d|...
   11840_23 .---------------------------------------------------------...
   11840_23 .Mean    |  1.0  2.0     | -2.9  4.9     |  1.1  2.2     |...
   11840_23 .Stddev  |  3.1          |  4.9          |  3.2          |...
   11840_23 .#Delete |    1    1     |    1    1     |    1    .     |...
   11840_23 .#Sites  |   22   22     |   26   26     |   28   29     |...
   11840_23    Number of sites:   38  20  48 106  (>3AC 2AC 1AC sum)  ...

3. TROP_wwwwd_hh.sum   (e.g. TROP_11840_02.sum):
   Summary report of each hourly combination in the format used for the
   final combination (contains also information for each station).

-------------------------------------------------------------------------



******************************************************************************
*                         Gerd Gendt            Phone : ++49 331 288 1114    *
*  _/_/_/  _/_/_/_/_/_/   GeoForschungsZentrum  Fax   : ++49 331 288 1111    *
* _/       _/       _/    Aufgabenbereich 1     E-Mail: gendt at gfz-potsdam.de *
* _/ _/_/  _/_/    _/     Telegrafenberg A17                                 *
* _/    _/ _/     _/      D-14473 Potsdam ,  GERMANY                         *
*  _/_/_/  _/    _/_/_/      AFTP: //ftp.gfz-potsdam.de/pub/igsprod          *
*                            www : //op.gfz-potsdam.de/S11/index_S11.html    *
******************************************************************************