[IGSMAIL-7387] Bias-SINEX V1.00 (and updated bias products from CODE)

[Stefan Schaer]

Dear colleagues,

A finalized draft version for the new Bias-SINEX Format (Version 1.00)
is now available at:

http://www.biasws2015.unibe.ch/documents.html
http://www.aiub.unibe.ch/download/bcwg/format/draft/sinex_bias_100_dec07.pdf

This format version has been developed on the basis of

- a first draft proposed and discussed at the IGS Bias Workshop 2015 in
   Bern, Switzerland,

- an updated draft prepared for the IGS Workshop 2016 in Sydney,

- substantial inputs from the IGS MGEX community (in particular from
   Oliver Montenbruck, DLR, Germany), and

- our experiences gained as part of the GNSS bias implementation
   performed at CODE.

The latest essential updates since the IGS Workshop 2016 include:

- Bias-SINEX was completely decoupled from the SINEX format and
   corresponding format descriptions.

- The previously used 2-digit year tag (YY) was generally replaced by
   a 4-digit year tag (YYYY) for all time tags (YYYY:DDD:SSSSS).

- Numerous bias (.BIA) example files could be prepared based on the
   new GNSS bias products generated at CODE.

The provided examples cover a wide range of applications and various
bias treatment methods (where biases are treated in a pseudo-absolute
or a relative/differential mode). The interested reader is encouraged
to have a look at these example files.

The Bias-SINEX format description includes an overview section listing
the available examples, or example files:

http://www.aiub.unibe.ch/download/bcwg/format/examples/bia_examples.pdf

All examples included in the Bias-SINEX format description are
available as plain text files at:

http://www.aiub.unibe.ch/download/bcwg/format/examples/

At CODE, a refined GNSS bias handling to cope with all available GNSS
systems and signals has been implemented and activated (in May 2016) in
all IGS analysis lines. As part of this major revision, processing
steps relevant to bias handling and retrieval were reviewed and
completely redesigned.

It should be mentioned that the current GPS C1W-C1C DSB (P1-C1 DCB)
product provided by CODE corresponds to a converted extract from our
new OSB final/rapid product line. A number of regularly updated CODE
OSB product files is made available at:

http://www.aiub.unibe.ch/download/bcwg/format/examples/updated_bia/

Our new bias implementation allows to combine bias results at
normal-equation level. We are thus able to combine bias results
obtained from clock analysis and from ionosphere analysis, and,
moreover, to compute coherent long-term OSB solutions. This could be
already achieved for the period starting with 2016:136:00000 up to
now. Corresponding long-term OSB solutions are updated daily and
posted to the above listed directory.

With the official release of the Bias-SINEX Format Version 1.00, we
will start to provide the new CODE bias product files to the IGS
community.

We are open for any feedback. We intend to finalize (and officially
fix) the presented format version in January 2017. Therefore, we can
only consider feedback on the actual data format received until
January 15, 2017.

Additional remark: Further descriptions on how to apply a Bias-SINEX
product will be added after the official release. This will include
instructions for users of the CC2NONCC utility.

Best regards,

Stefan Schaer and Arturo Villiger