[IGSMAIL-6842] Next Analysis Center Coordinator, Request for Proposal

Tue Dec 3 04:14:32 PST 2013

Dear Colleagues,

the terms of Jake Griffiths as the IGS Analysis Center Coordinator ends 
at the end of 2015. In order to allow for a smooth transition to a new 
ACC the IGS releases a Request for Proposals which you find included in 
this mail as well as at the IGS main web page
http://igs.org (in the Recent News section)
or
ftp://igs.org/pub/resource/pubs/IGS_RfP_nextACC_2013.pdf

Institutions are encouraged to consider supporting the IGS with this 
very important function. We would be glad to receiver expressions of 
interest until June 01, 2014. Do not hesitate to contact myself or the 
current ACC for further information.

Best regards
Urs Hugentobler
Chair, IGS Governing Board

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  Request for Proposal for next Analysis Center Coordinator

  2013-Nov-30

  Summary

The IGS invites proposals for a successor to the current Analysis Center 
Coordinator, starting in 2016. Here are the key dates:

·30 November 2013---this call for proposals

·01 June 2014---deadline for submission of expression of interest for 
next ACC

·31 September 2014---deadline for submission of response for next ACC

·31 December 2014---selection of next ACC

·01 July 2015---beginning of test and validation phase for new ACC

·01 January 2016---full operational responsibility by new IGS ACC

  Background

The IGS Analysis Center Coordinator (ACC) has overall responsibility for 
generating the main official IGS combined products. During the period 
2008 through 2015, the IGS ACC functions are performed by NOAA's 
National Geodetic Survey (NGS) in Silver Spring, Maryland, USA. 
Currently, there are three IGS product lines for GNSS satellite orbits 
and clocks, namely the Final (GPS and GLONASS independently), the Rapid 
(GPS only), and the Ultra-rapid (GPS and GLONASS independently) 
products. During previous periods, the ACC functions have been performed 
by the Deutsches GeoForschnungsZentrum (GFZ, Potsdam, Germany during 
2003-2008), Center for Orbit Determination in Europe (CODE, Bern, 
Switzerland and Vienna, Austria during 1999-2003), and Natural Resources 
Canada (NRCan, Ottawa, Canada during 1994-1998).

Certain IGS product combination tasks are shared with the ACC. For the 
Final products, those components involving the terrestrial reference 
frame, including the Earth rotation parameters, are produced by a 
combination of SINEX file submissions at Institut National de 
l'Information Géographique et Forestière//(IGN, France). (This function 
was at NRCan in Ottawa prior to 2010.) The internally realized 
timescales of the IGS, formed by a weighted ensemble of the frequency 
standards available in the IGS clock products, are maintained by the 
Naval Research Laboratory (NRL, Washington, DC, USA). Such 
high-stability timescales are supported for the IGS Rapid and Final GPS 
products, but not yet for GLONASS or the Ultra-rapids.

Other IGS products are formed by separate working groups not directly 
linked to the ACC, such as ionosphere maps, tropospheric path delays, 
and real-time services. Nevertheless, overall consistency should be 
maintained across all IGS products.

The present ACC combination system traces back to the early 1990s with 
many diverse components, written in a variety of coding languages, and 
many modifications since that time to accommodate changes. While the 
previous call, which was posted in August 2009 (IGSMAIL-5984), requested 
proposals for a next-generation combination system (ACC2.0), none were 
submitted. The legacy system continues to be used, but any efforts by 
the new ACC to incorporate newer GNSS constellations, new signals, or 
otherwise improve the existing combination system are encouraged. IGS is 
aiming at fully consistent Multi-GNSS products. The activities related 
to the IGS Multi-GNSS Experiment will eventually be fully integrated 
into the standard product streams.

The term of the current ACC will expire at the end of 2015. A new ACC 
will be needed to replace Jake Griffiths (NGS) starting January 1, 2016, 
with a transition and validation phase starting preferably no less than 
six months earlier.

The ACC is a fundamental task within the IGS.

Expressions of interest to succeed NGS starting January 1, 2016 are 
requested at the earliest opportunity, but no later than 01 June 2014.

Selections for the next ACC will be made by 31 December 2014, with a 
hand-over process beginning no later than mid-2015.

  Guiding Principles for ACC Combinations

The following are the historic principles that have guided IGS analysis 
product combinations:

1.Software independence---The IGS products should not favor any 
particular AC software design. In particular, least squares methods 
cannot have a preference over filter methods.

2.Diversity of approaches---Diverse modeling approaches are preferred as 
long as they are physically reasonable and compatible, and conform to 
accepted conventions. Only in this way can progress be achieved. 
Nevertheless, all AC solutions must attain comparable levels of accuracy 
in order for the product combinations to benefit.

3.Objective weighting---The combination strategy should use AC weights 
that are objectively based, usually on the basis of best agreement with 
the mean or with some external standard of sufficient accuracy.

4.Unconstrained---AC solutions should be either unconstrained or only 
minimally constrained. Generally the IGS should strive to move in the 
direction of lesser/weaker solution constraints, a goal that has been 
substantially advanced during the present ACC tenure.

  Specific ACC Tasks

1.*/Working Groups & Pilot Projects/*: The ACC is an ex officio member 
of all IGS working groups and pilot projects, and is also a voting 
member of the IGS Governing Board. Responsibilities described in the IGS 
Terms of Reference are given at igs.org/organization/bylaws.html.

2.*/Core products/*: The ACC is responsible for forming and distributing 
the IGS core products, i.e.:

a.Ultra-rapid GPS & GLONASS satellite orbits and clocks with ERPs, 
presently issued four times daily with an initial delay of 3 hr;

b.Rapid GPS satellite orbits and clocks with ERPs and station clocks, 
presently issued daily with a delay of 17 hr;

c.Final GPS & GLONASS satellite orbits and clocks with station clocks, 
presently issued weekly with a delay of about 12 days.

Expansion of this product set to include new GNSS constellations or to 
implement other enhancements is encouraged, provided that the ACs and 
other supporting organizations approve and contribute.

3.*/Reprocessed products/*: From time to time, the IGS expects to 
reprocess all GNSS observational data using the latest models and 
procedures to achieve the highest possible product accuracy and to 
maintain long-term consistency.

a.Detailed specifications and performance metrics for these products are 
given at acc.igs.org. In the future, new or expanded combination 
products might be indicated.

4.*/Coordinate with TRF and clock products/*: The formation of the Rapid 
and Final clock time scales and the Final station coordinate/ERP 
products requires close interaction with the Coordinators for those 
products. Electronic exchanges of data files must be synchronized and 
monitored in order to avoid product interruptions.

5.*/Monitor AC products/*: The ACs must be promptly informed whenever 
problems occur in the quality or availability of their input solutions 
and it is sometimes necessary to intervene in the combination process to 
minimize adverse impacts. Changes made by ACs often require 
corresponding changes in the ACC procedures.

6.*/Monitor ACC products/*: The quality and reliability of the IGS 
official products must be continuously monitored for any deficiencies, 
which must be promptly addressed. Difficulties with the flow of product 
files to the IGS Data Centers must also be resolved as quickly as possible.

7.*/Report station data problems/*: Many types of data anomalies at the 
tracking stations can have adverse effects on the IGS products. When 
these are detected it is important to notify the station operators promptly.

8.*/Maintain external interactions and interfaces/*: The ACC procedures 
depend on data files from certain external organizations which must be 
continuously updated. Likewise, the ACC products flow continuously to 
various external users. These interfaces must be reliably maintained and 
updated as needed, which requires routine interactions with such 
external groups as the International Earth Rotation and Reference 
Systems Service (IERS). Also included in this activity is maintenance of 
the IERS Conventions upon which the IGS data reductions rely.

9.*/Research and improvements/*: The ACC should normally play an active 
role, together with the ACs and other scientists, in evaluating the 
quality and comprehensiveness of present IGS products and developing 
approaches for their improvement.

10.*/IGS Workshops/*: The ACC ordinarily identifies key technical topics 
that should impact the planning and organization of IGS workshops.

11.*/Website/*: The ACC maintains a website of information concerning 
the IGS core products, their quality, and other information helpful to 
the ACs and general users.

12.*/Outreach/*: It is necessary to provide users information about the 
combined IGS products on a regular basis, as needed.

13.*/Reports/*: The results of each ACC product combination are 
documented in regular reports distributed by the IGS. Other reports and 
scientific papers should be prepared to document future developments and 
accomplishments.

It is expected that the transition to the next ACC will require a visit 
to NGS by personnel from the successor host organization.

  Responses

Expressions of interest and proposals for the successor to the current 
Analysis Center Coordinator should be addressed to the IGS Central 
Bureau (igscb at igscb.jpl.nasa.gov) with the following information:

·names of key personnel

·level of support to be provided

·computing system to be used for tasks and other technical information

·available starting date

·duration of commitment

  Schedule

·30 November 2013---this call for proposals

·01 June 2014---deadline for submission of expression of interest for 
next ACC

·31 September 2014---deadline for submission of response for next ACC

·31 December 2014---selection of next ACC

·01 July 2015---beginning of test and validation phase for new ACC

·01 January 2016---full operational responsibility by new IGS ACC

  References

G. Beutler, J. Kouba, T. Springer (1995) Combining the orbits of the IGS 
Analysis Centers, Bull. Geod., 69, 200-222, doi: 10.1007/BF00806733

J. Kouba, Y. Mireault, F. Lahaye (1995) Analysis Coordinator report, in 
International GPS Service for Geodynamics 1994 Annual Report, Jet 
Propulsion Laboratory publication 95-18, pp 59-94, available at: 
http://igscb.jpl.nasa.gov/igscb/resource/pubs/94an_repta.pdf

J. Kouba, J. Ray, M.M. Watkins (1998) IGS Reference Frame Realization, 
in 1998 IGS Analysis Center Workshop Proceedings, European Space 
Operations Centre, Darmstadt, Germany, pp 139-171, available at: 
http://igscb.jpl.nasa.gov/igscb/resource/pubs/wksp_2.pdf

J. Griffiths 
<http://link.springer.com/search?facet-author=%22Jake+Griffiths%22>, J. 
Ray <http://link.springer.com/search?facet-author=%22Jim+R.+Ray%22> 
(2009) On the Precision and Accuracy of IGS Orbits, J. of Geodesy, 
83(3-4), 277-287, doi: 10.1007/s00190-008-0237-6

J. Griffiths 
<http://link.springer.com/search?facet-author=%22Jake+Griffiths%22>, J. 
Ray <http://link.springer.com/search?facet-author=%22Jim+R.+Ray%22> 
(2013) Sub-daily Alias and Draconitic Errors in the IGS Orbits, GPS 
Solutions, 17(3), 413-422, doi: 10.1007/s10291-012-0289-1

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