IGS Reference Frame Working Group Charter
Remi Ferland
Geodetic Survey Division
Natural Resources Canada
Ottawa, Ontario, Canada
CHARTER
For the
IGS REFERENCE FRAME WORKING GROUP
INITIAL GOALS
The collective effort of the working group participants is to generate the official IGS station coordinates and velocities, Earth Rotation Parameters (ERP) and geocenter estimates along with the appropriate covariance information. The estimated parameters will be aligned to the International Terrestrial Reference Frame (ITRF). The group will strive for consistency, reliability and accuracy of the above products.
The station coordinates and ERP information from the Analysis Centers (AC), the Global Network Associate Analysis Centers (GNAAC), the Regional Network Associate Analysis Centers (RNAAC) and potentially other sources will be compared and used to generate and validate the IGS official products. A new solution will be computed and made available regularly. It will initially contain station coordinates, daily ERP, weekly geocenter estimate, and relevant information on the equipment used at each station.
The "epoch" estimated station coordinate solutions will be added to the cumulative solution. The cumulative solution will contain at least a set of estimated coordinates and velocities at a reference epoch for each station. The AC, GNAAC, RNAAC, "epochs", cumulative, ITRF and potentially other solutions will be compared and residual files will be made available. The cumulative solution will be submitted as needed to IERS in order to contribute to the definition of ITRF. The solutions will be limited to about 200 to 250 well distributed and high quality stations, forming an IGS polyhedron.
Abnormal station coordinates behavior will be reported. Potential inconsistencies in the past and current coordinates solutions will be investigated and corrected whenever possible. The performance and long term characteristics of the network based on the station coordinate time series will be monitored and reported. The network will consist of a number of well-distributed and quality stations. In collaboration with interested users, the network will be reassessed regularly as part of the maintenance.
The IGS Reference Frame working group will promote improvements to the products through refinement in the analysis, modeling and algorithms. As a result, enhancements to current exchange standards and reports may be proposed. This group will collaborate with other groups and scientific organizations to improve the IGS products and to promote their use.
The use of the IGS realization of ITRF will also be promoted. The products will be suitable for other IGS products as well as various studies such as plate tectonic, regional deformations, temporal variations. The definition of national reference systems can also benefit from the IGS realization of ITRF.
STRUCTURE
The working group will be composed of one coordinator with a number of active members. The working group reports to the IGS Governing Board. Modifications to the goals and working plan will be arrived at through consultation among the working group.
WORKING PLAN
In coordination with the group members, the ongoing objectives are to:
- Analyze the time series station coordinates residuals; report on the findings and if appropriate implement improvements to the processes.
- Compare the products with other solutions/models, report the findings and if appropriate implement improvements to the processes.
- Analyze/compare ERP solutions, report the findings and if appropriate implement improvements to the processes.
- Inform responsible groups/organizations to help resolve station related inconsistencies.
In coordination with the group members, the objectives for the first year are to:
- Get the weekly combination and reporting procedure to run smoothly, with a concise and informative weekly report.
- Reanalyze the AC and/or GNAAC and/or RNAAC stations coordinates solutions available since GPS week 837 and report the results.
In coordination with the group members, the objectives for the second year are to:
- Monitor and report the performance and long term characteristics of the network based on the stations coordinates time series
- Continue the analysis with emphasis on the reliability and accuracy of the products
- Include AC and/or GNAAC and/or RNAAC stations coordinates solutions available before GPS week 837 and report the results.
In coordination with the group members, the following objectives will be considered as time and resources are available to:
- Provide graphical interface for the reporting of the time series residuals and other types of data.
MEMBERS
The working group will be potentially composed of the IGS coordinator, the Director of the IGS Central Bureau, one representatives from each AC, one from each GNAAC and one from the ITRF/IERS section. Other members may be added as required.
The current members are:
- R. Neilan Director, IGS Central Bureau "member ex officio"
- G. Gendt IGS Analysis Center Coordinator / GFZ "member ex officio"
- R. Ferland IGS Reference Frame Coordinator / EMR
- S. Schaer COD
- C. Garcia ESA
- M. Heflin JPL
- W. Kass NGS
- P. Fang SIO
- K. Nurutdinov NCL
- T. Herring MIT
- M. Rothacher IERS
- J. Kouba Past IGS Analysis Center Coordinator
- R. Weber Past IGS Analysis Center Coordinator
- J. Ray Past ITRF Working Group Chairman
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