Please complete the protocol for Session 5 "Discussion and Summary".

Date

Introduction

  • Hartmut: need to resolve do:  RS define the frame, or all absolute (including Field)?    Let’s spend 30 minutes
  • Next steps? Graham Appleby will present on parallels with ILRS/laser ranging
  • Let’s discuss publication and outlook for a governing board

Which Stations Realize the Frame?

  • Vojtech: Single epoch stations
  • Derek : single epochs are “nodes” of the frame that may “decay” over time
  • Vojtech: start by assessing traceability multi-epoch stations and instruments.   Categorize stations by history, stability. 

 

  • Frame defined physically by a benchmark and its traceable gravity value
    • Reference ITGRF stations: either characterized by (traceable) AG  and a reference function or multiple AG measurements, etc.     A reference station should be able to provide the current gravity value and uncertainty along with the linking/trace information.
    • Single/multiple epoch stations whose uncertainty needs to include the (initially unknown) site stability.
  • Derek: need to assess the current inventory to start the ITGRF and also mechanism to enlarge the ITGRF with new instruments and sites
  • Hartmut: we need to users to be able to access the ITGRF in spite of the sparseness of AGs, etc.

 

  • Discussion of what “realizes” the system and the frame?

 

  • Frame is realized through absolute gravity measurements that are traceable either via comparisons and/or reference functions.
  • Access to the frame via traceable observations including field stations, AG observations.
  • Tradeable measurements are the realization of the system and the benchmark gravity value provides access to the frame

 

  • Discussion of ITGRF Operation
    • Graham to present on parallels with laser ranging ILRS governing board
      • Nonhomogeneous distribution of stations
      • Observations stations, center, data centers, analysis centers, a central bureau, a governing board. “Components required to achieve the goals of the service”
      • Governing board is outward facing component (e.g. to IAG)
      • Analysis standing committee ensure consistent quality across analysis centers
      • Network engineering ensures instrument consistency and quality
    • Graham recommends to start with a governing board (GB)
    • George Vergios: instead of a service, recommends “coordination center” approach

 

  • Hartmut: let’s initiate a core group structure today
    • Propose to have the ITGRF “Coordination Group” (CG) under the BGI
    • Four representatives/responsibilities
      • Comparisons and traceability
      • Reference Stations and Regional Coordinators. One on the CG
      • Database / dissemination. Tolouse  AGrav
      • Analysis and processing of gravity. Time series analysis, links to IGETS.   Building up reference functions, etc.
      • Chairperson: general administration, outreach, papers, resolution, etc.
    • BGI will renew its GB soon, good time to add ITGRF representation
    • Derek: what tasks will this new group be responsible for?
    • Ezequiel/Sylvain: we need an immediate roadmap and strategy.  Guidelines, list of attributes, future structure, paper and resolution…
    • Need to reach out for more regional participation: Middle East, Africa, SE Asis/Pacific, Australia, India
    • CG Volunteer list;
      • Hartmut Wziontek (Europe) – Chairperson
      • Sylvain Bonvalot (Europe) – Co-chairperson (database)
      • Derek van Westrum (North America) – reference station coordination
      • Vojtech Palinkas (Europe) – traceability and comparisons
      • To Be Determined - analysis and processing.   Sylvain:  possibly depends on AGrav attributes and future capabilities.

 

  • Immediate Steps
    • IUGG Resolution
    • Current status and publication
    • Find out what requirements for IUGG. Prefer to have a paper (white, peer?) at least submitted by the time the IUGG proposal process starts
    • Paper contributors: Hartmut, Derek, Vojtech, Sylvain.   Outline of paper mirrors the outline of this JWG meeting.  
    • All materials from this week will be on the BKG wiki.

 

  • Next meeting: EGU session proposal (Marvin Reich).   Early May 2027.
    • Previous sessions in 2018 and 2019.
    • Splinter meeting in 2027.  Probably no remote participation
    • Next online JWG meeting:  Possibly the week of 30 November (week 49)
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