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4th Unified Analysis Workshop

California Institute of Technology, Pasadena, California, USA, 27 - 28 June 2014

A Not barrier-free file. summary (PDF, 168KB) and the presentations are available.

Aims of the workshop and issues to be addressed

The following topics were the mains ones to be addressed at the Unified Analysis Workshop. Papers were invited that would address these areas and follow-up after the workshop should lead to resolution or a better understanding of the issues.
There is no specific order to the issues listed below but some are more critical to be addressed than others.

  1. ~1 ppb scale difference between VLBI and SLR. This issue is critical to the ITRF realization and should be addressed as thoroughly as possible.
  2. Antenna phase center models for DORIS systems. The recent implementation of phase center models for the DORIS ground transmitters has increased the scale difference between DORIS results and the ITRF2008 scale. It is likely this difference will persist with ITRF2013 as well.
  3. Time variable gravity field effects (DORIS LEO satellites). Although the IDS raised this issue, it also has impacts on the ILRS and even GNSS orbits could be affected by time variable low degree gravity field coefficients.
  4. Sub-daily loading and S1/S2 loading. Two issues are involved here (a) the coefficients of the S1 and S2 loading signals and how they vary during the year and (b) the effects of any remaining sub-daily variations after the S1 and S2 terms are removed.
  5. Update time scales for atmospheric and hydrographic loading: Frequency dependence and signal to noise ratio of loading?
  6. Diurnal and Semidiurnal EOP variations. Impact of new models available from the IVS and how these model impact geodetic parameter estimates.
  7. EOP parameterization for high-time resolution representation: Is piece-wise linear adequate for current accuracies?
  8. Collocation issues: Ground and space based: Assessment of where we stand at the moment.
  9. Monument stability (Large and small, physical and electrical): UNAVCO and NASA SGP have been studying this issue and there are measurements that try to address this issue.
  10. Intersystem observations (e.g. VLBI of satellites, SLR of GNSS systems): Assessment of current status, future prospects and likely impacts on geodetic parameter estimates.
  11. Error models for data and parameter estimates: What are the impacts and best methods for determining correlations within and between geodetic systems and how do account for these correlations so that error estimates on geodetic parameters are more robust and realistic.
  12. Unification of gravity contributions: How do we start addressing the integration of gravity services with the geometric services to ensure consistent models and results?
  13. Combination at the Observation level (COL) results. Update on current status and long term impact of these approaches.

Download: Not barrier-free file. summary (PDF, 168KB)

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