Systematic Errors in the DORIS System: Lessons learned from ITRF2008 and Future Possibilities (Invited)

For the development of ITRF2008, the International DORIS Service (IDS) for the first time developed a combination based on the contributions of seven analysis centers using five separate software packages. Data from 1993 to 2009 were processed in weekly batches using the latest geodetic processing standards, mostly consistent with the IERS standards. Although the quality of the DORIS contribtution was improved with respect to ITRF2005, the development of ITRF2008 highlighted a number of important issues that affect the quality of the DORIS geodetic contribution to the reference frame. It was shown for example that mismodelling of the nonconservative forces impacts the solution in a number of ways: through solar radiation pressure mismodelling which can alias into the time series of geocenter and scale, and through deterioration of the positioning quality and EOP solutions during high drag periods. In addition, in analysis for the preparation of the GOP DORIS contribution to ITRF2008, Stepanek et al. (2010) showed that SPOT-5 shows evidence of a possible SAA effect, that perturbs particularly the South American DORIS stations. In addition, DORIS being a radiometric technique is strongly affected by the choices made for troposphere modeling, especially in terms of a priori meteorological data and mapping function. We review the current status of analysis as shown by the ITRF2008 results, and discuss prospects for improvements including improved force modeling, improved modeling of the troposphere, and other issues. The contribution of Jason-2 in terms of data strength and geometry is also reviewed, in comparison to the traditional and historical contributions of the DORIS satellite constellation.