DORIS scale consistency in GOP time series
Event: 2018 IDS Workshop
Session: SESSION II: IDS Processing and Plans for the Next ITRF
Presentation type: Type Oral
We analyzed the scale of the DORIS (Doppler Orbitography and Radiopositioning Integrated by Satellite) solutions w.r.t. DPOD (ITRF) 2014 with the main goal to explain the scale inconsistencies and to find the optimal solution reaching low-biased and consistent scale time series. Our analysis profits from 5 different strategies based only on GOP analysis center solution, using DORIS Doppler exchange format data 2.2. A difference in the sequence of the solutions directly corresponds to one of the changes in the solution settings: data elevation dependent weighting (sin2 E), application of data validity indicators and application of phase center - reference point correction. We processed multi-satellite and single-satellite solutions for the time period 2011.0 - 2017.0. Our analysis examines scale inconsistency issues in 2011/2012 and in 2015. 2011/2012 scale increment is explained as a result of the concurrence of changes in satellite constellation and change in the provider data validity standards for Cryosat-2 and Jason-2. The scale increment in 2015 is explained as the effect of change in the standards for phase center - reference center corrections for Saral, Jason-2 and Cryosat-2. Moreover, comparing the solutions with and without elevation dependent data downweighting using the same elevation cut off (10 degrees), we found a significant reduction of scale bias and scale variation applying the data downweighting. We demonstrated that the solution, which is completely free from the additional data associated with observations in DORIS exchange format 2.2, includes the data downweighting law and the corrected value of HY-2A antenna offset, eventuates in a consistent scale time series with the offset w.r.t. DPOD 2014 (version 1.0) under 1cm and its weekly variations around 2 mm.