Estimation of the Length of Day (LOD) from DORIS observations
Vikash Kumar (IIT Kanpur, India)
Event: 2024 IDS Workshop
Session: Research activities and new applications using DORIS data, or new methods of processing DORIS data
Presentation type: Oral
DOI: 10.24400/312072/i03-2024.3921
Abstract
We estimated the true Length of Day (LOD) from DORIS observations. The DORIS RINEX data has been processed by the DORIS development version of the Bernese GPS Software 5.2. We performed single satellite and multisatellite (Sentinel-6A, Sentinel-3A, Sentinel-3B, Jason-3, Jason-2, HY-2C, HY-2D, HY-2C, SARAL, and Cryosat-2), and pre-eliminated solutions. The DORIS data has been processed separately for each satellite on a daily arc basis. The troposphere, frequency offset, and orbit parameters were pre-eliminated from the normal equation systems and the finalized matrices were combined weekly. Hence, individual satellite solutions as well as multi-satellite combined solutions were created. The LOD estimates have been obtained from a not-transformed free network solution.
In LOD estimation, we experimented with 4 different solution versions (called L1-L4) for the years 2016-2023. We performed solutions with different settings, in particular with different handling of cross-track once per revolution harmonic parameters (adjusted with different constraints for L2 (5×10^(-9) m/sec^2), L3 (5×10^(-8) m/sec^2), L4 (5×10^(-6) m/sec^2), or not adjusted for L1), since the amplitude of sine term correlates with LOD. For a comparison of our results, we used the IERS 20 C04 model as a reference. With recent data, we have reached a mean difference of 32 µsec with an RMS of 88 µsec for the L1 solution. Our results indicate that only solution with stronger constraints provides accurate LOD estimation.
Contribution: IDS24_s4_Kumar_LODestimation.pdf (pdf, 2224 ko)
Corresponding author:
Vikash Kumar
IIT Kanpur
India
