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Main Title: High-frequency earth rotation variations deduced from altimetry-based ocean tides
Author(s): Madzak, Matthis
Schindelegger, Michael
Böhm, Johannes
Bosch, Wolfgang
Hagedoorn, Jan
Type: Article
Language Code: en
Abstract: A model of diurnal and semi-diurnal variations in Earth rotation parameters (ERP) is constructed based on altimetry-measured tidal heights from a multi-mission empirical ocean tide solution. Barotropic currents contributing to relative angular momentum changes are estimated for nine major tides in a global inversion algorithm that solves the two-dimensional momentum equations on a regular 0.5^\circ grid with a heavily weighted continuity constraint. The influence of 19 minor tides is accounted for by linear admittance interpolation of ocean tidal angular momentum, although the assumption of smooth admittance variations with frequency appears to be a doubtful concept for semi-diurnal mass terms in particular. A validation of the newly derived model based on post-fit corrections to polar motion and universal time (\Delta UT1) from the analysis of Very Long Baseline Interferometry (VLBI) observations shows a variance reduction for semi-diurnal \Delta UT1 residuals that is significant at the 0.05 level with respect to the conventional ERP model. Improvements are also evident for the explicitly modeled K_1, Q_1, and K_2 tides in individual ERP components, but large residuals of more than 15 \upmu as remain at the principal lunar frequencies of O_1 and M_2. We attribute these shortcomings to uncertainties in the inverted relative angular momentum changes and, to a minor extent, to violation of mass conservation in the empirical ocean tide solution. Further dedicated hydrodynamic modeling efforts of these anomalous constituents are required to meet the accuracy standards of modern space geodesy.
Issue Date: 2016
Date Available: 29-Aug-2017
DDC Class: 550 Geowissenschaften
Subject(s): earth rotation variations
empirical ocean tides
tidal currents
angular momentum changes
Journal Title: Journal of geodesy
Publisher: Springer
Publisher Place: Berlin, Heidelberg
Volume: 90
Issue: 11
Publisher DOI: 10.1007/s00190-016-0919-4
Page Start: 1237
Page End: 1253
EISSN: 1432-1394
ISSN: 0949-7714
Appears in Collections:FG Satellitengeodäsie » Publications

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