dot
Detailansicht
Katalogkarte GBA
Katalogkarte ISBD
Suche präzisieren
Drucken
Download RIS
Hier klicken, um den Treffer aus der Auswahl zu entfernen
Titel An updated model of short-period Earth rotation variations deduced from altimetry-based elevations and barotropic currents
VerfasserIn Matthias Madzak, Michael Schindelegger, Johannes Böhm, Wolfgang Bosch, Jan Hagedoorn, Harald Schuh
Konferenz EGU General Assembly 2015
Medientyp Artikel
Sprache Englisch
Digitales Dokument PDF
Erschienen In: GRA - Volume 17 (2015)
Datensatznummer 250103210
Publikation (Nr.) Volltext-Dokument vorhandenEGU/EGU2015-2612.pdf
 
Zusammenfassung
Improving the current conventional model of short period ocean tidal effects in polar motion and changes in length-of-day is a key challenge of present Earth rotation research. Accurate estimates of ocean tidal angular momentum (OTAM) that are required to this end can be inferred from a purely altimetry-based method, in which measured elevations determine the OTAM mass signal and also the horizontal velocity field through an inversion of the classical shallow water equations. Some of the subtleties of this global adjustment, which we investigate here in the context of Earth rotation, include the weighting schemes for different observation equations, the treatment of closed boundaries, as well as the choice of bathymetry and the amount of bottom friction. We perform a range of test inversions, where the optimal parameter set for diurnals and semi-diurnals is found by working with a data-assimilative global tide model for which both heights and barotropic currents are known. Having completed the fit of tidal velocities to elevations from an up-to-date altimetric model of major constituents, OTAM values are computed and supplemented by the contributions from minor tides using admittance assumptions. We assess the quality of the derived high-frequency Earth rotation model by deploying it as an a priori in the analysis of VLBI (Very Long Baseline Interferometry) observations and comparing its performance to that of the conventional model and those of empirical solutions.