Assimilation of geodetic dynamic ocean topography using ensemble based Kalman filter

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • T. Janjíc - , Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research (Author)
  • J. Schröter - , Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research (Author)
  • A. Albertella - , Technical University of Munich (Author)
  • W. Bosch - , Technical University of Munich (Author)
  • R. Rummel - , Technical University of Munich (Author)
  • R. Savcenko - , Technical University of Munich (Author)
  • J. Schwabe - , Chair of Geodetic Earth System Research (Author)
  • M. Scheinert - , Chair of Geodetic Earth System Research (Author)

Abstract

Estimation of ocean circulation is investigated via assimilation of satellite measurements of the dynamic ocean topography (DOT) into the global finite-element ocean model (FEOM). The DOT was obtained by means of a geodetic approach from carefully cross-calibrated multi-mission altimeter data and GRACE gravity fields. The spectral consistency was achieved by consistently filtering both, the sea surface and the geoid. The filter length is determined by the spatial resolution of the gravity field and corresponds to approximately 241 km half width for the GRACE-based gravity field model ITG-Grace03s.

The assimilation of the geodetic DOT was performed by employing a local singular evolutive interpolated Kalman (SEIK) filter in combination with the method of weighting of observations. It is shown that this approach leads to a successful assimilation technique that reduced the RMS difference between the model and the data from 16 cm to 5 cm during one year of assimilation. The ocean model returns an optimized mean dynamic ocean topography. The effects of assimilation on transport estimates across several hydrographic World Ocean Circulation Experiment (WOCE) sections show improvements compared to the FEOM run without data assimilation. As a result of the assimilation, DOT estimates are available in the polar or coastal regions where the geodetic estimates from satellite data alone are not adequate. Furthermore, more realistic features of the ocean can be seen in these areas compared to those obtained using the filtered data fields.

Details

Original languageEnglish
Pages (from-to)92-98
Number of pages7
JournalJournal of geodynamics / European Geophysical Society, Solid Earth Geophysics and Geodesy Sections
Volume2012
Issue number59-60
Publication statusPublished - 13 Jul 2011
Peer-reviewedYes

External IDs

Scopus 84863841738
ORCID /0000-0002-0892-8941/work/142248918

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