Assimilation of geodetic dynamic ocean topography using ensemble based Kalman filter

Tijana Janjić, Jens Schröter, Alberta Albertella, Wolfgang Bosch, Reiner Rummel, Roman Savcenko, Joachim Schwabe, Mirko Scheinert

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

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.

Original languageEnglish
Pages (from-to)92-98
Number of pages7
JournalJournal of Geodynamics
Volume59-60
DOIs
StatePublished - Sep 2012

Keywords

  • Data assimilation
  • GRACE
  • Geodetic dynamic ocean topography
  • Hydrographic WOCE sections
  • Mass transport

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