Performance of GOCE and GRACE-derived mean dynamic topographies in resolving Antarctic Circumpolar Current fronts

Denis L. Volkov, Victor Zlotnicki

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

Presently, two satellite missions, Gravity Recovery and Climate Experiment (GRACE) and Gravity field and steady-state Ocean Circulation Explorer (GOCE), are making detailed measurements of the Earth's gravity field, from which the geoid can be obtained. The mean dynamic topography (MDT) is the difference between the time-averaged sea surface height and the geoid. The GOCE mission is aimed at determining the geoid with superior accuracy and spatial resolution, so that a more accurate MDT can be estimated. In this study, we determine the mean positions of the Antarctic Circumpolar Current fronts using the purely geodetic estimates of the MDT constructed from an altimetric mean sea surface and GOCE and GRACE geoids. Overall, the frontal positions obtained from the GOCE and GRACE MDTs are close to each other. This means that these independent estimates are robust and can potentially be used to validate frontal positions obtained from sparse and irregular in situ measurements. The geodetic frontal positions are compared to earlier estimates as well as to those derived from MDTs based on satellite and in situ measurements and those obtained from an ocean data synthesis product. The position of the Sub- Antarctic Front identified in the GOCE MDT is found to be in better agreement with the previous estimates than that identified in the GRACE MDT. The geostrophic velocities derived from the GOCE MDT are also closer to observations than those derived from the GRACE MDT. Our results thus show that the GOCE mission represents an improvement upon GRACE in terms of the time-averaged geoid.

Original languageEnglish (US)
Pages (from-to)893-905
Number of pages13
JournalOcean Dynamics
Volume62
Issue number6
DOIs
StatePublished - Jun 2012
Externally publishedYes

Keywords

  • Antarctic Circumpolar Current
  • Antarctic Circumpolar Current fronts
  • GOCE
  • GRACE
  • Mean dynamic topography
  • Polar front
  • Satellite altimetry
  • Satellite gravity
  • Sea surface height gradients
  • South ACC front
  • Southern Ocean
  • Sub-Antarctic front

ASJC Scopus subject areas

  • Oceanography

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