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AGU: Journal of Geophysical Research, Oceans

 

Keywords

  • GRACE
  • combination
  • ocean

Index Terms

  • Geodesy and Gravity: Ocean monitoring with geodetic techniques
  • Geodesy and Gravity: Ocean/Earth/atmosphere/hydrosphere/cryosphere interactions
  • Geodesy and Gravity: Time variable gravity
  • Geodesy and Gravity: Integrations of techniques
Abstract
Cited By (7)
 

Abstract

JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 114, C11004, 17 PP., 2009
doi:10.1029/2009JC005449

Changes in total ocean mass derived from GRACE, GPS, and ocean modeling with weekly resolution

R. Rietbroek

Helmholtz Centre Potsdam, German Research Centre for Geosciences, Potsdam, Germany

Institute of Geodesy and Geoinformation, Bonn, Germany

S.-E. Brunnabend

Alfred Wegener Institute, Bremerhaven, Germany

C. Dahle

Helmholtz Centre Potsdam, German Research Centre for Geosciences, Potsdam, Germany

J. Kusche

Helmholtz Centre Potsdam, German Research Centre for Geosciences, Potsdam, Germany

Institute of Geodesy and Geoinformation, Bonn, Germany

F. Flechtner

Helmholtz Centre Potsdam, German Research Centre for Geosciences, Potsdam, Germany

J. Schröter

Alfred Wegener Institute, Bremerhaven, Germany

R. Timmermann

Alfred Wegener Institute, Bremerhaven, Germany

We derive changes in ocean bottom pressure (OBP) and ocean mass by combining modeled ocean bottom pressure, weekly GRACE-derived models of gravity change, and large-scale deformation patterns sensed by a global network of GPS stations in a joint least squares inversion. The weekly combination allows a consistent estimation of geocenter motion, loading mass harmonics up to degree 30, and a spatially uniform mass correction term, which serves as a correction for forcing of the ocean model. We provide maps and time series of ocean mass and bottom pressure variations. Furthermore, we discuss the estimated geocenter motion and the estimated model correction. Our results indicate that the total ocean mass change is predominantly annual, with a maximum amplitude corresponding to 7.4 mm in October, which is in line with earlier work. The mean ocean bottom pressure (i.e., ocean plus atmospheric mass) shows an annual amplitude of 8.7 mm and is shifted forward by about 1.5 months. In addition, the solution exhibits typical autocorrelation times of about 2 weeks. A comparison with in situ bottom pressure time series in the southern Indian Ocean shows a good agreement, with correlations of 0.7–0.8. Based on these comparisons, we see that our results monitor realistic submonthly variations, which are strongest at high latitudes. The addition of GRACE data in the inversion is found to improve these high-latitude variations and enables better separability of the geocenter motion from other unknowns. Increasing the OBP model error from 3 cm to 4.8 cm affects mainly the higher-degree coefficients.

Received 17 April 2009; accepted 31 July 2009; published 3 November 2009.

Citation: Rietbroek, R., S.-E. Brunnabend, C. Dahle, J. Kusche, F. Flechtner, J. Schröter, and R. Timmermann (2009), Changes in total ocean mass derived from GRACE, GPS, and ocean modeling with weekly resolution, J. Geophys. Res., 114, C11004, doi:10.1029/2009JC005449.

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