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heimbach |
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Global ocean circulation and mass fields |
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and the Earth's variable rotation |
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Rui M. Ponte, Detlef Stammer, Carl Wunsch |
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Advances in modeling and observational capabilities occurring in |
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recent years as part of the WOCE legacy have made possible the |
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realistic determination of the ocean circulation and mass fields on a |
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global scale. With the ability to calculate these time varying fields |
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came the opportunity to study globally integrated quantities such as |
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ocean angular momentum (OAM). Global estimates of sea level, density, |
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and horizontal currents are used to show that improved OAM estimates |
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are being obtained from advanced ocean state estimation methods. |
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Comparisons with independent Earth rotation data demonstrate the good |
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quality of OAM estimates and reveal the importance of OAM variability |
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in explaining observed signals in length of day and polar motion. |
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The equatorial components of OAM are particularly relevant for the |
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planet's rotation budget and can account for a major part of the |
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Chandler and seasonal wobble excitation, thus providing an answer to a |
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long standing unsolved problem in geophysics. Results point to the |
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value of combining satellite altimetry and gravity data, Earth rotation |
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data, and ocean models to address various oceanographic and geodetic |
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research questions in the future. |
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