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Dynamically balanced absolute sea level of the global ocean derived from near‐surface velocity observations
Author(s) -
Niiler Pearn P.,
Maximenko Nikolai A.,
McWilliams James C.
Publication year - 2003
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2003gl018628
Subject(s) - geodesy , geology , drifter , geostrophic wind , sea level , pressure gradient force , altimeter , momentum (technical analysis) , ocean surface topography , pressure gradient , hydrostatic equilibrium , climatology , physics , meteorology , oceanography , economics , mathematical physics , finance , lagrangian , quantum mechanics
The 1992–2002 time‐mean absolute sea level distribution of the global ocean is computed for the first time from observations of near‐surface velocity. For this computation, we use the near‐surface horizontal momentum balance. The velocity observed by drifters is used to compute the Coriolis force and the force due to acceleration of water parcels. The anomaly of horizontal pressure gradient is derived from satellite altimetry and corrects the temporal bias in drifter data distribution. NCEP reanalysis winds are used to compute the force due to Ekman currents. The mean sea level gradient force, which closes the momentum balance, is integrated for mean sea level. We find that our computation agrees, within uncertainties, with the sea level computed from the geostrophic, hydrostatic momentum balance using historical mean density, except in the Antarctic Circumpolar Current. A consistent horizontally and vertically dynamically balanced, near‐surface, global pressure field has now been derived from observations.