Combining altimeter and subsurface float data to estimate the time‐averaged circulation in the upper ocean

[1] A new technique is presented for estimating time-averaged, upper ocean geostrophic velocity from a combination of altimeter data and subsurface float data. The technique makes uses of the strong relationship between sea-surface height anomaly and anomalous velocity at depth to reduce mesoscale eddy variability in subsurface float displacements. The technique is demonstrated on a region in the North Atlantic that was well sampled by Argo floats. The 2004 through 2006 time-averaged density field was estimated from the surface to 2000 db by combining altimeter and hydrographic data from the floats. In addition, a reference velocity field was estimated at 1000 db based on a combination of altimeter data and subsurface float displacements. The reference velocity field was combined with geostrophic shear based on the density field to produce a three-dimensional estimate of geostrophic velocity from the surface to 2000 db. The Gulf Stream transport in the upper 2000 db is estimated to be 76 Sv at 73°W. In addition, an estimate of the 3-year average dynamic height at the surface was computed by combining the 1000-db reference dynamic height and the time-averaged density field.

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