Knut Aagaard (UW), Andrew Roach, Richard Moritz (UW), Jens Meincke (University
of Hamburg)

Corresponding author: Knut Aagaard (


The export of freshwater through Fram Strait in the form of sea ice has been hypothesized to influence the global ocean overturning circulation.  To address the variability of this freshwater discharge, we collected six years of ice thickness observations over the continental slope at 79° N in Fram Strait.  During a number of these years the annual cycle of ice thickness was out of phase with the thermodynamic forcing, since the maximum observed ice thickness occurred in summer and the minimum in winter.  Using these observations, we scale the mean thickness equation for sea ice, finding that the ice thickness in Fram Strait depends on the shifting balance among the first-order effects of thermodynamics, advection, and divergence.  The divergence is computed as the residual in this procedure, yielding a mean value of about 10-8 s-1, in agreement with the estimate of Kwok and Rothrock [1999].  We suggest that the variability of the southward ice flux is smaller than has been thought, perhaps one-half as large, but that the amplitude and phase of the annual cycle, which appears to be controlled locally, is critical to the actual volume transport.


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  AWI, No.91, 150pp.

We gratefully acknowledge financial support for this work from the National Oceanic and Atmospheric Administration (NOAA).

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