THE THICKNESS VARIABLE IN SEA-ICE MODELS

The thickness distribution function is considered a fundamental state variable for sea-ice. However, certain assumptions are implicit in its use. Based largely on observations, we estimate upper and lower bound s on the spatial scale for which the usual interpretation of the thick ness distribution function is valid. These scales turn out to be simil ar to 200 km and similar to 10 km respectively for central Arctic cond itions, although the upper bound is expected to decrease near coastlin es and open-water boundaries. At scales larger than the upper bound re al geophysical variations of the thickness distribution occur, violati ng the assumption of homogeneity. At scales smaller than the lower bou nd, the distribution function is not sufficiently well sampled to ensu re that it varies smoothly in space.