Sea-ice model validation using submarine measurements of ice draft

Abstract

AbstractSea-ice thickness distributions from 12 submarine cruises under the North Pole are used to evaluate and enhance the results of sea-ice model simulations. The sea-ice models include versions with cavitating fluid and elastic-viscous-plastic rheologies, and versions with a single thickness and with multiple (5–27) thicknesses in each gridcell. A greater portion of the interannual variance of observed mean thickness at the Pole is captured by the multiple-thickness models than by the single-thickness models, although even the highest correlations are only about 0.6. After The observed thickness distributions are used to ˚tune" the model to capture the primary mode of the distribution, the largest model-data discrepancies are in the thin-ice tail of the distribution. In a 41 year simulation ending in 1998, the model results show a pronounced decrease of mean ice thickness at the Pole around 1990; the minimum simulated thickness occurs in summer 1998. The decrease coincides with a shift of the Arctic Oscillation to its positive phase. The smallest submarine-derived mean thickness occurs in 1990, but no submarine data were available after 1992. The submarine-derived thicknesses for 1991 and 1992 are only slightly smaller than the 12–case mean.