Melting characteristics of horizontal ice surfaces in cold saline water

Abstract

The results of an experimental investigation of the buoyancy driven flow adjacent to and below a horizontal ice surface melting in cold water at near oceanic salinity are presented. This melting configuration is characteristic of circumstances encountered by sea ice, for example, by new ice and, also, on the bottom of tabular ice floes. Several ambient water temperatures t∞ are investigated, from t∞ = −1.75°C to t∞ = 3°C. Time exposure photographs of the flow field reveal that distinctively different flow regimes occur, across even that narrow range of ambient temperature. At all temperature levels, the flow immediately below the ice surface is found to be horizontally radially inward toward the center of the ice. Also, another outward moving horizontal layer appeared, parallel to and below the inward moving layer. The downward extent of penetration of this layer motion was seen to vary with t∞. The lower layer sinks lower into the ambient medium with increasing t∞. Measured water‐ice interface temperatures and ice melt rates are also presented. These results are compared with earlier similar measurements for vertical surfaces melting in cold saline water and found to vary in a similar way with ambient temperature t∞.