A method was developed to relate the thickness of sea-ice to its surface temperature and other meteorological parameters controlling the surface heat exchange between sea-ice and the atmosphere. The method was based on a one-dimensional thermodynamic sea-ice model, allowing an optional snow cover. The surface temperature and the albedoof sea-ice were derived from radiance measurements of the Thematic Mapper. The method was applied to the NorthEast Water polynya in winter (East of Greenland) to estimate the polynya's ice thickness and its surface energy exchange. The results were compared with the pack-ice zone surrounding the polynya. The polynya is covered by thin ice surrounded by thicker multi-year ice. The surface heat exchange in the polynya (-150Wm-2) was significantly larger than above Arctic pack-ice (-25Wm−2 to -50Wm−2). © 1999 Taylor and Francis Ltd.