THE INFLUENCE OF RIVER DISCHARGE ON THE THAWING OF SEA-ICE, MACKENZIERIVER DELTA - ALBEDO AND TEMPERATURE ANALYSES

Multi-temporal satellite images, field observations and field measurem ents were used to investigate the mechanisms by which sea ice melts of fshore from the Mackenzie River Delta. Satellite data recorded between April and August 1986 were corrected to a map projection and calibrat ed such that albedo and temperature values could be compared. Three st ages in the melting of sea ice were identified: flooding (overflows), insolation and melting by warm river water. The albedo values of overf lows were as much as 1/7 that of ice values while the albedo of ice de creased by 1/3 over the summer. Approximately two weeks after the over flows develop, sea surface temperatures rise as the river-discharge pe aks and becomes the dominant source of energy. By this process, ice re moval in the delta regime is initiated two months earlier than adjacen t coasts with minimal runoff. However, the net result is only a two-we ek acceleration of ice removal in the delta region.