A RIVER-COASTAL SEA-ICE INTERACTION-MODEL - MACKENZIE-RIVER DELTA

It has been observed that arctic coastal regions which receive river d ischarge show significant ice regression in advance of other coastal a reas without this source of sensible heat. This phenomena has been par ticularly apparent on satellite imagery. The work reported here attemp ts (1) to quantify and assess the influence of springtime river discha rge on the removal of nearshore ice and (2) to demonstrate the utility of satellite imagery as a source of, data to ''drive'' a model assess ing the influence of springtime river discharge on the removal of near shore ice. Central to this work is a sequence of advanced very high re solution radiometer images of the Mackenzie Delta region, Northwest Te rritories, Canada. These images constitute a database establishing the temporal sequence of observable breakup events from which a thermodyn amic model for the ice decay can bi: parameterized. The emphases of th is model is the influence of the riverine sensible heat on the melting of sea ice and the ability of satellite imagery to monitor this proce ss. For simplicity, climatological values rather than meteorological v alues for atmospheric and solar influences have been used. The results suggest that the river discharge supplies a significant amount of sen sible heat to the base of the nearshore ice, accounting for nearly hal f of the energy required to melt the ice cover. As a result the coasta l ice is removed 7-14 days in advance of areas without significant riv er discharge.