Synoptic controls on the energy budget regime of an ablating fast ice surface

Energy budget studies over fast ice were carried out near Broughton Island N.W.T. from June 13 to July 20, 1972. Turbulent flux calculations have been performed via an aerodynamic profile approach. Two clearly differentiated energy budget regimes can be related to the stage of decay of the fast ice. The division between the two regimes occurs at the beginning of July. Cluster analysis has been used to group together days with similar turbulent flux characteristics within each of these two regimes. In each set one group of days was found that tends to advance, and another that tends to retard, the snow or ice ablation. These groupings are found to be statistically significant. The groups in each regime can also be differentiated in terms of pressure patterns, direction of airflow and average temperature.