How important is terminus cliff melt?: a study of the Canada Glacier terminus, Taylor Valley, Antarctica

The glacier terminus cliffs on Canada Glacier, Taylor Valley, Antarctica represent 2% of the total ablation zone, but account for 15–20% of the overall meltwater runoff from the glacier during the 1995–1996 and 1996–1997 summers. To ascertain what drives this enhanced melt, meteorologic measurements were made on the Canada Glacier terminus cliffs during the summers of 1995–1996 and 1996–1997. The results indicate that, unlike on the glacier surface where sublimation accounted for 40% of the ablation in 1995–1996, on the terminus cliffs ablation is almost entirely due to melt. This melt is driven primarily by shortwave radiation and varies with location on the terminus cliff as a result of varying exposure. Discharge in Andersen Creek, which is fed by Canada Glacier, is correlated with extended periods of above-freezing air temperatures at the terminus cliffs. Since air temperatures in the valley vary as the dry adiabatic lapse rate and the terminus cliffs are significantly lower in altitude than the glacier surface, this implies that terminus melt is important in maintaining streamflow during cool periods, particularly the beginning and end of summer. Terminus cliff melt may, therefore, be instrumental in extending the seasonal streamflow in the dry valleys.