Gayle L. Dana

Glacier mass balances (1993–2001), Taylor Valley, McMurdo Dry Valleys, Antarctica

Mass balances were measured on four glaciers in Taylor Valley, Antarctica, from 1993 to 2001. We used a piecewise linear regression, which provided an objective assessment of error, to estimate the mass balance with elevation. Missing measurements were estimated from linear regressions between points and showed a significant improvement over other methods. Unlike temperate glaciers the accumulation zone of these polar glaciers accumulates mass in summer and winter and the ablation zone loses mass in both seasons. A strong spatial trend of smaller mass-balance values with distance inland (r 2 = 0.80) reflects a climatic gradient to warmer air temperatures, faster wind speeds and less precipitation. Annual and seasonal mass-balance values range only several tens of millimeters in magnitude and no temporal trend is evident. The glaciers of Taylor Valley, and probably the entire McMurdo Dry Valleys, are in equilibrium with the current climate, and contrast with glacier trends elsewhere on the Antarctic Peninsula and in temperate latitudes.

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

Abstract 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.