Surface elevation changes at the front of the Ross Ice Shelf: Implications for basal melting

Abstract

Rapid melting beneath the Ross Ice Shelf (RIS) occurs near the ice front, likely in response to a secondary buoyant plume with tidal mixing, and is sensitive to seasonal water temperatures in front of the ice shelf. The front of the RIS is examined using GLAS ICESat laser altimetry data. Spatial and temporal changes in surface elevations are attributed to enhanced basal melting of the ice shelf near the ice front. Melt rates (Ṁb) increase exponentially as the front is approached, from approximately zero at 40 km from the front to an average of 2.8 ± 1.0 m a-1 within the front kilometer. Melt estimates within the front 60 km are best fit by the relationship Ṁb = 2.0 × exp(-x/11900) m a-1, where x denotes distance from the front. Frontal melt totals approximately 16 km3 a-1 in the front 40 km, which accounts for between 10% and 40% of current published estimates of total melt beneath the RIS. Spatial averaging along the front reveals a different pattern of melt in regions that have recently calved as compared to regions that have not calved. Frontal melt is modeled as a one-dimensional buoyant plume with tidal currents included. These model results imply that modest increases in sea surface temperatures will lead to considerable increases in melting beneath the ice shelf front. Copyright 2011 by the American Geophysical Union.