Melt rate predictions for the Totten and Dalton ice shelves from a numerical model

The Totten Glacier drains a large proportion of the East Antarctic ice sheet, much of it marine based (grounded below sea level) and rapidly losing mass. It has been suggested that mass loss is driven by changes in oceanic forcing; however, the details of the ice-ocean interaction are unknown. Here we present results from an ice shelf-ocean model of the region that includes the Totten, Moscow University and Dalton Ice Shelves, based on the Regional Oceanic Modeling System for the period 1992-2007. Simulated net basal mass loss for the Totten and Dalton ice shelves are 44.5 Gt ice/yr and 46.6 Gt ice/yr, respectively. The melting of the ice shelves varies strongly on seasonal and interannual timescales. Mass loss from the Totten ice shelf has a mean range of variability of 28 Gt ice/yr on interannual timescales and 17 Gt ice/yr on seasonal timescales. This study links basal melt of the Totten and Dalton ice shelves to warm water intrusions across the continental shelf break and atmosphere-ocean heat exchange. Totten ice shelf melting is high when the nearby Dalton polynya interannual strength is below average, and vice versa. Melting of the Dalton ice shelf is primarily controlled by the strength of warm water intrusions across the Dalton Rise and into the ice shelf cavity. During periods of strong westwards coastal current flow, Dalton melt water flows directly into the Totten ice shelf further reducing melting. This is the first such modelling study of this region, providing a valuable framework for directing future observational and modelling efforts.