Sensitivity of Totten Glacier dynamics to sliding parameterizations and ice shelf basal melt rates

Abstract. Totten Glacier in East Antarctica holds a sea level potential of 3.85 m and is mostly grounded below sea level. It has the third highest annual ice discharge, 71.4±2.6 Gt yr^-1, among East Antarctic outlet glaciers and has been losing mass over recent decades. Recent thinning of the Totten ice shelf is likely to be due to high basal melt rates driven by increasing intrusion of warm Circumpolar Deep Water. Here we simulate the evolution of the Totten Glacier subregion using a Full-Stokes model with different basal sliding parameterizations (linear Weertman, nonlinear Weertman, and regularised Coulomb) as well as sub-shelf melt rates to quantify their effect on the projections. The modelled grounding line retreat and decline in ice volume above floatation using the linear Weertman and the regularised Coulomb sliding parameterizations are very close, and both larger than that using the nonlinear Weertman sliding parameterization. The simulated grounding line retreat occurs only with maximal basal melt rate higher than 40 m yr^-1, and is mainly on the eastern and southern grounding zone of Totten Glacier. The change of sub-shelf cavity thickness is not sensitive to the choice of basal sliding parameterization, only to sub-shelf melt rates, yielding strong volume above floatation dependence on melting through the mechanism of reduced buttressing.