Two-dimensional prognostic experiments for fast-flowing ice streams from the Academy of Sciences Ice Cap

Abstract

The prognostic experiments for fast-flowing ice streams on the southern side of the Academy of Sciences Ice Cap in the Komsomolets Island, Severnaya Zemlya archipelago, are implemented in this study. These experiments are based on inversions of basal friction coefficients using a two-dimensional flow-line thermo-coupled model and the Tikhonov’s regularization method. The modeled ice temperature distributions in the cross-sections were obtained using the ice surface temperature histories that were inverted previously from the borehole temperature profile derived at the summit of the Academy of Sciences Ice Cap and employing elevational gradient of ice surface temperature changes, which is equal to about 6.5 °C km-1. Input data included InSAR ice surface velocities, ice surface elevations, and ice thicknesses obtained from airborne measurements and the surface mass balance, were adopted from previous investigations for the implementation of both the forward and inverse problems. The prognostic experiments reveal that both ice mass and ice stream extents decline for the reference time-independent surface mass balance. Specifically, the grounding line retreats (a) along the B–B′ flow line from ∼40 km to ∼30 km (the distance from the summit), (b) along the C–C′ flow line from ∼43 km to ∼37 km, and (c) along the D–D′ flow line from ∼41 km to ∼32 km considering a time period of 500 years and assuming time-independent surface mass balance. Ice flow velocities in the ice streams decrease with time and this trend results in the overall decline of the outgoing ice flux. Generally, the modeled evolution is in agreement with observations of deglaciation of Severnaya Zemlya archipelago.