Abstract
Abstract. Prognostic experiments for fast-flowing ice streams on the southern side of the Academy of Sciences Ice Cap on Komsomolets Island, Severnaya Zemlya archipelago, were undertaken in this study. The experiments were based on inversions of basal friction coefficients using a two-dimensional flow-line thermocoupled model and Tikhonov's regularization method. The modeled ice temperature distributions in the cross sections were obtained using ice surface temperature histories that were inverted previously from borehole temperature profiles derived at the summit of the Academy of Sciences Ice Cap and the elevational gradient of ice surface temperature changes (about 6.5 °C km−1). Input data included interferometric synthetic aperture radar (InSAR) ice surface velocities, ice surface elevations, and ice thicknesses obtained from airborne measurements, while the surface mass balance was adopted from previous investigations for the implementation of both the forward and inverse problems. The prognostic experiments revealed that both ice mass and ice stream extent declined for the reference time-independent surface mass balance. Specifically, the grounding line retreated: (a) along the B–B′ flow line from ∼ 40 to ∼ 30 km (the distance from the summit), (b) along the C–C′ flow line from ∼ 43 to ∼ 37 km, and (c) along the D–D′ flow line from ∼ 41 to ∼ 32 km, when considering a time period of 500 years and assuming a time-independent surface mass balance. Ice flow velocities in the ice streams decreased with time and this trend resulted in the overall decline of the outgoing ice flux. Generally, the modeled glacial evolution was in agreement with observations of deglaciation of the Severnaya Zemlya archipelago.
Highlights
There are many relevant diagnostic observations of glaciers available, including digital Landsat imagery and satellite interferometric synthetic aperture radar (InSAR), airborne measurements, borehole ice temperature, and ice surface mass-balance measurements
It was assumed that the ice temperature linearly increased from −15 ◦C at the surface to −5 ◦C at the ice base at the division, and it increased from −2 ◦C to −1 ◦C at the grounding line
The inverted friction coefficient distributions along the B– B and D–D flow lines had the same qualitative trends, i.e., they gradually decreased along the flow line from a higher to a lower level
Summary
There are many relevant diagnostic observations of glaciers available, including digital Landsat imagery and satellite interferometric synthetic aperture radar (InSAR), airborne measurements, borehole ice temperature, and ice surface mass-balance measurements. These observations provide data for prognostic experiments that allow the prediction of future glacier conditions for different climatic scenarios in the future. Bedrock elevations of these areas were below sea level, and the ice flow velocities attained a value of 70–140 m a−1 (Fig. 2) Such fast flow-line features are typical for outlet glaciers and ice streams in both the Arctic and the Antarctic. These ice streams are the major locations of iceberg calving from the Academy of Sciences Ice Cap (Dowdeswell et al, 2002)
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