Abstract
Ice shelvesbuttress the fast-flowing glaciers draining ice sheets, so changes in the ice shelves may alter the buttressing effect and the discharge of grounded ice, therefore influencing sea level. Basal melting of the ice shelves would reduce their ability to restrain the discharge of grounded ice into the ocean. However, estimating the basal melt rate is challenging due to the large uncertainty in the calculation. In this study, we use a Lagrangian framework to improve the basal melt rate derivation and apply the method to the Shackleton ice shelf as a case study. We use the CryoSat-2 data to characterize the spatial distribution patterns of ice shelf surface elevation changes between 2010 and 2018. Combining these results with the ice surface velocity and output from the regional climate model, we obtain a map of the basal melt rate and calculate the total and average basal mass balance. The total basal meltwater production for the Shackleton ice shelf is 54.6 ± 7.2 Gt/yr. The highest melt rates, which exceed 50 m/yr, are found close to the grounding line and the main trunk of Denman glacier. Based on the analysis, we show that the Lagrangian method can provide more spatially coherent patterns of ice shelf surface elevation changes and reduce the uncertainty in basal melt rate calculation.
Highlights
An ice shelf is a body of ice that extends from an ice sheet and floats in the ocean
We describe the method of calculating elevation change rate, the surface mass balance Ms and firn air content Ha, the ice equivalent thickness Hi and the ice surface velocity v
Eulerian and Lagrangian Elevation Changes. Both the Eulerian and Lagrangian rates of elevation change were calculated with 8 years (July 2010 to June 2018) of CryoSat-2 Baseline-C Level 2 surface elevation measurements recorded by the SAR Interferometric Radar Altimeter (SIRAL) instrument
Summary
An ice shelf is a body of ice that extends from an ice sheet and floats in the ocean. Over the past few decades, Antarctic ice shelves have experienced rapid thinning [3,4], an outcome that can be traced to increasing basal melting This has dramatically reduced the buttressing that ice shelves exert on the inland flow and dominated the dynamic thinning of the Antarctic Ice Sheet [5]. The ice shelf basal melt rate can be derived from the residual of all other processes that contribute to changes in its elevation or thickness, and these changes can be measured with remote sensing data [20]. Lagrangian method and analyze the limitations and potential of altimetry data for ice shelf basal melt rate assessments
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