THE ICE-FREE TOPOGRAPHY OF SVALBARD.

We present an ice-free topography of the Svalbard archipelago based on a two-step massconserving approach for mapping glacier ice thickness. For this reconstruction, almost 73,000 individual thickness measurements were assimilated. The considered surveys covered a total length of ~7,600 km. The approach is further informed by surface mass balance from a regional climate model and several products inferred by satellite remote sensing: a recent digital elevation model, surface elevation changes and glacier surface velocities. For Svalbard, we infer a total ice volume of 6,573 km3 . Aggregation of the values of an associated error-estimate map provides upper and lower ice-volume bounds of 5,274 and 8,555 km3. These bounds are partly exhausted by the last two estimates from volume-area scaling, which reported 5,350 and 9,089 km3 . Thickness values from a recent distributed reconstruction sum up to an elevated ice volume of 8,123 km3 (Huss and Farinotti, 2012). Part of this difference is explained by, on average, 50 % higher ice-cliffs of the marine terminating glaciers on Svalbard. [ABSTRACT FROM AUTHOR]