Spatial and temporal distributions of accumulation rates on the catchment of Thwaites Glacier, West Antarctica

We make a first-order calculation of accumulation rates in the catchment of Thwaites Glacier (TG), West Antarctica using the Nye and Daansgard-Johnson methodologies. Both formulations compute accumulations as a function of the age-depth relationship, including a thinning correction due to ice flow. For this purpose, I track and firn-correct two continuous, shallow ice layers obtained from radio echo soundings surveyed during the 2004-05 AGASEA expedition. The layers range from 60 to 700 meters depth between the ice divide and the coast. Dating of layers come from the ice core WDC06A, located on the West Antarctic Ice Sheet (WAIS) ice divide, which have ages 548 and 725 years, respectively. We compare our accumulation results with four independent datasets: 1)IceBridge snow radar (2009-2010), optimized for tracking near-surface layers; 2) a contemporary model of snowfall precipitation, 3) an interpolation of ice core data using satellite passive microwave; 4) ice cores data. We test the hypothesis that accumulation rates have increased since the beginning of the industrial era, a change that has not been observed. Indeed, I find that observations indicate that accumulation rates in the TG catchment have not changed during the past ~700 years. From here I assess the mass balance of the system and analyze what it tells about the history of the glacier.