Bi-monthly iceberg and sea-ice distributions used to estimate freshwater flux in Southeast Greenland fjords

Abstract:

Since the mid 2010s, mass loss from the Greenland Ice Sheet has added roughly 1100 km³/yr of freshwater to the surrounding ocean. Icebergs and sea-ice can therefore significantly impact seasonal freshwater fluxes around the ice sheet. However, given coarse (both spatial and temporal) resolution time-series of their distributions in Greenland fjords, it is difficult to quantify this flux or realistically include it in ocean models. We implement a new iceberg distribution and sea-ice coverage algorithm to estimate freshwater flux in 52 SE Greenland fjords, twice a month, from 2017 - 2019.

Our automatic iceberg distribution algorithm and sea-ice classification algorithm relies on Sentinel-1 SAR imagery with IW and EW swaths, at 10 m and 40 m pixel spacing. The freshwater estimates include iceberg melt arising from wave erosion, turbulent water motion, convection, wind driven melt, and solar radiation. Additional freshwater inputs include terrestrial runoff and sub-glacial discharge which are extracted from reanalysis products (RACMO and MAR). Here we report time-series of freshwater flux estimates with high spatiotemporal resolution along with individual contributors of melt, providing crucial improvements to model parameterizations.