Meeting Documents

Understanding Iceberg Melt Rates at Local to Regional Scales: Insights from Observational data and Modeled Ocean Forcings

Abstract

50% of the Greenland Ice Sheet’s mass loss is through ice discharged as icebergs, which are a crucial source of freshwater to fjords. The melting of icebergs impacts fjord circulation, nutrient concentrations, and marine productivity. However, there are few estimates of how quickly icebergs are converted to liquid freshwater within fjords. In this study, we examine variations in iceberg melt rates from 25 fjords around Greenland from 2011 through 2022 using an elevation-differencing approach. We compare our melt rate estimates to modeled hydrography from the Estimating the Circulation and Climate of the Ocean (ECCO) LLC 270 solution, downscaled to 500-m resolution, in order to assess how heat transport into fjords influences iceberg melt rates. We find that regardless of geographical location, melt rates generally increase with iceberg draft >100 m. While there are no clear temporal trends in melt rate, there are regional differences: northeast had the lowest melt rate (<0.4 m/day), followed by moderate melt rates in the central east and central west (0.4-0.7 m/day). Regardless of the season, the highest average melt rate is in southeast Greenland, where ocean currents tend to be the strongest, suggesting strong iceberg melt dependence on ocean current behavior. There are exceptions to these regional patterns, however, such as the high (~1 m/day) melt rates observed near Nordenskiöld glacier in the northwest that suggest local modifications to water conditions such as temperature, salinity and wave effects can increase melt rates. The regional variations in melt rates appear to follow the temperature patterns averaged over the draft of the iceberg suggesting that we can utilize ocean data to reproduce large-scale variations in iceberg melting.