Estimating ocean heat transports and submarine melt rates in Sermilik Fjord, Greenland, using lowered acoustic Doppler current profiler (LADCP) velocity profiles

Abstract

Submarine melting at the ice-ocean interface is a significant term in the mass balance of marine-terminating outlet glaciers. However, obtaining direct measurements of the submarine melt rate, or the ocean heat transport towards the glacier that drives this melting, has been difficult due to the scarcity of observations, as well as the complexity of oceanic flows. Here we present a method that uses synoptic velocity and temperature profiles, but accounts for the dominant mode of velocity variability, to obtain representative heat transport estimates. We apply this method to the Sermilik Fjord-Helheim Glacier system in southeastern Greenland. Using lowered acoustic Doppler current profiler (LADCP) and hydrographic data collected in summer 2009, we find a mean heat transport towards the glacier of 29 × 109 W, implying a submarine melt rate at the glacier face of 650 m a-1. The resulting adjusted velocity profile is indicative of a multilayer residual circulation, where the meltwater mixture flows out of the fjord at the surface and at the stratification maximum.