Exploring a subglacial channel beneath Kamb Ice Stream with Icefin

Abstract

Kamb Ice Stream (KIS) is one of the largest tributaries to the Ross Ice Shelf, grounded near the southermost edge of the massive ice shelf.  Stagnant for some 150 years, the rerouting of subglacial water beneath the ice stream and others in the region is likely critical to the stagnation of the ice stream, as well as present and future dynamics.  As part of the Antarctic New Zealand-led Antarctic Science Platform, our NSF- and NASA- funded team was able to participate in two field seasons accessing below KIS.  In Austral summer 2021-2022,  a hot water drilled borehole was made through the ice and into the major subglaciall channel upstream of the grounding line that carries subglacial water in to the ocean.  The access hole allowed for ice, ocean, sediment, and environemental observations inside the channel.  We deployed the Icefin ROV, which is a novel platform that provides hydrographic, imaging, and sonar exploration in situ below the ice.  Here, we report the first Icefin observations from within the channel.  We report channel geometry, ice-ocean interactions at the top and side walls of the channel, and sonar and imaging data of the sediment along a 500m mission extending upstream of the borehole.  In particular, we report bathymetric observations of the bed of the channel, which varied by 10s of me in width over the mission, and into which a small, meandering ~4m deep channel was incised into the sediments.  We discuss observations of boulder and sediment drape and suspended particulates in the water colum, and discuss implications for hydrological activity within the channel.