Advances in high resolution fiber-optic based ice shelf and sub-ice shelf ocean profiling

High spatial- and temporal-resolution temperature measurements in both ice shelves and sub-ice shelf cavities are crucial for understanding ice shelf basal melting processes and ice-ocean interactions. Since 2011, several Antarctic ice shelves have been or are being monitored using fiber-optic-based Raman backscatter distributed temperature sensing (DTS). DTS provides an essentially instantaneous, continuous, high-accuracy thermal profile based on thermally controlled photon scattering properties within a suspended glass fiber. Recent advances in temporal and spatial resolution of the instruments, and reduction in power requirements, have enabled designs for systems that provide over-winter automated monitoring. Hot-water drilling to install the systems provides relatively easy installation (albeit with significant logistical effort) and advances in slim hole coring and melting can be used to further reduce logistical effort. We present data from moorings on the Nansen Ice Shelf co-located with an AMIGOS-II® autonomous ocean and meteorological monitoring station on planned deployments as part of the joint US/UK Thwaites Glacier monitoring program in West Antarctica demonstrating the use of very low power DTS systems for ice shelf and ice shelf cavity monitoring. We compare this data with earlier work on the McMurdo Ice Shelf to demonstrate both ice-ocean interaction differences but also advances in resolution and power use. Both ice shelf cavities are dominated by high-salinity shelf water (HSSW) but both show significant seasonal variations. (AMIGOS: Automated Meteorology-Ice-Geophysics-Ocean observation System)