2017-2018 USAP Field Season
Estimation of Antarctic ice melt using stable isotopic analyses of seawater
Dr. Robert Dunbar
Supporting Stations: RV/IB Nathaniel B. Palmer
Current estimations of ice-sheet mass balance in Antarctica and Greenland rely directly on satellite-based observations of the ice-sheet surface, ice margins, and ice shelves. The extent of melting ice sheets as a driver of sea level rise is not yet well understood. This project will use independent tracers of freshwater introduction from the ice sheets to the surrounding ocean to improve the ability to track how fast and where continental ice is melting. Polar ice is greatly depleted in two stable isotopes, O-18 and deuterium, relative to Southern Ocean seawater and precipitation. Using these as tracers of freshwater introduction from the ice sheet, in conjunction with precise observations of seawater temperature and salinity, the inputs of freshwater derived from melting glacial ice can be discriminated from regional precipitation.
Field Season Overview
One participant will sail on the RV/IB Nathaniel B. Palmer on cruise NBP18-01 from Punta Arenas, Chile to research areas in the Amundsen Sea. At various locations, the participant will collect sea water samples using a conductivity temperature depth (CTD) rosette and will conduct near real-time isotopic and salinity analyses of those samples. For each sample taken for isotopic analyses (O-18 and deuterium), high quality salinity data must also be collected on the same sample. Analyzing samples with an Autosal, especially in highly stratified areas, will be essential for post-processing comparisons with the CTD data. To that end, the participant will use the USAP Autosal in conjunction with a Picarro cavity ring down spectroscopy (CRDS) system, and may also use a Guildline Portasal Salinometer. The cruise will make a brief port call at McMurdo Station and will terminate in Hobart, Australia.
Deploying Team Members