Long-term observing system for the oceanic regime of Filchner-Ronne Ice Shelf, Antarctica

 

Long term observations of the flow of dense waters from their area of formation to the abyss of the World Ocean, and the return flow of warm waters, are central to climate research. For the Weddell Sea an important component of such a system entails monitoring the formation of High Salinity Shelf Water (HSSW) on the continental shelf north of Ronne Ice Front, the transformation to Ice Shelf Water (ISW) beneath the floating Filchner-Ronne ice shelf, and the flux of ISW overflowing the shelf break to the deep Weddell Sea. Equally important is the return flow of warm water toward the Filchner-Ronne Ice Shelf system. We operate a number of monitoring stations in the southern Weddell Sea. The systems build upon techniques and methods developed over several decades and have a proven record of high data return. Here we present plans for extending, integrating and operating the existing long term observatories to increase our knowledge of the natural variability of the ocean-ice shelf system, and to allow early identification of possible changes of regional or global importance. The S2 observatory at the Filchner sill was established in 1977 and continues to deliver the longest existing marine time series from Antarctica. As a key site for monitoring the ISW overflow. The existing S2 observatory consists of sub-surface mooring carrying sensors for current velocity, temperature, salinity and dissolved oxygen measurements. Site 5 at the Ronne Ice Shelf was first established in 1999 and in 2014/15 austral summer the site was reoccupied and three instrumented moorings for long term monitoring of the circulation beneath Ronne Ice Shelf were deployed. In addition, three phase sensitive radars (ApRES) were deployed at the snow surface to monitor the melting/freezing rate at the ice shelf base. Some of the systems transmit in real-time and are designed to operate for more than 10 years. In 2015/16 we will extend the observing network by deploying observatories on Filchner Ice Shelf. The Filchner-Ronne Ice Shelf and S2 observatories will provide the first ever concurrent observations from the ice-shelf cavity where ISW is formed, and the sill where it starts its descent towards the deep Weddell Sea, and will provide a unique dataset allowing us to link processes and variability within the cavity directly to overflow properties and deep water formation.

    The Site-5 Observatory

    Use the buttons for drawings, plot, data and more information
  • Site-5 : Drawing of the instrument string
  • Speed, Direction, Temperature amd Oxygen from  4 depths
  • Poster presentation
  • Map: Site-5 and S2 positions 
  • Data: Near Real Time data download (MatLab format)