UACE2017 Proceedings: The UNDER-ICE experiment – Overview and preliminary results

• Session:
  Acoustics in polar environments
• Paper:
  The UNDER-ICE experiment – Overview and preliminary results
• Author(s):
  Espen Storheim, Hanne Sagen, Peter F. Worcester, Matthew A. Dzieciuch
• Abstract:
  Fram Strait is the main deep passage through which the major ocean mass and heat exchange between the Atlantic and Arctic Ocean takes place. To understand the on going climate change it is important to estimate the transports through the strait. The ultimate approach is to combine data from satellites, acoustic systems, moorings, and high-resolution ice-ocean models through data assimilation. An acoustic system for acoustic thermometry was developed under the ACOBAR project. Results from this experiment showed that it was important to monitor the heat content in the north going current and the south going current separately. Furthermore, the acoustic propagation conditions in this region make it difficult to separate the arrivals in time domain.\nIn September 2014 a continuation and extension of the acoustic system was implemented within the UNDER-ICE project funded by the Research council of Norway. The acoustic system was designed to provide accurately measured travel times along 7 sections in the deep part of the Fram Strait every three hours for two years. In this upgraded system the goal was to separate the north going current with warm water, from the south going current with cold water. To improve resolution of arrivals the receiver arrays were extended with additional receivers. To support the oceanographic interpretation of the acoustic results the moorings were augmented with a significant number of oceanographic instruments, e.g. thermistors and Acoustic Doppler Current Profilers. This system was recovered in July 2016. \nIn this paper, preliminary results are shown from the processing and analysis of the acoustic data, oceanographic measurements, and comparison between acoustic observations and modeling results. A technical assessment of the experiment will also be given. \n
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Contact details

• Contact person:
  Dr Espen Storheim
• e-mail:
  
• Affiliation:
  Nansen Environmental and Remote Sensing Center
• Country:
  Norway