Keynote Abstract

Acoustic Remote Sensing Instrumentation 
for the Arctic Ocean

Peter Mikhalevsky, Ocean Sciences Division, 
Science Applications International Corporation (SAIC)
peter@osg.saic.com

The large changes in the Arctic Ocean documented over the last 10 years, including increases in the temperature of the Arctic Intermediate Water (AIW), and thinning of the Arctic sea ice reveal an ocean that is much more variable than previously thought.  The need for real time synoptic monitoring of the Arctic Ocean is evident. 

Acoustic remote sensing, namely acoustic thermometry, was first demonstrated in the Arctic Ocean in 1994 revealing the basin scale warming of the AIW.  Acoustic thermometry and tomography provides an integrated measurement of temperature and currents that can be applied to a variety of observational scales.  

For basin scales acoustic thermometry integrates over mesoscale and higher wavenumber phenomena to provide large scale averages of temperature and heat content that are needed for climate oriented studies and are difficult, if not impossible, to obtain with an ensemble of point measurements, especially in the Arctic Ocean.  Measurement of transport, thermocline depth, even salinity and sea ice properties are also possible and are in various stages of development.  

Acoustic remote sensing requires an acoustic source and hydrophones.  These can be installed on “conventional” oceanographic moorings and can therefore extend the point measurements obtained at the moorings with integrated measurements between the moorings.  If the acoustic capability is designed into the moorings at the planning stages the marginal cost is comparable to other sensor packages.  Connecting such Arctic Ocean moorings back to shore is envisioned exploiting an existing sea-shore link in the Lincoln Sea and a planned link into the Beaufort Sea from Barrow, Alaska providing the real-time synoptic capability for Arctic Ocean observations.