======================== Originally posted 2010-8-27 ============================= North Pole Environmental Observatory 2007 Expendable Current Profiles - International Polar Year NSF Grants ARC-0909408 Sensitivity of Arctic Ocean Change to Background Mixing and ARC-0856330, OPP-9910305, OPP-0352754 North Pole Environmental Observatory These Expendable Current Profilers were recorded during the Beaufort Gyre Exploration Project ( http://www.whoi.edu/beaufortgyre/index.html ) 2007 Cruise aboard the Canadian icebreaker Louis S. St-Laurent in August 2007 by Canada's Institute of Ocean Sciences (IOS), who also collected CTD profiles. They worked through Arctic Ocean summer weather and ice conditions. XCP Drop 2 2007-08-01/1003 UTC 70deg 48.889min North 140deg 04.460min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #016 file=d200720_016.cnv XCP Drop 3 2007-08-04/0032 UTC 71deg 24.540min North 152deg 02.659min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #025 file=d200720_025.cnv XCP Drop 4 2007-08-04/0558 UTC 71deg 33.071min North 151deg 28.900min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #027 file=d200720_027.cnv XCP Drop 5 2007-08-04/1609 UTC 72deg 00.089min North 150deg 21.725min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #031 file=d200720_031.cnv XCP Drop 6 2007-08-05/1302 UTC 73deg 59.504min North 150deg 01.911min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #036 file=d200720_036.cnv XCP Drop 7 2007-08-07/1739 UTC 75deg 39.970min North 156deg 17.859min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #042 file=d200720_042.cnv XCP Drop 8 2007-08-13/1513 UTC 78deg 01.313min North 149deg 12.067min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #063 file=d200720_063.cnv XCP Drop 9 2007-08-16/1505 UTC 78deg 55.841min North 139deg 58.603min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #073 file=d200720_073.cnv XCP Drop 10 2007-08-20/0915 UTC 75deg 45.978min North 129deg 51.981min West Closest CTD Cast was Louis S. St-Laurent 2007-20 #084 file=d200720_084.cnv These measurements were made with a Sippican Expendable Current Profiler either from the ship or an inflatable boat nearby, as part of the Beaufort Gyre Exploration Project 2007 cruise. A brief description of XCPs may be found at http://www.sippican.com/contentmgr/showdetails.php/id/312 . XCP Drop 1 failed to record. CTD stations recorded nearest in space and time to these XCP drops are available at the BGEF website ( http://www.whoi.edu/beaufortgyre/data_hydro.html ), and are a source of buoyancy data for further XCP analysis. The XCP measures velocity by sensing the voltage generated by the movement of conductive seawater through the earth's magnetic field. The voltage difference is measured between two electrodes on the surface of the XCP, which rotates about once every meter of fall. We use a MATLAB program written by John Dunlap of the UW Applied Physics Lab to process the raw data. This program is available at http://ohm.apl.washington.edu/~dunlap/xcpdsp/ In processing, the components of a harmonic fit to the oscillating potential that are in phase and in quadrature with the oscillating output of a flux gate compass are taken as the magnetic north and magnetic east components of velocity. In order to maximize the potential vertical resolution of the resulting profiles, we chose to do the fits over 2-m, half overlapping "chunks". This gives a vertical wavenumber cutoff of 0.5 cycle m-1 that for the Arctic data is well into the noise floor of the instrument. Users may then filter these basic data in ways appropriate to their applications. We would like to express our gratitude to- Andrey Proshutinsky, Sarah Zimmermann, Tim Kane, and Luc Rainville of the 2007 Beaufort Gyre Exploration Project cruise for dropping the XCPs in the Beaufort Sea. Further analysis using these data may be viewed at (http://psc.apl.washington.edu/northpole/Mixing.html). For further information, please contact Dr. James Morison morison@apl.washington.edu (206) 543-1394 Roger Andersen roger@apl.washington.edu (206) 543-1258 at Polar Science Center, Applied Physics Lab, University of Washington 1013 NE 40th, Seattle, WA 98105-6698 USA FAX (206) 616-3142