========================= Originally posted 2010-8-26 ============================= North Pole Environmental Observatory 2007 Expendble Current Profiles NSF Grants ARC-0909408 Sensitivity of Arctic Ocean Change to Background Mixing and ARC-0856330, OPP-9910305, OPP-0352754 North Pole Environmental Observatory Dropped at NPEO 2007 CTD Station 5 Sta84N_135W XCP Drop 2 2007-04-23/2304 UTC 84deg 28.69min North 134deg 42.94min West Dropped at NPEO 2007 CTD Station 6 Sta86N_135W XCP Drop 3 2007-04-24/0307 UTC 85deg 44.53min North 134deg 08.85min West Dropped at NPEO 2007 CTD Station 8 Sta87N_135W XCP Drop 4 2007-04-28/1758 UTC 87deg 10.41min North 136deg 11.58min West Dropped at NPEO 2007 CTD Station 9 Sta89N_135W XCP Drop 5 2007-04-28/2155 UTC 88deg 35.00min North 136deg 02.40min West Dropped at NPEO 2007 CTD Station 10 Sta89N_90E XCP Drop 6 2007-04-29/0223 UTC 89deg 03.85min North 084deg 30.37min West Dropped at Switchyard 2007 LDEO CTD Station 1 XCP Drop 7 2007-05-02/2153 UTC 88deg 08.49min North 090deg 43.39min West Dropped at Switchyard 2007 LDEO CTD Station 4 XCP Drop 8 2007-05-05/2123 UTC 84deg 55.05min North 066deg 27.94min West Dropped at Switchyard 2007 LDEO CTD Station 5 XCP Drop 9 2007-05-08/2154 UTC 89deg 09.60min North 102deg 56.95min West These measurements were made with a Sippican Expendable Current Profiler following a Twin Otter landing at these positions on the Arctic sea ice, as part of the observational programs of the North Pole Environmental Observatory and Freshwater Switchyard of the Arctic Ocean. 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 profiles recorded during the same stations are included in CADIS archives for NPEO and Switchyard at CADIS ( http://aoncadis.ucar.edu/home.htm ) 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. 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