======================== Originally posted 2011-8-30 ============================= North Pole Environmental Observatory 2011 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 NPEO 2011 XCP Drops Dropped at NPEO 2011 CTD Station 1 Barneo XCP Drop 1 2011-04-15/1928 UTC 89deg 27.1min North 134deg 40.7min East XCP Drop 10 2011-04-20/1100 UTC 89deg 31.0min North 133deg 40.0min East XCP Drop 11 2011-04-20/2215 UTC 89deg 31.4min North 133deg 34.2min East Dropped at NPEO 2011 CTD Station 2 NP86N_90E XCP Drop 2 2011-04-17/1400 UTC 86deg 04.0min North 089deg 36.4min East Dropped at NPEO 2011 CTD Station 4 NP87N_90E XCP Drop 3 2011-04-18/1412 UTC 86deg 59.1min North 090deg 29.7min East Dropped at NPEO 2011 CTD Station 5 NP89N_90E XCP Drop 4 2011-04-18/1838 UTC 88deg 56.8min North 089deg 34.7min East Dropped at NPEO 2011 CTD Station 6 NP87N_180 XCP Drop 5 2011-04-19/1318 UTC 87deg 02.0min North 179deg 52.8min East Dropped at NPEO 2011 CTD Station 8 NP85N_170W XCP Drop 6 2011-04-20/1647 UTC 85deg 06.8min North 170deg 43.2min West Dropped at NPEO 2011 CTD Station 9 NP86N_175W XCP Drop 7 2011-04-20/2041 UTC 86deg 03.3min North 173deg 56.7min West Dropped at NPEO 2011 CTD Station 10 NP88N_180 XCP Drop 8 2011-04-21/1550 UTC 88deg 14.1min North 173deg 51.7min 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 program of the North Pole Environmental Observatory. A brief description of XCPs may be found at http://www.sippican.com/contentmgr/showdetails.php/id/312 . NPEO 2011 XCP Drop 9 failed to record. CTD profiles recorded during the same stations are included in the Dataset - North Pole Environmental Observatory Aerial CTD Survey 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