======================= Originally posted 2010-7-23 ============================ Aerial Hydrographic Surveys for IPY and Beyond: Tracking Change and Understanding Seasonal Variability September 2009 Expendable CTD Survey Arctic Ocean AXCTDs by USCG C-130 NSF Grants ARC-0634226, OPP-0352754 and ARC-0856330 AXCTD Position Latitude _ Longitude Drop Date _ Time AXCTD 1 72 deg 10.006 min North _ 157 deg 32.073 min West 2009-9-30/2054 UTC AXCTD 2 72 deg 44.977 min North _ 158 deg 02.081 min West 2009-9-30/2114 UTC AXCTD 3 73 deg 00.038 min North _ 158 deg 15.073 min West 2009-9-30/2128 UTC AXCTD 4 73 deg 37.761 min North _ 158 deg 48.379 min West 2009-9-30/2147 UTC AXCTD 5 74 deg 06.779 min North _ 159 deg 13.573 min West 2009-9-30/2204 UTC Probes manufactured by The Tsurumi-Seiki Co., LTD. http://www.tsk-jp.com Drop T.S.K. AXCTD serial number 1 07116859 2 07116842 3 07116841 4 07116844 5 07116858 Each profile is an ASCII file of six numerical columns with a short header- _ Depth (m) _ Pressure (dbar) _ Temperature in situ (deg C) _ Conductivity (S/m) _ Salinity (psu) _ Density (sigma-theta) Calculation of Salinity uses Conductivity of Standard Seawater C(35,15,0) = 42.914. Depth is obtained from probe fall rate, and pressure is derived from depth also as a function of latitude. The trailing wire limits the profile depths to about 1000m. AXCTD 1 struck the bottom at 69 meters, AXCTD 2 at 365 meters. The National Science Foundation's North Pole Environmental Observatory carries out Arctic Ocean CTD-chemistry stations from Twin Otter skiplane landings in the North Pole region during April. In 2008, this related project, Aerial Hydrographic Surveys for IPY and Beyond, extended that to include a survey of the Beaufort Sea, and The digital Airborne eXpendable Conductivity, Temperature, and Depth probes (AXCTD) manufactured by the Tsurumi-Seiki Co., LTD. (http://www.tsk-jp.com/tska/PDF_Files/AXCTD.pdf) were successfully used to obtain accurate hydrographic profiles beyond the range of a Twin Otter loaded with a heavy winch and other equipment needed for the surface stations. Planning for subsequent seasons, it was realized that, as long as sufficient open water could be found, these air-dropped probes could extend the sample season and geographic area, a particular goal of this project. Logistically, the burden is small enough to allow such a survey to "piggy-back" on flights over the Arctic Ocean scheduled for other purposes. The United States Coast Guard C-130s based in Kodiak, Alaska schedule Arctic Domain Awareness flights approximately twice monthly. This dataset consists of the ocean profiles obtained by AXCTDs dropped from the ADA flight over the Arctic Ocean north of Barrow, Alaska on 30 September 2009. Finding open water in September posed no difficulty, and all five AXCTD drops were successfully recorded. For further information, please contact Dr. James Morison morison@apl.washington.edu (206) 543-1394 Dr. Michael Steele mas@apl.washington.edu (206) 543-6586 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