HR: 1340h
AN: OS43B-0564    [Abstracts]
TI: An Ice-Tethered Profiler: Initial results and role in a future Arctic network of Ice-Based Observatories
AU: * Toole, J M
EM: jtoole@whoi.edu
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AU: Doherty, K W
EM: kdoherty@whoi.edu
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AU: Doherty, K W
EM: kdoherty@whoi.edu
AF: McLane Research Laboratories, Inc., 121 Bernard Saint Jean Drive, East Falmouth, MA 02536 United States
AU: Frye, D E
EM: dfrye@whoi.edu
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AU: Hammar, T R
EM: thammar@whoi.edu
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AU: Kemp, J N
EM: jkemp@whoi.edu
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AU: Krishfield, R A
EM: rkrishfield@whoi.edu
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AU: Packard, G E
EM: gpackard@mclanelabs.com
AF: McLane Research Laboratories, Inc., 121 Bernard Saint Jean Drive, East Falmouth, MA 02536 United States
AU: Peters, D B
EM: dpeters@whoi.edu
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AU: Proshutinsky, A
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AU: von der Heydt, K
AF: Woods Hole Oceanographic Institution, 38 Water Street, Woods Hole, MA 02543 United States
AB: On August 19, 2004 a prototype Ice-Tethered Profiler (ITP) was deployed from a 4-m-thick ice floe near 77 N, 141 W within the Canada Basin of the Arctic Ocean. The ITP was conceived as a polar complement to the international ARGO program of drifting floats that is returning temperature and salinity profile data from the temperate oceans. Having physical dimensions similar to a profiling float, the ITP, deployed on a weighted, plastic-jacketed wire rope suspended below an ice floe, uses a traction drive system to move up and down the wire on a pre-programmed sampling schedule. At the completion of each one-way profile, raw 1-Hz Conductivity - Temperature - Depth (CTD) data and engineering information are telemetered in turn from the underwater profiling module to the surface unit via the wire tether using an inductive modem, and from the surface unit to a shoreside data server with over an Iridium satellite telephone link. Status messages from the surface controller (including position information) are also telemetered on an independent schedule. The first ITP was programmed with an accelerated sampling plan of 6 one-way profiles per day between 10 and 750 m depth. Profiling speeds of 26-28 cm/s are being routinely achieved with profile-averaged motor current from the 10.8 V battery supply ranging between 100 and 250 mA. Larger motor currents are observed at times of fast ice floe motion (approaching 25 cm/s on occasion) when we presume that drag on the Profiler and wire are increased. These figures are consistent with our instrument design goal of a three-year lifetime with average sampling rate of 1-2 profiles per day. The CTD profile data so far obtained document interesting spatial variations in the major water masses of the Beaufort Gyre including the low-salinity surface mixed layer, the complex forming the Pacific Halocline Waters characterized by multiple temperature extrema between 40 and 180 m depth indicative of the Alaska Coastal Water, the Summer and Winter Bering Strait Waters and winter shelf waters emanating from Barrow and possibly Herald Canyons, and the temperature maximum around 350 m depth characterizing the Atlantic Water. Additionally, the 1 Hz CTD data resolve well the thermohaline staircase stratification above the Atlantic Layer thought to be caused by double diffusion and the "nested" intrusive structures that incise the Atlantic Water. In addition to results from this prototype instrument, a concept for future deployments of ITP's within a network of Ice-Based Observatories will also be presented.
UR: http://www.whoi.edu/itp/
DE: 4227 Diurnal, seasonal, and annual cycles
DE: 4294 Instruments and techniques
DE: 4524 Fine structure and microstructure
DE: 4540 Ice mechanics and air/sea/ice exchange processes
SC: Ocean Sciences [OS]
MN: 2004 AGU Fall Meeting