Since 1998 researchers have been monitoring the volume, heat, and freshwater fluxes that pass through Lancaster Sound. The aim is to quantify the transports and realize their impact on the heat and freshwater budgets of the Arctic Ocean as well as their impact on the circulation and vertical ventilation of the North Atlantic and to the global meridional overturning. Time series of salinity, temperature, and velocity and the derived estimates of the volume, freshwater, and heat fluxes passing through Lancaster Sound show large seasonal and inter-annual variability.
Data Collection
Yearlong measurements of current speed and direction, temperature, and salinity from a region only 700 km from the North magnetic pole have been made for a decade (1998 to present). The strategy employed to make the required measurements has combined several different commercially and in-house-designed-and-built devices. Additional data of ice draft/drift and fluorescence has been collected for several years.
Instruments
An Acoustic Doppler Current Profiler (ADCP) manufactured by R. D. Instruments is used to give current speeds over an 80 m depth interval.
Since the current profiler compass is inadequate at this location, a
high precision heading reference system (Watson Compass) manufactured by Watson Industries, Inc. is used to measure the orientation of the ADCP relative to the magnetic pole.
The ADCP and SHR-360 Watson compass are housed in a SUBS A2 buoyancy module manufactured by Open Seas Instrumentation, Inc. The SUBS unit not only provides a stable platform for optimal ADCP data quality, but also maintains a constant alignment to the flow.
CTD's were attached to the moorings to give conductivity and temperature profiles.
In 2002, the subsurface, moored, continuous profiler, known as the Icycler, was moored to obtain high-frequency temperature and salinity CTD profiles beneath the ice.
Work area for Barrow Strait studies: X's show southern and northern mooring sites and red lines show the CTD transects.
Since 1998, SUBs were moored at different depths so that the shallow package would give currents in the top 80 m, while the deeper package would give currents over the 80 to 160 m levels. Some depth overlap between the two data sets allows for validation of the currents over the total water column.
SUBS unit with compass
The Icycler is an energy efficient profiler designed for yearlong deployment to collect daily oceanic surface layer parameters (0 m to 50 m) in a mobile pack ice environment. Its main design function was to monitor the freshwater content of the surface Arctic water that cannot be monitored by conventional CTD units because of the keel-ice hazard.
The ADCP backscatter intensity is being used to infer a zooplankton population indext to study the seasonal and interannual zooplankton population variability. The daily fluorescence profiles of the Icycler are being used to provide a phytoplankton density index and to provide data on timing of the phytoplankton bloom, relative concentrations and depth of maximum values throughout the year.
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Hamilton, J. M. 2001. "Accurate Ocean Current Direction Measurements Near the Magnetic Poles"
Hamilton, J. M. 2004. "Accurate Ocean Current Direction Measurements from Instrumented Arctic Moorings"
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Hamilton, J., S. Prinsenberg, and L. Malloch. 2002. Moored Current Meter and CTD Observaitons from Barrow Strait 1998-1999
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Pettipas, R., J. Hamilton, and S. Prinsenberg. 2006. Moored Current Meter and CTD Observaitons from Barrow Strait 2002-2003
Prinsenberg, S. J. and J. Hamilton. 2003. "Monitoring the mass, freshwater, and heat fluxes passing through Lancaster Sound of the Canadian Arctic Archipelago"
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Prinsenberg, S. J. and E. B. Bennett. 1987 "Mixing and transports in Barrow Strait, the central part of the Northwest Passage".
van der Baaren, A. and S. J. Prinsenberg. 2002. Geostrophic Transport Estimates from the Canadian Arctic Archipelago
van der Baaren, A., B. Petrie, and S. J. Prinsenberg. 2003. Low Frequency Variability in Lancaster Sound
van der Baaren, A. and S. J. Prinsenberg. 2006. Principal Component Analysis of ADCP and Moored CTD Data in Three Parts with Variations: Lancaster Sound
