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Field Notes 2005

Heading northwest from Alert, the team hopes to find cracks with thin ice across the shelf break. This year there is open water everywhere ...

and, yes, that is fog in the distance. Together with a persistent, stiff south wind which makes watching the fuel supply carefully to make sure the helo can get home to Alert, flying conditions are challenging. Out of seven days available, only three are clear enough to allow the Bell 206 to reach the study area. But that proves to be just enough to complete the Switchyard oceanographic transect.

Sea ice forms complex and fascinating patterns.

They fly to the station position and seek easy access through the ice within a nautical mile. It is tricky to work along the edge of a wide lead. More than a few inches is too thick to chip through with the ice chisels. Perfect is a one-foot wide open water crack just adjacent to a flat spot for the helicopter.

Too smashed up

This will work.

Right about ... there.

The thin ice is thick enough to stand on and we can dig a platform on the edge of the thick ice for the winch.

Chiseling the hole, ...

using a kitchen strainer to clean out the chips and slush.

Setting up the winch for the CTD cast.

Connect the CTD to the locking carabiner, turn it on, make sure the winch has power, set the instrument in the hole without using the cable while avoiding slush in the intake, and run the winch out un-powered.

Coming up level-winding the winch drum by hand.

The insulated duffel bag keeps the instrument warm when it comes out of the hole wet.

Sometimes it is not so easy to land the helicopter next to the thin spot.

Wendy prepares to hang the ADCP just below the bottom of the ice.

Ensuring the yoke still hangs plumb.

Don't forget to remove the yellow protective cover from the transducer faces.

ADCPs are pricey, so anchor the other end of the rope to the helicopter skid.

Acoustic Doppler Current Profilers use sound beams reflected off tiny critters and other detritus in the water to profile the currents down to about 100 meters.

Ten minutes provides an adequate sample.

An ice chisel across a small hole is a convenient way to suspend the ADCP at a known depth.

Preparing the radio receiver and sound recorder for an Expendable Current Profiler drop.

The new sound recorder stores the data digitally on Compact Flash cards, a huge improvement over tape, especially in the cold.

Polar Science Center
Applied Physics Laboratory
1013 NE 40th Street
Seattle, WA 98105

University of Washington

This material is based upon work supported by the National Science Foundation under Grant No. 0230427.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the
National Science Foundation.

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