Daily Updates from
our Teacher at Sea
Recovery of the Moorings
| At the beginning of our trip, the University
of Washington - Polar Science
Center, deployed three moorings,
Information about the moorings can be found on the update from August 23rd.
The instruments on the mooring have been recording water temperature, salinity, and flow velocity every hour since they were first deployed. These data will help us better understand the Arctic Ocean Boundary Current,
Mooring Recovery Day morning sun.
Getting closer to the mooring.
|We arrived at the recorded location of the site of the first mooring on Sunday morning, around 6:30am. Knut Aagaard and Jim Johnson are the two scientists who have the pleasure of going out on a small aluminum boat to find the exact spot of the moorings.|
| In order to pinpoint the location
of a mooring for recovery, a GPS and hydrophone are used. When the
recovery boat is in the general area, Jim will enter software codes into
the Acoustic Command Unit (ACU) for each transponding instrument on the
mooring, like the location transponder at the top and the acoustic release
at the bottom.
When Jim sends an acoustic signal to the location device at the top of the mooring, it will send back one sound ping to the ACU that Jim will have in front of him.
Once he and Knut feel the mooring will pop up in open water (if possible) and not under an ice floe, they will "talk" to the Acoustic Release with the ACU, thereby releasing the anchor weight at the bottom.
While it is deployed, the mooring is at a fixed
point because of the anchor attached to the bottom. The ice above
is moving however, so patches will drift over the top. Once the mooring
anchor weight has been released, the glass floats on the line will then
pull it to the surface with the instruments trailing on the line behind.
The recovery boat will then retrieve the floats and line with instruments still attached, and tow everything back to the ship.
First sign of the mooring after floating
to the surface.
Pulling mooring onto the Polar Star.
| Once at the ship, it is then the job of
the deck crew at the stern, to pull the mooring aboard by crane.
| Of the three, the first mooring floated up under
an ice floe. As such, this one took a little time to retrieve.
Jim and Knut first walked out onto the ice floe to try and find it.
One technique that Knut used was to put his ear down onto the ice to try
and hear it.
Once located, he and Jim placed a pole with a trash bag flying from the top of it, on the spot where they believed the mooring to be (this resembled a flag).
Because the ice over this particular mooring was thick, the Polar Star crept closer, slowly floating through a small piece of it. The ship created a large crack causing the ice floe to separate, making room for the mooring to pop up.
"Flag" identifying location of mooring under ice.
Ron and Gail cleaning instruments.
|Once on board, Ron and I were responsible for cleaning the salt water off the equipment and disassembling everything.|
| Between all three moorings, we were two for three
getting them to pop up in open water, and one coming up under ice.
I asked Jim about this part of his job and he said he loved it. Each instrument recovery is different and like solving a puzzle.
Mooring Recovery Day morning sun.
For me, this was a wonderful experience. It gave me a completely different view of the ice by standing inches from it.
I went out with Knut and Jim to recover the third mooring, and saw a ringed seal and a walrus as well.
Again, it was beautiful!