On to recover an old friend

by Femke de Jong

August 2, morning:

Today we, the NIOZ team, get to recover the first mooring. This particular mooring is not really part of OSNAP, it was originally deployed in 2003 as part of the Long-term Ocean Circulation Observations or LOCO project. It has been here ever since, except for a day or two between recovery and redeployment every summer.

LOCO is located on the 3km isobath on the western side of the Irminger Sea, right underneath a meteorological feature called the Greenland Tip Jet. This enhanced barrier wind that extends over the ocean causes very strong cooling in this region in winter. It’s what causes the warmish, salty surface water to cool, increase in density, and mix with the waters below. With LOCO we have a twelve year record of that mixing and we can study how it relates to the wind forcing and general changes in the Irminger Basin. As I’m writing this we’re steaming to LOCO to recover the thirteenth year. We’re hoping this will be our lucky number. Roald and Yvo have prepared everything on deck and in the last couple of days I’ve tested all my processing scripts. We’re all ready to go.

August 4, update:

We arrived at the LOCO position at 16:00 and started the mooring recovery. Because of the long stretch of empty cable (2400 m for the profiler) it’s quite a boring recovery. Mostly some instruments to get out at the beginning and end. All was on deck around 19:30. 

Roald and I have installed ourselves in the NIOZ container that was put on board before leg 1. We spend most of the rest of the day there reading out and re-programming the instruments. All of the instruments were still recording, so none of them ran out of batteries. That’s very comforting for us as this time they will go out for two years rather than one and it gives us some confidence that the estimates of how long they will run are correct. We stopped servicing at midnight to get some well-deserved rest.

Back to programming after breakfast. All the instruments had fresh batteries and programming around 10:30 so we started the mooring deployment. The anchor was dropped around 13:30. The final act consisted of a trilateration of the mooring position by ranging the distance to the anchor releases from several points around the mooring, which gives us the exact position of where we’ll find our friend in 2018. In the meantime we’ll let the instruments record some interesting things.




Photos by Femke de Jong

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