During my time on the ship thus far, I have talked to various members of the science party who are physical oceanographers. I am particularly interested in the interactions between biogeochemistry and the physics of the region, so talking to physical oceanographers aboard about this region is very exciting to me. Many of them are involved with the Overturning in the Subpolar North Atlantic Program (OSNAP). This program manages an array of 50 moorings that spreads across the North Atlantic Ocean, broken up into two lines. The western line runs from Labrador to Greenland and the eastern line runs from Greenland to Scotland. The program includes seven countries, each of which manage a portion of the array, and the program aims to understand all aspects of North-South water movement in this region. The array lies at 60°N, allowing scientists to measure the exchange of water across this boundary. The moorings include instruments to measure temperature, salinity, and currents.
In addition to the moorings we will be deploying for OOI, some of the OSNAP team is onboard the Armstrong in order to deploy four moorings for their program. They will be taking over responsibility for a set of 4 moorings from their collaborators in the UK. The UK team is also at sea right now, and will remove their moorings soon before, or after, we deploy ours. Amy Bower, who is also blogging about her experience on this cruise, is the Principal Investigator who will be in charge of these moorings. One advantage of the quick turnaround between the UK team and Amy is that there will be either a small, or nonexistent, gap in the data collected by the array.
|An OSNAP buoy aboard the Armstrong that will be deployed later in the cruise.|
OSNAP was loosely based on another program called RAPID, which also monitors the exchange of north-south waters in the Atlantic, at 26°N. Having both of these arrays allows scientists to compare the exchange of waters across both 60°N and 26°N, seeing how water transport varies based on location. Both of these programs aim to redefine the model of ocean currents. The basic idea is that warm, light water moves north, and dense, cold water moves south beneath that water. This system is often simplified to a conveyor belt model of water movement. However, ocean systems are much more complex, and are influenced by everything from wind, to diffusion, to heat exchange. OSNAP will allow oceanographers to better understand these complexities.