Late last night, we finished our second transect along our part of the OSNAP line. At the cruise outset, we transited from west to east (from off the coast of Greenland to Scotland) laying down about 20 deep-sea moorings. Then we turned right around and re-traced our steps, this time using the CTD package to measure the water properties along the same line. As we expected, this has taken us back to the colder side of the North Atlantic. Not to be deterred by the cooler weather, we had an outdoor supper on the fantail. “A beautiful summer day!” according to our Scottish colleagues.
We completed 65 profiles of temperature, salinity, dissolved oxygen and transmissivity. Transmi-what? There is one sensor on the CTD package that measures how cloudy the water is. The water may look clear to the human eye, but infact there are many microscopic particles in every cup, including living and dead plankton, fecal matter from the organisms above and sediments swept up by the currents. I’m particularly interested in the latter as an identifier of the deep currents where we released the floats. Those currents have been flowing pretty rapidly along the sea floor for hundreds of miles (well, by deep ocean standards, ½ mile per hour is rapid) and that means they are capable of picking up silt and mud from the sea floor and carrying it along. In contrast, the water just above has not been in contact with the sea floor and is expected to be much more clear.
So now that the CTD profiling is done, and we have a few more days before we are due back in Reykjavik, we are off to do a favor for one of our OSNAP colleagues, Dr. Laura de Steur from the Royal Netherlands Institute for Sea Research (NIOZ). Laura and her team of students and technicians came along on this cruise to deploy the 5 moorings which they have contributed to OSNAP. Meanwhile, another OSNAP investigator from Germany, was to be recovering another NIOZ mooring from the central Irminger Basin that has been maintained at the same location for many years. The German cruise was cancelled however, due to engine problems with their ship, leaving the NIOZ mooring abandoned. As luck would have it, the mooring’s position is about 12 hours away from our last CTD profile, and we have the time to make the trip to recover it. We should be there in a couple of hours.
This is one of the aspects of this field that I love. It is not universal among all scientists in all fields, but for the most part in oceanography, there is a strong sense of cooperation and collegiality. Some projects are so large and complex, that it is really impossible to make scientific progress without working together. The demise of the German cruise (which by the way, has been rescheduled on a different ship with a different cruise track) triggered a multitude of responses from interested colleagues in the OSNAP program who wanted to offer what they could to make up for the lost ship time. I suppose we all recognize what a rare and valuable resource research ship time is, and that at any moment, one of us could find ourselves in the same situation. I myself was bailed out some years ago when a failed sound source was recovered by the same German group that had the cancelled cruise this year.