Sorry for the delay in blog posts. Ever since we started heading for the Bight Fracture Zone, I’ve been busy with the onboard work, and it’s been quasi rough. That is all behind us now, as we are safely tied up to the dock in Reykjavik, Iceland. Cruise kn221-02 is officially over, and my colleagues and I are heading out for a celebratory drink at The Dubliner (weird name for a pub in Iceland). The ship’s engines are turned off, and the incessant vibration and noise they caused has mercifully ceased. I’m hoping for a good night’s sleep tonight.

Our survey of the Bight Fracture Zone revealed a deep current of high-salinity water escaping from the eastern North Atlantic through this crack in the mid-Atlantic ridge. This flow had mainly been in our imaginations until now — based on an assemblage of circumstantial evidence. Read More→

Well, it finally happened. The unusually fine weather we had for nearly three weeks came to an end last night as a moderately strong low pressure system swept by us. The winds picked up, as did the seas, and the shampoo bottle — my highly sophisticated barometer -tumbled over as the Knorr pitched and rolled about. I had previously been marveling at its stability for so many days, but this is the North Atlantic after all, and this cruise would not have been complete without some kind of stormy weather.  All in all it wasn’t too bad — the highest wind speed I saw was about 38 knots (similar to miles per hour) and the seas were maybe 10-15 feet. I took some Dramamine last night before going to bed in anticipation of the coming storm–I’m not sure which makes me feel worse, the ship’s motion or the medication! As the seas rose, I had a hard time sleeping, but overall didn’t feel too badly.

Fortunately for all the scientists on board, today was mostly a day off from the normal CTD routine as we have been steaming toward our final study site, the Bight Fracture Zone.This is the one time in this cruise where we might discover something new right away, without having to wait to recover our moorings or for floats to surface in two year’s time. Read More→

Not the greatest day today. I had been hoping to deploy another of my sound source moorings, but at the last minute it didn’t work out. Since we added this side trip toward Greenland, I had an opportunity to re-position a sound source mooring that was actually scheduled to be set during the next OSNAP cruise leg. The new position would have meant that it was easier to track the RAFOS floats over the next few years. I didn’t think I would have the opportunity to put a sound source at the better location when we planned the cruise tracks six months ago. But due to the unexpected deviation of our cruise to recover the Dutch mooring, I thought, “Ah Ha! A golden opportunity to improve our ability to track the floats .”

So I spent a good part of yesterday thinking and re-thinking this re-positioning and deciding on the best new position that would not take us too far out of our way. I really agonized over this potential change in plans. On the one hand, our original sound source mooring posisions were well thought out and I think we had a good plan given the constraints of where the vessel would actually be going. Now I was considering altering some of that plan, which had been in place for many months. Should I change it? Should I not change it? Read More→

Laura de Steur, Maurits Kooreman (both from NIOZ), and Mark Graham (UMiami) enjoy a chilly summer picnic on the fantail.

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.

Amy, John Beaton (SAMS) and Heather Furey (WHOI) enjoy a fine summer’s picnic. Cans of soda pop and bags of chips are a novelty on board, brought out for special occasions.

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. Read More→

We’ve just started the busiest portion of this cruise for the RAFOS float program. Today we have released the first 2 of the 10 deep floats that will sink to near the sea floor and drift with the currents there for the next two years. It is very tricky to find the best positions for the float releases because the sea floor is very rough here along the flank of the mid-Atlantic ridge. We don’t want to perch a float on top of some underwater mountain, where it might stay stuck for days or longer. It’s rather tense, and not made any easier by the fact that I have to rely on others to read off information from the various displays (Latitude, longitude, water depth, etc). My associate Heather is usually waiting at the ready on the back deck, waiting for the signal to release the float. I need to make the final decision and call up to the bridge to let them know it’s time to slow down so we can release a float. It’s past midnight now and I’ve been up since 9 AM. It will probably be a few more hours before I can catch a short nap. We will be releasing more floats tomorrow, every few hours. Back online when we are done or when I have a spare minute to write.

On Saturday, we reached the eastern-most point of this expedition, just a few 10s of miles off the western coast of Scotland. We could almost hear the bagpipes ! Our Scottish colleagues, led by OSNAP principal investigator Stuart Cunningham,  deployed the last of the moorings–a trawl-resistant frame with an acoustic Doppler current profiler, or ADCP, inside. This frame is like a protected cave for the ADCP. the top face has sloping sides so that when a fishing trawl runs into it, the trawl should just roll up and over the frame. The instrument stays in place and the fishers get their nets back intact. Everyone is happy. The ADCP meanwhile sends acoustic pings upward every three minutes, and from the Doppler (frequency) shift of the return echos, the speed and direction of the currents at all depths from the sea bottom (at 400 meters) up to the sea surface can be determined.  The data are stored inside the instrument for a year, after which Stuart and his team will retrieve it and replace it with a new instrument that will monitor the currents for the second year.

This talk about data storage reminds me that what we are doing on this cruise is making an investment for a better understanding of the long-term climate of our one and only planet, Earth. Read More→

Before the instruments are put on the moorings and deployed, their accuracy is checked by deploying them (attached to red straps) at the same time as the CTD and rosette. This gives three different measurements of the same water, and enables mooring instrument calibration. The water collected in the Niskin bottles attached to the rosette are the ‘gold standard’, to which all other instruments are corrected.

We are slowly getting closer to the Scottish coast, the eastern end of our “line”. We have just 2 or 3 more moorings to deploy before we turn back west and re-trace our steps, or maybe more accurately, our wake. The air and water temperatures are warmer here – almost 60F! A heat wave! It will be sort of sad when we turn around and head back toward the colder waters to the west. As we move westward, we will be lowering the CTD package down to the sea floor at about 60 locations between Scotland and Greenland. With this instrument, which is sort of a “package” of several sensors, we will measure the temperature, salinity and other water properties from sea surface to sea bottom. We use the water properties to help us understand better where the water is coming from and (perhaps) how climate changes are affecting the ocean.

Fly by of Nick Hancock on Rockall (Hasselwood Rock), located on Rockall Plateau, 200 miles from land. He sleeps in the small yellow pod tied to the rock near the top; food stores are in the blue containers above that. He has just broken the record of longest solo stay on the rock, and 42 days.

Early this morning, we had our “fly by” of Nick Hancock, the fellow who has set up camp on Rockall, a rock that sticks up by itself about 200 miles from the Scottish coast. He is trying to set a new record for the longest stay on this rock (yes, as amazing as it sounds, others have done it too!) to raise money for war veterans in the UK.  Read More→

I took the weekend off from blogging, but that doesn’t mean that science stopped on Saturday or Sunday. Our work continues almost 24 hours a day, 7 days a week. Research vessels like the R/V Knorr are so expensive to operate that once we are at our work site, we need to keep moving along constantly. To accomplish this, we work in shifts. Most of the ship’s crew work for 4 hours, and then get 8 hours off, then work 4 hours again, etc. The scientists keep a different schedule–each shift spends 8 hours working and then has 16 hours off. That means someone is always sleeping, so it’s “library quiet” down below around the cabins.

So where are we anyway? Read More→