Dispatch 3: Let the Science Begin!     Print

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Joey Wenig

September 23,2014

Today officially marked the start of scientific data collection onboard ship. Anticipating a mid-morning arrival at the station where we would undertake our first (and second) CTD/rosette casts, we awoke to a stiff, cold, wind, and flurries of snow. Seemingly foreboding conditions until you remember you’re in the Arctic, and the fact that temperatures are hovering a couple of degrees above freezing means you’re actually getting lucky with the weather. So we threw on some layers, our inflatable suits, our gloves and our hardhats, and prepared to cast a CTD/rosette! (I wish there was a catchier name than ‘CTD/rosette’, but to the best of my knowledge there just isn’t.)

So, this CTD/rosette, as I mentioned briefly in yesterday’s dispatch, is a bundle of instruments for making underwater measurements and communicating with surface software, and Niskin bottles. There are twenty-four of these Niskin bottles, to be precise, except for certain stations where one or two of them will be swapped out to make room for additional instrumentation. They are arrayed in a ring about the CTD, forming the distinctive rosette shape. The Niskin bottles are plastic, a couple of feet in length, and are used to sample seawater at different depths. They work in the following manner: while the CTD/rosette is on the downward half of the ‘cast’, the bottles are open, with seawater constantly circulating through them. On the ascending half of the cast, however, the bottles are triggered manually to close one-by-one at predetermined depths. This gives researchers access to samples from throughout the water column. The CTD, meanwhile, records (among other things) the salinity, temperature, dissolved oxygen content, and pressure of the water it passes through on the descending portion of the cast, relaying this information in real-time to a surface control.

Once the CTD/rosette has been recovered from the frigid depths and is safely back in the shack on deck where it spends its downtime, a suite of different samples are drawn from the full Niskin bottles. These include samples for analyses of Dissolved Inorganic Carbon, Dissolved Oxygen, Nutrients, Barium, Oxygen isotope (δ¹⁸O), Alkalinity, and the list goes on. Depending on the depth, the CTD/rosette cast can take up to around four hours round-trip, but the sampling process is also quite lengthy. Lots of the samples are analyzed immediately on board, or require further attention before they can be stored. Let me put it this was: after participating in my first ever CTD/rosette station today, I’m exhausted, and my share of the responsibilities was small relative to most of the team.

My exhaustion was quickly forgotten, however, when an announcement over the ship’s intercom system was made this evening requiring the presence in the Forward Lounge of all those aboard the Louis who had never been to the Arctic before. When all of us rookies, and a good number of onlookers, were assembled, we were given our orders: we are to carry with us, at all times during the next five days, a raw egg with a face drawn on it. We need to be able to produce this egg upon request. My only hope—thanks to a smart suggestion—is to hard-boil the egg as soon as possible. Otherwise I’ll be walking around with a pocket full of yolk by noon tomorrow.

A competition was also held this evening, where newcomers to the Arctic had five minutes to don the most layers of clothing they possibly could. Congratulations to the winner, WHOI’s own Jeff O’Brien. I can honestly say I’ve never seen anyone simultaneously wear that many t-shirts.