Jonathan Tinker Met Office Hadley Centre
Image credit: Elizabeth Comer University of Southampton, National Oceanography Centre.
I’m fairly new to research cruises, so thought I might write a blog entry to give a fresh perspective.
So it’s now day two on the Cruise, or Julian Day 160, as I’m starting to get used to referring to it as. We sailed out of Glasgow yesterday, with lovely conditions, having seen porpoises, seals, a submarine and several whales. Yesterday was mainly about getting into the swing of the cruise, safety drills, starting to get everything ready for research once we get on site.
We had our first practice instrument deployment (the “shake-down”) this morning (red circle on the map). We had planned to do this at the continental shelf break, north of Ireland, where the water first drops to 500m. However, this would have been in the middle of the night so we planned our practice run for after breakfast, in about 2000m of water. This involved lowering a rig, with a number of instruments and 24 water bottles (“rosette sampler”) to take water samples. The instruments measure a number of things, including the temperature and salinity of the water (via the CTD), chlorophyll, oxygen concentration etc. It’s interesting lowering expensive equipment off the side of the ship! The rig was winched off the deck by the crane, and then lowered over the side to 500 m. On the way back up, the water bottles were closed (“fired”) at 9 different depths to take water samples, with many replicates.
Once on deck, the rosette sampler was flooded by scientists, learning what we’re going to have to do over the next 71 CTD casts (the black dots on the map). There was strict order to who sampled the water bottles, to minimise contamination. The first samples were used to measure oxygen, followed by dissolved (inorganic) carbon. This was followed by water samples for salinity, density, nutrients (Nitrate, Phosphate, Silicate), and finally trace metals. This took us about an hour to learn all the very careful techniques, and all the logs we had to fill in – when we do it for real, we’ll have to be much faster. After this, the hydrophone was lowered to listen for marine mammals (a sperm whale was heard in the distance) and to study marine noise.
We are now steaming for Iceland where we will begin our transect line, and all the CTD casts (and well as the “epibenthic sled” – more on this later!). We have crossed the Rockall Trough and the Anton Dohrn Seamount – this seamount may cause more mixing which is a good environment for creatures. Perhaps this is what attracted the beaked whales we saw. I was surprised how blue the water is here.
However… we have to make a detour to pick up a poorly ocean glider, with a failing battery pack (the red star on the map). Ocean gliders are marine robots. This one had glided from Scotland all the way to Iceland and back, until one of the battery packs had failed. We have been in contact with it and hope to pick it up tomorrow – stay tuned…