By Penny Holliday
Once again we’ve been lucky enough to have fine views of Greenland. The conditions yesterday were calm but grey, with flat light that made photos quite serene, but perhaps not quite as stunning as the sunny day ones from last week. The science party are not yet tired of this beautiful scenery, and throughout the afternoon and evening little clusters of cold, pink-cheeked scientists could be found on the aft deck, the fore deck and the monkey island. The monkey island is above the bridge and has the best views I think, although it can be a bit exposed if there is a fresh breeze. I have finally realised that wearing gloves keeps my hands warm, but have yet to remember to put on an extra pair of socks, and standing on a cold metal deck really chills your toes.
There has been little wildlife seen on this trip so far; a few instances of pilot whales, one sighting of a larger whale, and very few birds. But yesterday, in the thick ice surrounding our station closest to land, we were treated to a rare sight. Some lucky folk saw a snowy owl with her prey in her talons (see the photos by Ian Brown below). Sadly I missed that but I’m not too downhearted because I was lucky enough to see seals rolling off the ice and slipping into the water as we came upon them. This view, remarkably, was from my seat at dinner – as I finished off my cheese course I could see the dark mountains, the bright ice and a brief glimpse of fat, brown seals.
You might be wondering what keeps taking us out into deep water and then back to the Greenland coast again. We are doing four sections (lines of stations) at approximately right angles to Greenland, so that they cut across the main currents. The currents flow parallel to the main shape of the coast and they follow a curved path around the southern tip of Greenland (Cape Farewell). However the currents change as they progress along the path, so we are surveying them in four different places to establish what those changes are.
Some of my previous research has shown that about one-third of the water carried by these currents actually peels away from the main current at Cape Farewell and flows into the middle of the deep ocean basin (see the cartoon below, red dots are station positions). We want to know if that observation was a quirk of the data we collected earlier, or whether it is a long standing feature of the area. We have designed an experiment that will test my idea (a “hypothesis” in the language of science), and measure how much water stays in the main current, how much leaves it at Cape Farewell, and how much joins from the Labrador Sea. This will be an important contribution to OSNAP because it will help us understand what happens at between our two main sections (OSNAP West and OSNAP East).
You will notice from the cartoon that one of the sections (the line of stations shown as red dots) is short and incomplete. This is what happens when you are at sea; something comes along and your beautifully designed survey ends up looking rather different. When Brian (the Principal Scientist) and I made the cruise plans we developed an order of priority for the various parts of it, knowing that we may need to discard the lower priority elements if there was a delay. Delays can be caused by bad weather, thick ice, a problem with an instrument, or something else. In this case, the storm that caught up with us a couple of days ago was forecast to blow hard in that spot for a while. Between Brian, myself and the captain, we decided that it was better to give up on that section and steam to a place where we could continue working. The change of plan will still allow us to complete the experiment successfully (even though the station plot looks sadly unbalanced now), and we still have enough time to complete the rest of our high priority plans.
Images: Views of ice and Greenland (photos by Penny), the snowy owl (photos by Ian Brown), and a cartoon showing the branching currents of the area and the JR302 station positions (by Penny).