At 6am local time this morning, we arrived at the location of our first station, “Test Station No. 1”. As we travel across the ocean eastward from Canada we will be stopping every few miles to complete a station, which is the term we use for our way of working. A “station” to us means holding the ship steady a selected location, and lowering a frame carrying a large collection of instruments and water-sampling bottles over the side of the ship, through the water all the way to the seafloor. The package (the “CTD”) is raised again, and when it is back on board, the station is finished and we move off to the next location.
The sensors on the CTD are recording data continually, and on the way down the winch lowers the package without stopping, to give us a nice clean record of the water properties from the surface to the sea floor. At this first station the water depth was about 3000m, but throughout the cruise the stations will vary in depth from a few tens of metres to nearly 4000m. In fact we stop the descent of the CTD at about 10m off the seafloor so we dont damage the delicate instruments by either hitting rock or getting them covered in mud. On the way up, we stop 24 times and each time “fire” a bottle – this just means that we send an electronic signal to close the top and bottom of the bottle to capture a 10 litre sample of water from that depth.
When the CTD is back on deck, we crowd around the bottles to draw off samples of the cold ocean water, and take them away to test them for a range of properties. The purpose of a test station is to giving us the chance to make sure that the instruments are working, and that the samplers are fully prepared and trained. The sampling needs to be done in a strict order and with refined techniques to prevent spoiling samples. The test station allows us to make mistakes as we learn, or to perfect our technique without fear of spoiling the data set we need for our experiment. This first test was a success – the instruments work, the novices had their first practice, and despite it being very crowded around the bottles, all went to plan. We are doing another test station this evening, and then tomorrow we will start at our first proper station.
I am happy to report that for the first time in my seagoing career, and despite my pessimistic predictions in the last post, I have actually not been at all seasick so far. This incredible and fortunate situation seems to have come about because it has been amazingly calm in the first 48 hours at sea. There is a small swell and the winds are light, so the movement on the ship is very slight. I cant believe my luck – but there is a downside…. I have not seen beyond a few tens of metres from the ship since we left St Johns and sailed into a fog bank. We have been surround by mist the entire time! I’m disappointed by the lack of a view, but that is more than made up for by the gentle start to the cruise.
Images: The CTD package, sampling the test station (crowded, but successful!), and foggy views of the ship.