By Walaa Thabet and Eoghan Daly |
The senior scientists are telling us the first station on the cruise will be the most difficult one. But what if, the first station is the first station you have ever done so deep? We were about to sample water from different depths in the Atlantic Ocean, therefore we used a CTD and a water sampler.
It was very interesting preparing the CTD and water sampler before entering the water. The water sampler is actually a set of 24 bottles that can be automatically closed from the winch room at a chosen depth. We started with cleaning, checking that all bottles were open and preparing a plan for the station. We had just one chance. Once in the water we saw the temperature, salinity, oxygen and chlorophyll content as a curve on the computer screen as its sank to the deep.
“The most interesting part was firing the bottles in the winch room where all the action happens. If you are going 2000m deep, it is difficult to decide at what depths to fire the bottles and why. It was one of the most exciting things that I have ever tried”, one scholar said. The CTD cast took about two hours before it came on deck again. We could feel the aprehension in the winch room, communicating clearly with the crew and chief scientist, while also deciding bottle depth and a sampling plan.
We could see different water masses on the computer such as the water that flows out of the Mediterranean Sea (Mediterranean outflow (MOW)) with a maximum salinity and then diluted again with oceanic Atlantic waters. We are attempting to merge data from the deep to the high atmosphere at specific places at the same time as we travel south across the Atlantic equator. This gives us images of local and regional conditions that feeds into a global climate change picture. For most of us it is the first time we have participated in an international programme that surveys across the equator and the experience is nothing short of awesome. Having all different backgrounds we are literally now sitting in the same boat. To be an oceanographer in Egypt it is not easy to find a well-equipped research vessel with the latest technologies so it was a great opportunity for me to learn and to be one of the scholars on NoSoAT to experience highly resource equipment and programmes. In Ireland we are at the forefront of mapping and surveying our maritime economic zone. Although resource limited the motivation is there to understand our ocean and the changes happening in climate.
“CTD” stands for conductivity, temperature and depth and is an oceanographical instrument to determine these parameters. The CTD may be incorporated into an array of Niskin bottles referred to as a rosette. The sampling bottles are closed at different depths, triggered by a computer, and the water samples may subsequently be analyzed further for biological, physical and chemical parameters.
About the authors
Walaa: I am a researcher at National Institute of Oceanography and Fisheries (NIOF) in Egypt; I recently gained my PHD from the Institute of Graduate Studies and Research at Alexandria University from the Environmental Studies Department. I was very excited when I was accepted to the NoSoAT 2016, because it is my first blue ocean expedition. I usually collect samples for one or two days with our research vessel but not to the same extent as NoSoAT.
Eoghan: I am a recent graduate of Earth and Ocean Sciences at the National University of Ireland, Galway. Gaining a place on the NoSoAT has been a dream for me, as it provides practical training exactly in my areas of interest that are operational and physical oceanography. Also, the strong link between ocean and climate change looked at here, interests me greatly.