Hi Everyone,
Today was a very exciting day as it was the first day that we got to launch the CTD. In this blog I will talk a fair bit about the science we will be doing, in particular what I will be doing. The CTD (which stands for Conductivity Temperature Depth) is a large ring mounted on a long wire which is lowered into the water down to the depths of the ocean (often down to 5000m or more). As it descends, it measures the conductivity of the water, the temperature of the water and the pressure (to calculate the depth). This gives us very valuable information about the water masses present in the area and how they are mixing and moving throughout the region. The CTD is also used for a number of other measurements, including bottles which are closed at a range of depths to collect water for sampling. There is a great deal of competition and discussion about where the bottles should be closed and how much water can be dedicated to different tasks. The water can be used for detailed salinity, dissolved oxygen, dissolved methane, and microplastics amongst many other uses. I am personally focused on the salinity calculations (which we were given a brief introduction to). The details of the salinity and temperature are particularly crucial on this cruise as we are trying to understand the motion of the deep waters. These Antarctic deep waters are critical in taking carbon out of the atmosphere and controlling the global ocean circulation, so understanding their dynamics and variation under climate change is critical.
I am also focusing on the Vessel Mounted Acoustic Doppler Current Profiler (VMADCP) and another student is working on the Lowered version (LADCP) which is placed on the CTD. These use sonar pulses (like bats or radar) to calculate the speed of the water around the ship, again giving crucial information about the motion of the water masses and how they have been changing. I still have a lot to learn about the intricacies of these, there are a plethora of ways that these can be confused or damaged, and these need to be compensated for.
On top of this, the biologists on board also took the opportunity to test the nets that they have brought aboard and this was great fun as they caught many cool Antarctic critters. I will attempt to attach some photos of these creatures, though I don’t know how well they will come out. My favourites were the salps, which are little jelly-like creatures, kind of like mini-jellyfish. We also saw a huge number of copepods and small worms, which we could watch zipping around the bucket very merrily! I have high hopes that with the larger nets we will see some cool fish and larger marine organisms over the next few days as well!
Finally, we ended the day with the start of our Christmas activities, some impromptu carol singing. This consistent of the whole group singing along to an electric piano, accordion and myself on guitar, an eclectic mix by any standards. It was a very wholesome evening and certainly helped us all get into the Christmas spirit, I hope you are all enjoying the Christmas holidays too!
24/12/22
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