In 2018 when we were on the RV Neil Armstrong we did the same research cruise to swap over deep-sea oceanographic moorings and calibrate instruments. We are only doing the eastern side of all of the moorings this year because collaborators and different scientists are on the Neil Armstrong completing the moorings from greenland toward iceland to fill in the gaps. This is the 3rd time I have done oxygen analysis on a research cruise, but this time I was in charge of packing, transporting, and sorting out all of the chemicals and equipment. It is pretty stressful because if you mess up mixing the chemicals or don't pack something it can really impact the analysis.
Just like the cruise in 2018. I am calibrating sensors, "These instruments include the CTD (conductivity aka salinity, temperature & depth profiler), sensors like microcats which are placed on the mooring buoys at certain depths. These mooring buoys will be measuring pressure (depth), salinity, temperature, oxygen, and many other oceanographic parameters throughout the water column. The most important one on that list for us is the oxygen sensors that are both on the CTD and the ODO Microcat situated along the moorings.
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| This is the CTD. So it is basically a big rosette full of different sensors measuring everything from carbon, salinity, temperature, depth, oxygen, and a few others. The grey bottles are called niskins which are fired (closed) at different depths across the water column so that we can take water samples from different depths to see how all of the parameters that the CTD sensors are measuring change across the water column. This is important because at some stations it can be up to 2000 m. We also try to pick the same depths that the moored sensors are measuring this data. The main aim is for my point measurements to be compared against the sensor data to see what drift we are getting, this is called calibrating the sensors. |
We reuse bottles and this is my handwriting and a random smiley face from 2018, its goot to make yourself smile right? haha
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| Late night winkler |
Then comes the titrations! I am doing oxygen titrations using a Titrino Winkler Titrator (photos of titrator http://sazreed.blogspot.com/2018/06/what-we-got-up-to-on-jr17005-nerc.html ) to measure the dissolved oxygen concentration at different depths (using the grey niskins fired at different depths) and this is then compared against the sensors measurement to see if there is any drift in the sensors over time.
Lots of samples, I am also collecting nutrient and carbon samples for analysis back at SAMS.
Mission complete. The samples that I have taken so far have been plotted and compared to historical data by Clare (our base at HQ) and the data is looting good and showing very limited drift.
The prominent reason that we calibrate sensors is so that the data collected on these long term data sets can be published and proven that they are high quality.
I always find a quiet (sunny - not all the time) spot for some wildlife spotting, reading, tea drinking and gernerally forgetting about the science and talking to people on the ship for an hour. I do this most days to reset.