Dispatch 16: Aurora Borealis     Print

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David Jones and Andrey Proshutinsky

21 September, 2017

Weather: partly cloudy, 10 knot winds, scattered ice covered seas

Temperature: 4 ˚C

Relative humidity: 70%

Location: Beaufort Sea, 71˚ 59’ N; 150˚01’ W

News

Aaagh, the elusive Aurora Borealis aka Northern Lights. We southerners whocome from the lower latitudes rarely if ever get a chance to see them. Usually when we do it is kind of a let down because they are faint or obscured by clouds etc. and we are left saying that the pictures of the Aurora Borealis are better than seeing the actual thing. BUT to this southern latitude soul, that changed last night. I was just drifting off to sleep when my beeper went off. Strange I thought, why would the bridge be beeping me at 11 pm? Maybe..........well I had no idea so I pulled on some clothes, grabbed my camera, and headed upstairs, and outside bumping into a couple of the CTD rosette night watch team members who said the Northern lights were out. And they....were....out!!! The interplay of the earths magnetic field and charged particles in the high atmosphere were on full display. I snapped off a couple dozen photos just as the camera battery died and hoped for the best. You can see the results of my efforts in the photos.

We are currently at the end of the 150˚ W meridian line and starting in on the "BL Line" which is a series of tightly spaced stations whose depth starts at 3000 meters and decreases to 60 meters as we move toward land and up the Beaufort Shelf. The BL line is a frenzy of sampling activity with a CTD rosette cast taking place at each station. Since the depth of the stations decrease as we move inland, the time between casts gets shorter and shorter which might not seem like a big deal, but to the crew that does the chemical analysis and sample preparations it is 15 + hours of nonstop work. Many of the analysis have to be completed within 12 hours of the sample being taken– getting behind is not an option.

One of the onboard analysis done is the Dissolved Inorganic Carbon or DIC. Marty Davelaar and Natasha Salter both from DFO-IOS use the VINDTA #030 – Dissolved Inorganic Carbon Analyzer to do the job.

Chemistry Timeout

How do we know how much carbon dioxide is dissolved in a sample of sea water? The VINDTA #030 – Dissolved Inorganic Carbon Analyzer is the instrument used to measure the concentration of dissolved inorganic carbon (DIC) in a sample of sea water. A known volume of sea water, taken from one of the Niskin bottles (grey in color) of the CTD rosette, is combined with phosphoric acid in a glass chamber. Here, during the reaction, the DIC, which is in the form of carbonate, is removed from the sea water producing CO₂. The reaction for this goes something like this: carbonate reacts with phosphoric acid to form carbon dioxide, water and hydrogen phosphate and is symbolized like this: CO₃^2- + H₃PO₄ --> CO₂ + H₂O + HPO₄^2-. Then, the resulting CO₂ is carried by a nonreactive inert gas, nitrogen in this case, into a titration cell where the quantity of CO₂ is determined coulometrically. As the CO₂ combines in the cell with a blue indicator dye a detectable change in color occurs. This color change, read by a machine called a coulometer, corresponds to the amount of DIC in the sample. Since we know how much seawater we started with, and now how much CO₂ was in that water, we expressed the concentration as micromoles CO₂ per kilogram of water or µmol CO₂/ kg H₂0. Thanks to Marty Davelaar and Natasha Salter for their contribution for this Chemistry Timeout.

Beautiful World of Reflections, Shades and Contrasts by Gary Morgan

A collection of photos by Gary Morgan, our icebreaker carpenter do not need captions… This is his art reflecting our Arctic work in colors, shades and surprisingly sharp contrasts and can be seen in today's photo gallery, photos 11-18.