Hello,
These lines are typed aboard the RV Sikuliaq, a research vessel currently braving the waves off the coast of California just north of Santa Barbara. It was in one of the courses I’m taking this quarter where my professor asked the four of us who are in that class if we would like to join his lab on a weeklong research cruise – Ehm, yes!

We left San Diego Harbor early Monday morning and will be out all week recovering and deploying moorings (research buoys) that his lab runs. The buoys have both meteorological and oceanographical instruments measuring everything from salinity, temperatur, pH, oxygen levels, nutrients and PAR (photosynthetically active radiation).

We’ve been out for about two days now and it’s been action non stop. We’ve been doing everything from practicing “abandon ship” (where you have to put on a polar class immersion suit, that looks like a space suit in size XXXL, and climb aboard the life boats) to more research oriented things like doing CTD-casts. CTD stands for conductivity, temperature and depth and is on of the most fundamental measurements you can do in the ocean. The conductivity gives you the salinity of the water, and together with temperature at certain depths you calculate the density and energy content of the water which is important for understanding ocean circulation, locally and globally.

A CTD-cast consists of deploying a so called CTD-rosette, a circular steel frame to which several long and thin bottles are attached. The bottles can open in both ends and when the rosette is lowered into the water they are all open. The instrument is then winched down to the desired depth, which can be several hundred meters (yesterday we did a cast down to 1800 m). Once the instrument is in position down there you fire a signal via the line to close a bottle and in that way you capture the water at that depth inside the bottle. You then slowly winch the instrument back up and fire as many bottles you want at different depths to capture water from different parts of the ocean. Usually a CTD-rosette has 12-24 bottles and the whole process takes some time as you should only go at about 60 meters/minute both up and down, and you might want to stop for 10-15 minutes at certain depths to allow the onboard instruments to stabilize. 

Once the CTD is back at the surface you empty the bottles and collect the water in them depending on what measurements you want to make. For salinity you fill up smaller bottles that are sealed and packed for later analysis back on land, for plankton the water is filtered in a special machine and the filters with all the plankton in them are stored in the freezer until the can be analyzed on land, and for oxygen you add chemicals containing iodine to the water, seal the bottles and store them in a cool and dark place, which preserves it for later analysis. 

It is very crucial that the samples are taken in the correct way to minimize the risk of contamination. For salinity for example everything needs to be rinsed very carefully to prevent any dried salt from other places ending up in the sample. The bottle is rinsed three times, as is the cap and your hands, before the sample is taken. Your fingers get pretty cold taking samples from the bottles that were closed at depth (6°C or colder), but it’s also pretty cool thinking about how that water comes from about two kilometers down in the ocean, definitely not a place you would otherwise find yourself.

I have a lot more to tell and show from this week, more than would fit in one post, and as wifi on board is slower than a sleepy snail, this will all be posted in a couple of different posts once I’m back in San Diego. Thus, stay tuned!

As always, thanks for reading and take care!