Easter post: floats, tow-yos, and Sonya's 50th

It is Easter Sunday.  I found a Kit-Kat candy bar under my door, delivered by an anonymous Easter Bunny.  Sonya and Nikki had more candies to pass around during the morning science discussions. 

The weather has been a mix of relatively mild and relatively wavy the past few days. We have accomplished much, and there have been a few days when we could actually sleep well to reduce sleep deprivation. I provide here an update on some of the happenings during the past week. Even so, a lot more has happened that will be the topic of future posts. 

Photo of chin strap penguins swimming near the ship. They offer great entertainment, though they are tough to see and photograph due to their speed and small size. This photo is the result of blowing up an otherwise nearly featureless shot taken among the quickly moving group passing the ship one day.

Stephen Griffies and Sonya Legg next to the ''Princeton Argo float'' just prior to its deployment in the Weddell Sea from the JC Ross back deck. Note the name on my hard-hat must be from its prior owner.

Princeton Argo float deployment  

Sonya Legg and I had the privilege of deploying an Argo float on 12 April.  It was the second of three Argo floats to be deployed on this cruise. We called it the ''Princeton Argo float'', given our association with Princeton University and NOAA/GFDL. 

The process of deploying an Argo float is rather simple, especially compared to the much more complex process of deploying a CTD or VMP.  Argo floats require no more than unpacking and then carefully dropping them in the ocean.  They are a bit heavy, so it took some help to get the float safely into the water.

Once deployed, and Argo float stays on the surface for a few minutes until it "understands" that it is in fact in the water and should turn vertical. Soon after, it drops into the ocean interior to start its multi-year job of measuring temperature, salinity, and pressure over the upper 2000m of the ocean column. Argo floats have revolutionized large-scale oceanography, along with satellite remote measurements.

I wrote a bit about the first Argo deployed on this cruise in the ''A taste of the science'' post on 19 March. As noted in that post, these floats will add to the nearly 4000 such floats around the planet. Argo floats record basic properties of the ocean such as temperature, salinity, pressure, from the surface to 2000m depth. They send signals to satellites every 10 days. These floats have a finite lifetime (few years), so it is desirable for research cruises to deploy a handful in order to keep the array strong. These floats are the main method used to determine how much the ocean is warming due to human effects.

Recovery of the French float, deployed in the cruise just prior to ours.  It was a very calm few hours that afternoon, thus affording those on the navigation bridge the ability to spot the float on the distant horizon.

French float recovery

Later on 12 April, we recovered a float deployed by the previous science team on the JC Ross.  This French team of scientists went further south into the Weddell Sea towards the continental shelf. They deployed a float that we recovered today.  It was an unusually calm day, which facilitated finding the float on the horizon. We will return the float to the French, who will download its data and analyze its results.

There was a big storm to our north, near the South Georgia Islands.  That storm sent us some massive swells.  Here, you see Andy Davies, Nikki, Steve McPhail, and Keith Nicholls leaning into the swell on the UIC. It is generally difficult to depict such motion with a photograph, but this one, taken by Eleanor Frajka-Williams, does a reasonable job.

Tow Yos

During 12-13 April, we also did a section of  ''Tow Yos''.  Tow yos are in essence a CTD cast, but taken while the ship is moving quite slowly rather than stationary. The rosetted is raised and lowered once on each ''yo'', then lowered again.  We did about 3-4 ''yos'' on two sections.  A tow-yo has the advantage of taking finer scale horizontal information, but at the sacrifice of a full depth profile.  We also do not fire bottles until the upcast of the final yo.  

Cliff on the winch during the tow yo section.  The swells are quite large here.  But they offer only modest difficulty so long as the CTD is in the water.  Recovery is tough, however, due to the ship motion.  Cliff and the crew did a great job of recovery in some rather difficult conditions. Doing so really helped meet the science goals for this section.

During the final few yos of the tow-yos, the swells became quite large due to a storm to our north at the South Georgia Islands.  The swells were projected to peak around 3pm.  Well, that was also the time to recover the CTD on the final yo.  Cliff and the deck crew did a masterful job of making the rather difficult process look simple.

Nikki, Christian, and Chris bring Sonya's birthday cake to the officer/science lounge, while Alex, Sonya, Adam, and Paul watch.

Sonya's 50th

Sonya Legg turned 50 on 14 April. To help celebrate, she brought some Chilean sparkling wine from Punta Arenas.  We also surprised her with a cake baked by one of the ship's cook, Chris, and a card put together by Nikki. We held the celebration after lunch, since Sonya is part of the midnight shift, so she is normally asleep from 3pm to 11pm.  An after lunch celebration thus ensured maximum participation.

Sonya's birthday cake, baked by Chris, one of  the ship's cook.

Christian, Chris, Helen, Sonya, Adam, and Paul during Sonya's birthday celebration.  Sonya is clearly relishing the moments.