First steps: collect the water

I'm working with Dr. Mark Wells, our principal investigator from
the University of Maine here, collecting water samples at various depths

Denis and I wake up early to set up the filtration lab station (Can you find it in one of the pictures in the previous post?) and the CTD Rosette submersible (pictured left); CTD stands for conductivity, temperature and density. Through coordination with the ship's crew and science crew, the CTD is lowered to predetermined depths by the scientists. At each, the canister or bottle, called a Niskin, fires, closing the top and bottom to collect the water at that depth. There are 24 Niskin bottles, and we usually make 2 collections at each desired depth.

The large A-frame (pictured above the CTD) moves forward, along with a crane and winch, to place the submersible into the water. As the CTD returns to the surface, it captures water samples by releasing the line and snapping closed the Niskin bottle from a computer system in the main lab. In real time, data is collected on the conductivity, temperature, density, salinity and dissolved oxygen. These data points will be farther investigated in the labs on board.

Notice how each bottle is attached to a release line.

Rachel Vander Giessen, University of Washington and NOAA-PMEL, communicates to the crane operator and us outside on the deck when to stop the CTD and take samples. 

Retrieving the CTD with carbon fiber poles and lines,
"Res Tech" (resident technician), Keith ensures safety.

With the line attached, now we reel it in.

Denis and Andrew preparing filters for measuring chlorophyll. One of many tests to be done from this one CTD cast.