Dispatch 3: Heading to the Beaufort Gyre     Print

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Mengnan Zhao

September 20, 2015

Today’s daily science meeting indicated the start of the busy preparation for our first station – AG5. We will arrive tomorrow afternoon, where we will take our first CTD measurements and collect Niskin bottle samples. CTD stands for conductivity (which indicates salinity), temperature and depth. These properties allow us to identify unique signatures of water masses in the ocean. For example, the main objective of my research is to study eddies in the Arctic Ocean which can carry water long distances. By analyzing the temperature and salinity properties of the water within the eddy, we can estimate the formation location. Niskin bottles are used to collect water samples from designated depths in the ocean. The analysis of the water will yield its chemical and biological properties such as methane, oxygen, nutrients, barium, etc.

The CTD and Niskin bottles are arranged together on a single round metal frame called a rosette which is lowered into the water by a winch on the ship. The CTD is in the center and 24 Niskin bottles are positioned around the perimeter. Initially the top and bottom of the bottles are both open, allowing water to freely flow through as the rosette is lowered. When the designated depth is reached, the lids close, trapping water inside the bottle.

One last personal note: I saw aurora for the first time last night! A very friendly seaman Gillian Annable invited me to the bridge (the best view on the ship). I have seen many photos of the aurora, and I was excited to see it on my own. It was so amazing! Green bands as light as chiffon swept through the dark sky. The shape and strength of the aurora changed frequently – like a group of fireflies gathering together and flying apart. This scene will exist in my mind forever.