28 March 2004

Sunday, 28 March 2004

What a breeze!

Before I even left the comfort of my bunk I knew we were in for a rough day. As the Tangaroa pitched downwards I was thrown from my pillow almost crashing my head on the bunk above. Outside tremendous waves broke on the bow and their white caps tailed off in a fine mist. High wind speeds (around 50 knots) were going to prevent us from doing many of the things planned for the day. In these conditions it is impossible to do a CTD cast because of the risk of cracking the cage against the hull, or snapping the steel cable. So there were no seawater samples today.

Strong waves continued throughout the day. If you were lucky you could catch a free ride up the stairs as the ship lurched, catapulting you upwards. However, if you caught it going in the opposite direction it was like taking steps under an enhanced gravity field. Unfortunately it’s difficult to do justice to waves like this in a photo. I got saturated on my attempt, but I hope you can appreciate some of the challenges of working at sea.

Atmospheric oxygen and carbon dioxide

Atmospheric scientists, however, don’t need seawater for their experiments. Instead they were kept occupied by securing air-sampling lines against strong gusts of wind. The atmospheric group is made up mostly of chemists, some making measurements of trace gases and others measuring aerosols.

Oxygen and carbon dioxide are being measured amongst other gases. Both these gases are biologically produced and consumed through the processes of photosynthesis and respiration. Photosynthesis is used by phytoplankton to manufacture carbohydrates using dissolved carbon dioxide and sunlight, and oxygen is released as a by-product. Its converse, respiration, produces carbon dioxide and consumes oxygen. Therefore, the concentrations of oxygen and carbon dioxide are anti-correlated and this can be seen on land as well as at sea.

Rona Thompson (NIWA)

View of the A-frame at the rear of the ship. One of the scientists makes their way to the plankton incubation tank.

Dawn Devries on the foredeck checking her air sampling device.

The seas we encountered today.

Atmospheric oxygen and carbon dioxide concentrations - click for full view

Research subject: Oceans