Underway Science

Lelethu and the pCO2 system in the underway lab onboard Agulhas II.

There is constant scientific analysis going on aboard Agulhas II, even when all the scientists are in bed. The ship has a pump that delivers surface seawater to the underway lab, where it is analyzed by machines that only need minimal attention (at least when it's working correctly!). Lelethu Nohayi, a technician from CSIR (Council for Scientific and Industrial Research), was in charge of the pCO2 system on this cruise. It measures the difference between carbon dioxide concentrations in the ocean versus the air just above the surface.

The 'wet box' (behind Lelethu in the above picture) recreates the air-sea interface using seawater pumped up from the bottom of the ship, about 5 meters below the surface, and air pumped in from the front of the bridge, which is uncontaminated by the ship's exhaust. The 'dry box' (on the left) consists of all the electronic components necessary for the measurements. 

Data can be collected constantly, and the pump was run every time the ship was underway. Lelethu also took samples that will be analyzed back in a shore-based lab in Stellenbosch that will be used to calibrate the system. pCO2 data has been collected all over the world by research vessels since the 1950s. This cruise will add to that important data set