Bloom hunting

- Tom Bell [UC Irvine]

Now that you’ve been introduced to the science party, it seems logical to introduce what we are trying to achieve on this cruise (or, as the French call it, Research Mission, which is far cooler). The primary focus of these few weeks at sea is to make measurements of the movement of gas between the ocean and atmosphere and the various factors that affect this process. The gases we are focusing on are carbon dioxide (CO₂) and DMS (a sulphur compound that is thought to play some role in the reflectance of incoming solar radiation away from the earth surface). Many measurements of concentrations of CO₂ and DMS have previously been made in the atmosphere and ocean and some estimation can be made of the sea-air flux from these. However, a number of assumptions have to be made in order to do this.

Measuring the flux directly - our current experimental method - avoids these assumptions, but requires that we make very rapid (10 times a second) measurements of the concentration in the atmosphere while recording the vertical dynamics of the wind, water vapour and temperature.

Almost all of our sampling takes place from a mast on the bow at the front of the ship. I’m currently reading Moby Dick, which contains a pertinent quote as to why we have to measure from there:

“The Commodore on the quarter-deck gets his atmosphere at second hand from the sailors on the forecastle. He thinks he breathes it first, but not so.”

When measuring the flux of any gas, we have to ‘breathe’ it first, before the gusts of wind are physically and chemically disturbed and the signal lost.

Currently we are steaming North and East away from the North American seaboard - our ultimate destination is the waters close to Iceland. Why go so far away from land to make our measurements? Every year, the waters in the North Atlantic light up with the green colour of chlorophyll.

The oceanic phytoplankton (algae) grow quickly as they make the most of available light and nutrients in the summer months. In the waters to the South and West of Iceland, the annual bloom is consistently dominated by a group of phytoplankton called coccolithophores. These are known to produce large amounts of DMS and, during a previous research cruise, strong flux signals were observed. We hope to try to find similar conditions this time round.

Further information:

Marandino C.A., W.J. DeBruyn, S.D. Miller, and E.S. Saltzman (2008): DMS air/sea flux and gas transfer coefficients from the North Atlantic summertime coccolithophore bloom. Geophys. Res. Lett. 35, L23812

The life aquatic

A safety drill was organized to introduce the science crew to the many risks that life at sea presents.

The science team

Here are the members of the scientific team. Please feel free to contact us if you have questions about our scientific goals during our cruise or life on a research vessel.

Who is onboard?

The science party includes researchers from the State University of New York at Albany, University of California at Irvine, National University of Ireland Galway, Scripps Institution of Oceanography, Texas A&M, the University of Sao Paulo, and the Brazilian Space Agency (INPE).  A range of research backgrounds are represented, including meteorology, atmospheric chemistry, physics, and physical and biological oceanography.  In following blog posts these research groups will provide more specific details about their activities on Knorr.
In addition to the science team, the R/V Knorr has a professional staff of 26 onboard who operate the ship, including maintaining the mechanical functioning (engines, electrical generators, communication, navigation) to assisting with deck operations (CTD casts, instrument deployments) to providing excellent food for everyone onboard.  Included in the ship’s staff are marine technicians who work with the science team to help them carry out their research.
This cruise is the result of a long planning process (over a year) that requires close coordination between the science team and the ship’s personnel so that specific needs of research projects can be met.  Between several weeks to a month before departure, science equipment was shipped from our home institutions to the ship in Woods Hole.  The science team convened in Woods Hole June 18^th to begin loading gear onto the ship and set up equipment for sampling.  The six days of setup time in port is long compared to most oceanographic cruises due to the complexity of the instrumentation used to measure air-sea gas exchange. 

The Research Vessel (R/V) Knorr

R/V Knorr is a 280 ft global class research vessel, owned by the U.S. Navy and operated by Woods Hole Oceanographic Institution in Massachusetts.  Click the link to the Knorr's website to see lots of information about the ship.  (Photo courtesy of Woods Hole Oceanographic Institution).