International experts set sail to see how the ocean creates clouds

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Next week, NIWA's research vessel Tangaroa will set sail for the Chatham Rise, for an international study of how microscopic organisms in the surface waters may affect the creation of clouds.

This work is important because, "We need to understand what role ocean processes play in cloud and climate," says voyage leader and NIWA Principal Scientist Dr Cliff Law.

The voyage is bringing together a 23-strong team of atmospheric and marine scientists from New Zealand, Australia, Finland, USA, Canada and Ireland for a three-week research voyage to examine this interaction between the ocean and atmosphere.

This project is called SOAP, short for Surface Ocean Aerosol Processes.

Dr Law says that some phytoplankton - the microscopic plant cells that live in the sunlit surface waters - release sulphur compounds that can escape to the atmosphere. Once in the atmosphere, these compounds form aerosol particles, upon which water starts to condense, stimulating the production of clouds.

Microorganisms concentrated at the sea surface produce organic compounds. There have recently been suggestions that when these compounds are associated with bubble bursting in breaking waves, tiny aerosol particles are produced.

The scientists aim to measure the composition of surface waters, the overlying air and also the exchange or "flux" between the two. Law is hoping they will see variation and trends in properties as they move across blooms of different phytoplankton along the Chatham Rise.

Measuring atmospheric composition is challenging on a research vessel with a smokestack. The scientists will use a large mast on the ship's bow that supports a number of air samplers. There will be further samplers on top of the ship, above the bridge.

In addition, a floating catamaran will measure gas emission and absorption by the ocean away from Tangaroa's influence. The team are also interested in the microlayer, the very thin layer at the ocean's surface, where material and microorganisms can become concentrated. Sampling this will involve working for an hour or two away from the Tangaroa in a small Naiad workboat.

Dr Laws says, "The SOAP voyage will be quite a challenge. In addition to finding plankton blooms we need calm conditions for some measurements and strong winds for others."

Dr Cliff Law is a team member and recipient of the recent 2011 Prime Minister's Science prize.

The New Zealand work is funded by the Ministry of Science and Innovation.

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Principal Scientist-Marine Biogeochemistry
Ocean Wave. (Credit: Peter Mariott)
Research subject: Oceans