Kaharoa in the Wellington Harbor in New Zealand
Photo by A. Blacklock

The Kaharoa finishes its seventh cruise to deploy Argo floats

The US and New Zealand Argo teams have taken a novel approach to Argo float deployment by using a 28-m research vessel, R/V Kaharoa, with 5 crew members to launch floats around the globe. The ship, belonging to New Zealand's National Institute of Water and Atmospheric research (NIWA), loads floats on board, usually in Wellington, New Zealand. It sets off on voyages of a month or longer, crossing the oceans to launch Argo floats and surface drifters. While this may sound fairly simple, without the over 400 Argo deployments made by the Kaharoa, Argo would not have global coverage. This is because the Kaharoa deploys floats mostly in the Southern hemisphere, in the most remote parts of the oceans seldom visited by merchant ships or other research vessels.

Kaharoa deployment cruises. Each dot represents a float being launched.

The Kaharoa just returned from its seventh Argo mission since beginning the program in 2004. Altogether, Kaharoa has spent nearly a year at sea for Argo. There are now 439 active Argo floats deployed by the Kaharoa. In order to protect the fragile temperature/salinity sensors, Argo floats are often deployed in biodegradable cardboard boxes that open in the ocean to release the float. Floats are "started" up to prepare them for deployment before the voyage begins. Once at sea, a technician readies the box for deployment and, at predetermined locations, easies it over the stern into the ocean to launch the float. Follow the photo diary below to see the whole float launching process. Other floats are launched as bare instruments (final photo).

Kaharoa entering San Diego harbor
Photo by D. Roemmich

The use of the Kaharoa to deploy floats is a perfect example of the international collabration that has made Argo a success. The funding of Kaharoa missions is shared between US Argo (supported by NOAA) and NIWA. Scripps Institution of Oceanography UCSD, the University of Washington, and New Zealand Argo provide floats to be deployed by the Kaharoa. The vessel also deploys surface drifters for the Global Drifter Program. The great impact of the Kaharoa deployment voyages on Argo's global coverage can be seen in the plot below of the locations of all active Argo floats. Active floats deployed by the Kaharoa are shown in red, while the others are shown in black.

Current location of active floats deployed by the Kaharoa shown in red. All other current float locations shown in black.

Click on the still shot for an animation of Kaharoa deployments (.avi movie will open in a new window)
Click here to download the .avi file to your computer. (13 Mb)

Click on the still shot for video of a Kaharoa deployment (.avi movie will open in a new window)
Click here to download the .avi file to your computer. (7 Mb)

Photo diary of an Argo float deployment aboard the Kaharoa

Phil Sutton, Dean Roemmich, Basil Stanton and Derek Vana running testing and startup
procedures on a SOLO Argo float at NIWA/Wellington.
Photo by A. Blacklock

John Hunt cutting the plastic covering off a box containing an Argo float aboard the Kaharoa

John Hunt cutting the Argo float box flaps open in preparation for launch.

Removal of the plastic covering.

John Hunt moving the Argo float box out to the deck.

Preparing to launch float off the stern.

John Hunt watching the float box enter the water.

Argo float box as it hits the water after launch.

Recently deployed Argo Apex float at the surface.

Series of photos showing the float deployment aboard the Kaharoa taken by M. Naidovici