How a sailboat helped Canada drop ocean sensors in the remote south Atlantic to study climate change

Canada is partnering in an unusual mission measuring climate change in the Atlantic Ocean it's using a 24-metre sailing yacht to deploy robotic sensors.

The French sailboat Iris is in the south Atlantic right now in the midst of a three-month trip that will release 100 autonomous sensors,including a dozen from Canada,to measure ocean conditions.

Canadian research scientist Blair Greenan says it's cheap, it's green and it solves a problem caused by the pandemic.

"As with most things during COVID, our at-sea operations were interrupted. This initiative came to fruition by looking at other opportunities to deploy these floats," says Greenan, who is based at the Bedford Institute of Oceanography in Halifax.

"It's also using a low-carbon approach to deploying these instruments in the water where we normally use large research vessels."

Sensors send climate data to satellite

The sensors gradually descend two kilometres beneath the surface leveland return to the top, taking temperature and salinity measurements along the way. Every 10days, the float breaks the surface to upload data to a satellite. The information is used by weather forecasters and scientists who can chartocean warming in real time.

The research is part of the Argo program, a network of 3,800 floating sensors around the world.

"It's really revolutionized our insights into the ocean because, prior to this, we've depended on research vessels going out and sampling the ocean and that's only done a limited amount of the year," says Greenan, who is the Canadian lead for the Argo program.

"We're able to monitor how the ocean is changing in real time; we're actually seeing that ... the ocean is heating over time."

The partners

A private company, Blue Observer, owns the yacht. Canada, the United States and the European Union are providing the floats, which cost about $25,000 each.

The first leg of the mission began in Brest, France, in November and saw 17 floats dropped into the mid-Atlantic for the European Union.

Last month, Iris tied up at the Woods Hole Oceanographic Institution in Massachusetts to resupply and pick up more floats, includingones sent from the Department of Fisheries and Oceans (DFO) in Nova Scotia.

About 1,000 Argo profiling floats must be released each year to sustain the Global Ocean Observing System, an Intergovernmental Oceanographic Commission program and part ofUNESCO.

And the yacht can go to places not easily visited by research ships.

Iris has crossed the equator since leaving Massachusetts. On Wednesday it completed the second leg of the trip when the ship and crew arrived at St. Helena Island, 1,950 kilometres west of the nearest landfall in southern Africa. The remote island was where Napoleon Bonaparte was exiled.

Afterward, Iris willhead towardNamibia.

Floats deployed in 2022 to havemore sensors

Using the sailing vessel ischeaper, too, with a day rate that's a fraction of the $50,000 a day it can cost for research ship time.

DFO has deployed 600 Argo floats off Canada in the last 20 years on the West Coast, in the Labrador Sea and off the Scotian Shelf south of Nova Scotia.

Each year between 20 and 40 are deployed to replace sensors that are retired.

This year, floats deployed in either the Labrador Sea or ScotianShelf will carry more advanced sensors that also measure biological and chemical conditions: for example pH levels, which can indicate acidification as the ocean absorbs more carbon dioxide.

The upgraded sensors can cost upwards of $100,000 each.

Greenan says there is no substitute for research at sea, but the floats are a bargain.

They provide data every 10 days for about fiveyears about 200 ocean profiles at a cost of about $125 per ocean profile from the standard sensor.

"This can't completely replace the data we can collect from a ship, but it's certainly an exceptionally cost-effective way of acquiring data," says Greenan.

A legacy of 2018 G7summit hosted by Canada

For Canada, the Iris mission is a legacy of the 2018 G7 Summit hosted by Prime Minister Justin Trudeau in Quebec.

The summit is remembered mainly for Donald Trump's early departure and insults levelled at Trudeau.

But at the meeting Canada committed to advance international co-operation in the oceans.

And one of the initiatives was to bolster partnerships in the Argo program.

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