Beachcombed flotsam of marine technology decorates the Viney homestead, if not, I hope, in the manner of some overeager seafood boutiques – no nets or starfish around the windows, at least. Brightly coloured plastic “trawler balls”, stacked up on ropes at the pillars of the woodshed, do lend great cheer to a dull winter garden, and the porch holds a precious, perfect string of Spanish globes of bottle-green glass, snatched up from a strand line across the bay back in the 1960s. There was even, once, a simple fisherman’s float with bamboo stick and flag whose unmistakable Caribbean colours – a singing turquoise, a fluorescent pink – made one thirsty for a rum-and-something.
But nothing, in all the years of trudging the sands, could compare in significance with the big yellow barrel of plastic foam and metal that drifted ashore on the Mullet peninsula of north Mayo last autumn and today, surrounded by its story on video, etc, is on exhibition at Belmullet arts centre.
The buoy is what remains of ITP47, an “ice-tethered profiler” installed on – or, rather, in – a thick ice floe close to the North Pole in April 2011 by a team of researchers from Woods Hole Oceanographic Institution, in the US. It was part of the intensive surveillance of the ocean that climate change has brought about, and especially of the rapid reduction of Arctic ice. Gear dangling some 750m below the buoy held sensors that travelled up a wire twice a day to report to a satellite on changing levels of temperature and salinity.
On Christmas Eve 2011, when the system was about 300km north of the tip of Greenland and had delivered about 1,000 profiles, the buoy fell silent, perhaps rafted over by ice. It woke up again, remarkably, in May 2012, when in the middle of the Denmark Strait, between Iceland and Greenland, and continued sending signals of a sort until October. Nothing more was known until its arrival on the Mullet, minus most of its electronic undercarriage.
Costly instruments such as ITP47 have been helping to fill the icebound Arctic gaps in the international ocean surveillance supplied by Argo floats. These submerging cylinders drift at 1,000m down, then, every 10 days, plunge to 2,000m before rising slowly to the surface to report on the temperature and salinity of different levels of currents and water masses. The array of floats across the world’s seas has now reached more than 3,600, but their limited lifetime and the need for wider distribution demand at least 800 new launches a year. Away from shipping routes and busy research zones, some NGOs and even private yachts are seeding floats into lonelier corners of the oceans.
Drifting Argos
Ireland's Marine Institute is adding three a year, at €11,000 each, launched from the Celtic Explorer research vessel. This is a modest contribution to the wider European Argo programme. France, for example, deploys 60 floats a year, and the Coriolis oceanographic centre in Brest manages the satellite data from hundreds of Argos now adrift across the Atlantic. Freely available online, the data has generated almost 1,000 research papers – if none, so far, from Ireland.
Along with with the Argo floats, space satellites monitor the ocean’s surface for everything from temperature, sea level and coastal tides to the algal blooms, some of them toxic, that make problems for coastal aquaculture. Last year saw the unexpected malfunction of the European Space Agency’s huge Envisat satellite, nine metres long, that was studying Earth, the Atlantic and its atmosphere in close detail. One of five successors, the Sentinels, is specifically an ocean-watcher and will be launched this year or next.
The need for more wide-ranging undersea measurements has spawned yet another technology. Evolving from the Argo floats, battery-powered “ocean gliders” are like small, winged torpedoes that move very slowly, for months on end and over great distances, surfacing regularly to report to satellites and get new directions. Coriolis offers its first glider-generated batch of data from one that crossed from Norway to the Fram Strait, the seabed passage beside Greenland through which the Arctic and the Atlantic exchange their great warm- and cold-water masses.
Meanwhile, the travels of one Argo float have intrigued the oceanographers of the Marine Institute. The general circulation of the North Atlantic is anticlockwise, so floats released off Ireland typically circle past Iceland, Greenland and Newfoundland before returning to the eastern Atlantic. Float 6900650, however, launched in rough seas from RV Celtic Explorer in the winter of 2008, west of the Porcupine Bank, took off south instead. It spent more than three years lolling about in a gyre of water flowing out from the Mediterranean, happily sending back signals of how warm and extrasalty it was.