Team reveals the secrets of a current profiler that had drifted all the way from Canada to the port of Bilbao
From Davis Strait, between Greenland and Canada, to the port of Bilbao. This is the route followed by an ocean current profiler which has been picked up recently by a vessel of the Fishery Inspection Service of the Basque Government; AZTI-Tecnalia researchers have been responsible for cleaning it and recovering the logged data. The instrument picked up is a current profiler (used to measure water current velocities which had been attached to a frame with eight buoys and which became detached from its mooring line in December 2012. Since then, it had been drifting until it was picked up about two kilometres to the north of the port of Bilbao.
When the instrument was found, it was covered in barnacles and other molluscs. Once it had been cleaned up, it turned out to be a current profiler belonging to Integrated Observational Platforms (IOP), a research group at the University of Washington, located in the city of Seattle (United States).
Despite the fact that the device was a hi-tech piece of equipment, Luis Cuesta, an AZTI technician, had no difficulty recovering the data stored in it, since they are used to deal with such kinds of instruments.
According to the recovered data, it was possible to confirm that this current profiler was placed in the sea on 5 October 2011 at 67⁰ 02.2´ N and 57⁰ 02.1´ W in Davis Strait. The profiler was part of an instrumented line moored at 690 metres depth. Various instruments for measuring temperature, salinity and currents, among other parameters, were arranged along the cable. The profiler found had in fact been submerged at a depth of 104 metres.
"According to the device's memory card, the line keeping the profiler and all the other instruments in place broke on 22 December 2012," said Cuesta. "The line could have been broken by the pressure of the layers of ice or as a result of vandalism by fishermen," he added.
On the basis of that, the AZTI technicians established the theory that the profiler had been dragged southwards by the ocean current known as 'Labrador' until it was trapped by the Gulf Stream.
This theory was corroborated by the experts themselves at the University of Washington who were contacted by the AZTI researcher Carlos Hernández. "We were informed by the University of Washington that one of the buoys that was part of the instrumented line moored in Davis Strait appeared in May 2013 off Fogo island, located off the northeast coast of Newfoundland (Canada)," remarked Hernández. The researcher explained that "this finding confirms that the two floating items had been dragged along the surface southwards by the 'Labrador' current, even though the one found in the port of Bilbao continued to drift until it entered the Gulf Stream, one of the branches of which comes all the way to the Cantabrian Sea".
"The American university has thanked us," said Hernández, "because we have enabled them to recover a year and a half's worth of information stored by the profiler since December 2012; apart from the considerable material value as we are talking about a 23,000-dollar piece of measuring equipment."
Hi-tech equipment
The familiarity of the AZTI technicians with the use of state-of-the-art oceanographic equipment enabled them to interpret the content of the information accumulated by the University of Washington's profiler. The R&D centre operates the deep-water buoys that Euskalmet (Basque Meterorology Service) has deployed in the Bay of Biscay for monitoring various metocean variables. The information sent by these buoys is used, among other things, to find out the places across which certain marine species may pass and even to help in the rescue of people who have fallen into the sea.
The voyage of the buoy recovered indicates that the great ocean currents find a significant point of confluence in the Bay of Biscay. This fact facilitates the arrival in this area of drifting objects which may have originated a very long way away.
Provided by Elhuyar Fundazioa