A Collaborative Month in the Irminger Sea

A team of 10 Woods Hole Oceanographic Institution scientists, who spent the month of August aboard the RV Neil Armstrong, arrived at home port in Woods Hole on 4 September, having successfully skirted Hurricane Laura as she headed in their direction. The bumpy ride home capped the successful deployment of all OOI Irminger Sea Array moorings in sometimes  turbulent seas.

While onsite at the array, the team successfully met all of its mission objectives by recovering and deploying four moorings and deploying two gliders. One glider transits the individual moorings, which are spaced approximately 20 km apart, while the second glider samples the upper 200-meters of the ocean above the centrally located hybrid profiler mooring, which measures the remainder of the 2800-m water column. A third glider was recovered soon after deployment because it had a microleak. The team also conducted CTD casts at each of the moorings, which measure onsite temperature, salinity, and oxygen conditions and validate data being collected and sent to shore by the array.

“The Irminger Sea array presents both unique opportunities and challenges for reporting ocean data,“ explained Sebastien Bigorre, who served as chief scientist on the Irminger Seven expedition. “It is located in a remote area of the North Atlantic with high wind and large surface waves, which present operational challenges. The area is also of great interest for scientists and society because of the intense exchange of energy and gases between the atmosphere and the ocean. The ocean there captures heat and carbon dioxide from the atmosphere, thus it is an important component of the climate system. It is also a region of high biological productivity, making it an important fishery. Recent studies have shown that the data collected at the Irminger array are essential to correctly describe the ocean circulation of the North Atlantic.”

It is an eight-day transit from Woods Hole to the Irminger Sea Array and another eight-day transit to return to home port. To maximize the use of ship time, the Irminger Sea Array Team shared ship space and mission time with scientists from OSNAP (Overturning of the Subpolar North Atlantic Program). OSNAP is seeking to provide a continuous record of the horizontal transport  of heat, mass, and freshwater in the subpolar North Atlantic, and is complemented by the much longer-term records of water-column properties and air-sea transfer of momentum, heat, and moisture that are provided by the OOI Irminger Sea Array. Once on site, the expedition started with deployment of OOI moorings and gliders, switched its focus to recovery and re-deployment of OSNAP moorings, before finishing with the recovery of the previous year OOI Irminger Sea moorings.

“Our partnership with OSNAP is an example of how we try to maximize our resources for scientific research, from cruise planning, to operations at sea. During transits, we test and triple check our equipment to ensure that comes deployment day, everything goes as smooth as possible. On site, we coordinate operations to accommodate for weather conditions or to optimize shared equipment or personnel. When there is a lull in scientific activities, we plan for the ship’s instrumentation to collect data that is relevant to our scientific objectives, so every hour of the cruise is used to its full potential,” added Bigorre.

The following images show the many tasks undertaken during the month-long expedition:

OOI Irminger Sea cruise participants James Kuo (foreground), Jennifer Batryn, and Collin Dobson demonstrate proper social distancing and PPE use on the deck of the R/V Neil Armstrong during departure from the Woods Hole Oceanographic Institution (WHOI) dock Sunday 9 August. Photo credit: Rebecca Travis©Woods Hole Oceanographic Institution.

The R/V Neil Armstrong is loaded with crew and equipment and ready to depart for the month-long expedition to the Irminger Sea Array. Photo credit: Rebecca Travis©Woods Hole Oceanographic Institution.

A place for everything, everything in its place. Aerial view of the R/V Neil Armstrong deck with equipment loaded for the OOI Irminger Sea Array service cruise. Photo credit: James Kuo©Woods Hole Oceanographic Institution.

Even the gliders took precautions for the Irminger Sea Expedition! (The tape was removed before deployment). Photo credit: Diana Wickman©Woods Hole Oceanographic Institution .

Global Surface Mooring loaded on the R/V Neil Armstrong deck. It replaced a mooring recovered at the site. Photo credit: James Kuo©Woods Hole Oceanographic Institution.

Engineer Collin Dobson performs function checks on OOI gliders in the lab of the R/V Neil Armstrong during the transit out to the OOI Irminger Sea array. Photo credit: Jennifer Batryn©Woods Hole Oceanographic Institution.

Two OOI gliders sit in the lab of the R/V Neil Armstrong during the transit out to the Irminger Sea array. The location of the glider oxygen sensors (blue housings forward of the tail fin) was modified so the sensor is exposed to the air when the glider surfaces. Photo credit:Jennifer Batryn©Woods Hole Oceanographic Institution.

Eyes at sea. This image was captured during the Irminger Global Surface Mooring deployment 17 August 2020 by a camera on the buoy shortly after the buoy was lowered into the water. The camera normally helps operators monitor ice buildup and storm conditions, but on that day it turned its lens on the action aboard the R/V Neil Armstrong. Photo credit:  Buoy camera©Woods Hole Oceanographic Institution.

Nico Llanos splices lines together, in preparation for the OOI Global Surface Mooring deployment. The surface mooring will be deployed in almost 3,000 m (1.8 mile) of water off of Greenland. Together, the nylon and Colmega add up to almost one mile of rope line, and provide the bottom part of the mooring above its anchor. Photo credit: Heather Furey©Woods Hole Oceanographic Institution .

Just like on land, a whiteboard serves as a notice of ongoing and completed activities aboard the R/V Neil Armstrong during the Summer 2020 Irminger Sea month-long expedition. Photo credit: Heather Furey©Woods Hole Oceanographic Institution .

Research Specialist Heather Furey prepares an Argo float for deployment off the stern of the R/V Neil Armstrong. The yellow straps are used to deploy the float while it is still in the box. The cardboard biodegrades in the water and releases the float. Photo credit: Jennifer Batryn©Woods Hole Oceanographic Institution.

OOI Engineer James Kuo checks the inductive communications on the Irminger Sea Flanking Mooring B during deployment.  Most of the instruments on this subsurface mooring transmit data to the mooring controller inductively.  The data is then sent acoustically to OOI Gliders which transmit the data to shore via satellite. Photo Credit: Jennifer Batryn©Woods Hole Oceanographic Institution.

The OOI team at the Irminger Sea Array deploying the Profiler Mooring. The yellow McLane Moored Profiler with a suite of science instruments is carefully lowered into the water.  It will measure water properties including temperature, salinity, fluorescence, dissolved oxygen and water velocity. Photo credit: Jennifer Batryn©Woods Hole Oceanographic Institution.

The OOI Irminger Sea Hybrid Profiler Mooring is deployed top-first and trails behind the ship.  Once the ship is at the desired location, the anchor is slid off the back deck, making quite a splash as it falls to the seafloor, pulling the mooring into place.  Photo credit: Jennifer Batryn©Woods Hole Oceanographic Institution.

The OOI and OSNAP science team poses on the back deck of the R/V Neil Armstrong on 27 August. 2020, after completing operations at the Irminger Sea Array. Using the last hours of good weather, equipment was secured before the eight-day voyage back to Woods Hole. Photo: Michael Sessa©Woods Hole Oceanographic Institution.

One of the advantages of going to the OOI Irminger Sea Array is the opportunity to see the northern lights (Aurora borealis).This photo was taken as the team transited home through the Labrador Sea. What a great reward for all of the hard work put in to have a successful cruise! Photo credit: Collin Dobson©Woods Hole Oceanographic Institution.