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: