Award: OCE-1657853

This project was focused on using data from an advanced oceanographic observatory, the Ocean Observatories Initiative Pioneer Array, to study ocean processes at the edge of the continental shelf. This observatory, located south of New England, has been in operation since late 2014 and provides data in near real time for a wide variety of sensors from both fixed locations using moorings as well as from vehicles including both gliders as well as Autonomous Underwater Vehicles. The ocean processes that the observatory was designed to study include both offshore motion of cold, fresh waters from the continental shelf as well as onshore motions of warm, salty water from the adjoining deep ocean. These ocean processes are very complex, and involve a wide variety of motions on different space and time scales. The biggest surprise of this project was the increasing influence of deep ocean water masses on the continental shelf. The Pioneer Array array data has identified numerous cases of large eddies formed from the Gulf Stream, called Warm Core Rings, that come close to the edge of the continental shelf and push warm salty waters onshore and cold fresh shelf waters offshore. The onshore passage of warm salty waters has become more frequent and penetrates much farther across the continental shelf than in previous decades. This has major ecological implications, as warm temperature anomalies in winter have been measured with values as high as 6 Degrees Centigrade (11 Degrees Fahrenheit) warmer than long term mean values. The Pioneer Array data has been used to identify a new exchange process in which cold fresh water is driven deeper in the water column as it is carried offshore around the periphery of a Warm Core Ring. The Pioneer Array is particularly well designed for identifying new processes as it offers both high horizontal resolution as well as extended duration, meaning that it can capture many more events than intermittent observations. An important result has been analysis of historical charts analyzing the Gulf Stream. The charts show that there was a big increase in the number of Warm Core Rings formed after the year 2000, going from 18 per year to 33 per year afterward. This has clearly had a big effect on the edge of the continental shelf, because these rings occur much more frequently. During the project, we made major efforts to communicate our results to the commercial fishing industry, the many legislative aides who visit the Woods Hole Oceanographic Institution, and the general public. One of our team members (Gawarkiewicz) regularly meets with fishers at the Commercial Fisheries Research Foundation in Rhode Island to discuss the latest research findings and how seasonal and year to year changes in temperature and salinity affect the fishing industry. In addition, our team has engaged in a number of media interviews including radio, television, and print outlets. We have all given a number of talks to the general public on the technology of the Pioneer Array, the use of gliders in ocean research, changes in the Gulf Stream and the continental shelf, and new ocean processes identified from the Pioneer Array data. We have also communicated with a number of international scientists who are interested in the design and operations of the Pioneer Array. To summarize, we have used a state of the art ocean observatory to identify significant changes in the ocean processes linking the water masses of the continental shelf and slope. The influence of the Gulf Stream, through increased Warm Core Rings, on the continental shelf water masses is increasing. The changes have significant impacts on the shelf ecosystem, due in part to the large warm temperature anomalies that have been observed. This has direct societal and economic impacts on coastal communities of New England. While our studies occurred south of New England, many of our findings can be applied to other geographic regions to determine whether similar changes in ocean processes have occurred. Last Modified: 09/17/2019 Submitted by: Glen G Gawarkiewicz