Clayton Jones

SLOCUM: an underwater glider propelled by environmental energy

SLOCUM is a small gliding AUV of 40 000-km operational range which harvests its propulsive energy from the heat flow between the vehicle engine and the thermal gradient of the temperate and tropical ocean. The design of both the glider and the thermal engine are discussed including the design genesis and approach, field trial results, concept strength, and limitations and potential use.

Slocum Gliders: Robust and Ready

Buoyancy driven Slocum Gliders were a vision of Douglas Webb, which Henry Stommel championed in a futuristic vision published in 1989. Slocum Gliders have transitioned from a concept to a technology serving basic research and environmental stewardship. The long duration and low operating costs of Gliders allow them to anchor spatial time series. Large distances, over 600 km, can be covered using a single set of alkaline batteries. Since the initial tests, a wide range of physical and optical sensors have been integrated into the Glider allowing measurements of temperature, salinity, depth averaged currents, surface currents, fluorescence, apparent and inherent optical properties. A command/control center, entitled Dockserver, has been developed that allows users to fly fleets of gliders simultaneously in multiple places around the world via the Internet. Over the last 2.5 years, Rutgers Gliders have logged 27 056 kilometers, and flown 1357 days at sea. Gliders call into the automated Glider Command Center at the Rutgers campus via satellite phone to provide a status update, download data, and receive new mission commands. The ability to operate Gliders for extended periods of time are making them the central in situ technology for the evolving ocean observatories. Off shore New Jersey Gliders have occupied a cross shelf transect and have documented the annual variability in shelf wide stratification on the Mid-Atlantic Bight and the role of storms in sediment resuspension. The sustained data permits scientists to gather regional data critical to addressing if, and how, the oceans are changing.

Using a fleet of slocum battery gliders in a regional scale coastal ocean observatory

Rutgers University is constructing the New Jersey Shelf Observing System (NJSOS), a regional-scale (300 km /spl times/ 300 km) observatory for the coastal ocean which includes the LEO15 site. Spatially extensive surface remote sensing systems (CODAR, satellites) are continuously collecting data in this region. However, only during the month of July in 1998, 1999, 2000 and 2001 were extensive subsurface physical and optical data collected and only in the LEO15 vicinity. The July samplings were labor and boat intensive. Obtaining the subsurface data in the LEO15 area required the use of up to seven boats and manpower to collect, process and analyze the information. To make the collection of subsurface data in the NJSOS more efficient, less expensive and more complete both spatially and temporally, Rutgers University has worked with Webb Research Corporation on their development of the Slocum Glider autonomous underwater vehicles. Currently Rutgers owns a fleet of four Gliders that can be used individually or as a group to collect subsurface data in the observatory region.

Automated control of a fleet of Slocum gliders within an operational coastal observatory

Rutgers University, Webb Research, Dinkum Software, Wetlabs, and Mote Marine Lab have been collaborating on the development and deployment of a fleet of Slocum gliders to continuously patrol the coastal oceans. The gliders are AUVs that move up and down in the water column in a saw-toothed pattern by changing their buoyancy. Presently, during a deployment, humans must look at the data, determine if a change in the sampling protocol is indicated by the data and if so, upload a new mission to the glider. Rutgers has been focusing on the development and testing of the software to automate the control of the gliders. Using agent oriented programming, the goal of the software is to assimilate data received by the command center from the gliders and other agents, such as CODAR and satellites, and generate new missions for the glider fleet. The software is being developed on a Linux system. The ability of the command center computer to automatically analyze data from a glider or gliders and recognize thermoclines and haloclines were the first pieces of the control software to be developed. Testing of the thermocline software has been completed using both hand generated data and real data collected in January 2003 from the Gulf of Mexico. New sensors are being added for applications in the New York Bight and on the West Coast Florida Shelf.

Lagrangian coherent structure assisted path planning for transoceanic autonomous underwater vehicle missions

Transoceanic Gliders are Autonomous Underwater Vehicles (AUVs) for which there is a developing and expanding range of applications in open-seas research, technology and underwater clean transport. Mature glider autonomy, operating depth (0–1000 meters) and low energy consumption without a CO2 footprint enable evolutionary access across ocean basins. Pursuant to the first successful transatlantic glider crossing in December 2009, the Challenger Mission has opened the door to long-term, long-distance routine transoceanic AUV missions. These vehicles, which glide through the water column between 0 and 1000 meters depth, are highly sensitive to the ocean current field. Consequently, it is essential to exploit the complex space-time structure of the ocean current field in order to plan a path that optimizes scientific payoff and navigation efficiency. This letter demonstrates the capability of dynamical system theory for achieving this goal by realizing the real-time navigation strategy for the transoceanic AUV named Silbo, which is a Slocum deep-glider (0–1000 m), that crossed the North Atlantic from April 2016 to March 2017. Path planning in real time based on this approach has facilitated an impressive speed up of the AUV to unprecedented velocities resulting in major battery savings on the mission, offering the potential for routine transoceanic long duration missions.

Enabling discovery based science with Webb Gliders

Buoyancy driven Slocum Gliders were a vision of Douglas Webb, which Henry Stommel championed in a futuristic vision published in 1989. Slocum Gliders have transitioned from a concept to a technology serving basic research and environmental stewardship. The long duration and low operating costs of Gliders allow them to anchor spatial time series. Large distances, over 600 kilometers, can be covered using a single set of alkaline batteries. Since the initial tests, a wide range of physical and optical sensors have been integrated into the Glider allowing measurements of temperature, salinity, depth averaged currents, surface currents, fluorescence, apparent and inherent optical properties. The ability to operate Gliders for extended periods of time are making them the central in situ technology for the evolving ocean observatories. Off shore New Jersey Gliders have occupied a cross shelf transect and have documented the annual variability in shelf wide stratification on the Mid-Atlantic Bight and the role of storms in sediment resuspension. The sustained data permit scientists to gather regional data critical to addressing if, and how, the oceans are changing. One of next major regions we will use this technology is to study the climate induced impacts on the food webs along the West Antarctic Peninsula.

Gliders as maturing technology: Using gliderpalooza as means to develop an integrated glider community

Underwater autonomous gliders have transitioned from exotic experimental systems to becoming a standard platform capable of collecting data over a critical range of spatial and temporal scales in the ocean. The data are proving to be extremely valuable for addressing a wide range of basic and applied research questions. These communities are growing from distributed research and/or education groups. It is crucial as systems continue to evolve that there is an effort to “harmonize” data products while preserving the diversity of approaches/science/experimentation. As the gliders have matured and new battery solutions provide additional energy, there is an increased focus on the integration of a wider range of sensors to be incorporated into gliders. Many of these new classes of sensors will be particularly effective for characterizing biological processes in the coastal ocean. As biological sensors generally provide proxy estimates of a parameter, developing robust quality control and assurance procedures is critical. These new sensors will be more power intensive thus requiring the development of planning tools for increasing energy efficiency during missions. Given the significant growth in the highly distributed glider community, efforts are now focusing on the development mission planning tools to allow for efficient operation of glider fleets. To further collaboration and standardization of the growing number of glider operators we have initiated a series of community efforts called glider paloozas. We had an exceptional turnout last year, encompassing 18 U.S. and Canadian partners, 28 gliders, 36 glider deployments, and spatial coverage from coastal regions of Newfoundland to the Gulf of Mexico and offshore to Bermuda. The coordinated effort focused on several research themes including continental shelf circulation, fish migrations, and storm activity. The main goals of last years effort were to produce a seamless flow of real-time glider data into the Global Telecommunications System (GTS) via DMAC and into the regional ocean models and demonstrate the potential of a U.S. national glider network. This is in line with the goal to increase glider data accessibility from Federal and Academic oceanographic modeling communities, the U.S. Integrated Ocean Observing System (IOOS), and other federal funding agencies (i.e., NSF). In order to demonstrate the value and necessity of the planned U.S. national glider network and build on last years successes, we hope to continue these efforts and require that all glider data produced by Gliderpalooza 2015 participants be uploaded by the individual operators to the DAC 2.0 and into GTS.

Observing storm-induced sediment resuspension processes in the mid-atlantic bight with Slocum Gliders

Storm-induced sediment resuspension events are examined using physical/optical sensors deployed on Slocum Gliders. Two types of storm response are found. In summer, the intense seasonal stratification limits sediment resuspension even during hurricanes. In contrast, winter storms suspend sediment throughout the full water column. The fall transition between seasons starts with surface cooling that preconditions the shelf for mixing during fall storms. Focusing on a classic fall northeaster, sediment resuspension was limited to below the weakening pycnocline early in the storm. After the pycnocline was eroded, particles immediately filled the water column. The optical signals suggest that suspended particles are likely similar materials, which implies the reduced slope of the backscatter profiles is caused by an increase in vertical transport or turbulent mixing. Wave bottom orbital velocities during this time were decreasing, and glider vertical velocities show no indication of enhanced vertical velocities reflecting full water column Langmuir cells. We conclude the enhanced mixing is related to the interaction of the surface and bottom boundary layers as the stratification is eroded, and the observed variability is associated with the tide.