John Kerfoot

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.

The Trans-Atlantic Slocum Glider Expeditions: A Catalyst for Undergraduate Participation in Ocean Science and Technology

This paper provides an overview of the education programs developed for underwater gliders, how these programs were applied to the trans-Atlantic missions, and the educational lessons learned. It concludes with a perspective on how this educational effort provides the foundation for an international partnership to explore the world ocean on a second NOAA challenge, a repeat of the 1870 Challenger Mission, the first scientific circumnavigation of the globe.

Transition of Slocum Electric Gliders to a sustained operational system

In the 1980s Slocum Gliders were a vision of Douglas C. Webb, which Henry Stommel promoted in a science fiction article published in Oceanography in 1989. In the early 1990s the glider concept was proven and in the late 1990s open water test flights were done at LEO15. In 2002 Rutgers University COOL Group began collaborating with Webb Research Corporation on the development and deployment of the Gliders. Initially the deployments were on the order of hours to a few days with constant human supervision. By the latter half of 2003 Slocum Gliders were routinely flying multiple week missions and calling in to the automated Glider Command Center on Rutgers main campus via satellite phone to provide a status update, download data and receive any new mission commands. The ability to operate Gliders with minimal human intervention for extended periods of time has allowed Rutgers to integrate them into the New Jersey Shelf Observing System. Since November 2003 a Glider has been occupying the Endurance Line, a 123 km track located between the LEO15 nodes and the shelf break, on a monthly basis. The sustained data set being collected permits scientists to go beyond collecting snapshots of information for short-term projects and gather long-term, expanded region data sets that would allow the tracking of trends over multiple years. While the Endurance Line Glider has been flying, additional Gliders have been operating for shorter periods of time on the West Florida Shelf, in the northwestern Mediterranean and in the Hudson River plume. Like the Endurance Line Glider, these Gliders are controlled by the Glider Command Center via satellite phone. Rutgers would be adding 2 Gliders to its fleet the end of this year bringing the total to 6 electric Gliders. One Glider would be dedicated to the West Florida Shelf Red Tide research program and the second would be used in the Mediterranean to look at the significance of Sahara Desert dust on biological and optical signals. Dedication of the new Gliders to these two research projects would enable Rutgers to have a continual presence in these regions as well as on the shelf of New Jersey.

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.

Wind-driven response of the Hudson River Plume and its effect on dissolved oxygen concentrations

The Lagrangian Transport and Transformation Experiment (LaTTE) study of the Hudson River Plume has now completed 2 of its 3 field seasons. The interdisciplinary study is being conducted in a sustained coastal research observatory that provides a spatial and temporal context for adaptive shipboard sampling. Observations from the second LaTTE field season are used here to describe the processes responsible for a previously unexplained recurrent hypoxia region along the New Jersey coast.

Laser line scan performance prediction

The effectiveness of sensors that use optical measurements for the laser detection and identification of subsurface mines is directly related to water clarity. The primary objective of the work presented here was to use the optical data collected by UUV (Slocum Glider) surveys of an operational areas to estimate the performance of an electro-optical identification (EOID) Laser Line Scan (LLS) system during RIMPAC 06, an international naval exercise off the coast of Hawaii. Measurements of optical backscattering and beam attenuation were made with a Wet Labs, Inc. Scattering Absorption Meter (SAM), mounted on a Rutgers University/Webb Research Slocum glider. The optical data universally indicated extremely clear water in the operational area, except very close to shore. The beam-c values from the SAM sensor were integrated to three attenuation lengths to provide an estimate of how well the LLS would perform in detecting and identifying mines in the operational areas. Additionally, the processed in situ optical data served as near-real-time input to the Electro-Optic Detection Simulator, ver. 3 (EODES-3; Metron, Inc.) model for EOID performance prediction. Both methods of predicting LLS performance suggested a high probability of detection and probability of identification. These predictions were validated by the actual performance of the LLS as the EOID system yielded imagery from which reliable mine identification could be made. Future plans include repeating this work in more optically challenging water types to demonstrate the utility of pre-mission UUV surveys of operational areas as a tactical decision aid for planning EOID missions.

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.

Successes and lessons learned from OOI end-to-end system data quality audit

The Ocean Observatories Initiative (OOI) consists of seven research sites with over 800 instruments collecting ocean, seafloor, and meteorological data in the worlds oceans, extending from the Irminger Sea to the Southern Ocean. The scale with which data are produced from the instruments and their platforms presents key challenges, including how to (1) build data and information management infrastructure that associates measurements from multiple instruments for concurrent observations, (2) develop data delivery mechanisms that meet a variety of needs, (3) ensure timely release of data, and (4) formulate capabilities to provide stable, longterm support for research and societal needs. As a strategy for maintenance of the sustained, large-scale, and variety of scientific observations collected, the OOI Cyberinfrastructure (CI) developed an end-to-end system designed to store, query, process, and disseminate the compiled information. These resources include raw instrument values and derived data products, metadata associated with instrument and platform deployments (e.g., deployment dates, water depths, instrument manufacturer, etc.), calibration coefficients, data provenance and descriptors of computational algorithms and transformation functions, and other related outputs. As with many data and information management systems, the need to monitor and improve upon the performance of the various interrelated components of the CI is an integral part in establishing the success of the system. For this reason, the data evaluation team at Rutgers initiated an end-to-end system data quality audit that ensures the system can accurately and completely deliver data within the required specifications. This was applied to a subset of representative platforms for all instrument types. Thus, based on specific system failures that can prevent production of quality data products, we prepared a set of tests and built tools that function as a troubleshooting method for system repair and enhancement. The method was used to report on the systems ability to: (a) Respond to data queries (b) Provide links to data product files (c) Produce all relevant data products (d) Produce correct provenance information (e) Produce quality science data products (f) Parse data with the correct specifications and the correct number of particles (g) Calculate different data levels with correct dimensions and units. To further assess the system fidelity to produce high quality data, a subject matter expert (SME) was consulted to provide outside validation of the OOI data quality, especially for some of the unique instrument classes that have less available documentation or publication records to consult. If the end-to-end system data quality audit logs successful system performance, the data checked were marked as ready to release to the public. If the data quality audit logs failures, they were investigated and a repair ensued, followed by another data check. Feedback from the end-to-end system data quality audit will be communicated to the public in form of annotations. This is needed to complete the end-toend systems ability to communicate information from and about the system. Considering that the data are continuously collected in the water and the system configuration can change over time, it is very important not to become complacent with the end-to-end system once it is in place. To ensure continuity of the required quality, an end-to-end system data quality audit is needed on regular basis.

The U.S. National glider network: Application of QARTOD recommended quality control methods to glider CTD data sets

A current focus of the Integrated Ocean Observing Systems National Glider Data Assembly Center (NGDAC) is on the adoption and implementation of quality control (QC) methods in use by the broader oceanographic community. In 2015, U.S. IOOS, soliciting input from this community, began drafting a glider specific QC manual focusing on temperature and salinity measurements made by autonomous underwater gliders. The manual implements guidance provided by the Quality Assurance/Quality Control of Real-Time Oceanographic Data (QARTOD) Manual for the Real-Time Quality Control of In-situ Temperature and Salinity Data manual [1] and focuses on the observations of temperature, conductivity, and on the calculation of practical salinity, collectively referred to herein as TS observations. The manual has recently been officially accepted and the NGDAC has started to design and implement a subset of the tests outline in the document. The NGDAC recognizes the unique knowledge and understanding, by the glider operators, of the global and local environments they work in. As such, we propose a two-fold approach to glider data quality control: 1) Glider operators may (or may not) apply global and/or locally unique QC checks of both real-time and delayed-mode glider data sets prior to submitting the data sets to the NGDAC, 2) In the event that these QC tests are not applied at the local level, the NGDAC will apply QARTOD recommended methods to the received data sets, storing the results of this process in an additional set of variable written to the NetCDF files distributed to the public and transmitted on the Global Telecommunication System. This approach preserves the original data sets while providing the first step in a comprehensive approach to ensuring that the data delivered by the National Glider DAC are suitable for science-quality analysis and model assimilation. We expect to provide this level of QC by the end of 2016.

Rutgers university coastal ocean observation laboratory (RU-COOL) advanced modeling system developed to cost-effectively support offshore wind energy development and operational applications

Studies are underway that are evaluating the offshore wind resource along the coast of New Jersey in an effort to determine the variability of the wind resource. One major source of variability is the sea-land breeze circulation that occurs during periods of peak energy demand. The sea breeze front, driven by the thermal difference between the warm land and relatively cooler ocean during hot summer afternoons, propagates inland and under weak atmospheric boundary layer wind conditions can affect much of the state. However, little is known about the offshore component of the sea breeze circulation. A large zone of subsidence over the coastal ocean, and subsequent divergence near the surface, is known to occur in unison with the inland-propagating sea breeze front. RU-COOLs unique monitoring and modeling endeavors are focused on exploring the details of these offshore dynamics of the sea breeze circulation and its development during both coastal upwelling and non-upwelling events. A case study from the August 13, 2012 is analyzed in this paper; coastal upwelling resulted from persistent south to southeasterly winds for days. In addition, a sea breeze front formed in the afternoon, propagating inland and producing a zone of weak winds offshore that coincides with the targeted area of offshore wind development. Model results, using unique declouded satellite sea surface temperature data, are validated inshore against weather radar and offshore against coastal ocean radar (CODAR). Small-scale offshore wind variability is resolved and verified in the model, which will be critical for producing accurate and reliable offshore wind resource assessments and precise operational forecasts for the future.