Author Posting. © The Oceanography Society, 2017.  This article is posted here by permission of The Oceanography Society for personal use, not for redistribution.  The definitive version was published in Oceanography 30, no. 2 (2017): 15–17, doi:10.5670/oceanog.2017.211.Oceanography relies heavily on observations to fuel new ideas and drive advances, creating a strong coupling between the science and the technological developments that enable new measurements. Novel observations, such as those that resolve new properties or scales, often lead to advances in understanding. Physical, biological, and chemical processes unfold over a broad range of scales—seconds to decades and millimeters to ocean basins—with critical interactions between scales. Observational studies work within a tradespace that balances spatial and temporal resolution, scope, and resource constraints. New platforms and sensors, along with the novel observational approaches they enable, address this challenge by providing access to an expanding range of temporal and spatial scales

Craig Lee

Daniel Rudnick

Melissa Omand

null null

Robert Todd

Theresa Paluszkiewicz

Oceanography

Lee, Craig M.

Paluszkiewicz, Theresa

Rudnick, Daniel L.

Omand, Melissa M.

Todd, Robert E.

Woods Hole Open Access Server

CITATIONLee, C.M., T. Paluszkiewicz, D.L. Rudnick, M.M. Omand, and R.E. Todd. 2017. Autonomous instruments significantly expand ocean observing: An introduction to the special issue on autonomous and Lagrangian platforms and sensors (ALPS). Oceanography 30(2):15–17, https://doi.org/10.5670/oceanog.2017.211.DOIhttps://doi.org/10.5670/oceanog.2017.211COPYRIGHTThis article has been published in Oceanography, Volume 30, Number 2, a quarterly journal of The Oceanography Society. Copyright 2017 by The Oceanography Society. All rights reserved. USAGEPermission is granted to copy this article for use in teaching and research. Republication, systematic reproduction, or collective redistribution of any portion of this article by photocopy machine, reposting, or other means is permitted only with the approval of The Oceanography Society. Send all correspondence to: info@tos.org or The Oceanography Society, PO Box 1931, Rockville, MD 20849-1931, USA.OceanographyTHE OFFICIAL MAGAZINE OF THE OCEANOGRAPHY SOCIETYDOWNLOADED FROM HTTP://TOS.ORG/OCEANOGRAPHYOceanography  |  June 2017 15 Autonomous Instruments Significantly Expand Ocean ObservingOceanography relies heavily on obser-vations to fuel new ideas and drive advances, creating a strong coupling between the science and the technolog-ical developments that enable new mea-surements. Novel observations, such as those that resolve new properties or scales, often lead to advances in under-standing. Physical, biological, and chemi-cal processes unfold over a broad range of scales—seconds to decades and millime-ters to ocean basins—with critical inter-actions between scales. Observational studies work within a tradespace that balances spatial and temporal resolu-tion, scope, and resource constraints. New platforms and sensors, along with the novel observational approaches they enable, address this challenge by provid-ing access to an expanding range of tem-poral and spatial scales.Over a decade ago, the 2003 Autonomous and Lagrangian Platforms and Sensors (ALPS) Workshop (Rudnick and Perry, 2003) brought together mem-bers of the then-small community of ALPS developers and users to assess existing technologies, articulate high- priority science that could be addressed by systems that employed ALPS, and identify promising directions for plat-form and sensor development. At the time of the workshop, Iridium, a critical enabling technology, was in only its fifth year of operation, the Argo array con-sisted of roughly 900 floats (of its 3,000-float target), ocean gliders were develop-mental, and small, low-power chemical (oxygen, nitrate) and bio-optical sen-sors were just beginning to be deployed for extended periods on autonomous platforms. With a few notable excep-tions, such as Argo, the Global Drifter Program, and the International Arctic Buoy Program, autonomous platforms were not widely applied to science prob-lems. The ALPS report thus focused on describing promising science applica-tions, including several ideas, such as observing boundary currents with glid-ers, the introduction of biogeochemical sensors to Argo, and autonomous plat-forms for sampling ice-covered environ-ments, that have come to fruition and are described in the papers of this ALPS spe-cial issue of Oceanography. The work-shop report noted that integrated systems composed of complementary platforms, including ALPS, ships, moorings, and remote sensing, would be needed to fully resolve the necessary spans of spatial and temporal scales. Recommendations for future development included larger, more capable floats, ALPS capable of collecting FROM THE GUEST EDITORSAn Introduction to the Special Issue on Autonomous and Lagrangian Platforms and Sensors (ALPS)By Craig M. Lee, Theresa Paluszkiewicz, Daniel L. Rudnick, Melissa M. Omand, and Robert E. ToddOceanography |  Vol.30, No.216sustained measurements under ice, bio-logical and chemical sensors, improved sensor stability and calibration protocols, and water sampling from ALPS.Autonomous platforms advanced rap-idly in the years following the 2003 ALPS workshop, fulfilling, at least in part, many elements of the vision articulated in the workshop report. A 2008 special issue of Limnology and Oceanography (Dickey et  al., 2008) focused on ALPS accom-plishments, and more recently Riser et al. (2016) and Rudnick (2016) reviewed the achievements of floats and gliders. The ALPS-2 meeting, held in February 2017 (see https://alps-ocean.us), engaged a broad community of developers and users to assess the state of ALPS tech-nologies, review their accomplishments, and discuss the way forward. This issue of Oceanography attempts to capture a sam-pling of recent scientific, technological, and operational advances.Floats have become workhorses for ocean observing. Argo has achieved global coverage with over 3,600 floats in the ice-free oceans, and includes deep and biogeochemical measure-ments (Jayne et  al.). Diverse float tech-nologies now include small, inexpensive air-deployable floats (Jayne and Bogue), water sampling and chemical analy-ses (Bresnahan et  al.), rapid profil-ing of the ocean surface boundary layer (ten Doeschate et al.), and profilers that harness surface wave energy to con-duct rapid, sustained sampling of the upper ocean (Lucas et  al.). Bio-optical sensors are now routinely deployed on autonomous platforms (e.g., Jayne et al.; Omand et  al.), with innovative analy-ses expanding the information that can be extracted from the resulting measure-ments (Omand et al.). ALPS have proven particularly effec-tive when used to create integrated observing systems capable of spanning a broad range of spatial and temporal scales. A system of drifters, floats, glid-ers, and autonomous surface vehicles, along with moorings, ship-based surveys, and satellite remote sensing, sampled in both mooring-centric Eulerian and float- following Lagrangian reference frames to investigate the processes that govern upper-ocean salinity (Lindstrom et  al.). In the program described, ALPS defined the Lagrangian reference frame and pro-vided sustained quantification of spa-tial structure around both the moorings and drifting floats. Drifters, floats, and gliders were used in the Arabian Sea to sample both boundary current variability and the small-scale dynamics that govern mixing and stirring in the interior basin (Centurioni et al.). Here, ALPS not only provided persistence and multiscale sam-pling, but also provided access to a region deemed to be too dangerous for ship-based sampling. Autonomous platforms tethered to drifting sea ice, sampling in conjunction with ALPS operating within the water column, have provided multimonth, sustained sampling of the atmosphere-ice-ocean boundary layer in the challenging Arctic seasonal ice zone (Lee et  al.). Here, ALPS provided access to ice-covered regions; persistent sampling spanning melt to freeze-up; simultaneous sampling across atmo-sphere, ice, and ocean; and the ability to resolve the small-scale processes that govern sea ice evolution. Patrolling gliders and air-deployed drifters and floats have targeted the paths of tropical cyclones, providing real-time measurements of subsurface tempera-ture and salinity to constrain intensity and path forecasts (Goni et  al.). Long-endurance gliders have been use for sus-tained, multiyear observing in coastal regions (Pattiaratchi et al.), marginal seas (Jones and Kattan), and western bound-ary currents (Todd and Locke-Wynn). Gliders provide persistent sampling of sections spanning hundreds of kilome-ters, with horizontal resolution of kilome-ters and temporal resolution of weeks, an excellent match for the dominant scales of many boundary regions. ALPS have also been used to mitigate risk, with glid-ers used to collect water column profiles over bottom-mounted acoustic Doppler current profilers in regions where trawl-ing threatens instruments that reside in the water column (Hall et al.).New platforms and sensors have expanded the utility of ALPS in novel directions. Long-endurance autono-mous surface vehicles have been used to collect boundary layer measure-ments in challenging environments that include the Arctic (Mordy et al.) and the Southern Ocean (Thomson and Girton). Faster, shorter-range autonomous kay-aks have sampled rapidly evolving small-scale variability in the Bay of Bengal and in the hazardous region near the calv-ing fronts of ice sheets (Nash et  al.). Turbulence sensors mounted on glid-ers have dramatically increased the spa-tial and temporal distribution of mixing measurements, facilitating new under-standing (St. Laurent and Merrifield; Rainville et al.). Tagged marine mammals have emerged as a compelling approach for sustained collection of profiles in regions that are difficult to access, while also pro-viding critical data about the animals themselves (Cazau et al.; Treasure et al.;  “ALPS have evolved from developmental to operational, with recent achievements demonstrating their effectiveness as tools for ocean observing.”. Oceanography  |  June 2017 17Roquet et  al.; Rossby et  al.). Powerful autonomous underwater vehicles (AUVs), guided by rigorously optimized search strategies, have been used to search for dif-ficult submerged targets, such as Project Recover’s efforts to locate the remains of US servicemen missing since the Second World War (Terrill et al.). ALPS can exploit numerical models to inform strategies and guide sampling, while also delivering data for assimilation. Goni et al. and Todd and Locke-Wynn describe the impact of assimilating data collected by ALPS into forecast models, where the real-time data delivery, per-sistent sampling, and spatial distribu-tion provided by ALPS make them valu-able contributors. Nguyen et al. examine the impact of Arctic observations of ocean state estimates and use a model to assess the practicality and potential impact of profiling float deployments in the ice- covered Arctic. Lermusiaux et al. describe an approach for optimizing sam-pling constrained by both the desire to reduce uncertainty and the practicali-ties of choosing efficient, achievable flight paths. Thompson et  al. detail recent efforts to automate glider sampling and path planning to better support deploy-ments of large numbers of vehicles, while Kaeli advocates for co-robotic control that retains humans in the loop, and pro-vides a summary-based mapping exam-ple of how decision-critical data might be transmitted to human operators using minimal bandwidth.Beyond the sampling capabilities provided by ALPS, the achievements of the past decade point to the impor-tance of the new operational modali-ties that they enable. Much of the effi-ciency provided by ALPS rests on their ability to exploit a wide range of deploy-ment and recovery options, reducing dependence on dedicated research ves-sels. In addition to conventional oper-ations from research ships, autono-mous platforms have been launched from aircraft (e.g.,  Jayne and Bogue) and deployed from vessels of opportu-nity (Centurioni et al.), which facilitates distributed observing. Recent drifter, float, and glider deployments in a remote region of the North Pacific have been serviced by a modest, chartered sail-boat (Lindstrom et  al.). Autonomous platform deployments onto sea ice are often supported by aircraft that land on sea ice to shift personnel and equipment (Lee et al.). Sustained observing requires efficient, cost-effective operations. ALPS often achieve this by relying on local logistics, where modest investments in training can provide responsive, flexible operations at low cost.ALPS have evolved from developmen-tal to operational, with recent achieve-ments demonstrating their effectiveness as tools for ocean observing. The per-sistence and scalability of autonomous approaches provide the ability to sam-ple regions of the spatial and temporal spectrum that have previously been dif-ficult to access. Integrated systems that include ALPS, moorings, ships, and/or remote sensing can resolve multiscale processes and support investigations at the interfaces between disciplines, sam-pling ocean, atmosphere, and ice dynam-ics and their interactions with ecosystems and biogeochemistry. The efficiencies provided by ALPS also make them prom-ising tools for climate-scale observing, where inexpensive approaches with sim-ple logistics are required to sustain criti-cal measurements over decades. In addi-tion to advancing capabilities, future ALPS developments might focus on plat-form efficiency, including efforts toward improved reliability and ease of use. Sensor calibration and cross- calibration grow in importance with the deploy-ment of large numbers of autonomous sensors and the use of new instruments for measuring biological and biogeo-chemical parameters. Sensors for oxy-gen, nitrate, pH, and a range of bio- opti-cal properties are being deployed widely, but the need for additional small, effi-cient sensors for biological and chemical parameters remains. As the articles in this special issue of Oceanography witness, ALPS have already logged significant scientific and operational achievements, and they promise exciting developments stretch-ing into the future. REFERENCESDickey, T.D., E.C. Itsweire, M.A. Moline, and M.J. Perry. 2008. Introduction to the Limnology and Oceanography Special Issue on Autonomous and Lagrangian Platforms and Sensors (ALPS). Limnology and Oceanography 53, https://doi.org/ 10.4319/lo.2008.53.5_part_2.2057.Riser, S.C., H.J. Freeland, D. Roemmich, S. Wijffels, A. Troisi, M. Belbéoch, D. Gilbert, J. Xu, S. Pouliquen, A. Thresher, and others. 2016. Fifteen years of ocean observations with the global Argo array. Nature Climate Change 5:145–153, https://doi.org/10.1038/nclimate2872.Rudnick, D.L. 2016. Ocean research enabled by underwater gliders. Annual Review of Marine Science 8:9.1–9.23, https://doi.org/10.1146/annurev-marine-122414-033913.Rudnick, D.L., and M.J. Perry, eds. 2003. ALPS: Autonomous and Lagrangian Platforms and Sensors: A Report of the Workshop Held March 31–April 3, 2003. 64pp., https://geo-prose.com/pdfs/alps_report.pdf.AUTHORSCraig M. Lee (craig@apl.washington.edu) is Senior Principal Oceanographer and Professor, Applied Physics Lab, University of Washington, Seattle, WA, USA. Theresa Paluszkiewicz is Program Officer, Office of Naval Research, Arlington, VA, USA. Daniel L. Rudnick is Professor, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA, USA. Melissa M. Omand is Assistant Professor, University of Rhode Island, Graduate School of Oceanography, Narragansett, RI, USA. Robert E. Todd is Assistant Scientist, Woods Hole Oceanographic Institution, Woods Hole, MA, USA.ARTICLE CITATIONLee, C.M., T. Paluszkiewicz, D.L. Rudnick, M.M. Omand, and R.E. Todd. 2017. Autonomous instruments significantly expand ocean observing: An introduction to the special issue on autono-mous and Lagrangian platforms and sensors (ALPS). Oceanography 30(2):15–17, https://doi.org/10.5670/oceanog.2017.211.

Autonomous instruments significantly expand ocean observing : an introduction to the special issue on autonomous and Lagrangian platforms and sensors (ALPS).

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Autonomous instruments significantly expand ocean observing : an introduction to the special issue on autonomous and Lagrangian platforms and sensors (ALPS).

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