Posts Tagged ‘Coastal Pioneer Array NES’
Wave Statistics from 3-Axis Motion Sensors on OOI Surface Buoys
The Ocean Observatories Initiative (OOI) Pioneer Array at the New England Shelf (Pioneer-NES) collected data for nine years from November 2013 through November 2022 across the shelf break. Of the three Surface Moorings in the array (Inshore – ISSM (40.37°N, 70.88°W); Central – CNSM (40.14°N, 70.77°W); Offshore – OSSM (39.94°N, 70.89°W), only CNSM was equipped with a surface wave sensor: the Axys Technologies Tri-Axys Directional Wave Sensor (WAVSS). This meant that observations on wave data were limited to a single location within the array. Recognizing that data from a single location could be restrictive for some types of analysis, the Coastal and Global Scale Nodes Group (CGSN) identified an opportunity to increase the number of surface wave observations and extend their geographic extent to the full cross-shelf span of the Pioneer-NES Moored Array. This was accomplished by using the engineering data collected by the MicroStrain 3-axis motion sensors (MOPAK) deployed on all three surface moorings. The data collected by the MOPAKs can be used to compute the bulk and directional wave statistics at each Surface Mooring in the array.
The MOPAK sensors collected triaxial acceleration, angular rate, and magnetic orientation for 20-minutes at 10 Hz once-an-hour. These data are used to compute the buoy displacements and velocities. A zero-crossing algorithm, which identifies the number of times the buoy vertical displacement (heave) crosses zero (indicative of wave motion), is used to calculate six bulk wave statistics: significant wave height (Hsig) and period (Tsig); wave height (H10) and period (T10) of the highest 10% of waves; and the mean wave height (Havg) and period (Tavg).
The wave power and cross-spectrums are used to compute five directional wave statistics: peak wave height (Hs) and period (Tp); mean wave direction and spread; and an alternative method for significant wave height (Hm0). The MOPAK-derived wave statistics were validated against, and showed excellent agreement with, both the WAVSS dataset from the CNSM mooring and wave datasets collected by National Data Buoy Center wave buoys 44097 (Block Island, RI – 40.97°N, 71.12°W) and 44008 (Nantucket, MA – 40.50°N, 69.25°W).
[media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/10/Screenshot-2023-10-31-at-3.12.55-PM.png" link="#"]Figure 1. The significant wave height (Top) and mean wave period (Bottom) at the Pioneer-NES Central Surface Mooring for Deployment 11 (Apr. 2019 – Sept. 2019) as measured by the WAVSS (blue), calculated from the MOPAK (red), and from the two nearest located NDBC buoys – Nantucket (green) and Block Island (grey).[/media-caption]The Python code to process a MOPAK dataset into a wave dataset is available to users as the process_mopak.py module in the public OOI Data Exploration GitHub repository. The wrapper function calculate_wave_statistics in the module accepts a deployment’s worth of MOPAK data and returns a new dataset with the calculated wave statistics, including attributes, units, and associated metadata, which may be saved as a new netCDF file. This process triples the number of surface wave datasets at the Pioneer-NES Array, allows for validation of the existing WAVSS wave dataset, and opens new possibilities for studying the wind-wave field across the NES-break.
We encourage users to work with the MOPAK code to generate surface wave statistics, and to submit any questions to the OOI HelpDesk.
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NSF Issues Notice of Draft Supplemental Site-Specific Environmental Assessment for Pioneer Relocation
The NATIONAL SCIENCE FOUNDATION posted the following announcement today, September 29, 2023:
MEMORANDUM FOR: TRIBES, GOVERNMENT AGENCIES, ORGANIZATIONS, INDIVIDUALS, AND INTERESTED PARTIES
FROM: NATIONAL SCIENCE FOUNDATION (NSF)
RE: Notice of Availability of a Draft Supplemental Site-Specific Environmental Assessment for the NSF Ocean Observatory Initiative (OOI) Pioneer Array Modifications and Relocation to the Mid-Atlantic Bight
The National Science Foundation (NSF) gives notice of the availability of the “Draft Supplemental Site-Specific Environmental Assessment for Pioneer Array Modifications and Relocation to the Mid-Atlantic Bight” (Draft SSSEA) for review and public comment.
NSF proposes to fund the relocation, operation, and maintenance of the NSF Ocean Observatory Initiative’s (OOI) Pioneer Array to the Mid-Atlantic Bight (MAB) off North Carolina in the Northwest Atlantic Ocean (Proposed Action). The OOI is a globally distributed, networked, ocean-focused research observatory with arrays of sophisticated instruments that utilize cutting-edge technologies to observe and study ocean processes. The Pioneer MAB Array would represent a Coastal Scale Node component of the OOI. The Pioneer MAB Array is designed to resolve transport processes and ecosystem dynamics in the vicinity of the shelf-break front, a region of high biological productivity and complex oceanographic dynamics that include intense mesoscale variability and episodic event disturbances (i.e., hurricanes). It would collect high-resolution, multidisciplinary, synoptic measurements spanning the shelf break on horizontal scales from a few kilometers to several hundred kilometers. The array is designed and planned to be relocatable approximately (~) every 5 years with new locations proposed by the NSF with input from the scientific community.
The Proposed Action would (1) relocate the Pioneer New England Shelf (Pioneer NES) Array to the southern MAB (Pioneer MAB Array, Figure 1); 2) modify the mooring designs for the new site water depths; and 3) include additional scientific instrumentation on the moorings. The Proposed Action would occur within the Exclusive Economic Zone (EEZ) of the U.S. but outside of state waters. The Pioneer MAB Array would be a T-shape array located off the coast of Nags Head, North Carolina, starting ~24 kilometers (km) (~13 nautical miles [nm]) offshore, extending ~59 km (~32 nm) east/west and ~49 km (~26 nm) north/south across the continental shelf, centered at the shelf-break front. The Project Area, including the surrounding area of potential effect, would consist of 10 moorings and a 2 km by 2 km (1 nm by 1 nm) square around the center point of each of the mooring locations. In addition, there would be mobile assets, such as autonomous underwater vehicles (AUVs) and gliders that would operate around the moorings. Gliders and AUVs would run underwater missions along tracks in the vicinity of the moored array. Two (2) AUVs and four (4) gliders would be used to provide underwater monitoring abilities along and across the shelf and within the waters of the continental slope. Gliders would be deployed on a 60-90-day rotation schedule and would be operated continuously along pre-determined paths, while the AUVs would be deployed for limited periods of ~4 days every 2 months.
[media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/09/SSSEA-Figure-1-revised38-scaled.jpg" link="#"]Figure 1. Proposed Pioneer MAB Array of Moorings and Surface Projection of Underwater Track lines for Mobile Assets[/media-caption]The Pioneer MAB Array is proposed to be deployed in April 2024. The array and associated AUVs and gliders would be serviced primarily by vessels from the U.S. Academic Research Fleet (ARF) with support from local chartered vessels when needed; a proposed schedule for installation, operations, and maintenance is included in the Draft SSSEA. Installation, operations, and maintenance activities would use standard methods and procedures currently used by the ocean observing community. Like on the Pioneer NES Array, the moorings deployed at Pioneer MAB would include anchors and benthic nodes designed to be fully recoverable, minimizing impact on the seabed.
The Draft SSSEA evaluated the potential impacts of the Proposed Action on the human and natural environment, pursuant to the National Environmental Policy Act (NEPA) and tiers to existing OOI NEPA documentation1. The Draft SSSEA focused on activities and associated potential impacts on marine resources (e.g., geological, marine biological, socioeconomic, etc.) that were not previously assessed by existing OOI NEPA analyses. The conclusions from the Draft SSSEA were used to inform the NSF Division of Ocean Sciences (OCE) of potential environmental impacts of the Proposed Action.
1OOI NEPA documents are available on the NSF website.
Impacts from the placement of proposed mooring anchors or nodes on the seafloor would include temporary disturbance of soft sediments and coverage of relatively small areas of substrate by the anchors and scientific sensors (~37 m2) for the deployment period. Over time, the natural movement of sediments by ocean currents and burrowing organisms would reestablish natural bottom topography. Upon conclusion of operations, the entire system, including anchors and nodes, would be removed from the MAB Project Area. A small amount of Essential Fish Habitat (EFH) may potentially be impacted during installation activities. The short-term and minor increases in turbidity and sedimentation resulting from system installation, operations, maintenance, and removal would not affect the ability of EFH to support healthy fish populations, and affected areas are expected to recover quickly. The vessels and activity associated with installation and maintenance of the moorings may cause marine species, such as Endangered Species Act (ESA)-listed marine mammals, to avoid the immediate vicinity of the proposed Pioneer MAB Array sites, but this impact would be brief and temporary due to the nature of the proposed activities (estimated time to deploy a mooring with one vessel is 12 to 24 hours). Entanglement and vessel strike/collision threats to marine mammals or sea turtles are not anticipated due to the equipment design, slow operational speed (0.5 to 2 knots), and use of NMFS standard oceanographic marine mammal vessel strike avoidance measures, including special measures for North Atlantic Right Whale. The use of gliders and AUVs is not expected to affect marine species, as the proposed gliders and AUVs are self-contained and move slowly within the water column similar to a dolphin or whale. Additional new scientific instrumentation sensors would be mounted on or incorporated into the existing mooring designs; however no adverse effects to marine species are anticipated from the new sensors. Mooring sites were selected to avoid historic and cultural resources (e.g., shipwrecks).
Specific sensitive areas were considered during early planning and siting of the Pioneer MAB Array. The array would not overlap with or be anticipated to impact artificial reefs or fishery nursery areas. Four of the Pioneer MAB Array moorings would be located within the loggerhead sea turtle Constricted Migratory Corridor; however, they are not anticipated to impede sea turtle migration. The Pioneer MAB Array would not overlap with loggerhead sea turtle Coastal Critical Habitat Designation (sargassum habitat). The Pioneer MAB Array’s southernmost mooring would be located within a joint Snapper-grouper/Coral Reefs and Hardbottom/Dolphin and Wahoo Habit Areas of Particular Concern (HAPC) designated by the South Atlantic Fisheries Management Council (SAFMC). The small scale and temporary nature of the single mooring would have little to no impact on the HAPC. A survey conducted of the sites also did not indicate the existence of corals.
Due to the distance from shore, small footprint, localized and temporary nature (~5 years), interactions between the Proposed Action and other ocean users, including fishing operations, in the study area are expected to be limited. Other activities, including fisheries, could occur within the proposed project area; a safe distance, however, would need to be kept from Pioneer MAB Array individual moorings. Any potential space-use conflicts would be minimized through outreach and communication with ocean users. The USCG would be contacted prior to the deployment of moorings as part of the Private Aids To Navigation (PATON) approval process and the Pioneer MAB Array moorings would be easily visible and avoidable. All mooring locations and associated components of the Pioneer Array would be published in NOAA charts, Notice to Mariners and Local Notice to Mariners. Gliders and AUVs would be marked with the name of the owning organization and a contact telephone number that ocean users could call to report any encounters at sea.
The Draft SSSEA also assessed potential cumulative effects of the Proposed Action. Overall, the combination of the proposed activities with other activities occurring in the region is expected to produce only a negligible increase in overall disturbance effects on the marine environment. Given the distance from shore, small footprint, temporary nature, and experience with Pioneer NES, significant impacts from the Proposed Action are not anticipated on the marine environment. While the Proposed Action may affect EFH and ESA-listed species, adverse effects are not likely. NSF will consult with federal regulatory agencies as applicable and appropriate.
Additional information about the proposed Pioneer MAB Array can be found in the Draft SSSEA and tiered OOI NEPA documentation, including details on relocation, operations, and maintenance; scientific instrumentation; potential effects, and diagrams of the array components.
After reviewing and considering all public comments received during the public comment period and regulatory processes, NSF will issue a Final Supplemental Site-Specific Environmental Assessment (Final SSSEA), accompanied by a decision document.
Public Comments:
The Draft SSSEA regarding the proposed action is posted for public comment on the NSF website closing on October 28, 2023. We welcome any comments you may have on the Draft SSSEA. Comments may be submitted via email to: nsfnepaooipioneer@nsf.gov. Comments received will be addressed in the Final SSSEA.
Read MoreOOI Engineers Develop New Rechargeable Lithium-ion Battery Pack
By John Lund, Research Associate, Woods Hole Oceanographic Institution
The final deployment of the Coastal Pioneer Offshore Mooring (CP04OSPM-00016) was the first deployment of a prototype rechargeable lithium-ion battery pack. The deployment was a success with the battery pack providing power throughout the entire 6.5-month deployment.
Working with Mathews Associates Inc. the OOI engineering team developed a drop-in replacement lithium-ion rechargeable battery pack to replace the original one-time use alkaline packs. Each alkaline pack consists of 72 D-sized batteries that are fabricated into a hexagonal assembly. Nine of these battery packs are fitted into a buoy battery chassis that fits inside the buoy well. The packs are wired together in parallel to provide the required voltage to power the computer (buoy controller) responsible for telemetry and data-logging.
Pioneer moorings are nominally deployed for 6-month intervals. Variability in ship scheduling requires that the buoys be capable of operating for 7+ months. The alkaline battery chassis was designed to fit enough packs to power the buoy for the planned duration and or until the recovery ship arrived.
[media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/08/Lithium-batteries.jpg" link="#"]Lithium Battery chassis during testing and integration with the buoy computer. Battery chassis is on the left. Buoy end cap with Linux computer board on the bench. Wire Following Profiler center on the floor collects the majority of the Profiler Mooring data set.[/media-caption]The Offshore mooring was selected to be a test mooring because it is one of the deeper moorings in the New England Shelf (NES) Pioneer Array and as such logs and transmits more data than a shallower mooring. The larger data sets mean that the buoy up-time, and therefore power usage, is greater than one in shallower water so this would be a tougher test of the lithium-ion packs.
Although there is an increased cost to purchasing the initial set of lithium batteries there are many advantages to the rechargeable batteries. Because the alkaline packs are conservatively sized for the deployment there is often a considerable amount of power remaining in the packs when they are recovered, yet this remaining power is insufficient for another full deployment, and new batteries must be used. The chief benefit of the rechargeable batteries will be to keep the one-time use alkaline packs from going to the landfill (~1 ton per year). There is also a considerable labor savings of not having to deconstruct and reload the chassis frames with replacement batteries. Our calculations indicate that we will break in terms of procurement cost compared to alkaline batteries in approximately six years and that the lithium-ion batteries have enough charge cycles (500) to last the duration of the program. With any luck these may be the last batteries we need to purchase for the Profiler Moorings!
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