Posts Tagged ‘Regional Cabled Array’
Visit to West Coast OOI Facilities
A group of Ocean Observatories Initiative (OOI) leaders visited OOI facilities at Oregon State University and the University of Washington last week to get a first-hand look at operations of the Coastal Endurance Array and Regional Cabled Array, respectively. National Science Foundation Program Director George Voulgaris, OOI Principal Investigator Jim Edson and Senior Program Manager Paul Matthias spent five days on the road meeting with their OOI west coast colleagues. The trip was designed to give recently appointed Voulgaris an opportunity to inspect the infrastructure and meet team members who keep the Coastal Endurance and Regional Cabled Arrays operational and reporting back data around the clock. Edson and Matthias seized the opportunity to meet in person with colleagues who they routinely see on the screen.
The following provides a glimpse of some of the activities that occurred during the trip:
[media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/02/20230207_140014.jpg" link="#"]Grant Dunn, Mechanical Engineer with the Electronic & Photonic Systems Department at UW-APL (left) describes the level-wind system on the RCA profiler mooring to Dr. George Voulgaris during a tour of the RCA laboratory facilities at the University of Washington as RCA Project Manager Brian Ittig looks on. Credit: Paul K. Matthias © WHOI.[/media-caption] [media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/02/20230207_144911.jpg" link="#"]Regional Cabled Array Principal Investigator Deborah Kelley (left) and OOI Senior Program Manager Paul Matthias take a selfie to commemorate their in-person visit during a tour of the RCA facilities at the University of Washington. Credit: Paul K. Matthias © WHOI.[/media-caption] [media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/02/20230207_141656.jpg" link="#"]NSF Program Director George Voulgaris (from left), OOI Principal Investigator Jim Edson look on as Regional Cabled Array technicians Grant Dunn, Mechanical Engineer with the Electronic & Photonic Systems Department at UW-APL, and RCA Chief Engineer Chuck McGuire explain the engineering associated with the RCA profiler mooring during a tour of RCA’s facilities at the University of Washington. Credit: Paul K. Matthias © WHOI.[/media-caption] [media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/02/20230209_123758.jpg" link="#"]NSF Program Director George Voulgaris (left) asks OSU technician Jonathan Whitefield questions about glider operations that provide critical water column data around the moorings of the Coastal Endurance Array. Credit: Paul K. Matthias © WHOI.[/media-caption] [media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/02/20230207_112718.jpg" link="#"]NSF Program Director George Voulgaris (foreground) and RCA Chief Engineer Chuck McGuire discuss the RCA data monitoring systems as OOI PI Jim Edson points to real-time data on the screen being relayed by instrumentation on the Regional Cabled Array. Credit: Paul K. Matthias © WHOI.[/media-caption] [media-caption path="https://oceanobservatories.org/wp-content/uploads/2023/02/20230209_130353.jpg" link="#"]NSF Program Director George Voulgaris (left) gets a hands-on look at the multiple instruments contained on multi-function node that will sit on the bottom of the ocean floor for six months collecting data for the Coastal Endurance Array. Coastal Endurance Array Principal Investigator Ed Dever (middle) and Project Manager Jonathan Fram the functionality of each instrument during the visit to Oregon State University. Credit: Paul K. Matthias © WHOI.[/media-caption]
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RCA and ROPOS: A Long-Term International Collaboration
A Canadian and American team worked side-by-side for 45 days in August in the NE Pacific Ocean during the eighth operations and maintenance expedition for OOI’s Regional Cabled Array (RCA). The team used the Canadian remotely operated vehicle (ROV) ROPOS to conduct maintenance operations on RCA’s underwater cabled observatory spanning the Juan de Fuca Plate and at water depths from 80 m to 2900 m. Intense operations included the recovery and reinstallation of 222 instruments and a 2700 m-tall, two-legged Shallow Profiler Mooring. This expedition took place on the global class research ship the R/V Thomas G. Thompson, operated by the University of Washington (UW). Twenty-six students joined the cruise as part of the UW at-sea experiential learning program called VISIONS.
ROPOS is operated by the Canadian Scientific Submersible Facility (CSSF). The vehicle was specially designed for cabled observatory work, bringing in components from the oil and gas field, and a uniquely designed Remotely Operated Cable Laying system (ROCLS) that allows the vehicle to install extension cables extending for several kilometers on the seafloor. Their work culminated in 2014 during an 83-day cruise onboard the R/V Thompson, which resulted in the installation of >15,000 m of extension cables (in total, ~33,000 m of extension cables was installed on the seafloor), >140 instruments, and platforms on the six-state of-the art moorings with instrumented profiling vehicles. They also installed 18 junction boxes at the key experimental sites using their underbelly latching system that allows the vehicle to directly secure loads up to 4,000 lbs beneath the vehicle. This latching system was adopted by the Deep Submergence Facility ROV Jason, which has conducted multiple RCA maintenance cruises.
[media-caption path="/wp-content/uploads/2022/12/R2209_20220812_091705_launch_ME.Axial-Base_Science-Pod_install-2.jpg" link="#"]The Shallow Profiler Science Pod being deployed with ROPOS during Leg 1 of the RCA 22 cruise at Axial Base. Credit: M. Elend, University of Washington, V22.[/media-caption]
During this latest expedition, ROPOS conducted 60 dives over 33 at-sea days. Keith Tamburri led seven members of the ROPOS team, who worked 12 hours on, 12 hours off for 45 days. Operations are more similar to industry with as little time on deck as possible for the ROV, typically about three hrs before ROPOS reentered the water. Team work is exemplified during ROPOS operations where two pilots each operate a manipulator to conduct complex operations. The ROPOS team was joined in the dive control laboratory by varying members of the RCA’s team, who directed ROPOS activities on the seafloor and throughout the water column, and the VISIONS’22 students who stood 4 hour watches. (A list of ROPOS and RCA team members can be found here).
During this 8th RCA recovery and deployment expedition, the R/V Thompson traveled to all of the RCA sites. ROPOS recovered and redeployed a diverse array of instruments and four small seafloor substations that provide power and communications to instruments on the seafloor and to the instrumented Deep and Shallow profiler moorings. The ROV also was used to install a 500 m long extension cable that allowed bringing the Southern Hydrate Ridge live again. ROPOS also recovered equipment and samples for externally funded principal investigators, including several novel instruments developed by scientists in the US and Germany. ROPOS tasks were many and varied. The vehicle emplaced packages up to 3200 lbs in weight and the pilots skillfully used the manipulators to do everything from scrubbing biofouling off cables to unplugging and plugging in instruments to the seafloor cable
In addition to RCA operations, ROPOS was used to help advance scientific investigations involving instruments added onto the RCA cabled network. For example, as part of an Early Career award to for Dr. Rika Anderson at Carleton College, ROPOS conducted sampling dives using a Universal Fluid Obtainer on the ROPOS porch to sample fluids for follow-on analyses of microbes and viruses. Through another NSF award to Dr. Wilcock and his UW colleague Dana Manalang, ROPOS installed a first of its kind acoustic network on the western and eastern rim of Axial Seamount and within its caldera to examine deformation within the caldera. A suite of CTD instruments were also turned within the caldera to test the hypothesis that brines are emitted from the subsurface associated with submarine eruptions as part of and NSF award to Dr. William Chadwick at the Oregon State University. Lastly, ROPOS inspected a Quantification sonar and recovered an Overview Sonar on Southern Hydrate Ridge as part of a project funded by the German Federal Ministry of Education and Research to MARUM at the University of Bremen, led by investigators Gerhard Bohrmann and Yann Macron. In addition, their 4K high-definition camera was cleaned and a CTD turned. The sonar and camera instruments are another example of an international collaboration.
“Our ROPOS team really enjoys working with the team from the University of Washington, School of Oceanography and Applied Physics Laboratory, who are responsible for the RCA. They are a professional, well-organized, efficient, friendly, and mutually respectful group, which makes these long missions at sea productive, efficient, and successful,” said Keith Shepherd, General Manager, Canadian Scientific Submersible Facility. “And for this cruise, in particular, it was a real pleasure working along with UW undergraduates onboard as part of UW’s at-sea experiential program VISIONS. The students brought a curiosity, enthusiasm, and energy that were always welcome during the long hours in the dive control van.”
Added Kelley, “It really takes a tremendous amount of time, effort, and teamwork to pull off an expedition of this length and complexity. We are grateful to have had the opportunity to work again with our Canadian colleagues. It was an excellent international collaboration to help maintain and expand the capabilities of the RCA. “ Because of the complex nature of the undersea work required to keep the RCA operational, few facilities are trained and equipped to execute such operations.
[media-caption path="/wp-content/uploads/2022/12/ROPOS-ROCLS_IEEE-copy-2.jpg" link="#"]ROPOS with the cable laying system ROCLS attached during the 2014 deployments of the extension cables. Credit: M. Elend, University of Washington, V14.[/media-caption]
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Nature Review Paper Reveals New Understandings of Mid-Ocean Ridge Systems
Only a small percentage of the global seafloor has been investigated, leaving the deep ocean as one of the last frontiers to be explored and sampled. Mid-ocean ridges (MOR) systems extend about 60,000 kilometers around the globe, are where 70% of the volcanism on Earth occurs, and are dynamic and active tectonic regions.
A recent Nature Review paper, Früh-Green, et al. 2022, written by a multi-disciplinary team of experts summarizes what is known about MORs, their importance in regulating seawater chemistry and global chemical fluxes, and the diverse ecosystems that they support in the absence of light and under extreme conditions. The authors describe the tectonic, magmatic, and hydrothermal processes that govern how they form and change and describe some of the biogeochemical cycles at varying spreading rates.
“The first hydrothermal vent was discovered in 1977, which was followed by myriad discoveries about these amazing deep-sea environments over the next 45 years,” said OOI’s Regional Cabled Array Principal Investigator, Deborah Kelley at the University of Washington and an author of the paper. “Yet, much remains to be understood about these environments, which play a key role in regulating seawater chemistry and global chemical fluxes. Key unknowns include the evolution of the novel microbial communities that they host and the diversity of viruses. This paper summarizes some of the key discoveries that researchers have made and questions that remain to be answered.”
Among the paper’s key findings are:
- Spreading rates control variations in heat sources, magma input, and tectonic processes along MORs, providing multi-faceted habitats for life.
- Seawater circulation and hydrothermal alteration regulate seawater chemistry and change the composition and physical properties of the lithosphere (crust and upper mantle).
- Roughly 50-60% percent of global MORs are spreading at slow to ultraslow rates resulting in the exposure of lower crustal and upper mantle rocks. This spreading is creating asymmetric ridge segments that support different structures, hydrothermal processes, and vent fluid chemistry.
- Serpentinization decreases density and seismic velocities of mantle rocks, weakening the oceanic lithosphere along faults. Serpentinization also produces hydrogen and organic molecules that provide energy for microbial life.
- Unlike serpentinizing systems, basalt-hosted systems support a vast, hot and diverse microbial biosphere. Advanced technologies are allowing better characterization of the genetic makeup and metabolism of microbes and the role of viruses in shaping biodiversity.
- Hydrothermal processes govern global chemical fluxes of magnesium, iron, manganese, and other volatiles and provide nutrients to the deep ocean. Microbial interactions and oxidation of organic compounds within hydrothermal plumes produce organic carbon.
[media-caption path="/wp-content/uploads/2022/11/Screen-Shot-2022-11-29-at-10.54.32-AM.png" link="#"]Global distribution of hydrothermal vents on the seafloor. Map of the global ridge system with distribution of known sites of hydrothermal venting and sites inferred to be present from water-column studies. Hydrothermal vents occur at MORs (65% of known sites), back-arc spreading centers (22%), submarine arc volcanoes (12%) and interplate hot spot volcanoes (1%). Data from the InterRidge Vents Database. Map adapted with permission from the Center for Environmental Visualization, University of Washington.[/media-caption]
“Ocean observatories like OOI’s Regional Cabled Array and Ocean Networks Canada , are providing researchers unprecedented real-time views into these highly dynamic regions that help form the face of our planet,” added Kelley. “RCA has allowed researchers to measure and monitor activity at the magmatically robust Axial Seamount, on the Juan de Fuca MOR for example, providing insights into when it might next erupt. Such underwater observatories will only continue to advance our knowledge as we expand capabilities to observe, monitor, and sample seafloor environments and the overlying water column in real time with more sophisticated sensors and advanced underwater vehicles and robotic technologies.”
Reference:
Früh-Green, G.L., Kelley, D.S., Lilley, M.D. et al. Diversity of magmatism, hydrothermal processes and microbial interactions at mid-ocean ridges. Nat Rev Earth Environ (2022). https://doi.org/10.1038/s43017-022-00364-y
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An Overview of Ambient Sound Using OOI Hydrophones
Adapted and condensed by OOI from Ragland, et al., 2022, doi.org/10.1121/10.0009836.
[media-caption path="/wp-content/uploads/2022/11/RCA-highlight.png" link="#"]Figure 1: Highlights of acoustic features from the five low frequency (Fs=200Hz) and six broadband (Fs = 64 kHz) hydrophones on the RCA.[/media-caption]Ragland et al., (2022) provides a wonderful overview of the unique opportunities for data and experimentally driven advancements in acoustics that are provided by (long-term) ambient sound recordings streamed live from hydrophones on the Regional Cabled Array. Figure 1, above (after Figure 5, Ragland et al., 2022), highlights acoustic features from the five low frequency (Fs=200Hz) and six broadband (Fs = 64 kHz) hydrophones on the RCA. Areas of research span the rare ability to conduct offshore monitoring of Fin whale migration, and the seasonal fluctuations and decade-long evolution of their calls, in situ offshore meteorological measurements with high temporal resolution to study wind and rain noise in the NE Pacific, the sound from commercial ships with impacts on the oceanic environment and marine life, ambient noise interferometry, volcanic eruptions, and both local and far-field earthquakes. As the authors note, the RCA-OOI data also provide significant opportunities for the development of machine learning tools for ocean acoustics. This work was supported by an award from the Office of Navy Research. The authors developed a public Python package (OOIPy) to access and explore the hydrophone data more easily (Schwock et al., 2021). OOIPy is also accessible through the OOI website tab Community Tools and Datasets.
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Ragland, J., F. Schwock, M. Munson, and S. Abadi (2022) Journal of the Acoustic Society of America, 151, 2085-2100, https://doi.org/10.1121/10.0009836.
Schwock, F., J. Ragland, L. Setiawan, M. Munson, D. Volodin, and S., Abadi (2021). OOIPY v1.1.3: A Python toolbox designed to aid in the scientific analysis of Ocean Observatories Initiative data, https://doi.org/10.5281/zenodo.5889288.
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Student Videos Give Inside Look at Research and Safety
Four students from Queens College were aboard the R/V Marcus G Langseth for a recent ten-day research expedition to the Axial Seamount, a submarine volcano in the northeast Pacific Ocean that erupted in 1998, 2011, and 2015. The students were assisting a National Science Foundation Research team that is deploying autonomous ocean-bottom seismometers on OOI’s Regional Cabled Array as part of a two-year experiment taking place within the predicted time window of the next eruption.
The NSF-funded project is led by William Wilcock from the University of Washington and co-led by Felix Waldhauser, Columbia Climate School’s Lamont-Doherty Earth Observatory, who served as chief scientist on this expedition, Maya Tolstoy (UW), and Yen Joe Tan from the Chinese University of Hong Kong, who also was onboard.
Queens college graduate student Jacqueline Singer was onboard to further work towards her master’s degree. She teamed up with undergraduates Rania Taib, Hema Muni, and Julia Sandke to create two videos – one explains their research, while the other provides an insider’s look at safety issues at sea. In the first video, the students give an in-depth look at how they deployed 15 autonomous ocean-bottom seismometers and how they work. In the second video, the students explain the importance of survival suit training, followed by a humorous look at the complex movements needed to successfully suit up in a “Gumby suit.”
Columbia University PhD candidate Theresa Sawi also provides a written account of the expedition here.
https://vimeo.com/user110037220/studentsataxialseamount
https://vimeo.com/user110037220/gumbysuitdemo
Read MoreVisions’22: Changing Students Lives
From Deb Kelley, UW, in OOI Quarterly Report, 2022.
This year, 25 undergraduate students and three graduate students participated on the Regional Cabled Array Operations and Maintenance cruise as part of the VISIONS’22 at-sea experiential learning program. They include students from the US, India, Saudi Arabia, France, and Kazakhstan. They represent a breadth of disciplines spanning Oceanography (11), Engineering (9: Mechanical, Industrial, Bioengineering, Environmental, and Aeronautics and Astronautics), Biology (6: Biology, Marine Biology, and Microbiology), Geology (1), and Policy Studies focused on ocean equity and the United Nations Convention (1). They stood 4 hour-on, 8 hour-off watches in the remotely controlled vehicle, ROPOS control center, learned how to conduct CTD casts and collect and process fluid samples, and worked on deck. Three additional undergraduate student ambassadors, who have participated in past VISIONS’ expeditions (1-3 years), helped mentor the students. All completed cruise blogs on the Interactiveoceans VISIONS’22 Expedition site, and science-engineering and/or engagement projects that will last a quarter to several years. Two students chose projects involving advanced genetic analyses of vent animals and protists for their Senior Thesis in Oceanography. Based on discussions with past students and what they relayed in their blogs, for many this is a life changing experience. Note: two past VISIONS students are now APL engineers as part of the RCA team.
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Catching the Next Eruption of Axial Seamount
Theresa Sawi, a PhD student in Columbia’s Department of Earth and Environmental Sciences and the Lamont-Doherty Earth Observatory, shares her reflections and more about the science behind a six-day research expedition to Axial Seamount. She gives a behind the scenes look as researchers from Columbia University on the R/V Marcus G Langseth deployed 15 autonomous ocean-bottom seismometers atop Axial Seamount, a submarine volcano in the northeast Pacific Ocean that erupted in 1998, 2011, and 2015. The research expedition was part of a two-year experiment taking place within the predicted time window of the next eruption.
The seismometers were added to OOI’s Regional Cabled Array. To read Sawi’s account, click here.
[media-caption path="/wp-content/uploads/2022/09/Langseth.png" link="#"]15 scientists were onboard the Langseth, with ranks ranging from professor to undergraduate researcher. Credit: Theresa Sawi.[/media-caption]Read More
Interview from Axial Seamount
In case you missed it, you can watch the video of Chief Scientist Michael Vardaro and student Andrew Paley being interviewed live aboard the R/V Thomas G. Thompson during the Regional Cabled Array for its eighth annual operations and maintenance cruise. The Exploring by the Seat of Your Pants program is designed to give students an opportunity to see scientists in action in the field, in the hope of piquing their interest in science and perhaps pursuit of scientific careers. (The piece is 45-minutes long so takes a moment to load. If you prefer, click on this link: https://www.youtube.com/watch?v=K–RlkjMjLo).
[embed]https://youtu.be/K–RlkjMjLo[/embed] Read More45 Days of Discovery: RCA’s 8th O&M Expedition
The Regional Cabled Array (RCA) team left port in Newport, Oregon on August 5 aboard the global class research ship the R/V Thomas G. Thompson for a 45-day expedition. This is the eighth operations and maintenance cruise to the array, a network of 900 kilometers of electro-optical cables that crosses a tectonic plate and powers sensors on the seafloor and in the water column, including instrumented profiling platforms on moorings.
The expedition is such a complex operation that it will be conducted in five legs, with the ship returning to Newport to offload recovered equipment and load new and refurbished equipment for a subsequent leg. A scientific and engineering team of 26 from the University of Washington will be joined by an engineering team of 8 that will operate the remotely operated vehicle ROPOS, owned by the Canadian Scientific Submersible Facility. These groups will be joined by 28 students from the University of Washington, participating in the at-sea-experiential learning program, VISIONS, which provides undergraduate students opportunities to conduct research at sea using advanced oceanographic research instruments.
[media-caption path="/wp-content/uploads/2022/08/Thompson-leaving-dock.-FZqU5VxUYAAWUie-scaled.jpeg" link="#"]The R/V Thompson as it left the dock in Newport and headed towards the OOI Slope Base site for the first dive of this 45-day expedition. Credit: NSF-OOI/UW/V22.[/media-caption]There will be a live feed video for the duration of the expedition. “During the cruise, website visitors will be able to directly observe parts of the seafloor rarely seen by humans, including the most active submarine volcano off our coast ‘Axial Seamount’ located ~300 miles offshore and nearly a mile beneath the oceans’ surface,” said Deb Kelley, principal investigator of the RCA. “ Visitors will be able to witness one of the most extreme environments on Earth – underwater 700°F hot springs teaming with life that thrive on volcanic gases and that live in the complete darkness of the deep sea. The team will also visit the Cascadia Margin, spending time at Southern Hydrate Ridge where methane ice deposits are sometimes exposed on the seafloor. This hummocky, sediment-rich environment hosts a large number of areas where methane gas seeps from the seafloor feeding dense microbial mats that also host large clams. ROPOS will also visit shallower sites that are some of the most biologically productive areas in the world’s ocean.”
The 45-day expedition required an immense logistics operation with ~20 trucks transporting >130,000 lbs. of gear to Newport. During the cruise, the ROV will deploy and recovery a diverse array of >200 instruments, several small seafloor substations that provide power and communications to instruments on the seafloor and on moorings that span depths of 2900 m (9500 ft) to 80 m (260 ft) beneath the oceans’ surface. In addition, several novel, externally funded instruments developed by scientists in the US and Germany will be installed.
Follow along as the journey unfolds: Live video feed. Student Blog. Expedition updates.
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Using Aircraft Expertise for Underwater Operations
Regional Cabled Array (RCA) Engineer Eric McRae came to the RCA Team with a 20+ year background keeping aircraft in the air, cars on the road, and medical devices safe. McRae worked on a Head-Up display and skid control and braking systems on some large commercial aircraft that are flying now. He also worked on a popular pacemaker/defibrillator for a medical instrument company. As a result of this experience, and long-term work in automotive engine control, McRae brought with him a mindset about correct behavior of control software to the RCA. He simply will not accept anything that is misbehaving. In the past, people’s lives were at stake, now it’s possible interruption of data collection or loss of scientific equipment.
McRae adopted his approach to help design and keep operational the Shallow Profilers on the RCA moorings which must work correctly for a year at a time in the cold, dynamic, and sometimes hostile, waters of the Pacific Ocean. The Shallow Profiler houses 10 scientific instruments and includes a winch that pays out power and communication cable allowing the science pod to rise through the water column to a depth below the surface determined by currents and wave conditions.
“I think that the Cabled Array Team is successful because many of us came from industries where it was not acceptable to produce something that could fail,” McRae explained. “We use this same mindset to figure out ways to make things work and keep them working even under the most difficult of circumstances.”
[media-caption path="/wp-content/uploads/2022/07/eric-selfie.png" link="#"]RCA Engineer Eric McRae stands with the components of one of the RCA Shallow Profilers that he programmed to successfully move up and down the water column in the Pacific since 2014. Photo: McRae.[/media-caption]From his first days at the RCA, Gary Harkins, his boss at the time, told McRae that his job was to make sure the Shallow Profiler was safe. “Safety was the top priority — not science, or anything else. Once we were sure the profiler could be operated safely, we could accomplish whatever the science mission wanted.” Initially, McRae worked with Dr. Doug Luther and Dr. Kendra Daly to understand how the science team wanted the profiler to run. Once he understood the science requirements, he worked with RCA’s mechanical designers to understand how they wanted to design the mechanical aspects of the system.
McRae then used his experience to influence the design and created a viable electronic control system that supports communications that keep the winch running and its science pod node traveling up towards the surface and back down nine times a day. A winched cable provides continuous power and communications to the science pod, allowing science and engineering data to flow to shore in real time. The mechanical design and control system have kept the Shallow Profiler operational since its launch in 2014.
[embed]https://vimeo.com/733359478[/embed]The control system continually “talks” to the winch and science pod to assess movement through the water. Near the bottom, the science pod doesn’t move very much, except for an occasional tilt caused by currents. As it gets close to the surface, however, surface waves can have a huge impact on how the profiler moves and how much tension is on the cable. The science pod weighs ~900 pounds in air so when it gets moving back and forth underneath waves, it could significantly stress the cable. To prevent this from happening, the science pod “reports” three times a second to the control system about the conditions it is experiencing. These reports include acceleration, rotation, proximity to the surface, wave length, and a slew of other variables so that needed adjustments can be made automatically to keep the winch and ultimately its valuable science pod “safe.” If conditions warrant, the control system has the capability of aborting a running profile and/or parking the science pod near the mooring to wait things out.
The Shallow Profiler is often on the move. Each of the nine daily profiles take between one and a half to two and a half hours, depending on the profile type and ocean conditions. There’s a gap of about 30 to 45 minutes between profiles, where the science pod is parked down near the mooring platform. During that time, the controller is constantly monitoring the waves on the surface. McRae developed an algorithm to look at the worst-case peak to trough wave pressure so that when the profiler starts up for a run towards the surface, it has already calculated what it thinks the worst wave height combination will be. The original requirements of the system were that the science pod can go no closer to the surface than five meters or three wave heights, whichever is greater, so when it starts up, it already knows the ceiling for the coming profile.
“As designed, the profiler is smarter than we are. It makes seven decisions three times a second to ensure that it is on the right path and has accounted for all predictable conditions” McRae said.
Of course, there are other hazards besides ocean conditions. In September of 2017, a trawler’s net hit the mooring line at the Oregon Offshore site and eventually the mooring platform itself, pulling the 14,000-pound mooring and its two huge anchors from the seafloor. The profiler was running at the time and recorded the action until the boat pulled hard enough that the seafloor cable came unplugged. There has also been a smattering of mechanical issues, but the system has matured nicely. Should something unexpected go wrong in the future, McRae has programmed the profiler to take “evasive” action, then notify him and his team on land. This performance record demonstrates that not only did McRae’s work help keep the profiler safe, it helped make it a reliable component of the RCA that scans through the water with ease. The three profilers have made >40,000 profiles since 2015, making unprecedented measurements of ocean parameters.
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