Posts Tagged ‘Endurance Array’
Summer 2021 Low Oxygen Event on the West Coast of North America
Adapted and condensed by OOI from Tetjana et al., 2022.
A team of researchers using OOI Coastal Endurance data reported a low oxygen event on the west coast of America. They found that while hypoxic events are known to occur seasonally in coastal bottom waters along the west coast of North America, 2021 was more severely hypoxic. The onset of low oxygen water was the earliest in 35 years (NOAA, 2021), lasted longer (Lundeberg, 2021), was anomalously low, and covered a larger extent, reaching north into Canadian waters where hypoxia is rare (Crawford and Pe.a, 2013).
[media-caption path="/wp-content/uploads/2022/04/Screen-Shot-2022-04-12-at-3.44.04-PM.png" link="#"]Dissolved oxygen measured from an underwater vehicle glider operated by Oregon State University on a cross-shore transect off Grays Harbor, Washington, USA (plots available at http://nvs.nanoos.org and data available at the U.S. Integrated Ocean Observing System Glider Data Acquisition Center, http://gliders.ioos.us ). Hypoxic water occupies the lower three-quarters of the water column near the mid-shelf mooring location (~80 m isobath) and stretches from the outer continental shelf, shoreward to at least the 50-m isobath.[/media-caption]
The paper was published in the Winter 2022 edition of Pices Press and can be reviewed here.
Uncovering Changing Life in the Water Column
Oregon State University Assistant Professor Jennifer Fehrenbacher needed a ship to carry out her National Science Foundation-funded research investigating the lives of foraminifera (single-celled organisms about the size of a grain of sand and smaller) in the northern Pacific. Her work, in collaboration with Dr. Claudia Benitez-Nelson at the University of South Carolina (UofSC), involves deploying bottom-moored sediment traps and collecting plankton tows while at sea, giving researchers the opportunity to explore foraminifera that live in lighted surface waters, and how these communities have changed over time in response to the surrounding ecosystem.
Fehrenbacher found her ship. She will be joining forces with the Endurance Array Team aboard the R/V Sikuliaq during its bi-yearly expedition to recover and deploy ocean observing equipment at its array in the northeast pacific off the coast of Oregon. Fehrenbacher and her team of four researchers will join the Endurance Array 16 team in early April for the second of its two-leg expedition. This will be a continuation of her research project that began in September 2021.
Last September, Fehrenbacher’s team put in place two tandem sediment traps that are located close to the OOI Slope base node. One was deployed at about 600 meters water depth, the other slightly above the sea floor. The last sediment trap study in this region was conducted around 30 years ago, and the foraminiferal species have likely changed since then, as have ocean conditions.
[media-caption path="/wp-content/uploads/2022/03/IMG_5185-copy.jpg" link="#"]Fehrenbacher’s team will be retrieving two tandem sediment traps that are located close to the OOI Regional Cabled Array slope base node. Credit: Jennifer Fehrenbacher, OSU.[/media-caption]
The sediment traps have been collecting material in place for the past six months and will be recovered along with the Endurance 16 team’s recovery and deployment work. Once the traps are back onboard, the collecting cups will be taken off, emptied, replaced, and the traps redeployed for another six-month period. The researchers will package the collected materials for analysis at OSU and UofSC.
The team also will be examining live specimens from night-time plankton tows, taking advantage of quiet night-time hours to conduct the plankton tows when the Endurance team is unable to work safely moving large, bulky, and unwieldy equipment in and out of the ocean. “This arrangement is a win-win for everyone,” said Endurance Array Chief Scientist Ed Dever. “It maximizes the use of ship time, while helping to provide data to answer some questions about how ocean conditions are changing.”
Fehrenbacher’s team will be conducting a series of discrete new tows from the surface to about 500 meters. “While I don’t anticipate a ton of critters in the really deep water, net tows haven’t been done extensively in these waters at these depths. The last one was 30 years ago by oceanographer Alan Mix and his graduate student Joseph Ortiz, so this new work will give us insight into how life in the water column may have changed over time, “ said Fehrenbacher.
Fehrenbacher’s team will be conducting experiments with live foraminifera in a portable travel lab they will bring onboard. A number of different experiments are planned:
PhD candidate Kelsey Lane will be collecting foraminifera (shortened version “forams”) to study their genetics and their microbial communities, other species living with forams.
Graduate student Grace Meyer will be striving to measure carbon and oxygen isotopes in individual forams. She will be collecting empty shells from both the water column and sediment trap material and compare what is found in both, providing information about water column processes that could alter shells’ composition.
Postdoctoral researcher Brittany Hupp will be collecting both live forams and empty shells to study the chemistry of different types of forams, looking at their isotopes and trace metals content.
Researcher Eric Tappa, a sediment trap expert from the UofSC, will be deploying and recovering the sediment trap equipment. Tappa has been working with sediment trap moorings for decades and have proven critical in providing longer time-series records of processes occurring in overlying waters.
As lead scientist Fehrenbacher will be participating in these onboard experiments. She also will be growing forams under controlled conditions and watching them to learn how temperature modulates their shells or their behaviors during the day-night cycle, and will continue her work with recovered forams once she returns to her home lab. There she will be measuring the trace element concentrations in foram shells so results can help inform the Paleo record. . She explained, “Foram shells are used basically as proxies for environmental conditions. So when we measure trace elements in their shells, this gives us information about the pH, temperature, nutrient content, and even the salinity of the ocean in the past.” The onboard experiments help scientists under how forams incorporate these elements into their shells when they are alive, which they can use in assessing past records.
[media-caption path="/wp-content/uploads/2022/03/IMG_5196-copy.jpg" link="#"]An anchor weighing ~2500 pounds is deployed to keep a sediment trap in place for six months until it is recovered with a treasure trove of marine life and particulates for investigation. Credit: Jennifer Fehrenbacher, OSU.[/media-caption]
Challenges of studying small living things
Studying single-celled organisms is difficult on dry land, but is compounded by a moving ship in rolling seas. Fehrenbacher’s team will be taking onboard multiple microscopes, including an inverted microscope to see their subjects, water circulators to keep them at constant conditions while they are alive, and a pH meter. High-powered microscopes are critical for the work because forams range in size from smaller than a grain of sand—about 100 microns— to up to about a millimeter.
“We look at forams in a petri dish under the microscope,” explained Fehrenbacher. “This is challenging as the ship moves back and forth so does the water in the petri dish so you’re looking back and forth as the ship moves.” The researchers have come up with the solution of holding the petri dish at an angle so the water and foram stay in one place and helps prevent researchers’ sea sickness.
Fehrenbacher predicts that the amount of material collected on the Endurance Array 16 cruise will keep she and her graduate students busy for at least the next two years and beyond. She added, “There’s really just nothing quite like the type of information you can get from sediment trap studies. While going out to sea for two weeks a year and doing plankton tows are helpful, we only get information about what’s in the water column at the exact moment of collection. But sediment traps provide months’ worth of data at really high resolution that we can compare with other OOI data and get a detailed picture of ocean conditions and how those conditions affect marine life.
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Sixteenth Turn of the Coastal Endurance Array
A team of ten scientists and engineers will depart aboard the R/V Sikuliaq in late March for a two-week expedition to recover and redeploy ocean observing equipment at the Coastal Endurance Array. Located in the northeast Pacific off the coasts of Oregon and Washington, the Coastal Endurance Array consists of two cross-shelf moored array lines, designed to observe cross-shelf and along-shelf variability in the region.
The team will recover and deploy seven moorings. Four of the moorings are located on the Washington Shelf, with the remaining three on the Oregon Shelf. The team also will be recovering a surface piercing profiler at the Washington Shelf site and deploying four surface piercing profilers on the Washington and Oregon lines. Another goal of the team is to deploy and recover gliders so that five are in the water and continue to sample and report back data over the next three months. The gliders collect data across the shelf in shallow water down to 200 meters and also collect data offshore down to depths of 1000 meters.
[media-caption path="/wp-content/uploads/2022/03/sea-lions.png" link="#"]The Endurance Array team has to contend with occasional visits of sea lions, which can weigh up to 1000 pounds, and who like to explore the components of the array. This expedition will be testing a re-enforce solar platform to see if can better bear the weight of these hefty and curious visitors. Credit: Endurance Array team.[/media-caption]
When not recovering and deployment equipment, members of the onboard team will be taking CTD (connectivity, temperature, and depth) casts to verify and calibrate instrumentation. Because of the quantity of the equipment to be recovered and deployed, the cruise will take place in two separate legs.
Measurements collected by this array capture the variability of ocean properties across a broad range of temporal and spatial scales. Scientists are using these data to examine ocean health issues such as hypoxia, ocean acidification, and harmful algal blooms, and changing ocean conditions such as intermittent marine heat waves.
“Every time we head out to turn the Endurance Array, the OSU team works together with folks at WHOI to improve the resilience of the gear we put out there and to improve the quality of the data collected,” said Ed Dever, Principal Investigator for the Coastal Endurance Array, serving as Chief Scientist for the Endurance 16 expedition. “It’s a tough environment. The equipment spends six months at sea, getting jostled by high waves and strong winds and serving as habitat for marine life big and small. Yet over the last eight years, we’ve continuously made improvements to the instruments and infrastructure to improve data return. It’s a real testament to the creativity and skills of the whole team. They never stop thinking about ways to make things even better.”
During the second leg of the cruise, a scientific party of five will join the expedition to collect sediment samples for an ongoing experiment led by Dr. Jennifer Fehrenbacher from Oregon State University. This specific scientific inquiry is an example of how the OOI was designed to add instrumentation and adapt sampling approaches to meet the needs of the scientific community it serves.
[media-caption path="/wp-content/uploads/2022/03/Sediment-trap.jpeg" link="#"]Dr. Jennifer Fehrenbacher’s team will be deployin this McLane Mark VII 13 cup Sediment Trap, which is used to collect a time-series of material falling through the water column. The stack of three railroad wheels (on right) are the anchor. Credit: University of South Carolina.[/media-caption]
To help answer other specific science questions, the Endurance 16 team also will be conducting sampling for researchers with instruments on the Endurance Array moorings. The team will test deployment of fish acoustic monitors on the near shore instrument frames (see picture below) of both inshore moorings and the Washington Shelf surface mooring for Taylor Chappel a researcher at Oregon State University. The team will also collect settling organisms on devices attached to multi-function nodes on the Oregon Offshore and Surface moorings for Oklahoma State researcher Ashley Burkett.
[media-caption path="/wp-content/uploads/2022/03/Endurance-mfn.png" link="#"]This Near-Surface Instrument Frame (NSIF) is an instrumented cage that is suspended below surface moorings. (7m for Coastal moorings, 12m for Global moorings). The NSIF contains subsurface oceanographic instruments attached to multiple data concentrator logger computers. During Endurance 16, fish acoustic monitors will be added to the standard equipment. Credit: Ed Dever, OSU.[/media-caption]
During this expedition, the team also will be deploying new equipment and other improvements. For example, a new anemometer, which sits at the top of the mooring to measure the wind speed will be deployed for the first time. A new camera made with off-the-shelf components will be put into field during for its first six-month deployment. And, the team will be testing the rigor of its newly reinforced solar panels, which often have to withstand the weight of the occasional visit by sea lions.
The team has followed all COVID protocols and are ready to go. They will be blogging and sharing photographs of their two-week expedition. Bookmark this page and follow along as they share their stories.
Read MoreObservations of Cross-Shelf Nitrate Fluxes over the Oregon Continental Shelf
Extracted from OOI Quarterly Report, 2022.
The US Pacific Northwest coastal ecosystems are primarily limited in growth from nitrate supply. The nitrate supply that drives the highly productive marine growth in this region is primarily a result of wind driven coastal upwelling. This work seeks to investigate cross-shelf nitrate fluxes over the continental shelf off the coast of Oregon following the installation of new nitrate and Acoustic Doppler current profilers (ADCPs) in the Ocean Observatories Initiative Coastal Endurance Array.
[media-caption path="/wp-content/uploads/2022/02/Endurance.png" link="#"]Figure 24. A velocity and nitrate profile from the shelf site at the Newport line. Data used was from the 2019 summer, approximately mid-June to early October (deployments 13, 14, and 15). The net nitrate flux found at that site over this time period, found by vertically integrating the values above, is roughly 1.16 mmol Nitrate/second/meter coastline. [/media-caption]
The primary onshore flow of nitrate-rich water over the continental shelf is found to originate at the middle depths, consistent with previous research in the region. However, the upwelling and cross-shelf nitrate fluxes on the continental shelf are found to be in poor agreement with common upwelling indices, e.g., coastal upwelling transport index (CUTI) and biologically effective upwelling transport index (BEUTI). Several factors for this disagreement are proposed, including the focus of the indices on dynamics farther offshore of the continental shelf. Observed coastal wind stress, calculated on a weekly rolling average, is found to be a potential alternative for predicting nearshore nitrate concentrations. Farther offshore at the mid-shelf, only a weak correlation between observed wind stress and observed surface transport is found, suggesting the need for additional dynamics to fully explain the observed surface transport and nitrate fluxes. Correctly modelling the nitrate supply for coastal ecosystems is essential for predicting phytoplankton blooms that are vital to the production of fisheries on the coast. Thus, understanding these limitations is of great importance for ocean-driven coastal economies.
Written by Andrew Scherer, California State University, Monterey Bay and Cleveland State University and Thomas Connolly, Moss Landing Marine Laboratories, San José State University
Andrew Scherer is an undergraduate physics student at Cleveland State University. In summer 2021, he performed this research with Prof. Tom Connolly (MLML, SJSU) as part of a National Science Foundation Research Experience for Undergraduates program and presented it at the Eastern Pacific Ocean Conference Stanford Sierra Center, Fallen Leaf Lake, California 26-29 Sep 2021.
Read MoreR/V Oceanus Remembered as a Workhorse of the U.S. Academic Research Fleet
The long service of the R/V Oceanus (1976-2021) came to end on November 21, 2021 as the ship pulled into port after having successfully completed its last interdisciplinary cruise for Oregon State University (OSU). The Oceanus began its 45-year-run of scientific investigations at Woods Hole Oceanographic Institution (WHOI) in 1976. After a major mid-life refit, the ship was transferred to OSU in 2012, and contributed to the Ocean Observatories Initiative (OOI) off both coasts.
“The Oceanus proved to be a real workhorse for the Academic Research Fleet and also played a pivotal role for the OOI during its initial launch,” said Ed Dever, PI of OOI’s Coastal Endurance Array, who sailed on the ship many times. “While at WHOI, The Oceanus performed some of OOI’s at-sea-mooring test deployments and later the ship was used for the initial deployment of the Coastal Endurance Array off the Oregon coast.”
In spring and fall 2014, after moving to OSU, Oceanus performed the initial deployments of the Oregon and Washington inshore moorings and Washington profiler mooring. The real test for the Oceanus, however, came during 2015, when it was tasked with deploying the full scope of the Endurance Array, including the four large coastal surface moorings at the Oregon and Washington shelf and offshore sites.
Explained Dever, “Thanks to some excellent ship handling, care on the part of the deck crew and a huge assist from some very kind weather, we got the moorings safely in the water using the ship’s crane to deploy the 10,000-pound buoy off the starboard fantail and the heavy lift winch to deploy the 11,000-pound multifunction node (MFN, bottom lander) through the A-frame. The size of the buoys and MFNs meant that Oceanus could only carry one buoy out at a time and the cruise was completed in five legs with some very efficient port stops. By the end of the cruise, it was evident that we would need to move future operations to global and oceans class ships and after one more deployment in fall 2015 (with recoveries carried out on the R/V Thomas G. Thompson), we made that transition.”
[embed]https://youtu.be/pDRagMTDUTk[/embed]After the initial Endurance Array deployments, OOI transitioned to using larger global and oceans class ships needed to recover the bulky coastal surface moorings, with one exception. In spring 2019, with tight schedules on global class ships, UNOLS (University-National Oceanographic Laboratory System charged with ship scheduling) requested that OOI Endurance split the spring mooring recovery and deployment cruise between the R/V Sikuliaq and the R/V Oceanus. The Oceanus ably performed the profiler mooring deployment, anchor recoveries, coastal surface piercing profiler deployments, and glider deployments over five days in April and May 2019.
While not directly working with the OOI, the Oceanus continued to work off Oregon at and around the OOI arrays. Research and student cruises often sampled over the years near OOI’s Endurance and RCA Arrays at the Oregon inshore, shelf, offshore and Hydrate Ridge sites to compare shipboard measurements and OOI time series. This work included CTD profiles, net tows, coring, and sediment trap deployments.
The last Oceanus cruise, in fact, was one such interdisciplinary research cruise led by OSU researcher Clare Reimers, who also served as chief scientist. During its final official outing, the team aboard the Oceanus sampled the outer shelf at the northern end of Heceta Bank, Oregon to help scientists determine any changes that may have occurred to a swath of the margin that was reopened to commercial bottom trawling in 2020 after an 18-year closure. Reimers said, “The R/V Oceanus and crew performed flawlessly, and our science mission was fully completed.”
Added Dever, “What better way to end its long and illustrious career? We at OOI join many others in appreciation of the R/V Oceanus, and the dedication and skills of all who sailed on her and supported ocean science throughout her many years at sea.”
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Special thanks to OOI Data Center Project Manager Craig Risien for sharing the GoPro time lapse of the loading of the Oregon Offshore mooring onto the R/V Oceanus in spring 2015.
Read MoreEndurance Array to Provide Hourly Meteorological Data
On 11 October 2021, the National Oceanic and Atmospheric Administration (NOAA)requested that OOI’s Coastal Endurance Array buoys provide hourly meteorological data to the National Data Buoy Center (NDBC) because a nearby NDBC buoy (46029, Columbia River bar) had gone offline. OOI buoy data are typically telemetered every two hours due to sampling schedule and bandwidth constraints (the actual sampling rate is higher).
Endurance Array team members examined sampling and telemetry schedules for the Endurance offshore coastal surface moorings to see if they could accommodate NOAA’s request. The team concluded that meteorological data from the moorings could be updated hourly while still meeting OOI sampling requirements.
“To help ensure continuity of data to the NDBC, we plan to distribute hourly meteorological data from the Endurance Array Oregon and Washington offshore sites for the duration of the outage at NBDC 46029,” said Edward Dever, lead of the Coastal Endurance Team. “We’re pleased to respond to NOAA’s request and hope these data prove useful to operational weather forecasts and marine safety.” The Oregon and Washington offshore sites have NDBC buoys designations of 46098 and 46100, respectively.
The Endurance Array team will continue to review the performance of the buoys and ensure the updated telemetry schedule does not impact OOI sampling. If data users do experience any impacts from this change in sampling frequency, please contact Jon Fram at Jonathan.Fram@oregonstate.edu.
Read MoreNew Underwater Camera with Off-the-Shelf Components
In September 2021, the Coastal Endurance Array began rolling out a much-needed upgrade to their underwater cameras. Endurance Array Innovator Chris Holm engineered a camera using off-the-shelf components to meet the specific needs of capturing environmental conditions and marine life in proximity to the Endurance Array moorings. The prototype was put in place on the inshore mooring (CE01) during the 15th turn of the Coastal Endurance Array.
[media-caption path="https://oceanobservatories.org/wp-content/uploads/2021/10/camera.png" link="#"]The newly configured Endurance Array underwater camera is attached to the inshore mooring, ready for deployment. Photo: Chris Holm, OSU.[/media-caption]The innovation came in multiple steps. Holm first tried to salvage the camera’s hardware and reprogram the camera with new software. He hit a snag, however, in that the motherboard that controlled the camera was no longer supported.
Since it didn’t make sense to rebuild the camera using an out-of-date motherboard, Holm looked into finding a new camera on the market. It had to be suitable for use underwater, with the capability to go into a low-power mode. “What is really needed for low-light conditions underwater is a camera with a large physical sensor, but with fewer megapixels,” explained Holm.
“Since the moorings run on battery power, the cameras need to be able to go into a very low-power sleep state in between taking photos,” said Holm. “If the sleep current is high, the deployment life is low. So, we were trying to find an off-the-shelf solution for a way to go into low power.”
After some searching, Holm obtained a Raspberry Pi High Quality Camera. Although the Raspberry Pi doesn’t come with native power management capabilities, Holm found he could use Sleepy Pi, an add-on-board from Spell Foundry that can power the Raspberry Pi on and off.
For its launch, the camera is programmed to autonomously take a burst of three images every four hours. The system can also take photos when triggered by a Data Concentration Logger (DCL) and can be partially configured remotely. Future iterations will be fully configurable remotely via the DCL.
The final touch to this first iteration was figuring out how to turn the lights and lasers on and off. Holm used a relay board from Waveshare Electronics to power the original systems lights and lasers. The lights adjust their brightness depending on the voltage being sent through a signal line which is controlled by the GPIO pins of the Raspberry Pi.
Altogether, the system is very suitable for the Endurance Array’s needs and is an extremely cost-effective, off-the-shelf solution. The cameras also can be easily swapped out if the Endurance team decides to upgrade the cameras.
Since this newly configured camera was put in place in early September, Holm said, it has been performing flawlessly, with the auto-exposure working well. Since this mooring uses a cell modem to transmit data, the team has been able to see the photos the camera is taking in near real-time. Once the formal approval process for the camera’s integration and use across the OOI is completed, Holm will be building more camera systems for the Endurance Array to deploy on the offshore and shelf moorings during the spring.
Since the cameras and its settings can be upgraded and/or optimized for different use cases, depending on what an investigator is interested in (such as marine snow or benthic organisms), Holm would like to hear from scientists about what they’d like the camera to focus on. He created a survey for data users interested in the underwater cameras.
“It would be very helpful to know what kind of data would be most useful to scientists using the system,” he said.
For those interested in seeing underwater, please complete the survey here.
[media-caption path="https://oceanobservatories.org/wp-content/uploads/2021/10/camera-output.png" link="#"]The Endurance Array team has the capability to adjust the settings of the underwater cameras based on researchers’ interests. In addition, some post-processing tools could be developed to sort images or extract useful information from them. Photo: Chris Holm, OSU.[/media-caption]
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Tackling Sea Surface Sampling Issues
The sea surface is the hardest place to work, according to Jonathan Fram, Project Manager of the Coastal Endurance Array. That’s because at the surface, waves are constantly sloshing around. At any time, a large wave can tug on mooring winch lines, creating sudden tension, which can wear down cables and even cause them to break.
Scuba divers know that surface waters are rough, but below a certain depth—about one wave orbital below the surface—the waters calm significantly. Unfortunately, a lot of great science takes place at the surface, so it’s important for sampling instruments like the Coastal Surface Piercing Profiler (CSPP) to be able to withstand the waves at and near the surface. Fortunately, OOI engineers have found ways to meet the many challenges of working in this rough environment.
“The Coastal Endurance Array Team has made changes to the CSPP to make it more robust, so that we can get the kind of continuous time series that are so valuable to scientists,” said Fram.
A CSPP spends most of its time near the sea floor, but either two or four times a day, the profiler winches itself up to the surface, taking samples as it ascends. Once it reaches the surface, the profiler sends its data back to shore and then quickly returns to the safety of the seafloor. Profilers are important ocean observatory tools because they can help capture what is happening at certain depths where stationary instruments aren’t present. “We’ve had times where you get a persistent chlorophyll bloom at a certain depth where there is zero mooring data,” explained Fram. “So the CSPP sampling is needed to make sense of what’s happening. It’s impossible to have all the instruments at all depths. The CSPP fills in this gap.”
Last year, the Coastal Endurance Array team reviewed their activities looking for ways to reduce lost time at sea. One thing they discovered was that the anchor systems of the CSPPs were unreliable. To deal with this problem, the team created a new kind of anchor. The old profiler anchors had a chain between the profiler and anchor that helped dampen the waves so that the device was not tugged on when resting in between profiles. The chain, however, made it difficult to deploy the anchor in an upright position. Anchors need to be deployed upright so their recovery floats can be acoustically released. The team redesigned the anchors so they now behave like a weeble wobble toy that is weighted so it always rights itself. This new design makes it hard to deploy an anchor upside down, making the anchors more reliable.
The team also made updates to the modems that send data to shore. When the CSPP is at the surface, the winch must stay on because it keeps the antenna vertical. This time-on takes up about a quarter of the battery power. To reduce the power demand, the team switched out some of the iridium modems for cellular modems, which has allowed the CSPPs to send data more quickly. A faster modem means that the profiler spends less time at the surface, not only saving power, but reducing the risk of being damaged by a large wave. The team is currently working on upgrading to faster cellular modems that can connect further from shore.
“At the same time we are making these updates on the Oregon Shelf Mooring, we’re also implementing them on the Washington Shelf Mooring,” said Fram. “So an improvement on one platform is also leading to an improvement on another platform.”
A third innovation involves improvements to the batteries.
“When waves tug on the winch, it goes from being a power sink to a power source. That sometimes creates power spikes that can fry the connectors. So we’ve rewired the batteries to make them more robust,” explained Fram. The rewiring is expected to reduce the number of power failures and keep the CSPPs running continuously. “Since April when we first started using the rewiring scheme, we’ve had four profilers in the water with no problems for six weeks,” said Fram.
The team also is in the process of replacing batteries that power the profiler with their own design of rechargeable batteries. While OOI engineers prefer to use commercially available parts for easier repair and replacement, when parts on the market don’t fit their needs, they design their own. The new batteries will be more reliable than those they are replacing. The newly designed batteries will also be deployed on the wire-following profilers on the Coastal Pioneer Array.
“My focus is on making all of the Coastal Endurance instrumentation work,” said Fram. “When we’re able to get a full three months’ deployment through the winter, through super rough seas, that makes my day. Making improvements is what I look forward to the most.”
Read MoreBottom Boundary Layer O2 Fluxes During Winter on the Oregon Shelf
Adapted and condensed by OOI from Reimers et al., 2022, doi:/10.1029/2020JC016828.
[caption id="attachment_21037" align="aligncenter" width="640"]
Fig. 1 Time series of physical conditions during the February 26–27, 2018 deployment (EC D1) at the mid-shelf site. (a) Wind vectors (15-min averages) measured at the OOI Shelf Surface Mooring (CE02SHSM), (b) wave properties (hourly averages) measured at the OOI Shelf Surface Mooring, (c and d) other near-bottom ADV parameters (15-min averages). Both the winds and ADV velocities are portrayed in earth coordinates (eastward is to the right along the horizontal axis and northward is positive along the vertical axis). ADV, Acoustic Doppler Velocimeter; EC D, eddy covariance deployment[/caption]
The oceanic bottom boundary layer (BBL) is the portion of the water column close to the seafloor where water motions and properties are influenced significantly by the seabed. This study (Reimers & Fogaren, 2021) reported in the Journal of Geophysical Research examines conditions in the BBL in winter on the Oregon shelf. Dynamic rates of sediment oxygen consumption (explicitly oxygen fluxes) are derived from high-frequency, near-seafloor measurements made at water depths of 30 and 80 meters. The strong back-and-forth motions of waves, which in winter form sand ripples, pump oxygen into surface sediments, and contribute to the generation of turbulence in the BBL, were found to have primed the seabed for higher oxygen uptake rates than observed previously in summer.
Since oxygen is used primarily in biological reactions that also consume organic matter, the winter rates of oxygen utilization indicate that sources of organic matter are retained in, or introduced to, the BBL throughout the year. These findings counter former descriptions of this ecosystem as one where organic matter is largely transported off the shelf during winter. This new understanding highlights the importance of adding variable rates of local seafloor oxygen consumption and organic carbon retention, with circulation and stratification conditions, into model predictions of the seasonal cycle of oxygen.
Supporting observations, which give environmental context for the benthic eddy covariance (EC) oxygen flux measurements, include data from instruments contained in OOI’s Endurance Array Benthic Experiment Package and Shelf Surface Moorings. Specifically, velocity profile time-series are drawn from records of a 300-kHz Velocity Profiler (Teledyne RDI-Workhorse Monitor), near-seabed water properties from CTD (SBE 16plusV2) and oxygen (Aanderaa-Optode 4831) sensors, winds from the surface buoy’s bulk meteorological package, and surface-wave data products from a directional wave sensor (AXYS Technologies) (see e.g., Fig 1 above).
Reimers, C. E., & Fogaren, K. E. (2021). Bottom boundary layer oxygen fluxes during winter on the Oregon shelf. Journal of Geophysical Research: Oceans, 126, e2020JC016828. https://doi.org/10.1029/2020JC016828
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Mission Accomplished: Endurance 14 Cruise Meets All Objectives
After a 15-day expedition, the Endurance Array Team returned to port aboard the R/V Sikuliaq on 7 April having successfully completed the 14th turn of the Endurance Array. The team recovered and deployed seven surface moorings and completed sampling at all recovery/deployment sites. They also deployed and recovered gliders and surface profilers.
Because of the size and weight of the moorings and other equipment, the trip was conducted in two legs. The first leg was primarily off Washington and the second off Oregon. Between legs, the R/V Sikuliaq returned to Newport, Oregon to offload recovered equipment from the Washington Line and load new equipment for the Oregon Line.
The weather was rough when the R/V Sikuliaq first set off from Newport on 24 March. On the first night out, they saw 19-foot waves and 35-knot winds. The team worked around the weather on the first leg to deploy three moorings and recover four. They also recovered and deployed gliders.
The second leg of the journey brought with it much better weather, which eased the recoveries, deployments, sampling, and other activities. During this leg, the team worked mostly off Oregon. The team deployed four moorings and three profilers and recovered three moorings, three gliders, and a profiler.
Each OOI deployment brings some technical improvement. On this deployment, the Endurance moorings are outfitted with redesigned solar panels on the buoy decks. These panels will deliver more power and be more resilient to wear and tear caused by sea lions who often find the buoys an inviting place to lounge. The redesign was implemented by OOI’s Coastal and Global Scale Nodes team at Woods Hole Oceanographic Institution.
This trip also marked the Endurance Array’s team first use of a OOI’s ROV (remotely operated vehicle). The ROV was used at the Oregon shelf site to recover a coastal surface piercing profiler and its anchor. Throughout the process, the R/V Sikuliaq maneuvered skillfully to place the ship over the target. Mooring lead Alex Wick piloted the ROV through strong currents and limited visibility. It took four dives, but the profiler and its anchor were recovered. On the third dive, the ROV was used to cut the winch line so the team could recover the profiler, and the anchor was recovered on the fourth and final dive.
The Endurance team also collected CTD samples and biofouling samples to share with researchers at the Smithsonian Institute and Oklahoma State University. The R/V Sikuliaq returned to Newport on 7 April with the recovered equipment, which will undergo refurbishment for the next turn of the Endurance Array in September.
“Since 2017, we’ve sailed on the R/V Sikuliaq for six out of nine cruises,” said Ed Dever, the Chief Scientist of Endurance 14. “It’s a match that works well. From ship handling and on-deck assistance to mobilization of underway science sensors, lifting gear, engineering, accommodations, and food, we are deeply appreciative of the Sikuliaq’s captain, crew, and the ship herself.”
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