Woods Hole Oceanographic Institution Research Articles

Modeling and oblique transmission characteristics of an underwater wireless optical communication channel based on ocean depth layering.

Underwater wireless optical communication is widely considered in the field of underwater communication due to its high bandwidth and low latency. In a real transmission link, the temperature and salinity of seawater, chlorophyll concentration, and bubble density vary with ocean depth. Therefore, the depth of the optical transmitter in seawater and the tilt angle of the beam will exhibit different beam transmission characteristics. In this paper, an underwater oblique-range layered channel model considering the combined effects of dynamic turbulence, absorption, and scattering is developed based on real data of seawater at different depths measured by the Global Ocean Observing Buoy Argo and the Woods Hole Oceanographic Institution BCO-DMO. The effects of transmission distance, transmitter tilt angle, and transmitter depth on the oblique-range transmission characteristics of the beam in seawater are discussed. The simulation results show that, at the same transmission distance, the beam centroid displacement increases with an increase in transmitter depth only when the transmitter is located above the interior of the thermocline. When the transmitter is located below the interior of the thermocline, the influence of the transmitter tilt angle on the beam centroid displacement decreases. This indicates that at different depths within the interior of the thermocline, the optical beam transmission characteristics exhibit significant variations.

In-domain versus out-of-domain transfer learning in plankton image classification

Plankton microorganisms play a huge role in the aquatic food web. Recently, it has been proposed to use plankton as a biosensor, since they can react to even minimal perturbations of the aquatic environment with specific physiological changes, which may lead to alterations in morphology and behavior. Nowadays, the development of high-resolution in-situ automatic acquisition systems allows the research community to obtain a large amount of plankton image data. Fundamental examples are the ZooScan and Woods Hole Oceanographic Institution (WHOI) datasets, comprising up to millions of plankton images. However, obtaining unbiased annotations is expensive both in terms of time and resources, and in-situ acquired datasets generally suffer from severe imbalance, with only a few images available for several species. Transfer learning is a popular solution to these challenges, with ImageNet1K being the most-used source dataset for pre-training. On the other hand, datasets like the ZooScan and the WHOI may represent a valuable opportunity to compare out-of-domain and large-scale plankton in-domain source datasets, in terms of performance for the task at hand.In this paper, we design three transfer learning pipelines for plankton image classification, with the aim of comparing in-domain and out-of-domain transfer learning on three popular benchmark plankton datasets. The general framework consists in fine-tuning a pre-trained model on a plankton target dataset. In the first pipeline, the model is pre-trained from scratch on a large-scale plankton dataset, in the second, it is pre-trained on large-scale natural image datasets (ImageNet1K or ImageNet22K), while in the third, a two-stage fine-tuning is implemented (ImageNet rightarrow large-scale plankton dataset rightarrow target plankton dataset). Our results show that an out-of-domain ImageNet22K pre-training outperforms the plankton in-domain ones, with an average boost in test accuracy of around 6%. In the next part of this work, we adopt three ImageNet22k pre-trained Vision Transformers and one ConvNeXt, obtaining results on par (or slightly superior) with the state-of-the-art, corresponding to the usage of CNN models ensembles, with a single model. Finally, we design and test an ensemble of our Vision Transformers and the ConvNeXt, outperforming the state-of-the-art existing works on plankton image classification on the three target datasets. To support scientific community contribution and further research, our implemented code is open-source and available at https://github.com/Malga-Vision/plankton_transfer.

Integrating fishers’ knowledge with oceanographic observations to understand changing ocean conditions in the Northeast United States

Recent warming in the Northeast United States continental shelf ecosystem has raised several concerns about the impacts on the ecosystem and commercial fisheries. In 2014, researchers from the Commercial Fisheries Research Foundation and Woods Hole Oceanographic Institution founded the Shelf Research Fleet to involve fishers in monitoring the rapidly changing ocean environment and encourage sharing of ecological knowledge. The Shelf Research Fleet is a transdisciplinary, cooperative program that trains commercial fishers to collect oceanographic information by deploying conductivity, temperature, and depth (CTD) instruments while commercially fishing. A total of 806 CTD profiles have been collected by the Shelf Research Fleet through December 2022. Participating vessels can view the conductivity and temperature water column profiles they collect in real-time. These profiles help inform their fishing practices and give insights when unexpected species appear in their gear or if their catch composition changes from previous years. The data collected by the Shelf Research Fleet are shared with and processed by researchers from numerous partnering institutions. The Shelf Research Fleet data have been used by researchers to better understand oceanographic phenomena including marine heatwaves, shelf-break exchange processes, warm core rings, and salinity maximum intrusions onto the continental shelf. The scope of the Shelf Research Fleet has grown over time to include efforts to more directly link oceanographic results with biological observations to better understand how changing ocean conditions are affecting commercially important species. This article describes the approach, successes, challenges, and future directions of the Shelf Research Fleet and aims to outline a framework for a cost-effective research program that engages fishers in the collection of oceanographic data, strengthening partnerships between fishing industry members and the scientific community.

Sun may make oil stick atop cold ocean

New research suggests that oil spills in cold locations with lots of sun exposure could play out much differently than warm-water spills, such as the one that followed the Deepwater Horizon explosion in 2010. Last week at the ACS Spring 2023 meeting, Danielle Haas Freeman , a PhD candidate at Woods Hole Oceanographic Institution, detailed how sunlight-driven photooxidation could leave a larger-than-expected fraction of spilled oil suspended on the surface of cold water. “What that means is that you would have more oil to clean up, and then you’d also end up with potentially more oil reaching sensitive coastal ecosystems,” said Collin P. Ward , a geochemist at Woods Hole who led the study. Freeman and Ward looked at the physical properties governing two different pathways for oil to be removed naturally from the water’s surface: entrainment, a process in which oil gets broken up and drawn down into the

Validation of turbulence intensity as simulated by the Weather Research and Forecasting model off the US northeast coast

Abstract. Turbulence intensity (TI) is often used to quantify the strength of turbulence in wind energy applications and serves as the basis of standards in wind turbine design. Thus, accurately characterizing the spatiotemporal variability in TI should lead to improved predictions of power production. Nevertheless, turbulence measurements over the ocean are far less prevalent than over land due to challenges in instrumental deployment, maintenance, and operation. Atmospheric models such as mesoscale (weather prediction) and large-eddy simulation (LES) models are commonly used in the wind energy industry to assess the spatial variability of a given site. However, the TI derivation from atmospheric models has not been well examined. An algorithm is proposed in this study to realize online calculation of TI in the Weather Research and Forecasting (WRF) model. Simulated TI is divided into two components depending on scale, including sub-grid (parameterized based on turbulence kinetic energy (TKE)) and grid resolved. The sensitivity of sea surface temperature (SST) on simulated TI is also tested. An assessment is performed by using observations collected during a field campaign conducted from February to June 2020 near the Woods Hole Oceanographic Institution Martha's Vineyard Coastal Observatory. Results show that while simulated TKE is generally smaller than the lidar-observed value, wind speed bias is usually small. Overall, this leads to a slight underestimation in sub-grid-scale estimated TI. Improved SST representation subsequently reduces model biases in atmospheric stability as well as wind speed and sub-grid TI near the hub height. Large TI events in conjunction with mesoscale weather systems observed during the studied period pose a challenge to accurately estimating TI from models. Due to notable uncertainty in accurately simulating those events, this suggests summing up sub-grid and resolved TI may not be an ideal solution. Efforts in further improving skills in simulating mesoscale flow and cloud systems are necessary as the next steps.

Sexual display from the abyss: Octopuses between heteronormativity and exorbitance


 
 
 This paper focuses on a footage recorded in 1993 by Woods Hole Oceanographic Institution at 2500m depth. It is the first visual experience of sexual activity between abyssal octopuses in their oceanic habitat: they are two males of two different species. This paper aims to analyze the gendered, affective, and moral structures that have produced texts and voice-offs in relation to this visuality, letting emerge how a transcultural, feminist, queer, and artistic gaze can lead to a reparative stance, beyond a replicated heteronormativity perceived as threatening, towards a more relaxed intimacy with animal sexualities, including a hybrid sense of eroticism that accompanies the human attraction for visual sexualities.
 
 

The design and evaluation of additively manufactured piezoelectric acoustic transducers

Ceramic additive manufacturing (AM) has been demonstrated as a capable method to fabricate piezocomposite acoustic transducers that exhibit augmented sensitivity, increased bandwidth, and controlled directivity by virtue of geometry. These improvements are intrinsic to the novel piezoelectric ceramic structure, which may be printed in forms that cannot be fabricated through conventional manufacturing methods. The AM process allows for functionally-graded apertures, 3-3 piezocomposite structures, and auxetic lattices which have been simulated, printed, and measured with compelling results. This presentation expands upon previous work completed through a collaboration between Lithoz America, LLC (Lithoz), MSI Transducers Corp. (MSI), and the MITRE Corporation (MITRE) to produce novel piezoelectric structures and validate acoustic and hydrostatic pressure performance of 1-3 piezocomposite structures under operationally relevant conditions. The presentation will encompass a discussion of Finite Element Analysis (FEA) of piezoelectric metamaterials conducted at MITRE, the lithography-based ceramic manufacturing (LCM) process of said structures at Lithoz, and empirical measurements of piezoelectric and acoustical specifications of the printed structures conducted at MSI. Finally, test data recorded at Woods Hole Oceanographic Institute (WHOI) will be shown, demonstrating the resilience of AM 1-3 piezocomposite under 10 000 PSI of hydrostatic pressure derived by means of in-situ electrical impedance measurements.

Identification of Sea Surface Temperature Anomaly during Earthquake in Southern Java Island using Google Earth Engine Datasets

The certainty of Sea Surface Temperature (SST) anomaly during earthquakes in Java Island was still not clear identified. This research tried to identify any possibilities of SST anomaly during earthquake in Southern Java Island. It used Google Earth Engine datasets including daily NOAA Climate Data Record (CDR) - Woods Hole Oceanographic Institution (WHOI): Sea Surface Temperature Version 2 which has resolution of 0.25 arc degrees for 20 years and processed them to depict SST trends in pre-earthquake and post-earthquake situation. The statistic test of t-Test Paired Two Sample was also applied to certain the significant difference of SST in both situations. SST fluctuation during the earthquake was still inconsistent and unclear to consider as an anomaly. There were other complicated factors excluding earthquake to influence SST fluctuation. The earthquake did not trigger directly to fluctuate SST, even not to make it being an anomaly.

Fertilizers disrupt the electric feel of flowers

Electricity is literally all around us. As humans, we generate weak electric fields whenever we move our muscles; spiders use static electricity in the air to fly across great distances; and geckos use static in their sticky feet to scale vertical walls with ease. Since everything has an electric field, we can imagine that this fundamental force of nature plays an important role in many ecological interactions. Among insects, bumblebees are known to alter the static electricity of flowers to communicate with members of their hive; the positive charge that collects on their tiny hairs alters the electric field around a visited flower for ∼100 s, communicating to the next bee that buzzes by that the nectar and pollen rewards from that flower have already been exhausted. Ellard Hunting and colleagues from University of Bristol, UK, and the Woods Hole Oceanographic Institution, USA, set out to test whether the application of agricultural sprays alters the electric field of flowers and whether bumblebees can detect these disruptions.The pervasive use of chemicals in agriculture is a substantial source of pollution. But besides chemical toxicity, little is known about how agrochemicals otherwise affect plant–pollinator interactions. Hunting and colleagues observed that bumblebees tend to hover around chemically treated flowers and decide not to land. To investigate the cause of this avoidance behaviour, the researchers developed a computational model for how the application of agricultural sprays may alter floral electric fields up to 4 cm from the flower. Their model considered how the presence of droplets on the flower's surface and localized increases in humidity from a spray application might impact the flower's electric field.Next, the researchers studied the effect of common agricultural fertilizers on flower features that bees recognize. To see if fertilizer sprays change the way bees see flowers, the researchers determined what wavelengths of light are reflected from droplets with and without fertilizers added. To study whether fertilizer sprays change the way flowers smell, they measured how much effort the bees put into feeding when offered sugar water laced with fertilizer compared with just sugar water. Lastly, to visualize the electric fields surrounding various blooms, the scientists sprayed charged coloured powder particles onto the centre of ragwort flowers and observed how the powder distributed across the surfaces. Although the fertilizers did not affect how bees see or smell flowers, the chemicals did alter the electric field around each bloom for several minutes.Next, Hunting and colleagues tested whether the adverse effects of spray applications persist over time. To do this, they planted electrodes into the cut stems of potted lavender and Texas bluebell plants and recorded the electrical current streaming down the stems in response to different spray applications. While a water spray caused a change in current that only lasted 30–60 s, a spray containing the fertilizer caused a consistent change in current that lasted up to 16 min. A spray with another common agricultural chemical – the pesticide Imidacloprid – induced a change in current that lasted up to 25 mins. Even subsequent water sprays, simulating rain, produced prolonged changes in the plant stem's electrical signature, suggesting that this effect can endure even after a single application of fertilizer.Finally, the researchers observed wild bumblebees foraging on cut flowers with artificially applied electric fields to mimic the effect of fertilizers. They pierced lavender stems with metal electrodes, placed them in glass jars of tap water, and attached a 13 V battery to produce an electric current in the plant. By recording 2 h videos and counting the number of bumblebees that approached versus those that landed on the lavender, the team showed that bumblebees somehow sense weird electricity as they approach a flower and land less as a result, serving as a healthy reminder that as humans we affect our environments in ways we can't even sense.

Coastal Surface Mooring Developments for the Ocean Observatories Initiative (OOI)

Abstract Multiple mooring components have been developed at Woods Hole Oceanographic Institution (WHOI) that represent significant advancements in mooring technology. The Ocean Observatories Initiative (OOI) Coastal Surface Moorings are a unique coalescence of these elements into a robust and capable electromechanical mooring design. This paper describes innovative design elements in three key areas that are used operationally on OOI moorings: (1) components at the interface between buoy base and mooring riser, (2) electro-mechanical mooring riser components, and (3) an integrated seafloor anchor and instrument frame. These elements work together as a system that not only provides the necessary mechanical integrity for the mooring, but also provides mounting points for instrumentation and a reliable electrical pathway from the surface to the seafloor.

Through an Ice Sheet, Darkly

Through an Ice Sheet, Darkly

James Ransom Heirtzler: A Tribute

AbstractJames Ransom Heirtzler passed away in Silver Spring, Maryland, on 15 July 2022, at age 96. He was born in Baton Rouge, Louisiana, on 16 September 1925. James served in the U.S. Navy in the tropical and western Pacific during 1944–1946. He graduated from New York University obtaining a Ph.D. in Physics in 1953 and taught at the American University of Beirut 1953–1956. Dr. Heirtzler was at Columbia University 1960–1969, at Woods Hole Oceanographic Institution 1969–1985, and then at NASA Goddard Space Flight Center until retiring in 2004. He authored or coauthored 168 scientific articles, edited numerous books and participated in the production of the documentary movie “Where the Earth Turns Inside Out.” James was a fellow of the American Geophysical Union, the Geological Society of America, and the American Physical Society. He led scientific cruises in all the oceans of the world and had expeditions in both Polar Regions. Dr. Heirtzler has two Antarctic geological features and a microfossil named for him: the Heirtzler Ice Piedmont (72°34′S and 61°25′W), the Heirtzler Fracture Zone (63°30′S and 162°30′E), and the microfossil “Pithonella heirtzleri.”

Graduate education in acoustic engineering, transduction, and signal processing University of Massachusetts Dartmouth

The University of Massachusetts Dartmouth has an established graduate program of study with a concentration in Applied Acoustics leading to the M.S. and Ph.D. degree in Electrical Engineering. The program offers courses and research opportunities in the area of electroacoustic transduction, underwater acoustics, and signal processing. Courses include the Fundamentals of Acoustics, Random Signals, Underwater Acoustics, Introduction to Transducers, Electroacoustic Transduction, Medical Ultrasonics, Digital Signal Processing, Detection Theory, and Estimation Theory. The ECE department established the university’s indoor underwater acoustic test and calibration facility which is one of the largest academic facilities supporting undergraduate and graduate thesis and sponsored research. The department has collaborations with many marine acoustic related companies including nearby Naval Undersea Warfare Center in Newport, RI and Woods Hole Oceanographic Institute in Cape Cod, MA. The presentation will highlight recent theses and dissertations, course offerings, and industry and government collaborations that support acoustical engineering, transduction, and signal processing.

“Mud acoustics” and the ocean acoustics program

Shallow water acoustics is one of the major thrusts of the Office of Naval Research Ocean Acoustics Program and has been an important area of interest to Navy programs since at least the work of Pekeris, Ewing, and Worzel in the 1940’s. In the 1950’s and early 1960’s, there was a flurry of activity both in the US and UK focused on propagation within and reflection from the seabed and the acoustical characteristics marine sediments. This work formed the basis of a research program carried out by the applied ocean acoustics branch of the acoustics division at the Naval Research Laboratory in the 1970’s. In April 1991, with the Cold War coming to an end, and a shift in interest from blue water to the littorals, ONR sponsored a workshop on shallow water acoustics at the Woods Hole Oceanographic Institution. This meeting, including underwater acousticians, geologists, geophysicists, and physical oceanographers, largely set the stage for the next 30 years of shallow water acoustics research supported by ONR. Prominent efforts include the ONR Geoclutter Program and the Shallow Water 2006 experiments, both focused on regions dominated by sandy bottoms. This talk describes more recent efforts in regions characterized by muddy bottoms.

Experimental Marine Vibrator With a Helmholtz Bubble Resonator in the Frequency Range 5–16 Hz

The use of coherent broadband signals instead of explosive, high-intensity air-gun pulses is one potential way to reduce sound pressure and sound exposure levels in marine surveys. A coherent type of seismic source achieves a higher resolution, hence a sharper image of deep layers. In the upper-frequency range of seismic signals (higher than 16 Hz), marine vibrators can successfully apply the known acoustic technology of low-frequency underwater transducers. This technology is not as effective at low seismic frequencies. The slow progress in the development of this technology requires finding a different approach. An alternative would be to employ a gas-filled underwater cylindrical bubble resonator. A large gas-filled resonance bubble covered with an elastic membrane and driven by a blower with airflow controlled by a proportional valve provides significant power in the low-frequency range. We achieved a suitable broadband frequency response by designing a double resonance system consisting of a bubble and an internal Helmholtz gas acoustic resonator. Experimental tests were conducted at the Woods Hole Oceanographic Institution. This article provides an overview of engineering solutions considered in the design, including drivers, membranes, and methods of increasing efficiency.

AUV-Assisted Diver Navigation

This letter presents a precise navigation technique for a scuba diver using an autonomous underwater vehicle (AUV) as a positioning aid. We develop and evaluate the state estimation algorithms and communication architecture for diver navigation based on subsurface human-AUV teaming with no requirement for ocean current data or exact diver speeds. By depending on acoustic communication and commercial AUV navigation capabilities, our method provides a unique capability for localizing a diver's position during an extended mission, without the requirement to maintain visual contact with the diver during the mission, or to deploy acoustic beacons. We utilize the Woods Hole Oceanographic Institution Micromodem 2 for range-only single-beacon navigation between two kayaks serving as proxies for the diver and REMUS 100 AUV. Range and odometry measurements are fused in a factor graph using incremental smoothing and mapping 2 (iSAM2) with appropriate motion and measurement models to provide real-time diver position estimates given unknown ocean currents. Field experiments demonstrate an average online endpoint error of 4.53 meters after 400-meter transits.

In the field: an interview with Sönke Johnsen

Sönke Johnsen is a Professor at Duke University, USA, investigating visual ecology. After completing his degree in mathematics at Swarthmore College, USA, and a PhD with William Kier at University of North Carolina at Chapel Hill, USA, Johnsen worked as a post-doc with Edie Widder at Harbor Branch Oceanographic Institution, USA, and Larry Madin at Woods Hole Oceanographic Institution, USA. He remained at Woods Hole as an Assistant Scientist before moving to Duke as an Assistant Professor. Johnsen talks about his experiences of collecting transparent animals while blue water diving and in a submersible, as well as outrunning Hurricane Katrina in 2005.

Geological transformations

Following its extraordinary desiccation, the Mediterranean basin is thought to have refilled when the Strait of Gibraltar opened and Atlantic waters flooded in Bill was introduced to geoscience in 1961, during a Woods Hole Oceanographic Institute research expedition that travelled across the Atlantic and into the Mediterranean Sea. “I was struck by the progressive decrease […]

A Ka-Band Wind Geophysical Model Function Using Doppler Scatterometer Measurements from the Air-Sea Interaction Tower Experiment

Physical understanding and modeling of Ka-band ocean surface backscatter is challenging due to a lack of measurements. In the framework of the NASA Earth Ventures Suborbital-3 Submesoscale Ocean Dynamics Experiment (S-MODE) mission, a Ka-Band Ocean continuous wave Doppler Scatterometer (KaBODS) built by the University of Massachusetts, Amherst (UMass) was installed on the Woods Hole Oceanographic Institution (WHOI) Air-Sea Interaction Tower. Together with ASIT anemometers, a new data set of Ka-band ocean surface backscatter measurements along with surface wind/wave and weather parameters was collected. In this work, we present the KaBODS instrument and an empirical Ka-band wind Geophysical Model Function (GMF), the so-called ASIT GMF, based on the KaBODS data collected over a period of three months, from October 2019 to January 2020, for incidence angles ranging between 40° and 68°. The ASIT GMF results are compared with an existing Ka-band wind GMF developed from data collected during a tower experiment conducted over the Black Sea. The two GMFs show differences in terms of wind speed and wind direction sensitivity. However, they are consistent in the values of the standard deviation of the model residuals. This suggests an intrinsic geophysical variability characterizing the Ka-band surface backscatter. The observed variability does not significantly change when filtering out swell-dominated data, indicating that the long-wave induced backscatter modulation is not the primary source of the KaBODS backscatter variability. We observe evidence of wave breaking events, which increase the skewness of the backscatter distribution in linear space, consistent with previous studies. Interestingly, a better agreement is seen between the GMFs and the actual data at an incidence angle of 60° for both GMFs, and the statistical analysis of the model residuals shows a reduced backscatter variability at this incidence angle. This study shows that the ASIT data set is a valuable reference for studies of Ka-band backscatter. Further investigations are on-going to fully characterize the observed variability and its implication in the wind GMF development.

Thyroid Bioassay and Dose Assessment System for 125I at Woods Hole Oceanographic Institution.

Woods Hole Oceanographic Institution (WHOI) conducts research involving 125I. When an individual handles or works near unsealed radioiodine, including 125I, above certain activities bioassays are required or may be required. Because of the quantities of 125I being used for a research protocol, a thyroid bioassay and dose assessment system and procedure was developed to comply with this requirement. This procedure includes detector calibration, quality control, determination of recording level, determination of minimum detectable activity, thyroid bioassay (baseline, routine, special, and termination measurements), and intake and dose assessment calculations.