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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Temporal variability of the Antarctic Circumpolar Current observed from satellite altimetry

Sea level measurements by the Seasat altimeter were used to study the temporal variability of the Antarctic Circumpolar Current between July and October 1978. Large-scale zonal coherence in the cross-stream sea level difference was observed, indicating a general increase in the surface geostrophic velocity of the current around the Southern Ocean. The result demonstrates the power of satellite altimetry to monitor the variability of large-scale ocean currents.

Fu, L.-L.↗
NASA NTRS1981

The variability of equatorial currents

The temporal variations of upper ocean currents along the equator, specially the equatorial undercurrent are discussed. Many mechanisms were proposed as explanations of the steady state undercurrent including vertical mixing, horizontal mixing, thermohaline effects, and nonlinear effects. All of these theories succeed to some extent in simulating some of the observed features of the undercurrent. To distinguish among these ideas, the time variability of equatorial currents was considered. Observations of surface currents, currents in the thermocline, and surface winds at the equator are shown.

Cane, M. A.↗
NASA NTRS1977

Current and future satellites for oceanic monitoring

Current applications and products from existing operational satellites, are reviewed. The future data and information that will become available before the end of this decade are described with emphasis on global oceanic data.

Sherman, J. W., III↗
NASA NTRS1983

TOPEX ground data system

The TOPEX Project is a proposed oceanographic mission to measure the topography of the sea surface for a period of three years. This mission is sponsored by the National Aeronautics and Space Administration and managed by the Jet Propulsion Laboratory. Measurements of topography are used to study ocean currents, tides, bathymetry and the oceanic geoid. Several of the primary goals of this mission are to process and verify the altimetric data, and distribute them within days to the science investigators. This paper describes the TOPEX end-to-end ground data system. In addition to controlling the TOPEX satellite, the ground data system has been designed to minimize the time from data acquisition to science processing and data distribution. A centralized design supports the favorable response time of the system and also allows for operational efficiencies. Networking of real time and non-real time elements of the data system provides for more effective data processing.

Rosell, S. N.↗
NASA NTRS2019

A Model Study of the Relative Influences of Scavenging and Circulation on 230Th and 231Pa in the Western North Atlantic

The oceanic cycles of thorium-230 and protactinium-231 are affected by a number of processes, such as removal by adsorption to settling particles and transport by ocean currents. Measurements obtained as part of GEOTRACES and earlier programs have shown that, in the North Atlantic, the activities of dissolved 230Th (230Thd) and 231Pa (231Pad) at abyssal depths are lower near the western margin than in the basin interior. At least two factors could explain the lower 230Thd and 231Pad near the margin: (i) intensified scavenging in benthic nepheloid layers (BNLs) extending a thousand meters or more above the seafloor; and (ii) ventilation by relatively 230Thd- and 231Pad-poor waters emanating from the Deep Western Boundary Current (DWBC).Here a regional ocean circulation model with ?eddy-permitting' resolution (1/4) that incorporates 230Th and 231Pa is used in an effort to reproduce the observed distributions of 230Th and 231Pa in the western North Atlantic. In this model, 230Th and 231Pa removal from solution is governed by a prescribed distribution of particulate matter that is derived from a recent synthesis of nephelometer and transmissometer data. The model simulates a meandering Gulf Stream and a DWBC along the continental slope and rise, although noticeable differences with physical observations also exist. A model solution is found that explains most of the variance of 230Thd measurements (85%) and 231Pad measurements (81%) from (pre-)GEOTRACES cruises. On the other hand, measurements of particulate 230Th (230Thp) and 231Pa (231Pap) are more difficult to reproduce, with the same solution accounting for only 49% (11%) of the 230Thp (231Pap) variance. Sensitivity experiments suggest that the low 230Thd and 231Pad activities observed near the western margin are due to enhanced removal rates of both nuclides in BNLs rather than to deep water ventilation from the western boundary. The radionuclide activities present in the DWBC at its inflow location are also found to strongly influence the basin-scale distributions of 230Th and 231Pa. Overall, our study points to BNLs as important sites of 230Th and 231Pa scavenging in the ocean and illustrates the difficulty to explain simultaneously radionuclide measurements in dissolved and particulate forms in the studied area.

Lerner, Paul↗
DOE OSTI2020

Lab-Scale, Closed-Loop Experimental Characterization, Model Refinement, and Validation of a Hydrokinetic Energy-Harvesting Ocean Kite

This paper presents a study wherein we experimentally characterize the dynamics and control system of a lab-scale ocean kite, and then refine, validate, and extrapolate this model for use in a full-scale system. Ocean kite systems, which harvest tidal and ocean current resources through high-efficiency cross-current motion, enable energy extraction with an order of magnitude less material (and cost) than stationary systems with the same rated power output. However, an ocean kite represents a nascent technology that is characterized by relatively complex dynamics and requires sophisticated control algorithms. In order to characterize the dynamics and control of ocean kite systems rapidly, at a relatively low cost, the authors have developed a lab-scale, closed-loop prototyping environment for characterizing tethered systems, whereby 3D printed systems are tethered and flown in a water channel environment. While this system has been shown to be capable of yielding similar dynamic characteristics to some full-scale systems, there are also fundamental limitations to the geometric scales and flow speeds within the water channel environment, making many other real-world scenarios impossible to replicate from the standpoint of dynamic similarity. Here, to address these scenarios, we show how the lab-scale framework is used to refine and validate a scalable dynamic model of a tethered system, which can then be extrapolated to full-scale operation. In this work, we present an extensive case study of this model refinement, validation, and extrapolation on an ocean kite system intended for operation in the Gulf Stream or similar current environments.

42 ENGINEERING↗
NASA NTRS1975

A New Current Drogue System for Remotely Monitoring Shelf Current Circulation

The author has identified the following significant results. An ocean current drogue system was developed for use in the coastal zone and continental shelf region. The method features an extremely simple radiosonde device whose position is determined from a pair of cooperative shore stations. These ocean sondes follow the tradition of the atmospheric radiosonde in that they are economically disposable at the end of their mission. The system was successfully tested in a number of environments, including the North Atlantic in two winter coastal storms. Tracking to the edge of the Baltimore and Wilmington trenches was achieved. The drogue system is being used in conjunction with remote sensing aircraft and satellites to chart current circulation at ocean waste disposal sites 40 miles off Delaware's coast.

Klemas, V.↗
NASA NTRS1998

Detection and Modeling of Non-Tidal Oceanic Effects on the Earth's Rotation Rate

Sub-decadal changes in the Earth's rotation rate, and hence in the length-of-day (LOD), are largely controlled by variations in atmospheric angular momentum. Results from two oceanic general circulation models (OGCMs), forced by observed wind stress and heat flux for the years 1992-1994, show that ocean current and mass distribution changes also induce detectable LOD variations.

Earth's rotation rate length-of-day LOD atmospheri↗
DOE OSTI2023

A Comprehensive Assessment Tool for Low-TRL Current Energy Converters

Along with a market-competitive levelized cost of energy, a current energy converter technology strongly benefits from an extensive consideration of socioeconomic, environmental, and regulatory factors early in the design process. As part of a technology performance level assessment, a series of assessment questions and guidance are developed and presented to evaluate an early-stage current energy technology on holistic criteria considering the entire device lifecycle. The assessment represents an accumulation of industry and research experience to date and relies on regular updates to ensure alignment with industry best-practices, regulatory requirements, and up-to-date technical understanding. A cradle-to-grave (materials, manufacturing, installation and deployment, operations and maintenance, and end-of-life) assessment of capabilities and functional requirements (i.e., high, medium, and low) performance criteria for current energy converters deployed in tidal, ocean current, and/or river applications. Key considerations related to manufacturing and installation include supply chain robustness, manufacturability and related job creation in the end-user and/or adjacent communities, and the time-to-repayment of the embodied energy debt. During deployment and maintenance operations, the safety of the device and subsystems during disconnect or grid failure, the difficulty and frequency of offshore heavy-lift activities, the avoidance or mitigation of area-use conflicts, the sea-states and weather conditions that permit maintenance access, and the availability of contingency plans (should conditions change unexpectedly) are a portion of the considered assessment criteria. Results include the potential impact of early-stage design decisions on the socioeconomic, environmental, and regulatory performance of a technology that allows developers to increase the product value and probability of success, and minimize costly late-stage design iterations through early and broad consideration of factors affecting overall performance and acceptability.

life cycle analysis↗
NASA NTRS1982

Laser/Heterodyne Measurement of Temperature and Salinity

Proposed visible-light laser/heterodyne receiver would remotely measure temperature and salinity of subsurface water. Operation is based on acoustic/optical scattering of light by sound waves. Application of this concept is foreseen in current research on energy conversion from ocean currents produced by thermal gradients and on future marine remote-sensing program.

Jobson, D. J.↗
NASA NTRS2007

Solutions Network Formulation Report: Improving NOAA's PORTS(R) Through Enhanced Data Inputs from NASA's Ocean Surface Topography Mission

The Nation uses water-level data for a variety of practical purposes, including nautical charting, maritime navigation, hydrography, coastal engineering, and tsunami and storm surge warnings. Long-term applications include marine boundary determinations, tidal predictions, sea-level trend monitoring, oceanographic research, and climate research. Accurate and timely information concerning sea-level height, tide, and ocean current is needed to understand their impact on coastal management, disaster management, and public health. Satellite altimeter data products are currently used by hundreds of researchers and operational users to monitor ocean circulation and to improve scientists understanding of the role of the oceans in climate and weather. The NOAA (National Oceanic and Atmospheric Administration) National Ocean Service has been monitoring sea-level variations for many years. NOAA s PORTS (Physical Oceanographic Real-Time System) DST (decision support tool), managed by the Center for Operational Oceanographic Products and Services, supports safe and cost-efficient navigation by providing ship masters and pilots with accurate real-time information required to avoid groundings and collisions. This report assesses the capacity of NASA s satellite altimeter data to meet societal decision support needs through incorporation into NOAA s PORTS. NASA has a long heritage of collecting data for ocean research, including its current Terra and Aqua missions. Numerous other missions provide additional important information for coastal management issues, and data collection will continue in the coming decade with such missions as the OSTM (Ocean Surface Topography Mission). OSTM will provide data on sea-surface heights for determining ocean circulation, climate change, and sea-level rise. We suggest that NASA incorporate OSTM altimeter data (C- and Ku-band) into NOAA s PORTS DST in support of NASA s Coastal Management National Application with secondary support to the Disaster Management and Public Health National Applications.

Guest, DeNeice↗
NASA NTRS2002

The Earth Gravitational Model 1996: The NCCS: Resource for Development, Resource for the Future

For centuries, men have attempted to understand the climate system through observations obtained from Earth's surface. These observations yielded preliminary understanding of the ocean currents, tides, and prevailing winds using visual observation and simple mechanical tools as their instruments. Today's sensitive, downward-looking radar systems, called altimeters, onboard satellites can measure globally the precise height of the ocean surface. This surface is largely that of the equipotential gravity surface, called the geoid - the level surface to which the oceans would conform if there were no forces acting on them apart from gravity, as well as having a significant 1-2- meter-level signal arising from the motion of the ocean's currents.

Source record↗
NASA NTRS1977

The N.A.S.A. earth and ocean dynamics programme

Practical applications of NASA space systems, science, and technology to the study of oceans and solid earth are discussed. Goals involving earth dynamics include earthquake hazard assessment and alleviation, and global surveying and mapping, while goals involving ocean dynamics include the determination of ocean currents and circulation, and the monitoring of ocean surface conditions. Satellites used to obtain data are described, and projects such as the study of open ocean tides and earth motion determination are reviewed, with consideration given to the techniques (e.g., laser ranging, satellite-to-satellite track) used in these studies. Several physical phenomena, the extent to which they presently can be measured, and possible future requirements for more accurate measurements are examined.

Vonbun, F. O.↗
NASA NTRS1981

Oceanographic influences on the sea ice cover in the Sea of Okhotsk

Sea ice conditions in the Sea of Okhotsk, as determined by satellite images from the electrically scanning microwave radiometer on board Nimbus 5, were analyzed in conjunction with the known oceanography. In particular, the sea ice coverage was compared with the bottom bathymetry and the surface currents, water temperatures, and salinity. It is found that ice forms first in cold, shallow, low salinity waters. Once formed, the ice seems to drift in a direction approximating the Okhotsk-Kuril current system. Two basic patterns of ice edge positioning which persist for significant periods were identified as a rectangular structure and a wedge structure. Each of these is strongly correlated with the bathymetry of the region and with the known current system, suggesting that convective depth and ocean currents play an important role in determining ice patterns.

Gratz, A. J.↗
NASA NTRSDate not supplied

FATE: The drifting Fish Aggregating Device (dFAD) TrajEctory Modeling Tool for Marine Protected Area Management

Drifting fish aggregating devices (dFADs) routinely enter marine protected areas (MPAs) and may undermine MPA protections by drifting out of the MPA with the aggregated fish biomass, or grounding and damaging sensitive coral reef habitats. MPA managers must decide whether to deploy resources in response to dFAD intrusions. To address this issue, we propose to quantify dFAD activity in relation to ocean currents, fish biomass, and animal telemetry at Palmyra Atoll, part of the Pacific Remote Islands Marine National Monument in the central Pacific Ocean. Specifically, we propose to develop the dFAD TrajEctory Tool (FATE). FATE is an innovative decision support tool that will use NASA observations and numerical models to predict future dFAD trajectories and inform TNC and USFWS whether they should deploy tactical resources (boats, personnel) to monitor, intercept, or retrieve dFADs that have entered the Refuge. The objectives are to use NASA observational constraints on ocean winds and currents to assist with the ecological management of the Palmyra Atoll NWR and MPA. Specifically, we will deliver an operational software tool that quantifies the grounding risk associated with each tracked dFAD and decision support for grounding risk mitigation via intercept at sea. This project addresses Element 3.3: Protected area management of the 2022 Ecological Conservation Solicitation by developing a tool needed by MPA managers to make tactical and strategic decisions focused on improving the effectiveness of MPAs. By quantifying the riskof dFADs, this project will help monitor and better inform the deployment of tactical (ships/personnel) and strategic (legislative) resources to better manage MPAs. This project is a collaboration between The Nature Conservancy, who operate long-term projects within the Palmyra MPA, and the U.S. Fish and Wildlife Service, who have the authority to make decisions related to its management. We expect that the results of our proposal will benefit marine resources within the Palmyra MPA and could be transferred to other remote MPAs within the US and other island nations within the Pacific Ocean.

TrajEctory↗
DOE OSTI2021

Grid Value Proposition of Marine Energy

Marine energy technologies convert the energy of ocean waves, and tidal, river, and ocean currents into electricity and other forms of usable energy. The marine energy resource potential in the United States is significant and geographically diverse, with a study commissioned by the U.S. Department of Energy estimating that the nation’s annual marine energy potential is approximately 2,300 TWh/year across the 50 states, or greater than 57 percent of U.S. electricity generation in 2019. However, the marine energy industry still faces hurdles to commercialization. While high costs relative to wind and solar remain a key challenge, other hurdles relate to marine energy’s value streams not being well characterized and not captured by traditional energy comparison metrics like the levelized cost of energy. To address this challenge, this project undertakes several types of analyses to identify and illustrate value propositions for marine energy resources. It provides a fresh framework for considering electric system benefits based on unique marine energy attributes, and provides analyses illustrating and quantifying those benefits. The authors find many opportunities for the deployment of marine energy technologies both in the near term and within typical utility planning timeframes (i.e. up to 20 years). From a resource and technology perspective, marine energy resources can deliver distinct and valuable benefits to different configurations of the grid, whether the bulk system, isolated distribution systems, or remote communities, islands, and microgrids. Marine energy resources can be valuable in increasing technology diversity in a generation portfolio, providing energy where it is otherwise difficult to come by, supporting local resiliency, complementing and being complemented by other resources including solar, wind, and energy storage, and avoiding land constraints.

16 TIDAL AND WAVE POWER↗
DOE OSTI2024

Recent Advances in Assessing Environmental Effects of Marine Renewable Energy Around the World

Marine renewable energy (MRE) is increasingly of interest to coastal nations as a source of renewable energy that can support climate change mitigation goals as well as provide secure locally-produced energy for coastal and island communities. MRE extracts power from tidal streams, waves, ocean currents, run of rivers, and gradients in the ocean, with specialized devices developed and tested for each energy resource. Alongside development of MRE technologies and systems, first in Europe and then in North America, Australia, Asia, and other regions, it has been universally recognized that there is also a need to examine potential effects on marine animals, habitats, ecosystem processes, local communities and other sea users, to ensure that the MRE industry can be developed in a responsible and sustainable manner. This paper looks at the status of assessment and monitoring for potential environmental effects associated with MRE projects around the world. Over 80 projects were identified worldwide as having been tested, demonstrated, or commercially deployed with associated environmental monitoring. Five of the projects that represent tidal stream, wave, and run of river projects are examined in more detail to determine the types of data and information collected for those projects, the outputs of the monitoring campaigns, and the actions taken as a result of the data collection and analysis. Recommendations are provided for standardization of the monitoring approaches, instruments, and analysis methods at MRE project sites worldwide.

marine renewable energy, environmental effects, ri↗
NASA NTRS1991

Ocean circulation modeling by use of radar altimeter data

The project will investigate the use of radar altimetry (RA) data in the determination of the ocean circulation models. RA data will be used to verify prognostic experiments of the steady state and seasonal cycle of large-scale circulation models and the statistical steady state of eddy-resolving models. The data will serve as initial and update conditions in data assimilation experiments and as constraints in inverse calculations. The aim of the project is a better understanding of ocean physics, the determination and mapping of ocean currents, and a contribution to the establishment of ocean circulation models for climate studies. The goal of the project is to use satellite radar altimetry data for improving our knowledge of ocean circulation both in a descriptive sense and through the physics that govern the circulation state. The basic tool is a series of ocean circulation models. Depending on the model, different techniques will be applied to incorporate the RA data.

Olbers, Dirk↗