Science.gov

Sample records for ocean wave power

  1. Power from Ocean Waves.

    ERIC Educational Resources Information Center

    Newman, J. N.

    1979-01-01

    Discussed is the utilization of surface ocean waves as a potential source of power. Simple and large-scale wave power devices and conversion systems are described. Alternative utilizations, environmental impacts, and future prospects of this alternative energy source are detailed. (BT)

  2. Power from Ocean Waves.

    ERIC Educational Resources Information Center

    Newman, J. N.

    1979-01-01

    Discussed is the utilization of surface ocean waves as a potential source of power. Simple and large-scale wave power devices and conversion systems are described. Alternative utilizations, environmental impacts, and future prospects of this alternative energy source are detailed. (BT)

  3. Power inversion design for ocean wave energy harvesting

    NASA Astrophysics Data System (ADS)

    Talebani, Anwar N.

    The needs for energy sources are increasing day by day because of several factors, such as oil depletion, and global climate change due to the higher level of CO2, so the exploration of various renewable energy sources is very promising area of study. The available ocean waves can be utilized as free source of energy as the water covers 70% of the earth surface. This thesis presents the ocean wave energy as a source of renewable energy. By addressing the problem of designing efficient power electronics system to deliver 5 KW from the induction generator to the grid with less possible losses and harmonics as possible and to control current fed to the grid to successfully harvest ocean wave energy. We design an AC-DC full bridge rectifier converter, and a DC-DC boost converter to harvest wave energy from AC to regulated DC. In order to increase the design efficiency, we need to increase the power factor from (0.5-0.6) to 1. This is accomplished by designing the boost converter with power factor correction in continues mode with RC circuit as an input to the boost converter power factor correction. This design results in a phase shift between the input current and voltage of the full bridge rectifier to generate a small reactive power. The reactive power is injected to the induction generator to maintain its functionality by generating a magnetic field in its stator. Next, we design a single-phase pulse width modulator full bridge voltage source DC-AC grid-tied mode inverter to harvest regulated DC wave energy to AC. The designed inverter is modulated by inner current loop, to control current injected to the grid with minimal filter component to maintain power quality at the grid. The simulation results show that our design successfully control the current level fed to the grid. It is noteworthy that the simulated efficiency is higher than the calculated one since we used an ideal switch in the simulated circuit.

  4. Oceanic wave measurement system

    NASA Technical Reports Server (NTRS)

    Holmes, J. F.; Miles, R. T. (Inventor)

    1980-01-01

    An oceanic wave measured system is disclosed wherein wave height is sensed by a barometer mounted on a buoy. The distance between the trough and crest of a wave is monitored by sequentially detecting positive and negative peaks of the output of the barometer and by combining (adding) each set of two successive half cycle peaks. The timing of this measurement is achieved by detecting the period of a half cycle of wave motion.

  5. Ocean powered pump

    SciTech Connect

    Westling, W. A.

    1985-04-30

    A pumping unit suitable for driving an electric generator and which is powered by ocean surf and waves. The unit includes a tower which is located on an ocean beach, and which includes a generally horizontal boom. The boom includes two forward sections disposed at right angles to one another. Two blades are mounted on the respective ends of the forward sections, and the forward sections are controlled so that the blades can be alternately dropped into the water to be driven toward the shore by the incoming surf and waves. As one blade is driven to the shore, it turns the boom in one direction about the vertical axis, causing the other blade to be moved out over the water. Then, the first blade can be lifted out of the water, and the second blade dropped into the water, so that the incoming surf will drive the second blade towards the shore turning the boom in the opposite direction about the vertical axis. The cycle is then repeated, and the resulting action is for the boom to turn reciprocally about the vertical axis. The boom is coupled to a pump, and its reciprocal action causes the pump to perform a desired pumping action.

  6. Ocean wave electric generators

    SciTech Connect

    Rosenberg, H.R.

    1986-02-04

    This patent describes an apparatus for generating electricity from ocean waves. It consists of: 1.) a hollow buoyant duck positioned in the path of waves including a core about the center axis of which the duck rotates, a lower chamber portion having liquid therein and an upper chamber portion having air therein. The air is alternately compressed and expanded by the liquid in the chamber during the rotational motion of the duck caused by waves. A turbine mounted in the upper portion of the duck is driven by the compressed and expanded air. A generator is coupled to the turbine and operated to produce electrical energy and an air bulb; 2.) a spine having a transverse axial shaft anchoring the spine to the ocean floor. The upper portion of the spine engages the duck to maintain the duck in position. The spine has a curved configuration to concentrate and direct wave energy. The spine configuration acts as a scoop to increase the height of wave peaks and as a foil to increase the depth of wave troughs.

  7. Directional Ocean Wave Spectra

    DTIC Science & Technology

    1991-01-01

    of Ocean Waves: Some Observations from R. K. Raney and LIMEX/LEWEX 󈨛 P. W, Vachon 104 Directional Spectra from the CCRS C-Band SAR during LEWEX P...11. Vachon , A. S. Bhogal, and i%’. G. Freeman I10 SAR Scattering Mechanisms as Inferred from LEWEX D. G, Tiller Spectral Intercomparisons 117...Duiring her stay. Michelle Champagne- on time scales usually recommended to define the mean. Philippe explored some of the aspects ofthe ’sind %aniahilits

  8. Ocean power technology design optimization

    DOE PAGES

    van Rij, Jennifer; Yu, Yi-Hsiang; Edwards, Kathleen; ...

    2017-07-18

    For this study, the National Renewable Energy Laboratory and Ocean Power Technologies (OPT) conducted a collaborative code validation and design optimization study for OPT's PowerBuoy wave energy converter (WEC). NREL utilized WEC-Sim, an open-source WEC simulator, to compare four design variations of OPT's PowerBuoy. As an input to the WEC-Sim models, viscous drag coefficients for the PowerBuoy floats were first evaluated using computational fluid dynamics. The resulting WEC-Sim PowerBuoy models were then validated with experimental power output and fatigue load data provided by OPT. The validated WEC-Sim models were then used to simulate the power performance and loads for operationalmore » conditions, extreme conditions, and directional waves, for each of the four PowerBuoy design variations, assuming the wave environment of Humboldt Bay, California. And finally, ratios of power-to-weight, power-to-fatigue-load, power-to-maximum-extreme-load, power-to-water-plane-area, and power-to-wetted-surface-area were used to make a final comparison of the potential PowerBuoy WEC designs. Lastly, the design comparison methodologies developed and presented in this study are applicable to other WEC devices and may be useful as a framework for future WEC design development projects.« less

  9. Infragravity waves across the oceans

    NASA Astrophysics Data System (ADS)

    Rawat, Arshad; Ardhuin, Fabrice; Aucan, Jerome

    2014-05-01

    The propagation of transoceanic Infragravity (IG) wave was investigated using a global spectral wave model together with deep-ocean pressure recorders. IG waves are generated mostly at the shorelines due to non-linear hydrodynamic effects that transfer energy from the main windsea and swell band, with periods of 1 to 25 s, to periods up to 500 s. IG waves are important for the study of near-shore processes and harbor agitation, and can also be a potential source of errors in satellite altimetry measurements. Setting up a global IG model was motivated by the investigation of these errors for the future planned SWOT mission. Despite the fact that the infragravity waves exhibit much smaller vertical amplitudes than the usual high frequency wind-driven waves, of the order of 1 cm in the deep oceans, their propagation throughout the oceans and signature in the wave spectrum can be clearly observed. Using a simplified empirical parameterization of the nearshore source of free IG waves as a function of the incoming wave parameters we extended to WAVEWATCH III model, used so far for windseas and swell, to the IG band, up to periods of 300 s. The spatial and temporal variability of the modeled IG energy was well correlated to the DART station records, making it useful to interpret the records of IG waves. Open ocean IG wave records appear dominated by trans-oceanic events with well defined sources concentrated on a few days, usually on West coasts, and affecting the entire ocean basin, with amplitude patterns very similar to those of tsunamis. Three particular IG bursts during 2008 are studied, 2 in the Pacific Ocean and 1 in the North Atlantic. It was observed that the liberated IG waves can travel long distances often crossing whole oceans with negligible dissipation. The IG signatures are clearly observed at sensors along their propagation paths.

  10. Wave Power Demonstration Project at Reedsport, Oregon

    SciTech Connect

    Mekhiche, Mike; Downie, Bruce

    2013-10-21

    Ocean wave power can be a significant source of large‐scale, renewable energy for the US electrical grid. The Electrical Power Research Institute (EPRI) conservatively estimated that 20% of all US electricity could be generated by wave energy. Ocean Power Technologies, Inc. (OPT), with funding from private sources and the US Navy, developed the PowerBuoy to generate renewable energy from the readily available power in ocean waves. OPT's PowerBuoy converts the energy in ocean waves to electricity using the rise and fall of waves to move the buoy up and down (mechanical stroking) which drives an electric generator. This electricity is then conditioned and transmitted ashore as high‐voltage power via underwater cable. OPT's wave power generation system includes sophisticated techniques to automatically tune the system for efficient conversion of random wave energy into low cost green electricity, for disconnecting the system in large waves for hardware safety and protection, and for automatically restoring operation when wave conditions normalize. As the first utility scale wave power project in the US, the Wave Power Demonstration Project at Reedsport, OR, will consist of 10 PowerBuoys located 2.5 miles off the coast. This U.S. Department of Energy Grant funding along with funding from PNGC Power, an Oregon‐based electric power cooperative, was utilized for the design completion, fabrication, assembly and factory testing of the first PowerBuoy for the Reedsport project. At this time, the design and fabrication of this first PowerBuoy and factory testing of the power take‐off subsystem are complete; additionally the power take‐off subsystem has been successfully integrated into the spar.

  11. Internal Ocean Waves

    NASA Image and Video Library

    2006-07-17

    The false-color VNIR image from NASA Terra spacecraft was acquired off the island of Tsushima in the Korea Strait shows the signatures of several internal wave packets, indicating a northern propagation direction.

  12. Equatorial Wave Line, Pacific Ocean

    NASA Technical Reports Server (NTRS)

    1993-01-01

    This Equatorial Wave Line (2.0 N, 102.5W) seen in the Pacific Ocean is of great interest to oceanographers because of the twice annual upwelling of the oceans nutrients. As a result of nearly constant easterly winds, cool nutrient rich water wells up at the equator. The long narrow line is an equatorial front or boundry between warm surface equatorial water and cool recently upwelled water as the intermix of nutrients takes place.

  13. Book review: Extreme ocean waves

    USGS Publications Warehouse

    Geist, Eric L.

    2017-01-01

    “Extreme Ocean Waves”, edited by E. Pelinovsky and C. Kharif, second edition, Springer International Publishing, 2016; ISBN: 978-3-319-21574-7, ISBN (eBook): 978-3-319-21575-4The second edition of “Extreme Ocean Waves” published by Springer is an update of a collection of 12 papers edited by Efim Pelinovsky and Christian Kharif following the April 2007 meeting of the General Assembly of the European Geosciences Union. In this edition, three new papers have been added and three more have been substantially revised. Color figures are now included, which greatly aids in reading several of the papers, and is especially helpful in visualizing graphs as in the paper on symbolic computation of nonlinear wave resonance (Tobisch et al.). A note on terminology: extreme waves in this volume broadly encompass different types of waves, including deep-water and shallow-water rogue waves (which are alternatively termed freak waves), and internal waves. One new paper on tsunamis (Viroulet et al.) is now included in the second edition of this volume. Throughout the book, the reader will find a combination of laboratory, theoretical, and statistical/empirical treatment necessary for the complete examination of this subject. In the Introduction, the editors underscore the importance of studying extreme waves, documenting a dramatic instance of damaging extreme waves that recently occurred in 2014.

  14. Microseisms and hum from ocean surface gravity waves

    NASA Astrophysics Data System (ADS)

    Traer, James; Gerstoft, Peter; Bromirski, Peter D.; Shearer, Peter M.

    2012-11-01

    Ocean waves incident on coasts generate seismic surface waves in three frequency bands via three pathways: direct pressure on the seafloor (primary microseisms, PM), standing waves from interaction of incident and reflected waves (double-frequency microseisms, DF), and swell-transformed infragravity wave interactions (the Earth's seismic hum). Beamforming of USArray seismic data shows that the source azimuths of the generation regions of hum, PM and DF microseisms vary seasonally, consistent with hemispheric storm patterns. The correlation of beam power with wave height over all azimuths is highest in near-coastal waters. Seismic signals generated by waves from Hurricane Irene and from a storm in the Southern Ocean have good spatial and temporal correlation with nearshore wave height and peak period for all three wave-induced seismic signals, suggesting that ocean waves in shallow water commonly excite hum (via infragravity waves), PM, and DF microseisms concurrently.

  15. Internal Ocean Waves

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Internal waves are waves that travel within the interior of a fluid. The waves propagate at the interface or boundary between two layers with sharp density differences, such as temperature. They occur wherever strong tides or currents and stratification occur in the neighborhood of irregular topography. They can propagate for several hundred kilometers. The ASTER false-color VNIR image off the island of Tsushima in the Korea Strait shows the signatures of several internal wave packets, indicating a northern propagation direction.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 60 by 120 kilometers (37.2 by 74.4 miles) Location: 34.6 degrees North latitude, 129.5 degrees East longitude Orientation: North at top Image Data: ASTER bands 3, 2, and 1

  16. Internal Ocean Waves

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Internal waves are waves that travel within the interior of a fluid. The waves propagate at the interface or boundary between two layers with sharp density differences, such as temperature. They occur wherever strong tides or currents and stratification occur in the neighborhood of irregular topography. They can propagate for several hundred kilometers. The ASTER false-color VNIR image off the island of Tsushima in the Korea Strait shows the signatures of several internal wave packets, indicating a northern propagation direction.

    With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER images Earth to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER provides scientists in numerous disciplines with critical information for surface mapping, and monitoring of dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation; thermal pollution monitoring; coral reef degradation; surface temperature mapping of soils and geology; and measuring surface heat balance.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

    Size: 60 by 120 kilometers (37.2 by 74.4 miles) Location: 34.6 degrees North latitude, 129.5 degrees East longitude Orientation: North at top Image Data: ASTER bands 3, 2, and 1

  17. Internal Waves, Western Indian Ocean

    NASA Image and Video Library

    1991-12-01

    STS044-79-077 (24 Nov.-1 Dec. 1991) --- This photograph, captured from the Earth-orbiting Space Shuttle Atlantis, shows sunglint pattern in the western tropical Indian Ocean. Several large internal waves reflect around a shallow area on the sea floor. NASA scientists studying the STS-44 photography believe the shallow area to be a sediment (a submerged mountain) on top of the Mascarene Plateau, located northeast of Madagascar at approximately 5.6 degrees south latitude and 55.7 degrees east longitude. Internal waves are similar to surface ocean waves, except that they travel inside the water column along the boundary between water layers of different density. At the surface, their passage is marked on the sea surface by bands of smooth and rough water. These bands appear in the sunglint pattern as areas of brighter or darker water. NASA scientists point out that, when the waves encounter an obstacle, such as a near-surface seamount, they bend or refract around the obstacle in the same manner as surface waves bend around an island or headland.

  18. Ocean wave energy converting vessel

    SciTech Connect

    Boyce, P.F.

    1986-08-26

    An ocean wave energy conversion system is described comprised of a four beam quadrapod supported by bouyant members from which is suspended a pendulum. The pendulum contains a vertical generator shaft and a generator, the generator shaft being splined and fitted with two racheted pulleys, the pulleys being looped, one clockwise and one counterclockwise with separate cables. The cables are attached at their ends to the bow and stern of the quadrapod, whereby the generator shaft will pin when the quadrapod rocks over waves and the pendulum tends toward the center of earth.

  19. The Promise of Wave Power (Invited)

    NASA Astrophysics Data System (ADS)

    Brekken, T.

    2010-12-01

    The solutions to today's energy challenges need to be explored through alternative, renewable and clean energy sources to enable diverse energy resource plans. An extremely abundant and promising source of energy exists in the world's oceans: it is estimated that if 0.2 % of the oceans' untapped energy could be harnessed, it could provide power sufficient for the entire world. Ocean energy exists in the forms of wave, tidal, marine currents, thermal (temperature gradient) and salinity. Among these forms, significant opportunities and benefits have been identified in the area of ocean wave energy extraction, i.e., harnessing the motion of the ocean waves, and converting that motion into electrical energy. Ocean wave energy refers to the kinetic and potential energy in the heaving motion of ocean waves. Wave energy is essentially concentrated solar energy (as is wind energy). The heating of the earth’s surface by the sun (with other complex processes) drives the wind, which in turn blows across the surface of the ocean to create waves. At each stage of conversion, the power density increases. Ocean wave power offers several attractive qualities, including high power density, low variability, and excellent forecastability. A typical large ocean wave propogates at around 12 m/s with very little attenuation across the ocean. If the waves can be detected several hundred kilometers off shore, there can be 10 hours or more of accurate forecast horizon. In fact, analysis has shown good forecast accuracy up to 48 hours in advance. Off the coast Oregon, the yearly average wave power is approximately 30 kW per meter of crestlength (i.e., unit length transverse to the direction of wave propagation and parallel to the shore.) This compares very favorably with power densities of solar and wind, which typically range in the several hundreds of Watts per square meter. Globally, the wave energy resource is stronger on the west coasts of large landmasses and increases in strength

  20. Rogue Waves in the Ocean

    NASA Astrophysics Data System (ADS)

    Waseda, Takuji

    2010-03-01

    Giant episodic ocean waves that suddenly soar like a wall of water out of an otherwise calm sea are not just a legend. Such waves—which in the past have been called “abnormal,” “exceptional,” “extreme,” and even “vicious killer” waves—are now commonly known as “rogue waves” or “freak waves.” These waves have sunk or severely damaged 22 supercarriers in the world and caused the loss of more than 500 lives in the past 40 years. The largest wave registered by reliable instruments reached 30 meters in height, and the largest wave recorded by visual observation reached about 34 meters, equivalent to the height of an eight-story building. Tales of seafarers from Christopher Columbus to the passengers of luxury cruise ships had long been undervalued by scientists, but in the past 10 or so years, those historical notes and modern testimonies have been scientifically dissected to reveal the nature of these monster waves.

  1. Wave action power plant

    SciTech Connect

    Lucia, L.V.

    1982-03-16

    A wave action power plant powered by the action of water waves has a drive shaft rotated by a plurality of drive units, each having a lever pivotally mounted on and extending from said shaft and carrying a weight, in the form of a float, which floats on the waves and rocks the lever up and down on the shaft. A ratchet mechanism causes said shaft to be rotated in one direction by the weight of said float after it has been raised by wave and the wave has passed, leaving said float free to move downwardly by gravity and apply its full weight to pull down on the lever and rotate the drive shaft. There being a large number of said drive units so that there are always some of the weights pulling down on their respective levers while other weights are being lifted by waves and thereby causing continuous rotation of the drive shaft in one direction. The said levers are so mounted that they may be easily raised to bring the weights into a position wherein they are readily accessible for cleaning the bottoms thereof to remove any accumulation of barnacles, mollusks and the like. There is also provided means for preventing the weights from colliding with each other as they independently move up and down on the waves.

  2. Tracking ocean wave spectrum from SAR images

    NASA Technical Reports Server (NTRS)

    Goldfinger, A. D.; Beal, R. C.; Monaldo, F. M.; Tilley, D. G.

    1984-01-01

    An end to end algorithm for recovery of ocean wave spectral peaks from Synthetic Aperture Radar (SAR) images is described. Current approaches allow precisions of 1 percent in wave number, and 0.6 deg in direction.

  3. Ocean Wave Simulation Based on Wind Field.

    PubMed

    Li, Zhongyi; Wang, Hao

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates.

  4. Ocean Wave Simulation Based on Wind Field

    PubMed Central

    2016-01-01

    Ocean wave simulation has a wide range of applications in movies, video games and training systems. Wind force is the main energy resource for generating ocean waves, which are the result of the interaction between wind and the ocean surface. While numerous methods to handle simulating oceans and other fluid phenomena have undergone rapid development during the past years in the field of computer graphic, few of them consider to construct ocean surface height field from the perspective of wind force driving ocean waves. We introduce wind force to the construction of the ocean surface height field through applying wind field data and wind-driven wave particles. Continual and realistic ocean waves result from the overlap of wind-driven wave particles, and a strategy was proposed to control these discrete wave particles and simulate an endless ocean surface. The results showed that the new method is capable of obtaining a realistic ocean scene under the influence of wind fields at real time rates. PMID:26808718

  5. Magnetic ocean wave effects in Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, C. R.; Chen, C. H.; Yen, H. Y.; Lin, J. Y.

    2016-12-01

    12 magnetic stations routinely monitor changes in the geomagnetic total intensity field are utilized in this study to examine magnetic ocean wave effects in Taiwan. The time-varied magnetic data are transferred into the frequency domain via the Fourier transform to investigate the frequency characteristics associated with ocean waves. Significant enhancements can be found from spectrums in the frequency band of about 0.05-0.3 Hz at stations located very close to the seashore. Frequency characteristics of magnetic data were compared with them of water-level heights monitored derived from nearby meteorological observation buoys operated by Weather Central Bureau. The agreement in the frequency characteristics suggests that the magnetic field is affected by ocean waves directly hitting the seashore in open oceans. In contrast, ocean waves with the double-frequency recorded by the marine metrological buoys reveal the locally dominate wave-wave interaction around bays.

  6. Global observations of ocean Rossby waves

    SciTech Connect

    Chelton, D.B.; Schlax, M.G.

    1996-04-12

    Rossby waves play a critical role in the transient adjustment of ocean circulation to changes in large-scale atmospheric forcing. The TOPEX/POSEIDON satellite altimeter has detected Rossby waves throughout much of the world ocean from sea level signals with {approx_lt} 10-centimeters amplitude and {approx_lt} 500-kilometer wavelength. Outside of the tropics Rossby waves are abruptly amplified by major topographic features. Analysis of 3 years of data reveals discrepancies between observed and theoretical Rossby wave phase speeds that indicate that the standard theory for free, linear Rossby waves in an incomplete description of the observed waves. 32 refs., 5 figs.

  7. A reappraisal of ocean wave studies

    NASA Astrophysics Data System (ADS)

    Yuan, Yeli; Huang, Norden E.

    2012-11-01

    A reappraisal of wave theory from the beginning to the present day is made here. On the surface, the great progress in both theory and applications seems to be so successful that there would be no great challenge in wave studies anymore. On deeper examination, we found problems in many aspects of wave studies starting from the definition of frequency, the governing equations, the various source functions of wave models, the directional development of wind wavefield, the wave spectral form and finally the role of waves as they affect coastal and global ocean dynamics. This is a call for action for the wave research community. For future research, we have to consider these problems seriously and also to examine the basic physics of wave motion to determine their effects on other ocean dynamic processes quantitatively, rather than relying on parameterization in oceanic and geophysical applications.

  8. Ocean internal waves interpreted as oscillation travelling waves in consideration of ocean dissipation

    NASA Astrophysics Data System (ADS)

    Jiang, Zhu-Hui; Huang, Si-Xun; You, Xiao-Bao; Xiao, Yi-Guo

    2014-05-01

    Most studies of the synthetic aperture radar remote sensing of ocean internal waves are based on the solitary wave solutions of the Korteweg—de Vries (KdV) equation, and the dissipative term in the KdV equation is not taken into account. However, the dissipative term is very important, both in the synthetic aperture radar images and in ocean models. In this paper, the traveling-wave structure to characterize the ocean internal wave phenomenon is modeled, the results of numerical experiments are advanced, and a theoretical hypothesis of the traveling wave to retrieve the ocean internal wave parameters in the synthetic aperture radar images is introduced.

  9. Ocean floor mounting of wave energy converters

    DOEpatents

    Siegel, Stefan G

    2015-01-20

    A system for mounting a set of wave energy converters in the ocean includes a pole attached to a floor of an ocean and a slider mounted on the pole in a manner that permits the slider to move vertically along the pole and rotate about the pole. The wave energy converters can then be mounted on the slider to allow adjustment of the depth and orientation of the wave energy converters.

  10. Deep Ocean Wave Cancellation Using a Cycloidal Turbine

    NASA Astrophysics Data System (ADS)

    Siegel, Stefan; Jeans, Tiger; McLaughlin, Thomas

    2009-11-01

    We investigate the use of a cycloidal turbine for deep ocean wave termination for the purpose of converting wave energy to shaft power. Cycloidal turbines consist of one or more hydrofoils that rotate around a central shaft and can be pitched during rotation. In the present investigation, the shaft is parallel to the wave crests, and the turbine operates in sync with the wave frequency by means of feedback control. The approach differs from traditional approaches in that it is a lift based system and therefore has the potential to be more efficient than existing drag based converters. It also allows for feathering of the blades in order to survive storms. We present two-dimensional inviscid results of potential flow simulations modeling the turbine blades as single point vortices of constant circulation rotating under a linearized free water surface. With suitable parameter choices for the turbine radius, blade number, submersion depth and airfoil circulation up to 97% of the incoming deep ocean Airy wave energy can be converted to shaft power. For a typical North Atlantic deep ocean wave this corresponds to 100 kW of power per meter of wave crest. The remaining energy is lost to harmonic waves travelling both in the up- and down wave directions.

  11. GENERAL: Self-organized Criticality Model for Ocean Internal Waves

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Lin, Min; Qiao, Fang-Li; Hou, Yi-Jun

    2009-03-01

    In this paper, we present a simple spring-block model for ocean internal waves based on the self-organized criticality (SOC). The oscillations of the water blocks in the model display power-law behavior with an exponent of -2 in the frequency domain, which is similar to the current and sea water temperature spectra in the actual ocean and the universal Garrett and Munk deep ocean internal wave model [Geophysical Fluid Dynamics 2 (1972) 225; J. Geophys. Res. 80 (1975) 291]. The influence of the ratio of the driving force to the spring coefficient to SOC behaviors in the model is also discussed.

  12. Oceanic-wave-measurement system

    NASA Technical Reports Server (NTRS)

    Holmes, J. F.; Miles, R. T.

    1980-01-01

    Barometer mounted on bouy senses wave heights. As wave motion raises and lowers barometer, pressure differential is proportional to wave height. Monitoring circuit samples barometer output every half cycle of wave motion and adds magnitudes of adjacent positive and negative peaks. Resulting output signals, proportional to wave height, are transmitted to central monitoring station.

  13. Oceanic-wave-measurement system

    NASA Technical Reports Server (NTRS)

    Holmes, J. F.; Miles, R. T.

    1980-01-01

    Barometer mounted on bouy senses wave heights. As wave motion raises and lowers barometer, pressure differential is proportional to wave height. Monitoring circuit samples barometer output every half cycle of wave motion and adds magnitudes of adjacent positive and negative peaks. Resulting output signals, proportional to wave height, are transmitted to central monitoring station.

  14. Detecting Internal Wave Activity in Ocean Models

    NASA Astrophysics Data System (ADS)

    Carter, R., Jr.

    2016-02-01

    Internal waves can create large changes in the ocean's vertical density structure. These changes affect the sound speed and buoyancy within the water column on scales that can impact naval operations. The operational Navy Coastal Ocean Model (NCOM) run by the Naval Oceanographic Office has the ability to forecast internal tidal waves when setup at sufficient grid resolutions. A technique for extracting the location of these internal tidal wave beds from NCOM fields will be discussed. The method involves identifying an "active isotherm" utilizing the National Oceanic and Atmospheric Administration's Ferret software, which is an interactive computer visualization and analysis environment. The technique is demonstrated in specific areas of the Western Pacific water.

  15. Ocean swell within the kinetic equation for water waves

    NASA Astrophysics Data System (ADS)

    Badulin, Sergei I.; Zakharov, Vladimir E.

    2017-06-01

    Results of extensive simulations of swell evolution within the duration-limited setup for the kinetic Hasselmann equation for long durations of up to 2 × 106 s are presented. Basic solutions of the theory of weak turbulence, the so-called Kolmogorov-Zakharov solutions, are shown to be relevant to the results of the simulations. Features of self-similarity of wave spectra are detailed and their impact on methods of ocean swell monitoring is discussed. Essential drop in wave energy (wave height) due to wave-wave interactions is found at the initial stages of swell evolution (on the order of 1000 km for typical parameters of the ocean swell). At longer times, wave-wave interactions are responsible for a universal angular distribution of wave spectra in a wide range of initial conditions. Weak power-law attenuation of swell within the Hasselmann equation is not consistent with results of ocean swell tracking from satellite altimetry and SAR (synthetic aperture radar) data. At the same time, the relatively fast weakening of wave-wave interactions makes the swell evolution sensitive to other effects. In particular, as shown, coupling with locally generated wind waves can force the swell to grow in relatively light winds.

  16. Open ocean Internal Waves, Namibia Coast, Africa.

    NASA Technical Reports Server (NTRS)

    1990-01-01

    These open ocean Internal Waves were seen off the Namibia Coast, Africa (23.0S, 14.0E). The periodic and regularly spaced sets of internal waves most likely coincide with tidal periods about 12 hours apart. The wave length (distance from crest to crest) varies between 1.5 and 5.0 miles and the crest lengths stretch across and beyond the distance of the photo. The waves are intersecting the Namibia coastline at about a 30 degree angle.

  17. Open ocean Internal Waves, Namibia Coast, Africa.

    NASA Image and Video Library

    1990-12-10

    These open ocean Internal Waves were seen off the Namibia Coast, Africa (23.0S, 14.0E). The periodic and regularly spaced sets of internal waves most likely coincide with tidal periods about 12 hours apart. The wave length (distance from crest to crest) varies between 1.5 and 5.0 miles and the crest lengths stretch across and beyond the distance of the photo. The waves are intersecting the Namibia coastline at about a 30 degree angle.

  18. Ocean waves monitor system by inland microseisms

    NASA Astrophysics Data System (ADS)

    Lin, L. C.; Bouchette, F.; Chang, E. T. Y.

    2016-12-01

    Microseisms are continuous ground oscillations which have been wildly introduced for decades. It is well known that the microseismicity in the frequency band from 0.05 to about 1 Hz partly results from ocean waves, which has been first explained by Longuet-Higgins [1950]. The generation mechanism for such a microseismicity is based on nonlinear wave-wave interactions which drive pressure pulses within the seafloor. The resulting ground pressure fluctuations yield ground oscillations at a double frequency (DF) with respect to that of current ocean waves. In order to understand the characteristics of DF microseisms associated with different wave sources, we aim to analyze and interpret the spectra of DF microseisms by using the simple spectrum method [Rabinovich, 1997] at various inland seismometer along the Taiwan coast. This is the first monitoring system of ocean waves observed by inland seismometers in Taiwan. The method is applied to identify wave sources by estimating the spectral ratios of wave induced microseisms associated with local winds and typhoons to background spectra. Microseism amplitudes above 0.2 Hz show a good correlation with wind-driven waves near the coast. Comparison of microseism band between 0.1 and 0.2 Hz with buoys in the deep sea shows a strong correlation of seismic amplitude with storm generated waves, implying that such energy portion originates in remote regions. Results indicate that microseisms observed at inland sites can be a potential tool for the tracking of typhoon displacements and the monitoring of extreme ocean waves in real time. Real- time Microseism-Ocean Waves Monitoring Website (http://mwave.droppages.com/) Reference Rabinovich, A. B. (1997) "Spectral analysis of tsunami waves: Separation of source and topography effects," J. Geophys. Res., Vol. 102, p. 12,663-12,676. Longuet-Higgins, M.S. (1950) "A theory of origin of microseisms," Philos. Trans. R. Soc., A. 243, pp. 1-35.

  19. Book review: Rogue waves in the ocean

    USGS Publications Warehouse

    Geist, Eric L.

    2011-01-01

    Review info: Rogue Waves in the Ocean. Advances in Geophysical and Environmental Mechanics and Mathematics. By Christian Kharif, Efim Pelinovsky and Alexey Slunyaev, 2009. ISBN: 978-3540884187, xiii, 216 pp.

  20. Collaboration on OPT Design for Generating Electrical Power from Ocean Waves. Cooperative Research and Development Final Report, CRADA Number CRD-14-542

    SciTech Connect

    LiVecchi, Al

    2016-06-01

    In the proposed project, Ocean Power Technologies Corporation (OPT) and the National Renewable Energy Laboratory (NREL) will collaboratively investigate the power output and loads associated with an asymmetric float previously investigated and designed by OPT, but will extend the analysis to include a compliant mooring.

  1. Scattering of Acoustic Waves from Ocean Boundaries

    DTIC Science & Technology

    2015-09-30

    J., “ Comparison of measured acoustic reflection fluctuations and estimates based on roughness,” J. Acous. Soc. Am., 137, 2391-2391 (2015), DOI:http...of Acoustic Waves from Ocean Boundaries Marcia... acoustic interaction with the ocean floor, including penetration through and reflection from smooth and rough water/sediment interfaces, scattering

  2. The SAE Measurement of Ocean Waves: Wave Session Whitepaper

    NASA Astrophysics Data System (ADS)

    Lehner, S.; Ocampo-Torres, F. J.

    2004-06-01

    Remote sensing techniques enable the measurement of ocean wave fields with both high resolution and large coverage. As the acquisition of active radar data is independent of daylight and cloud conditions, these data are therefore believed to be most suited for operational use at weather centers and governmental agencies, as well as for many ongoing scientific investigations. In the present overview paper the determination of sea state parameters from radar images together with some results from the operational use at weather centers are given.Synthetic aperture radar (SAR) yields high resolution two dimensional images of the radar backscatter properties of the sea surface and can thus be used to measure wind fields and sea state from space.The determination of ocean wave spectra from SARimage spectra is sensitive to various imaging effects due to sea surface features, spatial variation of wind speed, rain, current and motion of the sea surface. Thus, measuring ocean wave parameters is related to most of the other measurements of marine parameters described in this volume.In this paper an overview of the SAR satellite missions is given, as well as a description of the basic techniques to measure ocean waves by SAR and validation against wave model results and other space borne and in situ measurements.The full two dimensional SAR image spectrum provides information on the directional ocean wave spectrum. This can be used to determine expectation values of, e.g. , significant wave height, mean wavelength and direction in order to improve the wave model prediction. In addition information can be gathered from the radar images directly such as individual wave height, crest length and groupiness of the ocean waves. Thus, the distribution of maximum wave height can be investigated globally, or wave refraction and diffraction in coastal areas can be studied in detail.In the following an overview of ocean wave measurements from space are given, the papers presented in the

  3. Modelling Ocean Surface Waves in Polar Regions

    NASA Astrophysics Data System (ADS)

    Hosekova, Lucia; Aksenov, Yevgeny; Coward, Andrew; Bertino, Laurent; Williams, Timothy; Nurser, George A. J.

    2015-04-01

    In the Polar Oceans, the surface ocean waves break up sea ice cover and create the Marginal Ice Zone (MIZ), an area between the sea-ice free ocean and pack ice characterized by highly fragmented ice. This band of sea ice cover is undergoing dramatic changes due to sea ice retreat, with up to a 39% widening in the Arctic Ocean reported over the last three decades and projections predicting a continuing increase. The surface waves, sea ice and ocean interact in the MIZ through multiple complex feedbacks and processes which are not accounted for in any of the present-day climate models. To address this issue, we present a model development which implements surface ocean wave effects in the global Ocean General Circulation Model NEMO, coupled to the CICE sea ice model. Our implementation takes into account a number of physical processes specific to the MIZ dynamics. Incoming surface waves are attenuated due to reflection and energy dissipation induced by the presence of ice cover, which is in turn fragmented in response to external stresses. This process generates a distribution of floe sizes and impacts the dynamics of sea ice by the means of combined rheology that takes into account floe collisions and allows for a more realistic representation of the MIZ. We present results from the NEMO OGCM at 1 degree resolution with a wave-ice interaction module described above. The module introduces two new diagnostics previously unavailable in GCM's: surface wave spectra in sea ice covered areas, and floe size distribution due to wave-induced fragmentation. We discuss the impact of these processes on the ocean and sea ice state, including ocean circulation, mixing, stratification and the role of the MIZ in the ocean variability. The model predictions for the floe sizes in the summer Arctic Ocean range from 60 m in the inner MIZ to a few tens of meters near the open ocean, which agrees with estimates from the satellites. The extent of the MIZ throughout the year is also in

  4. On the dynamics of a novel ocean wave energy converter

    NASA Astrophysics Data System (ADS)

    Orazov, B.; O'Reilly, O. M.; Savaş, Ö.

    2010-11-01

    Buoy-type ocean wave energy converters are designed to exhibit resonant responses when subject to excitation by ocean waves. A novel excitation scheme is proposed which has the potential to improve the energy harvesting capabilities of these converters. The scheme uses the incident waves to modulate the mass of the device in a manner which amplifies its resonant response. To illustrate the novel excitation scheme, a simple one-degree of freedom model is developed for the wave energy converter. This model has the form of a switched linear system. After the stability regime of this system has been established, the model is then used to show that the excitation scheme improves the power harvesting capabilities by 25-65 percent even when amplitude restrictions are present. It is also demonstrated that the sensitivity of the device's power harvesting capabilities to changes in damping becomes much smaller when the novel excitation scheme is used.

  5. Monstrous ocean waves during typhoon Krosa

    NASA Astrophysics Data System (ADS)

    Liu, P. C.; Chen, H. S.; Doong, D.-J.; Kao, C. C.; Hsu, Y.-J. G.

    2008-06-01

    This paper presents a set of ocean wave time series data recorded from a discus buoy deployed near northeast Taiwan in western Pacific that was operating during the passage of Typhoon Krosa on 6 October 2007. The maximum trough-to-crest wave height was measured to be 32.3 m, which could be the largest Hmax ever recorded.

  6. Determination of ocean surface wave shape from forward scattered sound.

    PubMed

    Walstead, Sean P; Deane, Grant B

    2016-08-01

    Forward scattered sound from the ocean surface is inverted for wave shape during three periods: low wind, mix of wind and swell, and stormy. Derived wave profiles are spatially limited to a Fresnel region at or near the nominal surface specular reflection point. In some cases, the surface wave profiles exhibit unrealistic temporal and spatial properties. To remedy this, the spatial gradient of inverted waves is constrained to a maximum slope of 0.88. Under this global constraint, only surface waves during low wind conditions result in a modeled surface multipath that accurately matches data. The power spectral density of the inverted surface wave field saturates around a frequency of 8 Hz while upward looking SONAR saturates at 1 Hz. Each shows a high frequency spectral slope of -4 that is in agreement with various empirical ocean wave spectra. The improved high frequency resolution provided by the scattering inversion indicates that it is possible to remotely gain information about high frequency components of ocean waves. The inability of the inversion algorithm to determine physically realistic surface waves in periods of high wind indicates that bubbles and out of plane scattering become important in those operating scenarios.

  7. Spatial evolution of ocean wave spectra

    NASA Technical Reports Server (NTRS)

    Beal, R. C.

    1981-01-01

    The spatially evolving deep water synthetic aperture radar (SAR) directional spectra of a mixed ocean wave system are compared with a comprehensive set of surface and aircraft measurements. The evolution of the SAR spectra, at least for ocean wavelengths greater than 80 m, is seen as generally consistent with the auxiliary data set in both time and space. From the spatial evolution of the angular component of the spectra, it is possible to project back to an apparent remote storm source that is also consistent with the storm location via GOES satellite imagery. The data provide compelling evidence that the spatial evolution of SAR ocean wave spectra can be a useful tool in global ocean wave monitoring and forecasting.

  8. Open Ocean Internal Waves, South China Sea

    NASA Technical Reports Server (NTRS)

    1989-01-01

    These open ocean internal waves were seen in the south China Sea (19.5N, 114.5E). These sets of internal waves most likely coincide with tidal periods about 12 hours apart. The wave length (distance from crest to crest) varies between 1.5 and 5.0 miles and the crest lengths stretch across and beyond this photo for over 75 miles. At lower right, the surface waves are moving at a 30% angle to the internal waves, with parallel low level clouds.

  9. Freak waves in random oceanic sea states.

    PubMed

    Onorato, M; Osborne, A R; Serio, M; Bertone, S

    2001-06-18

    Freak waves are very large, rare events in a random ocean wave train. Here we study their generation in a random sea state characterized by the Joint North Sea Wave Project spectrum. We assume, to cubic order in nonlinearity, that the wave dynamics are governed by the nonlinear Schrödinger (NLS) equation. We show from extensive numerical simulations of the NLS equation how freak waves in a random sea state are more likely to occur for large values of the Phillips parameter alpha and the enhancement coefficient gamma. Comparison with linear simulations is also reported.

  10. Oceanic Path Effects of Microseismic Waves

    NASA Astrophysics Data System (ADS)

    Chen, X.; Wen, L.

    2015-12-01

    Microseismic surface waves originating from sources in ocean would propagate along parts of oceanic path before being recorded by on-land seismic stations. Studying the path effects on waveform, travel-time, magnitude and other properties of these microseismic signals is important in accurately determining the location, strength and generating mechanism of the sources. Strong effects are observed in the microseismic signals generated by Hurricane Sandy in 2012, and verified by synthetic seismograms. We find that Sandy-related seismic signals are significantly affected by oceanic path: only seismic signals share a similar length of oceanic path are cross-correlated and a large portion of the correlated signals can be traced back to sources at the ocean-continent boundary within a narrow azimuthal range from the hurricane center. In this presentation, we report that these observations can be explained by strong path effect of wave propagation from a seismic source in the hurricane center. The strong directionality of waveform cross-correlation can be explained by the propagation effect that waveform characteristics of Rayleigh wave are mostly controlled by transitional propagating path from ocean to the continental region, resulting in seismic signals being correlated only among stations sharing similar length of oceanic path; the sources at the ocean-continent boundary can be attributed to strong seismic scattering in the ocean-continent boundary, generating apparent seismic "sources" there. We also compare the synthetic vertical/transverse magnitude ratio of Rayleigh waves in an anisotropic velocity model with observations. Our results indicate that these types of seismic observations would be particularly useful for studying seismic structure of crust and upper mantle in the ocean-continent area.

  11. Wave power potential in Malaysian territorial waters

    NASA Astrophysics Data System (ADS)

    Asmida Mohd Nasir, Nor; Maulud, Khairul Nizam Abdul

    2016-06-01

    Up until today, Malaysia has used renewable energy technology such as biomass, solar and hydro energy for power generation and co-generation in palm oil industries and also for the generation of electricity, yet, we are still far behind other countries which have started to optimize waves for similar production. Wave power is a renewable energy (RE) transported by ocean waves. It is very eco-friendly and is easily reachable. This paper presents an assessment of wave power potential in Malaysian territorial waters including waters of Sabah and Sarawak. In this research, data from Malaysia Meteorology Department (MetMalaysia) is used and is supported by a satellite imaginary obtained from National Aeronautics and Space Administration (NASA) and Malaysia Remote Sensing Agency (ARSM) within the time range of the year 1992 until 2007. There were two types of analyses conducted which were mask analysis and comparative analysis. Mask analysis of a research area is the analysis conducted to filter restricted and sensitive areas. Meanwhile, comparative analysis is an analysis conducted to determine the most potential area for wave power generation. Four comparative analyses which have been carried out were wave power analysis, comparative analysis of wave energy power with the sea topography, hot-spot area analysis and comparative analysis of wave energy with the wind speed. These four analyses underwent clipping processes using Geographic Information System (GIS) to obtain the final result. At the end of this research, the most suitable area to develop a wave energy converter was found, which is in the waters of Terengganu and Sarawak. Besides that, it was concluded that the average potential energy that can be generated in Malaysian territorial waters is between 2.8kW/m to 8.6kW/m.

  12. Rogue Edge Waves in the Ocean

    NASA Astrophysics Data System (ADS)

    Polukhina, Oxana; Kurkin, Andrey; Pelinovsky, Efim

    2010-05-01

    The investigation of anomalously large amplitude surface gravity waves on the sea surface (rogue or freak waves), which can appear suddenly and disappear in the same abrupt way, is very extensive in the recent years (see e.g., book [Kharif, Pelinovsky, Slunyaev 2009] and references there). However, any sudden displacements of water level or changes in flow velocities can also appear in the ocean wave motions of other types, including geophysical large-scale fields. The number of observations of such waves is still very small, they are even almost absent, but the investigations of such possible processes seem to be important for the applications. In the present paper the problem of rogue waves is discussed for edge waves in the coastal zone. Such waves belong to the class of topographically trapped waves, which are supposed to play dominant role in the dynamics of oceanic coastal zone. The amplitude of the waves reaches a maximum at the edge, and they are attenuated offshore. Direct visual observations of such waves are difficult, but such waves have been detected instrumentally in the nearshore wave field many times (see e.g. [Huntley and Bowen 1973; Bryan, Hows and Bowen 1998]). Edge waves are often considered as the major factor of the long-term evolution of coastal line, forming the rhythmic crescentic bars [Dolan and Ferm 1968; Bowen and Inman 1971; Guza and Inman 1975; Guza and Bowen 1981; Holman and Bowen 1982; Komar 1998]. In the present paper we summarize the results of the study of the nonlinear mechanisms of possible freak edge wave appearance: nonlinear dispersion enhancement and modulation instability.

  13. Refraction of coastal ocean waves

    NASA Technical Reports Server (NTRS)

    Shuchman, R. A.; Kasischke, E. S.

    1981-01-01

    Refraction of gravity waves in the coastal area off Cape Hatteras, NC as documented by synthetic aperture radar (SAR) imagery from Seasat orbit 974 (collected on September 3, 1978) is discussed. An analysis of optical Fourier transforms (OFTs) from more than 70 geographical positions yields estimates of wavelength and wave direction for each position. In addition, independent estimates of the same two quantities are calculated using two simple theoretical wave-refraction models. The OFT results are then compared with the theoretical results. A statistical analysis shows a significant degree of linear correlation between the data sets. This is considered to indicate that the Seasat SAR produces imagery whose clarity is sufficient to show the refraction of gravity waves in shallow water.

  14. Refraction of coastal ocean waves

    NASA Technical Reports Server (NTRS)

    Shuchman, R. A.; Kasischke, E. S.

    1981-01-01

    Refraction of gravity waves in the coastal area off Cape Hatteras, NC as documented by synthetic aperture radar (SAR) imagery from Seasat orbit 974 (collected on September 3, 1978) is discussed. An analysis of optical Fourier transforms (OFTs) from more than 70 geographical positions yields estimates of wavelength and wave direction for each position. In addition, independent estimates of the same two quantities are calculated using two simple theoretical wave-refraction models. The OFT results are then compared with the theoretical results. A statistical analysis shows a significant degree of linear correlation between the data sets. This is considered to indicate that the Seasat SAR produces imagery whose clarity is sufficient to show the refraction of gravity waves in shallow water.

  15. Equatorial Wave Line, Pacific Ocean

    NASA Image and Video Library

    1993-01-19

    STS054-95-042 (13-19 Jan 1993) --- The Equatorial Pacific Ocean is represented in this 70mm view. The international oceanographic research community is presently conducting a program called Joint Global Ocean Flux Study (JGOFS) to study the global ocean carbon budget. A considerable amount of effort within this program is presently being focused on the Equatorial Pacific Ocean because of the high annual average biological productivity. The high productivity is the result of nearly constant easterly winds causing cool, nutrient-rich water to well up at the equator. In this view of the sun glint pattern was photographed at about 2 degrees north latitude, 103 degrees west longitude, as the Space Shuttle passed over the Equatorial Pacific. The long narrow line is the equatorial front, which defines the boundary between warm surface equatorial water and cool, recently upwelled water. Such features are of interest to the JGOFS researchers and it is anticipated that photographs such as this will benefit the JGOFS program.

  16. Modulation of short waves by long waves. [ocean wave interactions

    NASA Technical Reports Server (NTRS)

    Reece, A. M., Jr.

    1978-01-01

    Wave-tank experiments were performed to investigate the cyclic short-wave energy changes, related in phase to an underlying long wave, which occur during active generation of the short-wave field by wind. Measurements of time series of the short-wave slope were made by a laser-optical system, where the basic long-wave parameters were controlled and wind speeds were accurately reproducible. The short-wave slope variances were found to exhibit cyclic variations that are related to the phase of the long wave. The variations result from two combined effects: (1) the short wave frequency is varied by the long-wave orbital velocity; (2) the energy of the short waves is modulated by the actions of aerodynamic and hydrodynamic couplings that operate on the short waves in a manner related to the long-wave phase.

  17. Open ocean Internal Waves, Namibia Coast, Africa.

    NASA Technical Reports Server (NTRS)

    1990-01-01

    These open ocean Internal Waves were seen off the Namibia Coast, Africa (19.5S, 11.5E). The periodic and regularly spaced sets of incoming internal appear to be diffracting against the coastline and recombining to form a network of interference patterns. They seem to coincide with tidal periods about 12 hours apart and wave length (distance from crest to crest) varies between 1.5 and 5.0 miles and the crest lengths stretch beyond the image.

  18. Open ocean Internal Waves, Namibia Coast, Africa.

    NASA Image and Video Library

    1990-12-10

    These open ocean Internal Waves were seen off the Namibia Coast, Africa (19.5S, 11.5E). The periodic and regularly spaced sets of incoming internal appear to be diffracting against the coastline and recombining to form a network of interference patterns. They seem to coincide with tidal periods about 12 hours apart and wave length (distance from crest to crest) varies between 1.5 and 5.0 miles and the crest lengths stretch beyond the image.

  19. Bragg reflection of ocean waves from sandbars

    NASA Astrophysics Data System (ADS)

    Elgar, Steve; Raubenheimer, B.; Herbers, T. H. C.

    2003-01-01

    Resonant Bragg reflection of ocean surface waves by a field of natural shore-parallel sandbars was observed in Cape Cod Bay, MA. Waves transmitted through the bars were reflected strongly from the steep shoreline, and the observed cross-shore variations in the onshore- and offshore-directed energy fluxes are consistent with theory for resonant Bragg reflection, including a 20% decay of the incident wave energy flux that is an order of magnitude greater than expected for wave-orbital velocity induced bottom friction. Bragg reflection was observed for a range of incident wave conditions, including storms when sediment transported toward and away from nodes and antinodes caused by the reflecting waves might result in growth and maintenance of the sandbars.

  20. Global Ocean Internal Wave Database

    DTIC Science & Technology

    2001-09-30

    of Delaware,,Newark,,DE, 19716 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10 . SPONSOR...km. The wavelength is about 10 km. 4 Figure 2 ERS-1 SAR image of internal waves near the Galapagos Islands The ERS-1 SAR image

  1. Ocean Wave Energy Harvesting Devices

    DTIC Science & Technology

    2007-04-01

    coupled to a suitable buoy platform. 2. The approach of designing a device which meets the requirements for mounting on dogfish and generating...used on the tail of a marine life such as dogfish to harvest energy as it swims. The output power can be used to trickle charge battery packs to power...to be mounted to a dogfish to harvest energy from its motion. Due to the small fish size (approximate 40-50 inches, 25 pounds), the device was

  2. Long waves in the equatorial Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Philander, George; Halpern, David; Hansen, Donald; Legeckis, Richard; Miller, Laury; Watts, Randolph; Wimbush, Mark; Paul, Carl; Watts, Randolph; Weisberg, Robert

    Westward traveling waves, with a period of 3 weeks and a wavelength of ˜1000 km, are observed intermittently in the central and eastern equatorial Pacific Ocean (see cover). The waves were first detected in 1975 in satellite measurements of the sea surface temperature [Legeckis, 1977]. Since then, additional measurements (under the auspices of the NOAA program Equatorial Pacific Ocean Climate Studies (EPOCS)) with a variety of instruments—drifting buoys, current meters and temperature sensors on moorings, and inverted echo sounders—have provided considerable information about these waves and have confirmed the hypothesis that they are caused by instabilities associated primarily with the latitudinal shear of the surface currents near the equator [Philander, 1978a; Cox, 1980].

  3. Climate patterns derived from ocean wave spectra

    NASA Astrophysics Data System (ADS)

    Portilla-Yandún, Jesús; Salazar, Andrés.; Cavaleri, Luigi

    2016-11-01

    The fact that ocean surface waves are an integrated effect of meteorological activity has the interesting consequence that the memory of the wave systems is larger than that of the wind and storms that generated them. At each single point the related information is stored as its wave spectrum, a matrix containing the energy distribution of wave systems with different origins in space and time. We describe the concept of spectral partitioning and the technique used to obtain spectral statistics, whose outcome we associate with the physical reality. Using long series of spectral data we derive information of the, possibly very far, generation zones climatologically connected at a confluent point. Working on the eastern equatorial Pacific we focus on the prominent effects of El Niño events, for which interactions of mesoscale phenomena are revealed from the analysis of the local situation.

  4. Internal Waves and Wave Attractors in Enceladus' Subsurface Ocean

    NASA Astrophysics Data System (ADS)

    van Oers, A. M.; Maas, L. R.; Vermeersen, B. L. A.

    2016-12-01

    One of the most peculiar features on Saturn moon Enceladus is its so-called tiger stripe pattern at the geologically active South Polar Terrain (SPT), as first observed in detail by the Cassini spacecraft early 2005. It is generally assumed that the four almost parallel surface lines that constitute this pattern are faults in the icy surface overlying a confined salty water reservoir. In 2013, we formulated the original idea [Vermeersen et al., AGU Fall Meeting 2013, abstract #P53B-1848] that the tiger stripe pattern is formed and maintained by induced, tidally and rotationally driven, wave-attractor motions in the ocean underneath the icy surface of the tiger-stripe region. Such wave-attractor motions are observed in water tank experiments in laboratories on Earth and in numerical experiments [Maas et al., Nature, 338, 557-561, 1997; Drijfhout and Maas, J. Phys. Oceanogr., 37, 2740-2763, 2007; Hazewinkel et al., Phys. Fluids, 22, 107102, 2010]. Numerical simulations show the persistence of wave attractors for a range of ocean shapes and stratifications. The intensification of the wave field near the location of the surface reflections of wave attractors has been numerically and experimentally confirmed. We measured the forces a wave attractor exerts on a solid surface, near a reflection point. These reflection points would correspond to the location of the tiger stripes. Combining experiments and numerical simulations we conclude that (1) wave attractors can exist in Enceladus' subsurface sea, (2) their shape can be matched to the tiger stripes, (3) the wave attractors cause a localized force at the water-ice boundaries, (4) this force could have been large enough to contribute to fracturing the ice and (5) the wave attractors localize energy (and particles) and cause dissipation along its path, helping explain Enceladus' enigmatic heat output at the tiger stripes.

  5. Imaging of Ocean Waves by SAR

    DTIC Science & Technology

    1988-01-01

    SAR o Contract N00014-87-C-0687N TDTIC R.L. Schult iZ L E C T E F.S. Henyey -JAN 2 4 1989 J.A. Wright Center for Studies of Nonlinear Dynamics La...Waves by SAR R.L. Schult F.S. Henyey J.A. Wright Center for Studies of Nonlinear Dynamics La Jolla Institute 7855 Fay Avenue, Suite 320 La Jolla...TOWARD data. 467.abstract 7-13-󈨜 Imaging of Ocean Waves by SAR 1. Introduction Synthetic Aperture Radar images of long-wavelength features on the

  6. Modelling the ocean site effect on seismic noise body waves

    NASA Astrophysics Data System (ADS)

    Gualtieri, L.; Stutzmann, E.; Farra, V.; Capdeville, Y.; Schimmel, M.; Ardhuin, F.; Morelli, A.

    2014-05-01

    Secondary microseismic noise is generated by non-linear interactions between ocean waves at the ocean surface. We present here the theory for computing the site effect of the ocean layer upon body waves generated by noise sources distributed along the ocean surface. By defining the wavefield as the superposition of plane waves, we show that the ocean site effect can be described as the constructive interference of multiply reflected P waves in the ocean that are then converted to either P or SV waves at the ocean-crust interface. We observe that the site effect varies strongly with period and ocean depth, although in a different way for body waves than for Rayleigh waves. We also show that the ocean site effect is stronger for P waves than for S waves. We validate our computation by comparing the theoretical noise body wave sources with the sources inferred from beamforming analysis of the three seismogram components recorded by the Southern California Seismic Network. We use rotated traces for the beamforming analysis, and we show that we clearly detect P waves generated by ocean gravity wave interactions along the track of typhoon Ioke (2006 September). We do not detect the corresponding SV waves, and we demonstrate that this is because their amplitude is too weak.

  7. Ocean wave dynamics and El Nino

    SciTech Connect

    Schneider, E.K.; Huang, B.; Shukla, J.

    1995-10-01

    The response of an ocean general circulation model to specified wind stress is used to understand the role of ocean wave propagation in the evolution of El Nino events in sea surface temperatures (SST) in the equatorial Pacific Ocean. In a control experiment the ocean model reproduces observed equatorial Pacific interannual variability in response to forcing by the observed wind stress. The ocean model is then forced with the same wind stress but with the time evolution of the wind stress forcing reversed. An analysis of the anomalies from the annual cycle in these two experiments delineates the parts of the response that are in equilibrium with and out of equilibrium with the wind stress forcing. The experiment demonstrates that the heat content is not in equilibrium with the wind stress forcing either on or near the equator. Very close to the equator the slope of the thermocline is in equilibrium with the wind stress, but the mean heat content is far from equilibrium. Slightly off of the equator in the western Pacific westward propagating heat content anomalies appear to originate in regions of strong wind stress forcing and then propagate to the western boundary. These westward propagating anomalies also depart significantly from equilibrium with the wind stress forcing. Additional experiments allow these westward propagating anomalies to be identified as freely propagating Rossby waves. The Rossby waves are shown to determine the equatorial heat content response to the wind stress forcing when they arrive at the western boundary and to be responsible for the nonequilibrium behavior of the equatorial mean heat content. A simplified coupled model is derived by fitting the results and estimating parameter values from the numerical experiments. 45 refs., 16 figs.

  8. Ocean wave-radar modulation transfer functions from the West Coast experiment

    NASA Technical Reports Server (NTRS)

    Wright, J. W.; Plant, W. J.; Keller, W. C.; Jones, W. L.

    1980-01-01

    Short gravity-capillary waves, the equilibrium, or the steady state excitations of the ocean surface are modulated by longer ocean waves. These short waves are the predominant microwave scatterers on the ocean surface under many viewing conditions so that the modulation is readily measured with CW Doppler radar used as a two-scale wave probe. Modulation transfer functions (the ratio of the cross spectrum of the line-of-sight orbital speed and backscattered microwave power to the autospectrum of the line-of-sight orbital speed) were measured at 9.375 and 1.5 GHz (Bragg wavelengths of 2.3 and 13 cm) for winds up to 10 m/s and ocean wave periods from 2-18 s. The measurements were compared with the relaxation-time model; the principal result is that a source of modulation other than straining by the horizontal component of orbital speed, possibly the wave-induced airflow, is responsible for most of the modulation by waves of typical ocean wave period (10 s). The modulations are large; for unit coherence, spectra of radar images of deep-water waves should be proportional to the quotient of the slope spectra of the ocean waves by the ocean wave frequency.

  9. Wave-wave interactions and deep ocean acoustics.

    PubMed

    Guralnik, Z; Bourdelais, J; Zabalgogeazcoa, X; Farrell, W E

    2013-10-01

    Deep ocean acoustics, in the absence of shipping and wildlife, is driven by surface processes. Best understood is the signal generated by non-linear surface wave interactions, the Longuet-Higgins mechanism, which dominates from 0.1 to 10 Hz, and may be significant for another octave. For this source, the spectral matrix of pressure and vector velocity is derived for points near the bottom of a deep ocean resting on an elastic half-space. In the absence of a bottom, the ratios of matrix elements are universal constants. Bottom effects vitiate the usual "standing wave approximation," but a weaker form of the approximation is shown to hold, and this is used for numerical calculations. In the weak standing wave approximation, the ratios of matrix elements are independent of the surface wave spectrum, but depend on frequency and the propagation environment. Data from the Hawaii-2 Observatory are in excellent accord with the theory for frequencies between 0.1 and 1 Hz, less so at higher frequencies. Insensitivity of the spectral ratios to wind, and presumably waves, is indeed observed in the data.

  10. Breaking Waves on the Ocean Surface

    NASA Astrophysics Data System (ADS)

    Schwendeman, Michael S.

    In the open ocean, breaking waves are a critical mechanism for the transfer of energy, momentum, and mass between the atmosphere and the ocean. Despite much study, fundamental questions about wave breaking, such as what determines whether a wave will break, remain unresolved. Measurements of oceanic breakers, or "whitecaps," are often used to validate the hypotheses derived in simplified theoretical, numerical, or experimental studies. Real-world measurements are also used to improve the parameterizations of wave-breaking in large global models, such as those forecasting climate change. Here, measurements of whitecaps are presented using ship-based cameras, from two experiments in the North Pacific Ocean. First, a method for georectifying the camera imagery is described using the distant horizon, without additional instrumentation. Over the course of the experiment, this algorithm correctly identifies the horizon in 92% of images in which it is visible. In such cases, the calculation of camera pitch and roll is accurate to within 1 degree. The main sources of error in the final georectification are from mislabeled horizons due to clouds, rain, or poor lighting, and from vertical "heave" motions of the camera, which cannot be calculated with the horizon method. This method is used for correcting the imagery from the first experiment, and synchronizing the imagery from the second experiment to an onboard inertial motion package. Next, measurements of the whitecap coverage, W, are shown from both experiments. Although W is often used in models to represent whitecapping, large uncertainty remains in the existing parameterizations. The data show good agreement with recent measurements using the wind speed. Although wave steepness and dissipation are hypothesized to be more robust predictors of W, this is shown to not always be the case. Wave steepness shows comparable success to the wind parameterizations only when using a mean-square slope variable calculated over the

  11. Numerical study of ocean wave effect on offshore wind farm

    NASA Astrophysics Data System (ADS)

    Shen, Lian; Yang, Di; Meneveau, Charles

    2013-11-01

    Wind power at sea has become increasingly important in renewable energy study. For energy harvesting, winds over oceans have many advantages over winds on land, for example, larger and open surface area, faster wind speed, and more wind resource close to high population regions. On the other hand, the presence of ocean waves introduces complexities to wind turbines. There is a critical need to study the dynamical interactions among marine atmospheric boundary layer, ocean wave field, and floating turbines. In this research, we study offshore wind farm by performing large-eddy simulations for winds coupled with potential-flow-theory based simulations for broadband irregular waves, with the wind turbines represented by an actuator disk model. Our results show that windseas at different development stages result in different sea-surface roughness and have an appreciable effect on wind profile and the energy extraction rate of the turbines. If swells are present, swell-to-wind momentum and energy transfer further changes the wind field to introduce oscillations in as well as modify the mean of the wind power. DY and LS acknowledge the support of NSF-CBET-1341062. CM acknowledges the support of NSF-AGS-1045189 and NSF-OISE-1243482.

  12. Spatial characteristics of ocean surface waves

    NASA Astrophysics Data System (ADS)

    Gemmrich, Johannes; Thomson, Jim; Rogers, W. Erick; Pleskachevsky, Andrey; Lehner, Susanne

    2016-08-01

    The spatial variability of open ocean wave fields on scales of O (10km) is assessed from four different data sources: TerraSAR-X SAR imagery, four drifting SWIFT buoys, a moored waverider buoy, and WAVEWATCH III Ⓡ model runs. Two examples from the open north-east Pacific, comprising of a pure wind sea and a mixed sea with swell, are given. Wave parameters attained from observations have a natural variability, which decreases with increasing record length or acquisition area. The retrieval of dominant wave scales from point observations and model output are inherently different to dominant scales retrieved from spatial observations. This can lead to significant differences in the dominant steepness associated with a given wave field. These uncertainties have to be taken into account when models are assessed against observations or when new wave retrieval algorithms from spatial or temporal data are tested. However, there is evidence of abrupt changes in wave field characteristics that are larger than the expected methodological uncertainties.

  13. Wave-Breaking Turbulence in the Ocean Surface Layer

    DTIC Science & Technology

    2016-06-01

    Wave-Breaking Turbulence in the Ocean Surface Layer JIM THOMSON, MICHAEL S. SCHWENDEMAN, AND SETH F. ZIPPEL Applied Physics Laboratory, University of...2016) ABSTRACT Observations of winds, waves, and turbulence at the ocean surface are compared with several analytic formulations and a numerical model...Introduction Wave breaking at the ocean surface limits wave growth (Melville 1994), enhances gas exchange (Zappa et al. 2007), and generates turbulence that

  14. Soliton turbulence in shallow water ocean surface waves.

    PubMed

    Costa, Andrea; Osborne, Alfred R; Resio, Donald T; Alessio, Silvia; Chrivì, Elisabetta; Saggese, Enrica; Bellomo, Katinka; Long, Chuck E

    2014-09-05

    We analyze shallow water wind waves in Currituck Sound, North Carolina and experimentally confirm, for the first time, the presence of soliton turbulence in ocean waves. Soliton turbulence is an exotic form of nonlinear wave motion where low frequency energy may also be viewed as a dense soliton gas, described theoretically by the soliton limit of the Korteweg-deVries equation, a completely integrable soliton system: Hence the phrase "soliton turbulence" is synonymous with "integrable soliton turbulence." For periodic-quasiperiodic boundary conditions the ergodic solutions of Korteweg-deVries are exactly solvable by finite gap theory (FGT), the basis of our data analysis. We find that large amplitude measured wave trains near the energetic peak of a storm have low frequency power spectra that behave as ∼ω-1. We use the linear Fourier transform to estimate this power law from the power spectrum and to filter densely packed soliton wave trains from the data. We apply FGT to determine the soliton spectrum and find that the low frequency ∼ω-1 region is soliton dominated. The solitons have random FGT phases, a soliton random phase approximation, which supports our interpretation of the data as soliton turbulence. From the probability density of the solitons we are able to demonstrate that the solitons are dense in time and highly non-Gaussian.

  15. Observed ocean waves by tropical cyclones

    NASA Astrophysics Data System (ADS)

    Zhang, Lin; Oey, Leo

    2017-04-01

    Ocean waves produced by tropical cyclones (TC) modify air-sea fluxes which in turn are crucial to the storms' intensity and development, yet they are poorly understood. Here we use 24 years (1992-2015) of observed waves, winds and TC-track information to stratify storm-centered composite maps of waves and winds according to TC intensities and translation speeds (Uh). While the wind field is rightward-asymmetric independent of Uh, the wave field is rightward-symmetric in concert with the wind for slow-translating TCs (Uh ≤ 3 m s-1), but right-rear asymmetric with strongest waves in the 4th quadrant for medium to fast-translating TCs (3 < Uh ≤ 7 m s-1), especially for the very fast storms (Uh > 7 m s-1), all independent of TC-intensity. The dominance of the right-rear asymmetry for fast-translating TCs appears to be related to the development of cross swells as the storms move faster, but further research using models are needed to understand the physical mechanisms.

  16. numerical broadband modelling of ocean waves, from 1 to 300 s: implications for seismic wave sources and wave climate studies

    NASA Astrophysics Data System (ADS)

    Ardhuin, F.; Stutzmann, E.; Gualtieri, L.

    2014-12-01

    Ocean waves provide most of the energy that feeds the continuous vertical oscillations of the solid Earth. Three period bands are usually identified. The hum contains periods longer than 30 s, and the primary and secondary peaks are usually centered around 15 and 5 s, respectively. Motions in all three bands are recorded everywhere on our planet and can provide information on both the solid Earth structure and the ocean wave climate over the past century. Here we describe recent efforts to extend the range of validity of ocean wave models to cover periods from 1 to 300 s (Ardhuin et al., Ocean Modelling 2014), and the resulting public database of ocean wave spectra (http://tinyurl.com/iowagaftp/HINDCAST/ ). We particularly discuss the sources of uncertainty for building a numerical model of acoustic and seismic noise on this knowledge of ocean wave spectra. For acoustic periods shorter than 3 seconds, the main uncertainties are the directional distributions of wave energy (Ardhuin et al., J. Acoust. Soc. Amer. 2013). For intermediate periods (3 to 25 s), the propagation properties of seismic waves are probably the main source of error when producing synthetic spectra of Rayleigh waves (Ardhuin et al. JGR 2011, Stutzmann et al. GJI 2012). For the longer periods (25 to 300 s), the poor knowledge of the bottom topography details may be the limiting factor for estimating hum spectra or inverting hum measurements in properties of the infragravity wave field. All in all, the space and time variability of recorded seismic and acoustic spectra is generally well reproduced in the band 3 to 300 s, and work on shorter periods is under way. This direct model can be used to search for missing noise sources, such as wave scattering in the marginal ice zone, find events relevant for solid earth studies (e.g. Obrebski et al. JGR 2013) or invert wave climate properties from microseismic records. The figure shows measured spectra of the vertical ground acceleration, and modeled

  17. Modeling Non-linear Ocean Wave Amplification in Coastal Settings

    NASA Astrophysics Data System (ADS)

    Harrington, J. P.; Cox, R.; Brennan, J.; Clancy, C.; Herterich, J.; Dias, F.

    2016-12-01

    Coastal boulder deposits occur in many locations worldwide, along high-energy coastlines. They contain clasts with masses >100 t in some cases, deposited many m above high water and many tens of m inland, often at the top of steep cliffs. The clasts are moved by storm waves, despite being at elevations and inshore distances that should be unreachable by recorded sea states. The question is, therefore, how are storm waves amplified to the extent needed to transport megagravel inshore? As climate changes, with the risk of increased storminess, it is important to understand this issue, as it is central to understanding inland transmission of fluid forces during storm events. Numerical modeling is a powerful technique for exploring this complex problem. We used a conformal mapping solution to Euler's equations to explore runup of 2D wave trains against a vertical barrier (simulating a coastal cliff). Previous research showed that modeled wave trains passing over flat bathymetry experience vertical runup up to 6 times the initial wave amplitude for both short- (3 times water depth) and long- (125 times depth) wavelength waves. We increased the model complexity by including a bathymetric step, causing an abrupt depth decrease before the cliff. We found that the uneven bathymetry further amplified both short- and long-wavelength waves. Short-wavelength simulations were hampered by our code's limitations in solving Euler's equations for steep waves, and crashed before reaching maximum runups: ongoing work focuses on solving the computational problems. These problems did not affect the long-wavelength simulations, however, which returned maximum runup values up to 10 times initial amplitude. The key message is that bathymetric effects can drive large wave-height amplifications. This suggests that enhanced runup for long-wavelength waves caused by variable bathymetry could be a key factor in cases where ocean waves overtop steep cliffs and transport boulders well above high

  18. Determination of internal wave power from synthetic schlieren data

    NASA Astrophysics Data System (ADS)

    Lee, Frank M.; Allshouse, Michael; Morrison, P. J.; Swinney, Harry L.

    2014-11-01

    Internal waves are generated in the ocean by tidal flow over bottom topography, and they are of considerable interest because of their significant contribution to the energy budget of the ocean. One way of measuring internal waves produced in the laboratory setting is by a technique called ``synthetic schlieren,'' whereby the perturbation density field is obtained from the change in index of refraction in the fluid. However, the usual computation of power requires the velocity and pressure, or under certain assumptions, the stream function [Lee et al., ``Experimental determination of radiated internal wave power without pressure field data,'' Phys. Fluids 26, 046606 (2014)]. We present a method for computing the radiated internal wave power that uses only the perturbation density field, assuming the flow is sufficiently 2-dimensional, and we demonstrate the method using data from simulations and experiments.

  19. Effects of surface wave breaking on the oceanic boundary layer

    NASA Astrophysics Data System (ADS)

    He, Hailun; Chen, Dake

    2011-04-01

    Existing laboratory studies suggest that surface wave breaking may exert a significant impact on the formation and evolution of oceanic surface boundary layer, which plays an important role in the ocean-atmosphere coupled system. However, present climate models either neglect the effects of wave breaking or treat them implicitly through some crude parameterization. Here we use a one-dimensional ocean model (General Ocean Turbulence Model, GOTM) to investigate the effects of wave breaking on the oceanic boundary layer on diurnal to seasonal time scales. First a set of idealized experiments are carried out to demonstrate the basic physics and the necessity to include wave breaking. Then the model is applied to simulating observations at the northern North Sea and the Ocean Weather Station Papa, which shows that properly accounting for wave breaking effects can improve model performance and help it to successfully capture the observed upper ocean variability.

  20. Ocean thermal gradient hydraulic power plant.

    PubMed

    Beck, E J

    1975-07-25

    Solar energy stored in the oceans may be used to generate power by exploiting ploiting thermal gradients. A proposed open-cycle system uses low-pressure steam to elevate vate water, which is then run through a hydraulic turbine to generate power. The device is analogous to an air lift pump.

  1. Video-based ocean wave spectra

    NASA Astrophysics Data System (ADS)

    Harbitz, Alf

    1994-07-01

    A particular video spot detector provides an irradiance time series from an arbitrarily chosen pixel in the video frame. The detector is applied to video records of the ocean surface, and the correspondence between the 1D irradiance frequency spectrum and the corresponding ocean surface elevation spectrum is studied. A major experimental results is that the frequency peak in the irradiance spectrum for a typical wind-driven sea is significantly enhanced compared to the surface slope spectrum. Video experiments from the oil rig Gullfaks A in the North Sea show an excellent agreement between the enhanced peak frequency in the irradiance spectrum and the peak frequency in the surface elevation spectrum measured by a microwave remote ocean surveillance wave radar. The enhancement of the peak in the irradiance spectrum is explained by a strong nonlinear geometrical projection effect. This is due to the rather small look angle with the horizontal, which is chosen so as to neglect irradiance contributions from beneath the sea surface. Based on a simple stochastic model that takes the geometric effect into account, irradiance spectra are simulated and are in good agreement with the experimental spectra.

  2. Mesospheric Mountain Wave Breaking and Oceanic Wave Signatures During DEEPWAVE

    NASA Astrophysics Data System (ADS)

    Taylor, M. J.; Pautet, P. D.; Fritts, D. C.; Doyle, J. D.; Eckermann, S. D.; Williams, B. P.; Kaifler, B.; Bossert, K.; Criddle, N.

    2015-12-01

    DEEPWAVE is an international program designed to quantify gravity wave (GW) dynamics and effects from the ground to the upper mesosphere in unprecedented detail utilizing a range of airborne and ground-based measurements. DEEPWAVE was based on the South Island, New Zealand, to provide access to well-documented, but little understood, New Zealand and Tasmania "hotspots" as identified in satellite stratospheric measurements. Deep orographic GWs over New Zealand were a primary target, but multiple flights were also conducted over the Southern Ocean and Tasman Sea to quantify deep GW arising from convection, jet streams, and frontal systems. This presentation highlights new airborne and ground-based results obtained using an Advanced OH Mesospheric Temperature Mapper (AMTM) which creates high-quality intensity and temperature maps of a broad spectrum of mesospheric GWs. Two AMTM's were employed, one sited at the NIWA Observatory, Lauder (45°S), on the South Island, and one on the NSF GV Gulfstream aircraft which was supplemented by two side viewing IR OH imagers providing large field, ~900 km cross-track, GW maps. These instruments formed part of a comprehensive measurements capability including airborne Rayleigh and Na lidars, dropsondes, ground-based Rayleigh lidar, all-sky imagers and wind measurements. A total of 25 long duration (typically 7-8 hours) nighttime flights were conducted creating an exceptionally rich data set. Here we focus on two key initial findings (a) discovery of large amplitude, mesospheric mountain waves and their intermittent wave breaking signatures, and (b) first measurements of large-field open-ocean mesospheric GW and their near-identical stratospheric wave signatures using AIRS satellite and model forecasting data.

  3. Power systems for ocean regional cabled observatories

    NASA Technical Reports Server (NTRS)

    Kojima, Junichi; Asakawa, Kenichi; Howe, Bruce M.; Kirkham, Harold

    2004-01-01

    Development of power systems is the most challenging technical issue in the design of ocean regional cabled observatories. ARENA and NEPTUNE are two ocean regional cabled observatory networks with aims that are at least broadly similar. Yet the two designs are quite different in detail. This paper outlines the both systems and explores the reasons for the divergence of design, and shows that it arose because of differences in the priority of requirements.

  4. Power systems for ocean regional cabled observatories

    NASA Technical Reports Server (NTRS)

    Kojima, Junichi; Asakawa, Kenichi; Howe, Bruce M.; Kirkham, Harold

    2004-01-01

    Development of power systems is the most challenging technical issue in the design of ocean regional cabled observatories. ARENA and NEPTUNE are two ocean regional cabled observatory networks with aims that are at least broadly similar. Yet the two designs are quite different in detail. This paper outlines the both systems and explores the reasons for the divergence of design, and shows that it arose because of differences in the priority of requirements.

  5. Remote sensing of ocean wave spectra by interferometric synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Marom, M.; Thornton, E. B.; Goldstein, R. M.; Shemer, L.

    1990-01-01

    Ocean surface waves can be clearly observed by SAR in the interferometric configuration (INSAR) due to the ability of INSAR to provide images of the local surface velocity field. It is shown here that INSAR can be used to obtain wavenumber spectra that are in agreement with power spectra measured in situ. This new method has considerable potential to provide instantaneous spatial information about the structure of ocean wave fields.

  6. Ocean surface waves in an ice-free Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Li, Jian-Guo

    2016-08-01

    The retreat of the Arctic ice edge implies that global ocean surface wave models have to be extended at high latitudes or even to cover the North Pole in the future. The obstacles for conventional latitude-longitude grid wave models to cover the whole Arctic are the polar problems associated with their Eulerian advection schemes, including the Courant-Friedrichs-Lewy (CFL) restriction on diminishing grid length towards the Pole, the singularity at the Pole and the invalid scalar assumption for vector components defined relative to the local east direction. A spherical multiple-cell (SMC) grid is designed to solve these problems. It relaxes the CFL restriction by merging the longitudinal cells towards the Poles. A round polar cell is used to remove the singularity of the differential equation at the Pole. A fixed reference direction is introduced to define vector components within a limited Arctic part in mitigation of the scalar assumption errors at high latitudes. The SMC grid has been implemented in the WAVEWATCH III model and validated with altimeter and buoy observations, except for the Arctic part, which could not be fully tested due to a lack of observations as the polar region is still covered by sea ice. Here, an idealised ice-free Arctic case is used to test the Arctic part and it is compared with a reference case with real ice coverage. The comparison indicates that swell wave energy will increase near the ice-free Arctic coastlines due to increased fetch. An expanded Arctic part is used for comparisons of the Arctic part with available satellite measurements. It also provides a direct model comparison between the two reference systems in their overlapping zone.

  7. Electric power generation: Tidal and wave power. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    Not Available

    1994-12-01

    The bibliography contains citations concerning the feasibility of obtaining electric power from ocean disturbances such as waves, swells, and tides. The engineering and economic aspects are emphasized. Theoretical analysis of the power plant potential of selected sites around the world is included. (Contains 250 citations and includes a subject term index and title list.)

  8. Electric power generation: Tidal and wave power. (Latest citations from the Aerospace database). Published Search

    SciTech Connect

    Not Available

    1993-12-01

    The bibliography contains citations concerning the feasibility of obtaining electric power from ocean disturbances such as waves, swells, and tides. The engineering and economic aspects are emphasized. Theoretical analysis of the power plant potential of selected sites around the world is included. (Contains 250 citations and includes a subject term index and title list.)

  9. The viscous lee wave problem and its implications for ocean modelling

    NASA Astrophysics Data System (ADS)

    Shakespeare, Callum J.; Hogg, Andrew McC.

    2017-05-01

    Ocean circulation models employ 'turbulent' viscosity and diffusivity to represent unresolved sub-gridscale processes such as breaking internal waves. Computational power has now advanced sufficiently to permit regional ocean circulation models to be run at sufficiently high (100 m-1 km) horizontal resolution to resolve a significant part of the internal wave spectrum. Here we develop theory for boundary generated internal waves in such models, and in particular, where the waves dissipate their energy. We focus specifically on the steady lee wave problem where stationary waves are generated by a large-scale flow acting across ocean bottom topography. We generalise the energy flux expressions of [Bell, T., 1975. Topographically generated internal waves in the open ocean. J. Geophys. Res. 80, 320-327] to include the effect of arbitrary viscosity and diffusivity. Applying these results for realistic parameter choices we show that in the present generation of models with O(1) m2s-1 horizontal viscosity/diffusivity boundary-generated waves will inevitably dissipate the majority of their energy within a few hundred metres of the boundary. This dissipation is a direct consequence of the artificially high viscosity/diffusivity, which is not always physically justified in numerical models. Hence, caution is necessary in comparing model results to ocean observations. Our theory further predicts that O(10-2) m2s-1 horizontal and O(10-4) m2s-1 vertical viscosity/diffusivity is required to achieve a qualitatively inviscid representation of internal wave dynamics in ocean models.

  10. The modulation of the radar backscattering cross section by long ocean waves

    NASA Technical Reports Server (NTRS)

    Alpers, W.; Jones, W. L.

    1978-01-01

    The modulation transfer function which relates the backscattered microwave power to the long ocean wave field was measured in the North Sea during JONSWAP 75. Results from this tower experiment with an X-band scatterometer are presented and compared with the two-scale wave model (relaxation-time model).

  11. The modulation of the radar backscattering cross section by long ocean waves

    NASA Technical Reports Server (NTRS)

    Alpers, W.; Jones, W. L.

    1978-01-01

    The modulation transfer function which relates the backscattered microwave power to the long ocean wave field was measured in the North Sea during JONSWAP 75. Results from this tower experiment with an X-band scatterometer are presented and compared with the two-scale wave model (relaxation-time model).

  12. The sources of deep ocean infragravity waves observed in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Crawford, Wayne; Ballu, Valerie; Bertin, Xavier; Karpytchev, Mikhail

    2015-07-01

    Infragravity waves are long-period (25-250 s) ocean surface gravity waves generated in coastal zones through wave-wave interactions or oscillation of the breaking point. Most of the infragravity wave energy is trapped or dissipated near coastlines, but a small percentage escapes into the open oceans. The source of deep ocean infragravity waves is debated, specifically whether they come mostly from regions with strong source waves or from sites with particular morphologies/orientations. We correlate measurements of infragravity waves in the deep North Atlantic Ocean with infragravity wave generation parameters throughout the Atlantic Ocean to find the dominant sources of deep ocean infragravity wave energy in the North Atlantic Ocean. The deep ocean infragravity wave data are from a 5 year deployment of absolute pressure gauges west of the Azores islands (37°N, 35°W) and shorter data sets from seafloor tsunami gauges (DART buoys). Two main sources are identified: one off of the west coast of southern Europe and northern Africa (25°N-40°N) in northern hemisphere winter and the other off the west coast of equatorial Africa (the Gulf of Guinea) in southern hemisphere winter. These regions have relatively weak source waves and weak infragravity wave propagation paths to the main measurement site, indicating that that the site morphology/orientation dominates the creation of deep ocean infragravity waves. Both regions have also been identified as potential sources of global seismological noise, suggesting that the same mechanisms may be behind the generation of deep ocean infragravity waves and global seismological noise in the frequency band from 0.001 to 0.04 Hz.

  13. Short wind waves on the ocean: Long-wave and wind-speed dependences

    NASA Astrophysics Data System (ADS)

    Plant, William J.

    2015-09-01

    This second paper of our set on short wind waves on the ocean utilizes the wavenumber-frequency spectrum of short wave heights, F(k,f), derived in our previous paper to investigate kinematic effects on the dependence of the frequency spectrum, F(f), and the wavenumber spectrum, F(k), on long-wave height. We show that the model predicts that neither F(f) nor F(k) are exactly power law functions of their independent variables and that F(f) varies with significant wave height much more than F(k) does. After calibrating the model against wave gauges, we also investigate the dependence of mean-square-slopes (mss), mean-square heights (msh) and root-mean-square orbital velocities (rmsv) of short ocean waves on wind speed and maximum frequency or wavenumber. We use data from the wire wave gauges on University of Miami's Air-Sea Interaction Spar (ASIS) buoy for calibration purposes. Frequency spectra from the wave gauges begin to be affected by noise at about 2.5 Hz. Therefore, above 1 Hz, we utilize F(f) from the modeled F(k,f) to extend the frequency dependence up to 180 Hz. We set modeled spectral densities by matching measured spectra at 1 Hz. Using the calibrated F(f,k), we are able to estimate the average value of the total mss, for long and short waves, and its upwind and crosswind components up to 180 Hz for a variety of wind speeds. The average mss values are in good agreement with the measurements of Cox and Munk [1954], although the upwind and crosswind components agree less well.

  14. Sensitivity of Rogue Waves Predictions to the Oceanic Stratification

    NASA Astrophysics Data System (ADS)

    Guo, Qiuchen; Alam, Mohammad-Reza

    2014-11-01

    Oceanic rogue waves are short-lived very large amplitude waves (a giant crest typically followed or preceded by a deep trough) that appear and disappear suddenly in the ocean causing damages to ships and offshore structures. Assuming that the state of the ocean at the present time is perfectly known, then the upcoming rogue waves can be predicted via numerically solving the equations that govern the evolution of the waves. The state of the art radar technology can now provide accurate wave height measurement over large spatial domains and when combined with advanced wave-field reconstruction techniques together render deterministic details of the current state of the ocean (i.e. surface elevation and velocity field) at any given moment of the time with a very high accuracy. The ocean water density is, however, stratified (mainly due to the salinity and temperature differences). This density stratification, with today's technology, is very difficult to be measured accurately. As a result in most predictive schemes these density variations are neglected. While the overall effect of the stratification on the average state of the ocean may not be significant, here we show that these density variations can strongly affect the prediction of oceanic rogue waves. Specifically, we consider a broadband oceanic spectrum in a two-layer density stratified fluid, and study via extensive statistical analysis the effects of strength of the stratification (difference between densities) and the depth of the thermocline on the prediction of upcoming rogue waves.

  15. Imaging Ocean Waves with SAR, a SAR Ocean Wave Algorithm Development Program.

    DTIC Science & Technology

    1979-12-01

    document is Remote sensing D lital progessing unlimited. Data processing S ,ctral analysis SAR imagery Sei-causal Multi-frequency synthetic aperture ra...111 39. Speckle Pattern Decorrelation vs. Change in Processed Center Frequency for a Processed Bandwidth of 2 MHz .. ...... 114 40. Speckle...defining or processing the true ocean-wave frequency. A cubic expression for the slant-to-ground distortion was derived. This expression was then

  16. Radar Measurements of Ocean Surface Waves using Proper Orthogonal Decomposition

    DTIC Science & Technology

    2017-03-30

    please find the Final Technical Report with SF 298 for Dr. Erin E. Hackett’s ONR grant entitled Radar Measurements of Ocean Surface Waves Using Proper...request. Stephanie Cassavaugh, Director Enclosures P.O. Box 261954 Conway, South Carolina 29528-6054 Radar Measurements of Ocean Surface Waves Using...COVERED (From - To) 30-03-2017 Final Technical 22-01-2015-31-12-2016 4. TITLE AND S UBTITLE 5a. CONTRACT NUMBER Radar Measurements of Ocean Surface

  17. Baroclinic Rossby Wave Signature in a General Circulation Ocean Model.

    DTIC Science & Technology

    1983-06-01

    northwest with a wavelength cf 300 km. For other laritudes of the North acific Ocean , Price and Maqaard (1980) determined that first mode baroclinic Rossby...role in the latitude belt 40-50N in the North acific 10 -. - !o Ocean . Magaard (1983) ir. a paper discussing bariclin _c Rossty wave energetics...HD-AI132 219 BAROCLINIC ROSSBY WAVE SIGNATURE IN A GENERAL CIRCULATION OCEAN MODEL(U) NAVAL POSTGRADUATE SCHOOLU MONTEREY CA A H RUTSCH JUN 83

  18. Rogue Waves in the Ocean, Understanding and Prediction

    NASA Astrophysics Data System (ADS)

    Babanin, A. V.; Rogers, W.

    2013-12-01

    Rogue waves are abnormally high, with respect to the mean, waves in the ocean. Here, deep-water wind-generated dominant waves in absence of currents will be considered. Present understanding of their nature, and pathways to their prediction will be reviewed and discussed. Rogue waves can be due to quasi-linear superpositions of waves, and nonlinear effects such as instabilities of wave trains. Both mechanisms appear to be important and possible. Individual waves can be focused into a superposition due to either dispersive or directional features of wave fields. While probability of the former to lead to a relatively very high wave in oceanic conditions is low, the directional focusing appears to cause rare but regular extreme events. Nonlinear wave fields should be separated into stable and unstable conditions, with different probability distributions for wave heights/crests. In stable conditions, wave statistics is determined by the quasi-linear focusing, whereas in unstable wave trains high transient wave events can occur. Their maximal height/steepness is determined by combined dynamics of the instability growth and the limiting wave breaking. Both instability and breaking depend on mean wave steepness, spectral bandwidth, wave directionality, spectrum tail, wind forcing. In extreme wind-forcing conditions, such as hurricanes, modulational instability of wave fields may be suppressed, and the breaking process is controlled by different physics. Therefore, it is argued that rogue wave statistics in such circumstances is expected to be essentially altered.

  19. Seismic waves in the atmosphere and oceans

    NASA Astrophysics Data System (ADS)

    Kobayashi, N.

    2006-12-01

    We developed a new method to calculate normal modes of the earth and planets. It can treat anelasticity directly as imaginary parts of elastic constants and leaky modes due to the open boundary condition set at the upper atmosphere. The eigenvalue problem is described in complex numbers. It is similar to the Henyey type relaxation method used in solar seismology but a different method. In our method, the complex eigenvalue problem of a large system is reduced to an eigenvalue problem of a quite small size matrix. The eigenvalue of the small problem is a correction of an assumed complex eigenfrequency and components of the eigenvector are values of eigenfunctions at the outer boundary. Starting from an arbitrary complex frequency around the eigenfrequency of a target mode, we can arrive there within, at most, a dozen of steps of iterative calculations. Numerical examples show good behavior of the convergence to complex eigenfrequencies. Even for a model with an atmosphere in which the fundamental spheroidal mode 0S29 and the fundamental acoustic mode 0P29 nearly degenerate, we can easily reach the eigenfrequency of 0S29 and distinguish it from that of 0P29 without any confusion. In addition to the efficiency in the convergence to the eigenfrequencies, numerical tests show strong numerical stability of the method. For those reasons, we propose the method as an efficient way in calculating synthetic sesimograms, barograms and ionograms for recently observed phenomena relating with coupling between the solid earth, the oceans and the atmosphere. Using this method, we show some examples of synthetic seismic waves which are sum of normal modes along Rayleigh branch and Tsunami branch excited by large earthquakes. In paticular, we focus on wave fields of Rayleigh and Tsunami waves in the atmosphere.

  20. Infragravity waves in the deep ocean: An upward revision

    NASA Astrophysics Data System (ADS)

    Aucan, J.; Ardhuin, F.

    2013-07-01

    Ocean infragravity waves are surface gravity waves with periods of several minutes and corresponding wavelengths of up to tens of kilometers. When propagating freely in the deep ocean, these waves are typically small, several centimeters at most, so they have been seldom studied. In the context of future wide-swath altimetry missions, these waves need to be better quantified as they have wavelengths that will be resolved by such instruments. Here, we analyze the global climatology and variability of infragravity waves in the deep ocean using data from over 40 open ocean locations, with depths larger than 2000 m. We show that typical infragravity wave heights are higher than previously estimated, with winter-averaged values up to 11 mm off the U.S. West Coast, and typically less than 6 mm in the tropics. The mid to high latitudes exhibit a strong seasonal cycle consistent with the local variability of the wind-waves, while the tropical Pacific has a higher energy level during the Austral winter that does not correlate well with the local wind-waves, suggesting a remote source for the recorded infragravity waves. These infragravity wave energies are expected to be a significant contribution to the error budget for possible measurements of sea level associated to sub-mesoscale currents at horizontal scales around 10 km. Hence, a global numerical model of infragravity waves will likely be necessary for the analysis of the planned Surface Water Ocean Topography mission.

  1. The physics of anomalous (‘rogue’) ocean waves

    NASA Astrophysics Data System (ADS)

    Adcock, Thomas A. A.; Taylor, Paul H.

    2014-10-01

    There is much speculation that the largest and steepest waves may need to be modelled with different physics to the majority of the waves on the open ocean. This review examines the various physical mechanisms which may play an important role in the dynamics of extreme waves. We examine the evidence for these mechanisms in numerical and physical wavetanks, and look at the evidence that such mechanisms might also exist in the real ocean.

  2. Mechanical Extraction of Power From Ocean Currents and Tides

    NASA Technical Reports Server (NTRS)

    Jones, Jack; Chao, Yi

    2010-01-01

    A proposed scheme for generating electric power from rivers and from ocean currents, tides, and waves is intended to offer economic and environmental advantages over prior such schemes, some of which are at various stages of implementation, others of which have not yet advanced beyond the concept stage. This scheme would be less environmentally objectionable than are prior schemes that involve the use of dams to block rivers and tidal flows. This scheme would also not entail the high maintenance costs of other proposed schemes that call for submerged electric generators and cables, which would be subject to degradation by marine growth and corrosion. A basic power-generation system according to the scheme now proposed would not include any submerged electrical equipment. The submerged portion of the system would include an all-mechanical turbine/pump unit that would superficially resemble a large land-based wind turbine (see figure). The turbine axis would turn slowly as it captured energy from the local river flow, ocean current, tidal flow, or flow from an ocean-wave device. The turbine axis would drive a pump through a gearbox to generate an enclosed flow of water, hydraulic fluid, or other suitable fluid at a relatively high pressure [typically approx.500 psi (approx.3.4 MPa)]. The pressurized fluid could be piped to an onshore or offshore facility, above the ocean surface, where it would be used to drive a turbine that, in turn, would drive an electric generator. The fluid could be recirculated between the submerged unit and the power-generation facility in a closed flow system; alternatively, if the fluid were seawater, it could be taken in from the ocean at the submerged turbine/pump unit and discharged back into the ocean from the power-generation facility. Another alternative would be to use the pressurized flow to charge an elevated reservoir or other pumped-storage facility, from whence fluid could later be released to drive a turbine/generator unit at a

  3. Ocean Current Power Generator. Final Report

    SciTech Connect

    O'Sullivan, G. A.

    2002-07-26

    The Ocean Power Generator is both technically and economically suitable for deployment in the Gulf Stream from the US Navy facility in Dania, Florida. Yet to be completed is the calibration test in the Chesapeake Bay with the prototype dual hydroturbine Underwater Electric Kite. For the production units a revised design includes two ballast tanks mounted as pontoons to provide buoyancy and depth control. The power rating of the Ocean Power Generator has been doubled to 200 kW ready for insertion into the utility grid. The projected cost for a 10 MW installation is $3.38 per watt, a cost that is consistent with wind power pricing when it was in its deployment infancy, and a cost that is far better than photovoltaics after 25 years of research and development. The Gulf Stream flows 24 hours per day, and water flow is both environmentally and ecologically perfect as a renewable energy source. No real estate purchases are necessary, and you cannot see, hear, smell, or touch an Ocean Power Generator.

  4. The hydrothermal power of oceanic lithosphere

    NASA Astrophysics Data System (ADS)

    Grose, C. J.; Afonso, J. C.

    2015-03-01

    We have estimated the power of ventilated hydrothermal heat transport, and its spatial distribution, using a set of recently developed plate models which highlight the effects of hydrothermal circulation and thermal insulation by oceanic crust. Testing lithospheric cooling models with these two effects, we estimate that global advective heat transport is about 6.6 TW, significantly lower than previous estimates, and that the fraction of that extracted by vigorous circulation on the ridge axes (<1 Ma) is about 50% of the total, significantly higher than previous estimates. This low hydrothermal power estimate originates from the thermally insulating properties of oceanic crust in relation to the mantle. Since the crust is relatively insulating, the effective properties of the lithosphere are "crust dominated" near ridge axes (yielding lower heat flow), and gradually approach mantle values over time. Thus, cooling models with crustal insulation predict low heat flow over young seafloor, implying that the difference of modeled and measured heat flow is due to the heat transport properties of the lithosphere, in addition to ventilated hydrothermal circulation as generally accepted. These estimates may bear on important problems in the physics and chemistry of the Earth because the magnitude of hydrothermal power affects chemical exchanges between the oceans and the lithosphere, thereby affecting both thermal and chemical budgets in the oceanic crust and lithosphere, the subduction factory, and convective mantle.

  5. How ocean waves rock the Earth: Two mechanisms explain microseisms with periods 3 to 300 s

    NASA Astrophysics Data System (ADS)

    Ardhuin, Fabrice; Gualtieri, Lucia; Stutzmann, Eléonore

    2015-02-01

    Microseismic activity, recorded everywhere on Earth, is largely due to ocean waves. Recent progress has clearly identified sources of microseisms in the most energetic band, with periods from 3 to 10 s. In contrast, the generation of longer-period microseisms has been strongly debated. Two mechanisms have been proposed to explain seismic wave generation: a primary mechanism, by which ocean waves propagating over bottom slopes generate seismic waves, and a secondary mechanism which relies on the nonlinear interaction of ocean waves. Here we show that the primary mechanism explains the average power, frequency distribution, and most of the variability in signals recorded by vertical seismometers, for seismic periods ranging from 13 to 300 s. The secondary mechanism only explains seismic motions with periods shorter than 13 s. Our results build on a quantitative numerical model that gives access to time-varying maps of seismic noise sources.

  6. Multistable chain for ocean wave vibration energy harvesting

    NASA Astrophysics Data System (ADS)

    Harne, R. L.; Schoemaker, M. E.; Wang, K. W.

    2014-03-01

    The heaving of ocean waves is a largely untapped, renewable kinetic energy resource. Conversion of this energy into electrical power could integrate with solar technologies to provide for round-the-clock, portable, and mobile energy supplies usable in a wide variety of marine environments. However, the direct drive conversion methodology of gridintegrated wave energy converters does not efficiently scale down to smaller, portable architectures. This research develops an alternative power conversion approach to harness the extraordinarily large heaving displacements and long oscillation periods as an excitation source for an extendible vibration energy harvesting chain. Building upon related research findings and engineering insights, the proposed system joins together a series of dynamic cells through bistable interfaces. Individual impulse events are generated as the inertial mass of each cell is pulled across a region of negative stiffness to induce local snap through dynamics; the oscillating magnetic inertial mass then generates current in a coil which is connected to energy harvesting circuitry. It is shown that linking the cells into a chain transmits impulses through the system leading to cascades of vibration and enhancement of electrical energy conversion from each impulse event. This paper describes the development of the multistable chain and ways in which realistic design challenges were addressed. Numerical modeling and corresponding experiments demonstrate the response of the chain due to slow and large amplitude input motion. Lastly, experimental studies give evidence that energy conversion efficiency of the chain for wave energy conversion is much higher than using an equal number of cells without connections.

  7. Real world ocean rogue waves explained without the modulational instability

    NASA Astrophysics Data System (ADS)

    Fedele, Francesco; Brennan, Joseph; Ponce de León, Sonia; Dudley, John; Dias, Frédéric

    2016-06-01

    Since the 1990s, the modulational instability has commonly been used to explain the occurrence of rogue waves that appear from nowhere in the open ocean. However, the importance of this instability in the context of ocean waves is not well established. This mechanism has been successfully studied in laboratory experiments and in mathematical studies, but there is no consensus on what actually takes place in the ocean. In this work, we question the oceanic relevance of this paradigm. In particular, we analyze several sets of field data in various European locations with various tools, and find that the main generation mechanism for rogue waves is the constructive interference of elementary waves enhanced by second-order bound nonlinearities and not the modulational instability. This implies that rogue waves are likely to be rare occurrences of weakly nonlinear random seas.

  8. Real world ocean rogue waves explained without the modulational instability

    PubMed Central

    Fedele, Francesco; Brennan, Joseph; Ponce de León, Sonia; Dudley, John; Dias, Frédéric

    2016-01-01

    Since the 1990s, the modulational instability has commonly been used to explain the occurrence of rogue waves that appear from nowhere in the open ocean. However, the importance of this instability in the context of ocean waves is not well established. This mechanism has been successfully studied in laboratory experiments and in mathematical studies, but there is no consensus on what actually takes place in the ocean. In this work, we question the oceanic relevance of this paradigm. In particular, we analyze several sets of field data in various European locations with various tools, and find that the main generation mechanism for rogue waves is the constructive interference of elementary waves enhanced by second-order bound nonlinearities and not the modulational instability. This implies that rogue waves are likely to be rare occurrences of weakly nonlinear random seas. PMID:27323897

  9. Theoretical Studies of the Oceanic Internal Wave System.

    DTIC Science & Technology

    1982-08-31

    AD-A19 720 ILLINOIS UNIV AT URBANA DEPT OF PHYSICS Fie 8/3Al THEOkETICAL STUDIES OF THE OCEANIC INTERNAL WAVE SYSTEM. 1WAUG 52 1 WRIGHT N00014-80-C...Arlington Va. 22217 RE: N00014-80-C-840 Theoretical Studies of the Oceanic Internal Wave System Final report Dear Lou: The primary emphasis of this...contract was to calcu- late the parameters appropriate to a quasi-linear description of the oceanic internal wave field. The main results are described

  10. The hydrothermal power of oceanic lithosphere

    NASA Astrophysics Data System (ADS)

    Grose, C. J.; Afonso, J. C.

    2015-10-01

    We have estimated the power of ventilated hydrothermal heat transport, and its spatial distribution, using a set of recently developed plate models which highlight the effects of axial hydrothermal circulation and thermal insulation by oceanic crust. Testing lithospheric cooling models with these two effects, we estimate that global advective heat transport is about 6.6 TW, significantly lower than most previous estimates, and that the fraction of that extracted by vigorous circulation on the ridge axes (< 1 My old) is about 50 % of the total, significantly higher than previous estimates. These new estimates originate from the thermally insulating properties of oceanic crust in relation to the mantle. Since the crust is relatively insulating, the effective properties of the lithosphere are "crust dominated" near ridge axes (a thermal blanketing effect yielding lower heat flow) and gradually approach mantle values over time. Thus, cooling models with crustal insulation predict low heat flow over young seafloor, implying that the difference of modeled and measured heat flow is due to the heat transport properties of the lithosphere, in addition to ventilated hydrothermal circulation as generally accepted. These estimates may bear on important problems in the physics and chemistry of the Earth because the magnitude of ventilated hydrothermal power affects chemical exchanges between the oceans and the lithosphere, thereby affecting both thermal and chemical budgets in the oceanic crust and lithosphere, the subduction factory, and the convective mantle.

  11. Nonlinear shallow ocean-wave soliton interactions on flat beaches.

    PubMed

    Ablowitz, Mark J; Baldwin, Douglas E

    2012-09-01

    Ocean waves are complex and often turbulent. While most ocean-wave interactions are essentially linear, sometimes two or more waves interact in a nonlinear way. For example, two or more waves can interact and yield waves that are much taller than the sum of the original wave heights. Most of these shallow-water nonlinear interactions look like an X or a Y or two connected Ys; at other times, several lines appear on each side of the interaction region. It was thought that such nonlinear interactions are rare events: they are not. Here we report that such nonlinear interactions occur every day, close to low tide, on two flat beaches that are about 2000 km apart. These interactions are closely related to the analytic, soliton solutions of a widely studied multidimensional nonlinear wave equation. On a much larger scale, tsunami waves can merge in similar ways.

  12. Developing Malaysian Ocean Wave Database Using Satellite

    DTIC Science & Technology

    2004-11-01

    Malaysia , Johor Bahru. Shinkai A. and Wan S., (1996). Statistical Characteristics of the Global Wave Statistics Data and Long-term Predictions, ASME, Japan. ...5535700 Fax: +607-5574710 Email: omar@fkm.utm.my KEY WORDS: altimetry, statistics , wave periods, wave heights ABSTRACT. Correct wave data ...develop a more reliable and comprehensive wave database for Malaysia sea areas using satellite altimetry. Significant wave height data is extracted

  13. Relation between ocean wave parameters and primary microseismic noise

    NASA Astrophysics Data System (ADS)

    Juretzek, Carina; Hadziioannou, Celine

    2017-04-01

    Primary microseismic noise (12-15 second period) is mainly generated in shallow water. A theoretical framework for the Rayleigh wave generation exists, however the strong presence of Love waves in the primary microseism cannot be explained by this theory alone. In this study, we explore the relation between ocean wave parameters, local parameters of the noise source regions, and the properties of the surface seismic noise field. We consider 3 months of data in 2008/2009 and the full year for 2013, for 3 arrays in Europe. The main source regions for each Love and Rayleigh waves are localized and compared to ocean surface elevation, ocean wave propagation direction and local bathymetry. We find that beamformer results as well as correlation with ocean surface elevation show differences between noise strength of each wavetype emitted from the same coastal sections. Further, the British Isles and some parts of the coast of Norway serve as especially bright sources, meaning that they seem relatively more effective at noise generation. While both Rayleigh and Love wave noise amplitudes depend equally on the ocean surface elevation, we find a dependence of the wavetype ratio on ocean wave propagation direction. This hints towards an effective source radiation pattern and could provide insight into the source mechanism.

  14. Rogue waves in the ocean - review and progress

    NASA Astrophysics Data System (ADS)

    Pelinovsky, Efim; Kharif, Christian; Slunyaev, Alexey

    2010-05-01

    Rogue waves in the ocean and physical mechanisms of their appearance are discussed. Theyse waves are among waves naturally observed by people on the sea surface that represent inseparable feature of the Ocean. Rogue waves appear from nowhere, cause danger and disappear at once. They may occur at the surface of a relatively calm sea, reach not very high amplitudes, but be fatal for ships and crew due to their unexpectedness and abnormal features. The billows appear suddenly exceeding the surrounding waves twice and more, and obtained many names: abnormal, exceptional, extreme, giant, huge, sudden, episodic, freak, monster, rogue, vicious, killer, mad- or rabid-dog waves; cape rollers, holes in the sea, walls of water, three sisters… Freak monsters, though living for seconds, were able to arouse superstitious fear of the crew, cause damage, death of heedless sailors or the whole ship. All these epithets are full of human fear and feebleness. The serious studies of the phenomenon started about 20-30 years ago and have been intensified during the recent decade. The research is being conducted in different fields: in physics (search of physical mechanisms and adequate models of wave enhancement and statistics), in geoscience (determining the regions and weather conditions when rogue waves are most probable), and in ocean and coastal engineering (estimations of the wave loads on fixed and drifting floating structures). Thus, scientists and engineers specializing in different subject areas are involved in the solution of the problem. The state-of-art of the rogue wave study is summarized in our book [Kharif, Ch., Pelinovsky, E., and Slunyaev, A. Rogue Waves in the Ocean. Springer, 2009] and presented in given review. Firstly, we start with a brief introduction to the problem of freak waves aiming at formulating what is understood as rogue or freak waves, what consequences their existence imply in our life, why people are so worried about them. Then we discuss existing

  15. Understanding Rossby wave trains forced by the Indian Ocean Dipole

    NASA Astrophysics Data System (ADS)

    McIntosh, Peter C.; Hendon, Harry H.

    2017-06-01

    Convective variations over the tropical Indian Ocean associated with ENSO and the Indian Ocean Dipole force a Rossby wave train that appears to emanate poleward and eastward to the south of Australia and which causes climate variations across southern Australia and more generally throughout the Southern Hemisphere extratropics. However, during austral winter, the subtropical jet that extends from the eastern Indian Ocean into the western Pacific at Australian latitudes should effectively prohibit continuous propagation of a stationary Rossby wave from the tropics into the extratropics because the meridional gradient of mean absolute vorticity goes to zero on its poleward flank. The observed wave train indeed exhibits strong convergence of wave activity flux upon encountering this region of vanishing vorticity gradient and with some indication of reflection back into the tropics, indicating the continuous propagation of the stationary Rossby wave train from low to high latitudes is inhibited across the south of Australia. However, another Rossby wave train appears to emanate upstream of Australia on the poleward side of the subtropical jet and propagates eastward along the waveguide of the eddy-driven (sub-polar) jet into the Pacific sector of the Southern Ocean. This combination of evanescent wave train from the tropics and eastward propagating wave train emanating from higher latitudes upstream of Australia gives the appearance of a continuous Rossby wave train propagating from the tropical Indian Ocean into higher southern latitudes. The extratropical Rossby wave source on the poleward side of the subtropical jet stems from induced changes in transient eddy activity in the main storm track of the Southern Hemisphere. During austral spring, when the subtropical jet weakens, the Rossby wave train emanating from Indian Ocean convection is explained more traditionally by direct dispersion from divergence forcing at low latitudes.

  16. The physical basis for estimating wave-energy spectra with the radar ocean-wave spectrometer

    NASA Technical Reports Server (NTRS)

    Jackson, Frederick C.

    1987-01-01

    The derivation of the reflectivity modulation spectrum of the sea surface for near-nadir-viewing microwave radars using geometrical optics is described. The equations required for the derivation are presented. The derived reflectivity modulation spectrum provides data on the physical basis of the radar ocean-wave spectrometer measurements of ocean-wave directional spectra.

  17. The physical basis for estimating wave-energy spectra with the radar ocean-wave spectrometer

    NASA Technical Reports Server (NTRS)

    Jackson, Frederick C.

    1987-01-01

    The derivation of the reflectivity modulation spectrum of the sea surface for near-nadir-viewing microwave radars using geometrical optics is described. The equations required for the derivation are presented. The derived reflectivity modulation spectrum provides data on the physical basis of the radar ocean-wave spectrometer measurements of ocean-wave directional spectra.

  18. X-band microwave backscattering from ocean waves

    SciTech Connect

    Lee, P.H.Y.; Barter, J.D.; Beach, K.L.

    1994-01-04

    Backscattering experiments at microwave frequencies were conducted off the west coast of Scotland in the summer of 1991. Using a dual-polarization, 8-frequency X-band coherent scatterometer mounted on the bow of a boat, we measured time-resolved backscattering from ocean waves at a range of grazing angles from 10{degrees} to 70{degrees}. From the grazing-angle-dependent signals and their Doppler spectra, we differentiate Bragg scattering from non-Bragg scattering and resolve ``peak separation`` between the vertical and horizontal polarizations. We observe instances of ``super`` events, i.e., instances when the horizontal polarization return power equals or exceeds the vertical polarization power. We find that ``super`` events occur not only at low grazing angles but at any grazing angle for against-wind viewing directions. Statistics for such occurrences as a function of grazing angle are obtained. We study the coherence properties of scatterers and find strong evidence that at low grazing angles, lifetime-dominated, non-Bragg scattering contributes noticeably to returns of both polarizations, but is dominant in providing returns for the horizontal polarization. We examine ``spiking`` events and find that they can be related to, but need not be limited to, breaking wave events. By comparing the data of against-wind runs with cross-wind and circle runs, we obtain wind-direction dependence of Doppler spectra which further assists in the identification of scattering mechanisms.

  19. A simulation of synthetic aperture radar imaging of ocean waves

    NASA Technical Reports Server (NTRS)

    Swift, C. T.

    1974-01-01

    A simulation of radar imaging of ocean waves with synthetic aperture techniques is presented. The modelling is simplistic from the oceanographic and electromagnetic viewpoint in order to minimize the computational problems, yet reveal some of the physical problems associated with the imaging of moving ocean waves. The model assumes: (1) The radar illuminates a one-dimensional, one harmonic ocean wave. (2) The scattering is assumed to be governed by geometrical optics. (3) The radar is assumed to be down-looking, with Doppler processing (range processing is suppressed due to the one-dimensional nature of the problem). (4) The beamwidth of the antenna (or integration time) is assumed to be sufficiently narrow to restrict the specular points of the peaks and troughs of the wave. The results show that conventional processing of the image gives familiar results if the ocean waves are stationary. When the ocean wave dispersion relationship is satisfied, the image is smeared due to the motion of the specular points over the integration time. In effect, the image of the ocean is transferred to the near field of the synthetic aperture.

  20. The probability distribution of extreme wave load on space frame ocean structures

    SciTech Connect

    Tromans, P.S.; Dam, J. van

    1996-12-31

    The authors investigate different methods for calculating probability distributions of wave loads on fixed jacket structures. The first method is based on transformation of variables between crest elevation and wave force; the second is a first order reliability study in discrete components of the directional power spectrum of the ocean surface. Both approaches are simplified by representing the structure as a set of vertical columns and the wave kinematics by stretched linear theories. The methods are tested against time domain simulations of loads generated by random directional wave force models and against measured loads on a North Sea jacket.

  1. Fast Simulation Method for Ocean Wave Base on Ocean Wave Spectrum and Improved Gerstner Model with GPU

    NASA Astrophysics Data System (ADS)

    Zhang, Wenqiao; Zhang, Jing; Zhang, Tianchi

    2017-01-01

    For the randomness and complexity of ocean wave, and the simulation of large-scale ocean requires a great amount of computation, but the computational efficiency is low, the real-time ability is poor, a fast method of wave simulation is proposed based on the observation and research results of oceanography, it takes advantage of the grid which combined with the technique of LOD and projection, and use the height map of ocean which is formd by retrieval of ocean wave spectrum and directional spectrum to compute with FFT, and it uses the height map to cyclic mapping for the grid on GPU which combined with the technique of LOD and projection to get the dynamic height data and simulation of ocean. The experimental results show that the method is vivid and it conforms with randomness and complexity of ocean wave, it effectively improves the simulation speed of the wave and satisfied with the real-time ability and fidelity in simulation system of ocean.

  2. Field Evaluation of Ocean Wave Measurement With GPS Buoys

    DTIC Science & Technology

    2010-09-01

    surface waves. In the experiment, conducted off the coast of California near Bodega Bay, clusters off Datawell and prototype GPS buoys were...receivers to measure ocean surface waves. In the experiment, conducted off the coast of California near Bodega Bay, clusters off Datawell and...the coast near Bodega Bay, CA. .............................................................................................17 Figure 4. R/P FLIP

  3. Toward an Internal Gravity Wave Spectrum in Global Ocean Models

    DTIC Science & Technology

    2015-05-14

    14 MAY 2015 2. REPORT TYPE 3. DATES COVERED 00-00-2015 to 00-00-2015 4. TITLE AND SUBTITLE Toward an Internal Gravity Wave Spectrum in Global...resolution global ocean models forced by atmospheric fields and tides are beginning to display realistic internal gravity wave spectra, especially as

  4. Ionospheric Stimulation By High Power Radio Waves

    NASA Astrophysics Data System (ADS)

    Minami, S.; Nishino, M.; Suzuki, Y.; Sato, S.; Tanikawa, T.; Nakamura, Y.; Wong, A. Y.

    1999-01-01

    We have performed an experiment to artificially stimulate the ionosphere using higher power radio waves at the HIPAS (High Power Auroral Stimulation) facility in Alaska. A radio transmission of 2.85 MHz was made at 80 MW (ERP). Diagnostics were made at the other site located 35 km from the transmission site. The results of cross-correlating the excited HF wave and observed with an 8 channel, 30 MHz scanning cosmic radio noise absorption records revealed the excited height of 90 km. Also atmospheric pressure waves observed on the ground show evident propagation of pressure waves which are generated in the ionosphere by the high-power HF wave. The results determine the excitation height of 90 km in the ionosphere and show evidence of the pressure wave coupling between the ionosphere and the lower atmosphere for periods of 10 min

  5. Partitioning Ocean Wave Spectra Obtained from Radar Observations

    NASA Astrophysics Data System (ADS)

    Delaye, Lauriane; Vergely, Jean-Luc; Hauser, Daniele; Guitton, Gilles; Mouche, Alexis; Tison, Celine

    2016-08-01

    2D wave spectra of ocean waves can be partitioned into several wave components to better characterize the scene. We present here two methods of component detection: one based on watershed algorithm and the other based on a Bayesian approach. We tested both methods on a set of simulated SWIM data, the Ku-band real aperture radar embarked on the CFOSAT (China- France Oceanography Satellite) mission which launch is planned mid-2018. We present the results and the limits of both approaches and show that Bayesian method can also be applied to other kind of wave spectra observations as those obtained with the radar KuROS, an airborne radar wave spectrometer.

  6. Ocean Surface Wave Optical Roughness: Innovative Polarization Measurement

    DTIC Science & Technology

    2007-09-30

    whitecap breaking waves. * Prof. Michael L . Banner, School of Mathematics, The University of NSW, Sydney, Australia Dr. Bertrand Chapron...of microsacle breaking waves from infrared imagery using a PIV algorithm. Meas. Sci. Technol. 16, 1961-1969. Phillips, O. M., Posner, F. L ., and... Hansen , J. P. 2001 High resolution radar measurements of the speed distribution of breaking events in wind-generated ocean waves: surface impulse

  7. Ocean Surface Wave Optical Roughness - Innovative Measurement and Modeling

    DTIC Science & Technology

    2007-09-30

    and whitecap breaking waves. * Prof. Michael L . Banner, School of Mathematics, The University of NSW, Sydney, Australia Dr. Bertrand Chapron...microsacle breaking waves from infrared imagery using a PIV algorithm. Meas. Sci. Technol. 16, 1961-1969. Phillips, O. M., Posner, F. L ., and... Hansen , J. P. 2001 High resolution radar measurements of the speed distribution of breaking events in wind-generated ocean waves: surface impulse and

  8. Near Field Ocean Surface Waves Acoustic Radiation Observation and Modeling

    NASA Astrophysics Data System (ADS)

    Ardhuin, F.; Peureux, C.; Royer, J. Y.

    2016-12-01

    The acoustic noise generation by nonlinearly interacting surface gravity waves has been studied for a long time both theoretically and experimentally [Longuet-Higgins 1951]. The associated far field noise is continuously measured by a vast network of seismometers at the ocean bottom and on the continents. It can especially be used to infer the time variability of short ocean waves statistics [Peureux and Ardhuin 2016]. However, better quantitative estimates of the latter are made difficult due to a poor knowledge of the Earth's crust characteristics, whose coupling with acoustic modes can affect large uncertainties to the frequency response at the bottom of the ocean.The pressure field at depths less than an acoustic wave length to the surface is made of evanescent modes which vanish away from their sources (near field) [Cox and Jacobs 1989]. For this reason, they are less affected by the ocean bottom composition. This near field is recorded and analyzed in the frequency range 0.1 to 0.5 Hz approximately, at two locations : at a shallow site in the North-East Atlantic continental shelf and a deep water site in the Southern Indian ocean, where pressure measurements are performed at the ocean bottom (ca. 100 m) and at 300 m water depth respectively. Evanescent and propagating Rayleigh modes are compared against theoretical predictions. Comparisons against surface waves hindcast based on WAVEWATCH(R) III modeling framework help assessing its performances and can be used to help future model improvements.References Longuet-Higgins, M. S., A Theory of the Origin of Microseisms, Philos. Trans. Royal Soc. A, 1950, 243, 1-3. Peureux, C. and Ardhuin, F., Ocean bottom pressure records from the Cascadia array and short surface gravity waves, J. Geophys. Res. Oceans, 2016, 121, 2862-2873. Cox, C. S. & Jacobs, D. C., Cartesian diver observations of double frequency pressure fluctuations in the upper levels of the ocean, Geophys. Res. Lett., 1989, 16, 807-810.

  9. Book review: Nonlinear ocean waves and the inverse scattering transform

    USGS Publications Warehouse

    Geist, Eric L.

    2011-01-01

    Nonlinear Ocean Waves and the Inverse Scattering Transform is a comprehensive examination of ocean waves built upon the theory of nonlinear Fourier analysis. The renowned author, Alfred R. Osborne, is perhaps best known for the discovery of internal solitons in the Andaman Sea during the 1970s. In this book, he provides an extensive treatment of nonlinear water waves based on a nonlinear spectral theory known as the inverse scattering transform. The writing is exceptional throughout the book, which is particularly useful in explaining some of the more difficult mathematical concepts.  Review info: Nonlinear Ocean Waves and the Inverse Scattering Transform. By Alfred R. Osborne, 2010. ISBN: 978-125286299, 917 pp.

  10. Integration of ocean thermal energy conversion power plants with existing power systems

    SciTech Connect

    Arunasalam, N.

    1986-01-01

    The problem of integrating an Ocean Thermal Energy Conversion (OTEC) power plant with existing power systems is studied. A nonlinear model of an OTEC power system is developed. The dynamics of the large local induction motor load, and the coaxial cable connection to the mainland are included in the model. The effect of the motor load and the coaxial cable on the steady-state stability of the OTEC power plant is investigated using linearized analysis. The transient stability of the OTEC system is investigated through simulation. The contribution made by the motor load and the coaxial cable to the transient stability is studied. The occurrence of self excitation phenomena is analyzed using linear methods and simulation. The effects of wave and vessel motion on the electrical power output of the OTEC plant is investigated.

  11. Novel two-stage piezoelectric-based ocean wave energy harvesters for moored or unmoored buoys

    NASA Astrophysics Data System (ADS)

    Murray, R.; Rastegar, J.

    2009-03-01

    Harvesting mechanical energy from ocean wave oscillations for conversion to electrical energy has long been pursued as an alternative or self-contained power source. The attraction to harvesting energy from ocean waves stems from the sheer power of the wave motion, which can easily exceed 50 kW per meter of wave front. The principal barrier to harvesting this power is the very low and varying frequency of ocean waves, which generally vary from 0.1Hz to 0.5Hz. In this paper the application of a novel class of two-stage electrical energy generators to buoyant structures is presented. The generators use the buoy's interaction with the ocean waves as a low-speed input to a primary system, which, in turn, successively excites an array of vibratory elements (secondary system) into resonance - like a musician strumming a guitar. The key advantage of the present system is that by having two decoupled systems, the low frequency and highly varying buoy motion is converted into constant and much higher frequency mechanical vibrations. Electrical energy may then be harvested from the vibrating elements of the secondary system with high efficiency using piezoelectric elements. The operating principles of the novel two-stage technique are presented, including analytical formulations describing the transfer of energy between the two systems. Also, prototypical design examples are offered, as well as an in-depth computer simulation of a prototypical heaving-based wave energy harvester which generates electrical energy from the up-and-down motion of a buoy riding on the ocean's surface.

  12. Predicting dangerous ocean waves with spaceborne synthetic aperture radar

    NASA Technical Reports Server (NTRS)

    Beal, R. C.

    1984-01-01

    It is pointed out that catastrophes, related to the occurrence of strong winds and large ocean waves, can consume more lives and property than most naval battles. The generation of waves by wind are considered, Pierson et al. (1955) have incorporated statistical concepts into a wave forecast model. The concept of an 'ocean wave spectrum' was introduced, with the wind acting independently on each Fourier component. However, even after 30 years of research and debate, the generation, propagation, and dissipation of the spectrum under arbitrary conditions continue to be controversial. It has now been found that spaceborne SAR has a surprising ability to precisely monitor spatially evolving wind and wave fields. Approaches to overcome certain weaknesses of the SAR method are discussed, taking into account the second Shuttle Imaging Radar experiment, and a possible long-term solution provided by Spectrasat. Spectrasat should be a low-altitude (200 to 250 km) satellite with active drag compensation.

  13. Influence of mid-ocean ridges on Rossby waves

    NASA Technical Reports Server (NTRS)

    Wang, Liping; Koblinsky, C. J.

    1994-01-01

    Influence of mid-ocean ridges on Rossby wave activity is discussed in simple models. Ridges can influence Rossby waves in two ways, topographic scattering to model parameters such as frequency, ridge height, and ridge width in both barotropic and baroclinic models. In the barotropic model, for certain model parameters there is perfect transmission of Rossby waves, while for some other model parameters the transmission is rather weak. In a two-layer model, if the frequency is not low enough, trapping of baroclinic signals around topography will occur. The mid-ocean ridge is generally not as efficient as the eastern boundary in generating barotropic waves except at high frequencies in a barotropic model. It is much more efficient than the eastern boundary generating baroclinic waves when wind forcing has a very large zonal scale, while less efficient when wind forcing has a short zonal scale.

  14. Stochastic modeling of inhomogeneous ocean waves

    NASA Astrophysics Data System (ADS)

    Smit, P. B.; Janssen, T. T.; Herbers, T. H. C.

    2015-12-01

    Refraction of swell waves in coastal waters can result in fast-scale variations of wave statistics due to wave interference. These variations cannot be resolved by wave models based on the radiative transport equation. More advanced models based on quasi-coherent theory, a generalization of the radiative transfer equation, can be coupled or nested into larger-scale models to resolve such local inhomogeneous effects. However, source terms for quasi-coherent models to account for non-conservative and nonlinear effects are not available, which hampers their operational use. In the present work we revisit the derivation of quasi-coherent theory to consistently include a source term for dissipation associated with depth-induced wave breaking. We demonstrate how general source terms can be incorporated in this class of models and compare model simulations with the new dissipation term to laboratory observations of focusing and breaking waves over a submerged shoal. The results show that a consistent derivation of source terms is essential to accurately capture coherent effects in coastal areas. Specifically, our results show that if coherent effects are ignored in the dissipation term, interference effects are strongly exaggerated. With the development of source terms for quasi-coherent models they can be effectively nested inside or otherwise coupled to larger-scale wave models to efficiently improve operational predictive capability of wave models near the coast.

  15. Madden Julian Oscillation impacts on global ocean surface waves

    NASA Astrophysics Data System (ADS)

    Marshall, Andrew G.; Hendon, Harry H.; Durrant, Tom H.; Hemer, Mark A.

    2015-12-01

    We assess the impact of the tropical Madden Julian Oscillation (MJO) on global ocean wind waves using 30 years of wave data from a wave model hindcast that is forced with high resolution surface winds from the NCEP-CFSR reanalysis. We concentrate on the boreal winter season when the MJO has its greatest amplitude and is potentially a source of predictable wave impacts at intra-seasonal lead times. Statistically significant anomalies in significant wave height (Hs), peak wave period (Tp) and zonal wave energy flux (CgE) are found to covary with the intra-seasonal variation of surface zonal wind induced by the MJO as it traverses eastward from the western tropical Indian Ocean to the eastern tropical Pacific. Tp varies generally out of phase with Hs over the life cycle of the MJO, indicating that these MJO-wave anomalies are locally wind-generated rather than remotely generated by ocean swell. Pronounced Hs anomalies develop on the northwest shelf of Australia, where the MJO is known to influence sea level and surface temperatures, and in the western Caribbean Sea and Guatemalan-Panama Seas with enhanced wave anomalies apparent in the vicinity of the Tehuantepec and Papagayo gaps. Significant wave anomalies are also detected in the North Pacific and North Atlantic oceans in connection with the MJO teleconnection to the extratropics via atmospheric wave propagation. The impact in the north Atlantic stems from induction of the high phase of the North Atlantic Oscillation (NAO) about 1 week after MJO convection traverses the Indian Ocean, and the low phase of the NAO about one week after suppressed convection traverses the Indian Ocean. Strong positive Hs anomalies maximize on the Northern European coast in the positive NAO phase and vice versa for the negative NAO phase. The MJO also influences the occurrence of daily low (below the 5th percentile) and high (above the 95th percentile) wave conditions across the tropics and in the North Pacific and North Atlantic

  16. Further SEASAT SAR coastal ocean wave analysis

    NASA Technical Reports Server (NTRS)

    Kasischke, E. S.; Shuchman, R. A.; Meadows, G. A.; Jackson, P. L.; Tseng, Y.

    1981-01-01

    Analysis techniques used to exploit SEASAT synthetic aperture radar (SAR) data of gravity waves are discussed and the SEASAT SAR's ability to monitor large scale variations in gravity wave fields in both deep and shallow water is evaluated. The SAR analysis techniques investigated included motion compensation adjustments and the semicausal model for spectral analysis of SAR wave data. It was determined that spectra generated from fast Fourier transform analysis (FFT) of SAR wave data were not significantly altered when either range telerotation adjustments or azimuth focus shifts were used during processing of the SAR signal histories, indicating that SEASAT imagery of gravity waves is not significantly improved or degraded by motion compensation adjustments. Evaluation of the semicausal (SC) model using SEASAT SAR data from Rev. 974 indicates that the SC spectral estimates were not significantly better than the FFT results.

  17. Novel wave power analysis linking pressure-flow waves, wave potential, and the forward and backward components of hydraulic power.

    PubMed

    Mynard, Jonathan P; Smolich, Joseph J

    2016-04-15

    Wave intensity analysis provides detailed insights into factors influencing hemodynamics. However, wave intensity is not a conserved quantity, so it is sensitive to diameter variations and is not distributed among branches of a junction. Moreover, the fundamental relation between waves and hydraulic power is unclear. We, therefore, propose an alternative to wave intensity called "wave power," calculated via incremental changes in pressure and flow (dPdQ) and a novel time-domain separation of hydraulic pressure power and kinetic power into forward and backward wave-related components (ΠP±and ΠQ±). Wave power has several useful properties:1) it is obtained directly from flow measurements, without requiring further calculation of velocity;2) it is a quasi-conserved quantity that may be used to study the relative distribution of waves at junctions; and3) it has the units of power (Watts). We also uncover a simple relationship between wave power and changes in ΠP±and show that wave reflection reduces transmitted power. Absolute values of ΠP±represent wave potential, a recently introduced concept that unifies steady and pulsatile aspects of hemodynamics. We show that wave potential represents the hydraulic energy potential stored in a compliant pressurized vessel, with spatial gradients producing waves that transfer this energy. These techniques and principles are verified numerically and also experimentally with pressure/flow measurements in all branches of a central bifurcation in sheep, under a wide range of hemodynamic conditions. The proposed "wave power analysis," encompassing wave power, wave potential, and wave separation of hydraulic power provides a potent time-domain approach for analyzing hemodynamics. Copyright © 2016 the American Physiological Society.

  18. Oceanic lithospheric S-wave velocities from the analysis of P-wave polarization at the ocean floor

    NASA Astrophysics Data System (ADS)

    Hannemann, Katrin; Krüger, Frank; Dahm, Torsten; Lange, Dietrich

    2016-12-01

    Our knowledge of the absolute S-wave velocities of the oceanic lithosphere is mainly based on global surface wave tomography, local active seismic or compliance measurements using oceanic infragravity waves. The results of tomography give a rather smooth picture of the actual S-wave velocity structure and local measurements have limitations regarding the range of elastic parameters or the geometry of the measurement. Here, we use the P-wave polarization (apparent P-wave incidence angle) of teleseismic events to investigate the S-wave velocity structure of the oceanic crust and the upper tens of kilometres of the mantle beneath single stations. In this study, we present an up to our knowledge new relation of the apparent P-wave incidence angle at the ocean bottom dependent on the half-space S-wave velocity. We analyse the angle in different period ranges at ocean bottom stations (OBSs) to derive apparent S-wave velocity profiles. These profiles are dependent on the S-wave velocity as well as on the thickness of the layers in the subsurface. Consequently, their interpretation results in a set of equally valid models. We analyse the apparent P-wave incidence angles of an OBS data set which was collected in the Eastern Mid Atlantic. We are able to determine reasonable S-wave-velocity-depth models by a three-step quantitative modelling after a manual data quality control, although layer resonance sometimes influences the estimated apparent S-wave velocities. The apparent S-wave velocity profiles are well explained by an oceanic PREM model in which the upper part is replaced by four layers consisting of a water column, a sediment, a crust and a layer representing the uppermost mantle. The obtained sediment has a thickness between 0.3 and 0.9 km with S-wave velocities between 0.7 and 1.4 km s-1. The estimated total crustal thickness varies between 4 and 10 km with S-wave velocities between 3.5 and 4.3 km s-1. We find a slight increase of the total crustal thickness from

  19. High power millimeter wave source development program

    NASA Technical Reports Server (NTRS)

    George, T. V.

    1989-01-01

    High power millimeter wave sources for fusion program; ECH source development program strategy; and 1 MW, 140 GHz gyrotron experiment design philosophy are briefly outlined. This presentation is represented by viewgraphs only.

  20. Energy transfer due to nonlinear wave-wave interactions in deep ocean

    NASA Astrophysics Data System (ADS)

    Yokoyama, Naoto; Lvov, Yuri V.

    2007-11-01

    It was believed that the Garrett-Munk spectrum was the ``universal'' energy spectrum of oceanic internal waves. However, it has become apparent from recent categorization of oceanic observations that the Garrett-Munk spectrum can not be as universal as been previously thought. One may use the weak turbulence theory to attempt to explain the formation of the spectral energy density of internal waves. It turns out that the large wavenumbers (small scales) interact in triads via small wavenumbers (large scales). This hypothesis provides possible explanation for the variability of the energy spectra. Namely, several families of statistically steady solutions are found in consideration of the nonlocality in wavenumber spaces of resonant interactions. The new families of power-law exponents of the energy spectra are in good agreement with the observations. To check these theory we perform direct numerical simulations based on Hamiltonian formalism. It is shown also by the numerical simulations that the nonlocal interactions in the wavenumber space are dominant in the inertial wavenumbers. The validity of the weak turbulence theory is also discussed.

  1. Energy extraction from ocean currents and waves: Mapping the most promising locations

    NASA Astrophysics Data System (ADS)

    Ordonez, A.; Hamlington, P.; Fox-Kemper, B.

    2012-12-01

    Concerns about fossil fuel supplies and an ever-increasing demand for energy have prompted the search for alternative power sources. One option is the ocean, a power-dense and renewable source of energy, but its capacity to meet human energy demands is poorly understood. Although raw wave energy resources have been investigated at many scales, there is still substantial uncertainty regarding how much useful power can be extracted. Even less is known about the energy available in ocean currents, especially on a global scale. Moreover, no studies have attempted to examine wave and current energy simultaneously while at the same time taking into account geographical, environmental, and technical factors that can substantially limit the amount of extractable energy. In this study, we use high fidelity oceanographic model data to assess the availability, recoverability, and value of energy in ocean wind waves and currents. Global wave energy transport, coastal wave energy flux, and current energy are calculated and mapped using the model data. These maps are then incorporated into a geographic information system (GIS) in order to assess the U.S. recoverable ocean energy resource. In the GIS, the amount of recoverable energy is estimated by combining the power output from realistic wave and current energy farms with physical and ecological data such as bathymetry and environmentally protected areas. This holistic approach is then used to examine the distribution and value of extractable wave and current energy along the U.S. coast. The results support previous studies that show that the U.S. West Coast has large potential for wave energy extraction and that the Florida Strait has high potential for current energy extraction. We also show that, at any particular location, the amount of available ocean energy is only one factor of many that determines the ultimate feasibility and value of the energy. We outline ways in which the GIS framework used in this assessment can be

  2. Elastic waves in ice-covered ocean

    NASA Astrophysics Data System (ADS)

    Presnov, Dmitriy; Zhostkow, Ruslan; Gusev, Vladimir; Shurup, Andrey; Sobisevich, Alex

    2014-05-01

    The problem of propagation of acoustic waves in a shallow ice-covered sea is considered in frames of the mathematical model of the layered medium: ice sheet over a liquid layer (shallow sea) positioned on an elastic half-space (seabed). As the result of analytical solution the simplified dispersion equation has been derived and used for further analytical and numerical analysis. It has been shown that there are five types of waves subject to propagate in the layered model medium: flexural waves of ice-cover, Rayleigh-type wave on the boundary between elastic half-space and the liquid layer, normal modes in ice (as in waveguide), hydro-acoustic normal modes and quasi-longitudinal wave in ice plate. Variations initial conditions as well as source parameters allow obtaining solution for acoustical pressure. Field experiments with geophones, hydrophones and microphones were carried out on the Ladoga Lake (Leningrad Oblast in northwestern Russia) using small controllable explosions as source signals. The experiment has shown satisfactory agreement with theoretical results. Analysis of the dispersion equation for various parameters of the model provides an opportunity to estimate geophysical characteristics of the geophysical medium, based on the experimentally registered wave's velocities. It has been shown, that it is possible to extract valuable information from flexural and Rayleigh-type waves in the low-frequency domain of the recorded data via spatial-temporal analysis. Separate study of those waves allows measuring ice thickness (which is important because of ice melting and ecological situation in Arctic) and velocity of transverse waves in seabed (that can help to determine type of material and can be useful in mineral deposit prospecting).

  3. Ocean wavenumber estimation from wave-resolving time series imagery

    USGS Publications Warehouse

    Plant, N.G.; Holland, K.T.; Haller, M.C.

    2008-01-01

    We review several approaches that have been used to estimate ocean surface gravity wavenumbers from wave-resolving remotely sensed image sequences. Two fundamentally different approaches that utilize these data exist. A power spectral density approach identifies wavenumbers where image intensity variance is maximized. Alternatively, a cross-spectral correlation approach identifies wavenumbers where intensity coherence is maximized. We develop a solution to the latter approach based on a tomographic analysis that utilizes a nonlinear inverse method. The solution is tolerant to noise and other forms of sampling deficiency and can be applied to arbitrary sampling patterns, as well as to full-frame imagery. The solution includes error predictions that can be used for data retrieval quality control and for evaluating sample designs. A quantitative analysis of the intrinsic resolution of the method indicates that the cross-spectral correlation fitting improves resolution by a factor of about ten times as compared to the power spectral density fitting approach. The resolution analysis also provides a rule of thumb for nearshore bathymetry retrievals-short-scale cross-shore patterns may be resolved if they are about ten times longer than the average water depth over the pattern. This guidance can be applied to sample design to constrain both the sensor array (image resolution) and the analysis array (tomographic resolution). ?? 2008 IEEE.

  4. ERS-1 and Almaz ocean wave monitoring experiments

    NASA Technical Reports Server (NTRS)

    Beal, R. C.; Tilley, D. G.

    1992-01-01

    Preliminary results from two ocean wave monitoring experiments conducted in 1991 using the high-altitude ERS-1 synthetic aperture radar (SAR) and the low-altitude ex-USSR Almaz 1 SAR are presented. ERS-1 imagery of the Gulf Stream supports the idea that a future wide-swath scansar will be a valuable tool for monitoring large-scale ocean dynamics at high resolution. A direct comparison of ERS-1 and Almaz 1 ocean wave spectra shows major deficiencies in the ERS-1 high range-to-velocity ratio R/V sensor that are partially resolved with the lower-altitude Almaz platform. Optimum wave imaging from space will require both a low R/V and low off-nadir angle.

  5. Hilbert Spectra of Nonlinear Ocean Waves

    DTIC Science & Technology

    2006-02-08

    techniques [wavelet and fast Fourier transform (FFT) algorithms]. The wavelet technique is based on Fourier spectral analysis but with adjustable frequency...of wind-generated waves used for spectral comparison. The average wind speed is about 5 mn s. The data are measured by a fast response wire gauge...section 10.2. The wave record is acquired by using a fast -response wire gauge (Chapman and Monaldo 1991; HwangI :and Wang 2004) during a test deployment in

  6. Nonbreaking wave-induced mixing in upper ocean during tropical cyclones using coupled hurricane-ocean-wave modeling

    NASA Astrophysics Data System (ADS)

    Aijaz, S.; Ghantous, M.; Babanin, A. V.; Ginis, I.; Thomas, B.; Wake, G.

    2017-05-01

    The effects of turbulence generated by nonbreaking waves have been investigated by testing and evaluating a new nonbreaking wave parameterization in a coupled hurricane-ocean-wave model. The MPI version of the Princeton Ocean Model (POM) with hurricane forcing is coupled with the WAVEWATCH-III (WW3) surface wave model. Hurricane Ivan is chosen as the test case due to its extreme intensity and availability of field data during its passage. The model results are validated against field observations of wave heights and sea surface temperatures (SSTs) from the National Data Buoy Centre (NDBC) during Hurricane Ivan and against limited in situ current and bottom temperature data. A series of numerical experiments is set up to examine the influence of the nonbreaking wave parameterization on the mixing of upper ocean. The SST response from the modeling experiments indicates that the nonbreaking wave-induced mixing leads to significant cooling of the SST and deepening of the mixed layer. It was found that the nondimensional constant b1 in the nonbreaking wave parameterization has different impacts on the weak and the strong sides of the storm track. A constant value of b1 leads to improved predictions on the strong side of the storm while a steepness-dependent b1 provides a better agreement with in situ observations on the weak side. A separate simulation of the intense tropical cyclone Olwyn in north-west Australia revealed the same trend for b1 on the strong side of the tropical cyclone.

  7. Ocean Surface Wave Optical Roughness - Analysis of Innovative Measurements

    DTIC Science & Technology

    2013-09-30

    REFERENCES Banner, M . L ., C. J. Zappa, and J. Gemmrich (2013), A note on Phillips’ spectral framework for ocean whitecaps, Journal of Physical...C. J. Zappa, M . L . Banner, and R. P. Morison (2013), Wave breaking in developing and mature seas, Journal of Geophysical Research - Oceans, 118...doi:10.1002/jgrc.20334. Gemmrich, J. R., M . L . Banner, and C. Garrett (2008), Spectrally resolved energy dissipation and momentum flux of breaking

  8. Effects of Offshore Wind Turbines on Ocean Waves

    NASA Astrophysics Data System (ADS)

    Wimer, Nicholas; Churchfield, Matthew; Hamlington, Peter

    2014-11-01

    Wakes from horizontal axis wind turbines create large downstream velocity deficits, thus reducing the available energy for downstream turbines while simultaneously increasing turbulent loading. Along with this deficit, however, comes a local increase in the velocity around the turbine rotor, resulting in increased surface wind speeds. For offshore turbines, these increased speeds can result in changes to the properties of wind-induced waves at the ocean surface. In this study, the characteristics and implications of such waves are explored by coupling a wave simulation code to the Simulator for Offshore Wind Farm Applications (SOWFA) developed by the National Renewable Energy Laboratory. The wave simulator and SOWFA are bi-directionally coupled using the surface wind field produced by an offshore wind farm to drive an ocean wave field, which is used to calculate a wave-dependent surface roughness that is fed back into SOWFA. The details of this combined framework are outlined. The potential for using the wave field created at offshore wind farms as an additional energy resource through the installation of on-site wave converters is discussed. Potential negative impacts of the turbine-induced wave field are also discussed, including increased oscillation of floating turbines.

  9. Magnetic Noise Associated with Ocean Internal Waves

    DTIC Science & Technology

    2010-06-01

    earth’s magnetic field. Movement of sea water in the earth’s magnetic field produces an electromotive force with an associated electric current and... series of measurements were taken with the objective to measure and characterize the observable magnetic field of ocean dynamics and to compare these

  10. Overlooked Role of Mesoscale Winds in Powering Ocean Diapycnal Mixing.

    PubMed

    Jing, Zhao; Wu, Lixin; Ma, Xiaohui; Chang, Ping

    2016-11-16

    Diapycnal mixing affects the uptake of heat and carbon by the ocean as well as plays an important role in global ocean circulations and climate. In the thermocline, winds provide an important energy source for furnishing diapycnal mixing primarily through the generation of near-inertial internal waves. However, this contribution is largely missing in the current generation of climate models. In this study, it is found that mesoscale winds at scales of a few hundred kilometers account for more than 65% of near-inertial energy flux into the North Pacific basin and 55% of turbulent kinetic dissipation rate in the thermocline, suggesting their dominance in powering diapycnal mixing in the thermocline. Furthermore, a new parameterization of wind-driven diapycnal mixing in the ocean interior for climate models is proposed, which, for the first time, successfully captures both temporal and spatial variations of wind-driven diapycnal mixing in the thermocline. It is suggested that as mesoscale winds are not resolved by the climate models participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) due to insufficient resolutions, the diapycnal mixing is likely poorly represented, raising concerns about the accuracy and robustness of climate change simulations and projections.

  11. Overlooked Role of Mesoscale Winds in Powering Ocean Diapycnal Mixing

    PubMed Central

    Jing, Zhao; Wu, Lixin; Ma, Xiaohui; Chang, Ping

    2016-01-01

    Diapycnal mixing affects the uptake of heat and carbon by the ocean as well as plays an important role in global ocean circulations and climate. In the thermocline, winds provide an important energy source for furnishing diapycnal mixing primarily through the generation of near-inertial internal waves. However, this contribution is largely missing in the current generation of climate models. In this study, it is found that mesoscale winds at scales of a few hundred kilometers account for more than 65% of near-inertial energy flux into the North Pacific basin and 55% of turbulent kinetic dissipation rate in the thermocline, suggesting their dominance in powering diapycnal mixing in the thermocline. Furthermore, a new parameterization of wind-driven diapycnal mixing in the ocean interior for climate models is proposed, which, for the first time, successfully captures both temporal and spatial variations of wind-driven diapycnal mixing in the thermocline. It is suggested that as mesoscale winds are not resolved by the climate models participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) due to insufficient resolutions, the diapycnal mixing is likely poorly represented, raising concerns about the accuracy and robustness of climate change simulations and projections. PMID:27849059

  12. Overlooked Role of Mesoscale Winds in Powering Ocean Diapycnal Mixing

    NASA Astrophysics Data System (ADS)

    Jing, Zhao; Wu, Lixin; Ma, Xiaohui; Chang, Ping

    2016-11-01

    Diapycnal mixing affects the uptake of heat and carbon by the ocean as well as plays an important role in global ocean circulations and climate. In the thermocline, winds provide an important energy source for furnishing diapycnal mixing primarily through the generation of near-inertial internal waves. However, this contribution is largely missing in the current generation of climate models. In this study, it is found that mesoscale winds at scales of a few hundred kilometers account for more than 65% of near-inertial energy flux into the North Pacific basin and 55% of turbulent kinetic dissipation rate in the thermocline, suggesting their dominance in powering diapycnal mixing in the thermocline. Furthermore, a new parameterization of wind-driven diapycnal mixing in the ocean interior for climate models is proposed, which, for the first time, successfully captures both temporal and spatial variations of wind-driven diapycnal mixing in the thermocline. It is suggested that as mesoscale winds are not resolved by the climate models participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) due to insufficient resolutions, the diapycnal mixing is likely poorly represented, raising concerns about the accuracy and robustness of climate change simulations and projections.

  13. Boat powered by sea waves

    SciTech Connect

    Gargos, G.

    1984-11-06

    A boat having an external float pivotally fixed to the boat. Through linkage, the motion of the float relative to the boat resulting from wave motion drives a dual cylinder pump. The pump admits water from the body of water in which the boat is suspended and pressurizes that water for direction aft as a means for propulsion.

  14. An Arctic Ice/Ocean Coupled Model with Wave Interactions

    DTIC Science & Technology

    2015-09-30

    ocean waves and sea ice interact, for use in operational models of the Arctic Basin and the adjacent seas; – improve the forecasting capacities of...spectra and modify their directional spread. Being the primary focus of the current project, we are developing innovative methods to model these...during WIFAR (Waves-in-Ice Forecasting for Arctic Operators), a partnership between the Nansen Environmental and Remote Sensing Center (NERSC) in

  15. Ocean Surface Wave Optical Roughness - Innovative Measurement and Modeling

    DTIC Science & Technology

    2007-09-30

    F. L ., and Hansen , J. P. 2001 High resolution radar measurements of the speed distribution of breaking events in wind-generated ocean waves...small as a millimeter. This characterization includes microscale and whitecap breaking waves. * Prof. Michael L . Banner, School of Mathematics...The University of NSW, Sydney, Australia Dr. Bertrand Chapron, Oceanography, IFREMER, Brest, France Dr. Andres Corrada-Emmanuel, Physics Dept

  16. An Arctic Ice/Ocean Coupled Model with Wave Interactions

    DTIC Science & Technology

    2014-09-30

    its potential impact in several areas concerned with wave scattering (e.g. acoustics , electromagnetism, hydrodynamics), a paper describing the method...enabling fully directional seas generated by WAVEWATCH R® III or from experimental data to be input. Addition of ocean wave impacts to full scale...for a canonical related acoustic problem has been submitted for publication in SIAM Journal on Applied Mathematics (Montiel et al., submitted). The

  17. Scattering of Acoustic Waves from Ocean Boundaries

    DTIC Science & Technology

    2012-09-30

    environments with special emphasis on propagation in shallow water waveguides and scattering from ocean sediments. 3 ) Development of the new experimental...it does not display a currently valid OMB control number. 1. REPORT DATE 2012 2. REPORT TYPE N/A 3 . DATES COVERED - 4. TITLE AND SUBTITLE...Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 2 3 ) Incorporation of the Texas Advanced Computing Center for finite element analysis

  18. The Airy phase in oceanic Rayleigh and Scholte waves

    NASA Astrophysics Data System (ADS)

    Dorman, L. M.

    2010-12-01

    Both oceanic Rayleigh waves and seafloor Scholte waves frequently exhibit a prominent Airy phase because the amplitude reduction by geometric spreading is reduced for this arrival. Scholte waves travel as waves trapped by the low shear velocities of the seafloor, and contain detailed information about the mechanical properties of the surficial material. Although it is possible to model Scholte waves by waveform fitting (Nolet and Dorman, GJRAS, 1996) much Scholte wave data is not of such purity to allow fitting by a laterally uniform model, which is at the present limit of what can be easily synthesized. The next best thing to waveform systhesis is matching the observed group velocity to a synthetic one. In the many cases for Scholte waves, the group slowness maximum of the prominent Airy peak is easily interpretable as the slowness of a thin surficial layer of low velocity (the top few meters). In the case of oceanic Rayleigh waves, the Airy phase is caused by a slowness minimum in group slowness which has a particularly simple form, being well-matched to an upward-open parabola in a plot of slowness vs frequency. This can provide a good match over a frequency range of a factor of three (Savage, JGR, 1969). While this representation provides a simple and accurate parameterization, to the observations this seems not to say anything simple about the earth models which produce it. The data kernels for the observations do not have particularly simple forms and extend over the top 50km or so.

  19. Ocean Colour at Low Sun and High Waves

    NASA Astrophysics Data System (ADS)

    Hieronymi, Martin

    2015-12-01

    Many space-borne sensors are deployed to image the ocean in the visible portion of the spectrum. The colour of the sea, or more precisely the spectral water-leaving radiance, gives us information about the concentration of water constituents, e.g., chlorophyll, coloured dissolved organic matter, or suspended mineral matter. The bidirectional nature of the upwelling radiance just beneath the water surface and the interaction of this radiance with the air- sea interface depend on the viewing- and sun-geometry and surface waves. If we consider wave elevation and wave shadowing effects, perceptible deviations of the transmittance and reflectance of the air-water interface occur at low Sun (zenith angle of more than 60°) in comparison with wind-depending wave slope statistics. The inclusion of appropriate wind and wave data, i.e., wave heights and periods, can help to reduce uncertainties related to the Fresnel-reflecting ocean surface - in particular for large solar zenith angles. This especially regards remote sensing of ocean colour at high latitudes and atmospheric correction.

  20. Sun glitter imagery of surface waves. Part 2: Waves transformation on ocean currents

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, Vladimir; Yurovskaya, Maria; Chapron, Bertrand; Collard, Fabrice; Donlon, Craig

    2017-02-01

    Under favorable imaging conditions, the Sentinel-2 Multi-Spectral Instrument (MSI) can provide spectacular and novel quantitative ocean surface wave directional measurements in satellite Sun Glitter Imagery (SSGI). Owing to a relatively large-swath with high-spatial resolution (10 m), ocean surface roughness mapping capabilities, changes in ocean wave energy, and propagation direction can be precisely quantified at very high resolution, across spatial distances of 10 km and more. This provides unique opportunities to study ocean wave refraction induced by spatial varying surface currents. As expected and demonstrated over the Grand Agulhas current area, the mesoscale variability of near-surface currents, documented and reconstructed from satellite altimetry, can significantly deflect in-coming south-western swell systems. Based on ray-tracing calculations, and unambiguously revealed from the analysis of Sentinel-2 MSI SSGI measurements, the variability of the near-surface current explains significant wave-current refraction, leading to wave-trapping phenomenon and strong local enhancement of the total wave energy. In addition to its importance for wave modeling and hazard prediction, these results open new possibilities to combine different satellite measurements and greatly improve the determination of the upper ocean mesoscale vorticity motions.

  1. Numerical Simulation of Storm surges/Wave using KMA Operational Ocean Model

    NASA Astrophysics Data System (ADS)

    You, S.; Park, S.; Seo, J.; Cho, J.

    2007-05-01

    renewal process of power computing packs at KMA on the year 2005, the CRAY X1E system (14.5 Teraflops) replaced NEC SX5 (224 Gigaflops). Establishing of newly devised ocean prediction system is underway in conjunction with high computing environment. The main focus of new wave system lies in accommodating coastal wave/surge processes. The west and the south coastal area of Korean peninsular is one of the challenging places in ocean modeling for reasonable prediction of nearshore wave conditions and tides.

  2. Waves in the Ocean and the Atmosphere: Introduction to Wave Dynamics

    NASA Astrophysics Data System (ADS)

    Samelson, Roger M.

    Anyone who has stood on a ship or a beach will recognize that wave motions are an essential element of the ocean environment. And in its deeps, along its margins and across its basins, the ocean seethes with a wide spectrum of slow-moving interior waves that are invisible to the casual eye of the surface observer. Their influence may ultimately be felt across the globe, on land as well as at sea, for years, decades, or centuries. The winds that buffet a land-locked observer may seem less like waves and more akin to the continuous rush of water through a pipe or down a river channel. However, viewed from a broader perspective, even the ever-changing weather patterns of the Earth's atmosphere have their own particular wave dynamics. With Waves in the Ocean and the Atmosphere: Introduction to Wave Dynamics, leading geophysical fluid dynamicist Joseph Pedlosky provides an accessible and authoritative theoretical introduction to the wide variety of wave motions that occur in the planetary fluid environment. This is a fine book, tailor-made for graduate teaching, but also suitable for use as a desk reference for the basic elements of oceanic and atmospheric wave dynamics. The oceanographic perspective is emphasized. Aside from a few, largely cosmetic typographical errors, the only disappointment is that it does not go on a little longer: chapters on acoustic waves, tides, coastal-trapped ocean waves, and some pointers toward the many fascinating phenomena of nonlinear wave dynamics would have been welcome extensions, and one can hope that they may be added to a future edition.

  3. Ocean Wave Energy Regimes of the Circumpolar Coastal Zones

    NASA Astrophysics Data System (ADS)

    Atkinson, D. E.

    2004-12-01

    Ocean wave activity is a major enviromental forcing agent of the ice-rich sediments that comprise large sections of the arctic coastal margins. While it is instructive to possess information about the wind regimes in these regions, direct application to geomorphological and engineering needs requires knowledge of the resultant wave-energy regimes. Wave energy information has been calculated at the regional scale using adjusted reanalysis model windfield data. Calculations at this scale are not designed to account for local-scale coastline/bathymetric irregularities and variability. Results will be presented for the circumpolar zones specified by the Arctic Coastal Dynamics Project.

  4. Ambient Noise and Surface Wave Dissipation in the Ocean

    DTIC Science & Technology

    1993-06-21

    9 Ckq0 s I I follows hm the rlgi-hanmd nru A third coordinate system based on the wire wave gauge array was also defined such that the army x-axis...their research followed up in the literatum As we mentioned in our review, the research in wave and ambient noie relationship is relatively sparse. We...I AD-A279 650 AM’BIET NOISE AND SURFACE WAVE DISSIPATION IN THE OCEAN Q) I by S.tais C. Feliardo S. in C invl I Wagm Claude, 1985 Unhiaity of the

  5. Variational stereo imaging of oceanic waves with statistical constraints.

    PubMed

    Gallego, Guillermo; Yezzi, Anthony; Fedele, Francesco; Benetazzo, Alvise

    2013-11-01

    An image processing observational technique for the stereoscopic reconstruction of the waveform of oceanic sea states is developed. The technique incorporates the enforcement of any given statistical wave law modeling the quasi-Gaussianity of oceanic waves observed in nature. The problem is posed in a variational optimization framework, where the desired waveform is obtained as the minimizer of a cost functional that combines image observations, smoothness priors and a weak statistical constraint. The minimizer is obtained by combining gradient descent and multigrid methods on the necessary optimality equations of the cost functional. Robust photometric error criteria and a spatial intensity compensation model are also developed to improve the performance of the presented image matching strategy. The weak statistical constraint is thoroughly evaluated in combination with other elements presented to reconstruct and enforce constraints on experimental stereo data, demonstrating the improvement in the estimation of the observed ocean surface.

  6. Wave Power Assessment in the Presence of Currents: an Overview of Analytical Versus Complex Numerical Approaches

    NASA Astrophysics Data System (ADS)

    Hashemi, M. R.; Grilli, S. T.; Neill, S. P.

    2016-02-01

    Resource characterization studies at wave energy sites generally ignore the effect of tidal currents, due to the difficulties associated with running coupled wave-tide models. Further, there is a need to estimate the significance of wave-tide interaction effects on the wave power using simplified methods, before investing in time consuming and costly numerical models. Additionally, many wave buoy measurements are collected in deep waters, where wave-current interaction effects may not be significant; this makes validation of coupled models more challenging. Here, we give an overview of the application of simplified analytical methods as well as fully coupled wave-tide models to address this problem. Firstly, we present and validate a simplified analytical method, based on linear wave theory, to estimate the influence of tidal currents on the wave power resource. The method estimates the resulting increase (or decrease) in wave height and wavelength for opposing (or following) currents, as well as quantifying the change in wave power. Results demonstrate a high level of accuracy for the simplified analytical approach, which can thus be used as an efficient tool for making rapid estimates of likely tidal effects on the wave power resource. Secondly, we discuss the application of a coupled modelling system, COAWST (Coupled-Ocean-Atmosphere-Wave-Sediment Transport), and present issues such as computational cost, as well as the success of this approach in characterizing wave power in the presence of currents.

  7. Toward a better hindcast of waves in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Francis, Oceana; Panteleev, Gleb; Stroh, Jacob; Yaremchuk, Max

    2014-05-01

    Climate change has affected the entire Arctic Ocean and in particular its Pacific Sector where the minimum of the summer ice extent was observed during the last decade. Diminishing sea ice has yielded greater fetch thus affecting surface waves all around the Alaska. To better represent the wave hindcast in the Pacific sector, we present modeling results of the WAM model configured for the Pacific Sector of the Arctic Ocean and a novel way to assimilate wave information into the wave models using the Reduced space 4Dvar (R4Dvar) data assimilation approach. The model results include the validation of several wind products for the region and comparison with in situ and satellite observation. The employed assimilation method does not require development of the tangent linear and adjoint codes for implementation. It is based on minimization of the cost function in a sequence of low-dimensional subspaces of the control space. The twin-data experiments show that assimilation of the wave data allows improved wave hindcast and forecast. The future plans are to extend this project to the Northern Pacific (including Hawaii region) and analyze the inter-connection between wave activity in different regions.

  8. The shape of extreme waves on the open ocean

    NASA Astrophysics Data System (ADS)

    Adcock, Thomas A. A.; Taylor, Paul H.; Draper, Scott

    2016-04-01

    This study investigates how non-linear physics modifies the largest waves in random seas relative to linear evolution. Our method follows that described in [1]. We start with random simulations of extreme waves in linear sea-states with realistic spectra and directional spreading. Each wave-group, with the surrounding waves, is propagated backwards in time under linear evolution for ten periods. This is then used as initial conditions for non-linear simulations. We compare the maximum of the wave-group in the non-linear simulation with that in the linear case. We do this multiple times for different randomly generated extreme events. We find that, on average, there is relatively little extra elevation in the non-linear case - although in a few cases there is significant amplification. However, there are significant changes to the average shape of the group. For moderate wave steepness there is an expansion of the wave-group in the lateral direction forming a broader crest than predicted by linear evolution. For the most severe sea-states there is a significant contraction of the wave-group in the mean wave direction. There is also a movement of the largest wave to the front of the wave-group, suggesting that the largest waves will be preceded by relatively small waves. Reference [1] ADCOCK, T.A.A., TAYLOR, P.H. & DRAPER, S. (2015) Non-linear dynamics of wave-groups in random seas: Unexpected walls of water in the open ocean, Proceedings of the Royal Society A 471(2184).

  9. Theory of Seismic Noise Excitation by Ocean Waves

    NASA Astrophysics Data System (ADS)

    Tanimoto, T.

    2009-12-01

    It is becoming increasingly clear that seismic noise, recorded in continuous data, will be an important part of seismic data that will be used for seismic structure study. Causes of noise vary from frequency to frequency but the predominant noise, specifically in the microseismic frequency band (about 0.05-0.4 Hz), is now recognized to be ocean waves. The Hum, seismic noise in a lower frequency band about 0.003-0.015 Hz, may also be excited by this mechanism (Webb, 2007). The detailed excitation mechanism of microseisms by ocean waves is attributed to Longuet-Higgins (1950) (which credits earlier study by Miche, 1944) which beautifully explains one critical aspect of data, the double frequency noise peak. Longuet-Higgins (1950) basically showed how nonlinear advection term in the Navier-Stokes equation and the nonlinear term in the kinematic free-surface boundary condition lead to the generation of pressure when there are colliding ocean waves. In this paper, we will show that excitation of seismic noise can be formulated starting from the original nonlinear terms in the equations, basically skipping the intermediate pressure term derived by Longuet-Higgins. The equivalent body-force term by these nonlinear terms can be expressed in a compact formula and may be used to describe seismic wavefields. We will show 1. The equivalent Longuet-Higgins term arises from our approach but it is exact only for low frequencies below 0.1 Hz. At higher frequencies, depending on ocean depth, deviations up to a factor of 5-10 can arise. 2. At low frequencies (<0.005 Hz), a horizontal force term arises whose effects may become larger than pressure variations due to the Longuet-Higgins mechanism. Webb (2007) and Tanimoto (2007) pointed out this term. This term contains azimuthal effects (radiation pattern), as opposed to the isotropic vertical forcing by the Longuett-Higgins mechanism. 3. We also examine the excitation of the toroidal hum (Kurrle and Widmer, 2008). Infragravity waves

  10. The structure of short gravity waves on the ocean surface

    NASA Technical Reports Server (NTRS)

    Phillips, O. M.

    1981-01-01

    A brief review is given of the salient properties of short gravity waves and the way in which their structure is modified by longer waves or swell, by variable currents, and by internal waves. It is noted that an underlying swell produces a mottled pattern in synthetic aperture radar (SAR) imagery, and an expression is derived giving the fractional modulation in backscattering cross section of the ocean surface in terms of the slope of an underlying swell, the wind direction, and the direction of swell propagation relative to the angle of observation. The expression provides the possibility in appropriate circumstances of estimating the swell slope by remote sensing, in addition to the wavelength and direction of propagation, which can be measured directly from the imagery. An account is also given of the refraction of waves in variable currents and internal waves.

  11. Near-Inertial Internal Gravity Waves in the Ocean.

    PubMed

    Alford, Matthew H; MacKinnon, Jennifer A; Simmons, Harper L; Nash, Jonathan D

    2016-01-01

    We review the physics of near-inertial waves (NIWs) in the ocean and the observations, theory, and models that have provided our present knowledge. NIWs appear nearly everywhere in the ocean as a spectral peak at and just above the local inertial period f, and the longest vertical wavelengths can propagate at least hundreds of kilometers toward the equator from their source regions; shorter vertical wavelengths do not travel as far and do not contain as much energy, but lead to turbulent mixing owing to their high shear. NIWs are generated by a variety of mechanisms, including the wind, nonlinear interactions with waves of other frequencies, lee waves over bottom topography, and geostrophic adjustment; the partition among these is not known, although the wind is likely the most important. NIWs likely interact strongly with mesoscale and submesoscale motions, in ways that are just beginning to be understood.

  12. Near-Inertial Internal Gravity Waves in the Ocean

    NASA Astrophysics Data System (ADS)

    Alford, Matthew H.; MacKinnon, Jennifer A.; Simmons, Harper L.; Nash, Jonathan D.

    2016-01-01

    We review the physics of near-inertial waves (NIWs) in the ocean and the observations, theory, and models that have provided our present knowledge. NIWs appear nearly everywhere in the ocean as a spectral peak at and just above the local inertial period f, and the longest vertical wavelengths can propagate at least hundreds of kilometers toward the equator from their source regions; shorter vertical wavelengths do not travel as far and do not contain as much energy, but lead to turbulent mixing owing to their high shear. NIWs are generated by a variety of mechanisms, including the wind, nonlinear interactions with waves of other frequencies, lee waves over bottom topography, and geostrophic adjustment; the partition among these is not known, although the wind is likely the most important. NIWs likely interact strongly with mesoscale and submesoscale motions, in ways that are just beginning to be understood.

  13. Modelling wave-boundary layer interaction for wind power applications

    NASA Astrophysics Data System (ADS)

    Jenkins, A. D.; Barstad, I.; Gupta, A.; Adakudlu, M.

    2012-04-01

    Marine wind power production facilities are subjected to direct and indirect effects of ocean waves. Direct effects include forces due to wave orbital motions and slamming of the water surface under breaking wave conditions, corrosion and icing due to sea spray, and the effects of wave-generated air bubbles. Indirect effects include include the influence of waves on the aerodynamic sea-surface roughness, air turbulence, the wind velocity profile, and air velocity oscillations, wave-induced currents and sediment transport. Field observations within the boundary layers from floating measurement may have to be corrected to account for biases induced as a result of wave-induced platform motions. To estimate the effect of waves on the atmospheric boundary layer we employ the WRF non-hydrostatic mesoscale atmosphere model, using the default YSU planetary boundary layer (PBL) scheme and the WAM spectral wave model, running simultaneously and coupled using the open-source coupler MCEL which can interpolate between different model grids and timesteps. The model is driven by the WRF wind velocity at 10 m above the surface. The WRF model receives from WAM updated air-sea stress fields computed from the wind input source term, and computes new fields for the Charnock parameter and marine surface aerodynamic roughness. Results from a North Atlantic and Nordic Seas simulation indicate that the two-way coupling scheme alters the 10 metre wind predicted by WRF by up to 10 per cent in comparison with a simulation using a constant Charnock parameter. The changes are greatest in developing situations with passages of fronts, moving depressions and squalls. This may be directly due to roughness length changes, or may be due to changes in the timing of front/depression/squall passages. Ongoing work includes investigating the effect of grid refinement/nesting, employing different PBL schemes, and allowing the wave field to change the direction of the total air-sea stress.

  14. Seismic structure of the oceanic lithosphere inferred from guided wave

    NASA Astrophysics Data System (ADS)

    Shito, A.; Suetsugu, D.; Furumura, T.; Sugioka, H.; Ito, A.

    2012-12-01

    Characteristic seismic waves are observed by seismological experiment using Broad-Band Ocean Bottom Seismometers (BBOBSs) conducted in the northwestern Pacific from 2007 to 2008 and from 2010 to 2011. The seismic waves have low frequency onset (< 1 Hz) followed by high frequency later phases (2.5-10 Hz). The high frequency later phases have large amplitude and long duration for both P and S waves. The seismic waves are observed commonly at the BBOBS array from events in the subducting Pacific plate. To investigate generation and propagation mechanisms of the seismic wave will help us to understand the seismic structure and the origin of the oceanic lithosphere. High frequency phases travelling efficiently through the oceanic lithosphere more than 3000 km are well known phenomenon. These phases were previously called as Po/So waves. Po/So waves were observed as early as 1935, and were studied actively from the 1970s to 1990s. However, the mechanism of generation and propagation of the phases are still controversial. The guided waves propagating in subducting plate are also common phenomenon in the subduction zone. The waves are generally characterized by separation of low frequency and high frequency components. In order to explain the separation, Martin and Rietbrock [2003] considered the trapping of waves in the waveguide formed by thin low velocity former oceanic crust at the top of the plate. However, large amplitude and long duration of the high frequency component cannot be achieved by the model. From the analysis of waveform observed at the eastern seaboard of northern Japan and numerical simulation of seismic wave propagation, Furumura and Kennet [2005] demonstrate that the guided wave travelling in the subducting plate is produced by multiple forward scattering of high-frequency seismic waves due to small-scale random heterogeneity in the plate structure. We apply the method proposed by Furumura and Kennett [2005] to reproduce the seismograms recorded by

  15. Internal-wave time evolution effect on ocean acoustic rays.

    PubMed

    Flatté, Stanley M; Vera, Michael D

    2002-10-01

    A range-dependent field of sound speed in the ocean, c(x,z), caused by internal waves, can give rise to instabilities in acoustic ray paths. Past work has shown the importance of the background, range-independent, sound-speed profile; the ray initial conditions; the source-receiver geometry (depths and range); and the strength of the internal waves. However, in the past the time evolution of the internal waves has been ignored on the grounds that the speed of internal waves is much slower than the speed of the acoustic wave. It is shown here by numerical simulation that two rays with identical initial conditions, traveling through an ocean with the same background profile and the same random realization of internal waves, but with the internal waves frozen in one case and evolving in the other, travel significantly different trajectories. The dependence of this "frozen-unfrozen" difference on the initial ray launch angle, the background profile, and the strength of the internal-wave spectrum, is investigated. The launch-angle difference that generates similar arrival-depth differences to those induced by internal-wave time evolution is on the order of 100 microrad. The pattern of differences is measured here by the arrival depth at the final range of 1000 km. The observed pattern as a function of launch angle, change in the background profile, and change in internal-wave strength is found to be nearly the same for "frozen-unfrozen" change as for a slight change in launch angle.

  16. Ocean Wave Separation Using CEEMD-Wavelet in GPS Wave Measurement

    PubMed Central

    Wang, Junjie; He, Xiufeng; Ferreira, Vagner G.

    2015-01-01

    Monitoring ocean waves plays a crucial role in, for example, coastal environmental and protection studies. Traditional methods for measuring ocean waves are based on ultrasonic sensors and accelerometers. However, the Global Positioning System (GPS) has been introduced recently and has the advantage of being smaller, less expensive, and not requiring calibration in comparison with the traditional methods. Therefore, for accurately measuring ocean waves using GPS, further research on the separation of the wave signals from the vertical GPS-mounted carrier displacements is still necessary. In order to contribute to this topic, we present a novel method that combines complementary ensemble empirical mode decomposition (CEEMD) with a wavelet threshold denoising model (i.e., CEEMD-Wavelet). This method seeks to extract wave signals with less residual noise and without losing useful information. Compared with the wave parameters derived from the moving average skill, high pass filter and wave gauge, the results show that the accuracy of the wave parameters for the proposed method was improved with errors of about 2 cm and 0.2 s for mean wave height and mean period, respectively, verifying the validity of the proposed method. PMID:26262620

  17. The Breaking of Ocean Surface Waves.

    DTIC Science & Technology

    1984-06-06

    only in a qualitative sense and the mathematics are quite complex . : Cokelet (1977) has summarized most of the attempts to develop numerical... complex velocity potential. Then 9.. the complex Bernoulli equation and the kinematic equations at the free surface are integrated in time. A time...proifi l 41’i1o’ 4 k 611 .0 t30t t , Frigure- 12tti A’~ # coprio of a sefsiia anlyi aproiato of an Overturning gravity wave with the observed profile in

  18. Toward Ocean Wave and Radar Dependence (TOWARD)

    DTIC Science & Technology

    1990-09-15

    coul not-baneader in ed Inethd sond rocessite fooncau- Aloo neetitedpnec-fth nrydniya steps w253t r incd e te 25a n o i so t e dominant v f cus tota...WAVE IMAGES To formally generalize (5) for a narrowband longwave en- a transformation of the " dummy variables of integration" is semble, one may use a...response A.,, with mod- reflectivity density G when VAR is infinite. ulus The further changes of dummy variables X ?-1 = (I - VN.)x I4, V IA(x)l it

  19. Intraseasonal sea surface warming in the western Indian Ocean by oceanic equatorial Rossby waves

    DTIC Science & Technology

    2017-05-09

    an equatorial westward jet of 80 cm s1 associated with downwelling ER waves. When anomalous currents associated with ER waves are removed in the...Oceans in association with the Madden-Julian Oscillation (MJO) [Madden and Julian, 1972; Drushka et al., 2012; Halkides et al., 2015]. Similarly...intraseasonal sea surface temperature (SST) variations of 0.6°C are associated with the MJO, neglect- ing diurnal temperature variations that can exceed 2.0°C

  20. Using pressure and seismological broadband ocean data to model shear wave velocities in the north Atlantic.

    NASA Astrophysics Data System (ADS)

    Rios, Celia; Dahm, Torsten; Jegen, Marion

    2010-05-01

    Seafloor compliance is the transfer function between pressure and vertical displacement at the seafloor Infragravity waves in the oceanic layer have long periods in the range of 30 - 500 s and obey a simple frequency-wavenumber relation. Seafloor compliance from infragravity waves can be analyzed with single station recordings to determinate sub-seafloor shear wave velocities. Previous studies in the Pacific Ocean have demonstrated that reliable near-surface shear wave profiles can be derived from infragravity wave compliance. However, these studies indicate that, beside the water depth the compliance measurements are limited by instrument sensitivity, calibration uncertainties and possibly other effects. In this work seafloor compliance and infragravity waves are observed at two different locations in the Atlantic Ocean: the Logatchev hydrothermal field at the Mid Atlantic Ridge and the Azores (Sao Miguel Island). The data was acquired with the broadband ocean compliance station developed at the University of Hamburg as well as ocean station from the German instrument pool for amphibian seismology (DEPAS) equipped with broadband seismometers and pressure sensors. Vertical velocity and pressure data were used to calculate power spectral densities and normalized compliance along two profiles (one in each location). Power spectral densities show a dominant peak at low frequencies (0.01-0.035Hz) limited by the expected cut-off frequency, which is dependent on the water depth at each station. The peak has been interpreted as a strong infragravity wave with values between 10-14 and 10-11 (m/s2)2/Hz and 104 and 106 (Pa2)2/Hz for acceleration and pressure respectively. The results show compliance values between 10-10 and 10-8 1/Pa and its estimations take into account the coherence between seismic and pressure signals in order to confirm that the seismic signals in the infragravity waves are caused by pressure sources. Shear wave velocity models, with depth resolution

  1. Revisiting internal waves and mixing in the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Guthrie, John D.; Morison, James H.; Fer, Ilker

    2013-08-01

    To determine whether deep background mixing has increased with the diminishment of the Arctic sea ice, we compare recent internal wave energy and mixing observations with historical measurements. Since 2007, the North Pole Environmental Observatory has launched expendable current probes (XCPs) as a part of annual airborne hydrographic surveys in the central Arctic Ocean. Mixing in the upper 500 m is estimated from XCP shear variance and Conductivity-Temperature-Depth (CTD) derived Brunt-Väisälä frequency. Internal wave energy levels vary by an order of magnitude between surveys, although all surveys are less energetic and show more vertical modes than typical midlatitude Garrett-Munk (GM) model spectra. Survey-averaged mixing estimates also vary by an order of magnitude among recent surveys. Comparisons between modern and historical data, reanalyzed in identical fashion, reveal no trend evident over the 30 year period in spite of drastic diminution of the sea ice. Turbulent heat fluxes are consistent with recent double-diffusive estimates. Both mixing and internal wave energy in the Beaufort Sea are lower when compared to both the central and eastern Arctic Ocean, and expanding the analysis to mooring data from the Beaufort Sea reveals little change in that area compared to historical results from Arctic Internal Wave Experiment. We hypothesize that internal wave energy remains lowest in the Beaufort Sea in spite of dramatic declines in sea ice there, because increased stratification amplifies the negative effect of boundary layer dissipation on internal wave energy.

  2. Response of ocean bottom dwellers exposed to underwater shock waves

    NASA Astrophysics Data System (ADS)

    Hosseini, S. H. R.; Kaiho, Kunio; Takayama, Kazuyoshi

    2016-01-01

    The paper reports results of experiments to estimate the mortality of ocean bottom dwellers, ostracoda, against underwater shock wave exposures. This study is motivated to verify the possible survival of ocean bottom dwellers, foraminifera, from the devastating underwater shock waves induced mass extinction of marine creatures which took place at giant asteroid impact events. Ocean bottom dwellers under study were ostracoda, the replacement of foraminifera, we readily sampled from ocean bottoms. An analogue experiment was performed on a laboratory scale to estimate the domain and boundary of over-pressures at which marine creatures' mortality occurs. Ostracods were exposed to underwater shock waves generated by the explosion of 100mg PETN pellets in a chamber at shock over-pressures ranging up to 44MPa. Pressure histories were measured simultaneously on 113 samples. We found that bottom dwellers were distinctively killed against overpressures of 12MPa and this value is much higher than the usual shock over-pressure threshold value for marine-creatures having lungs and balloons.

  3. Observations and models of inertial waves in the deep ocean

    NASA Technical Reports Server (NTRS)

    Fu, L.-L.

    1981-01-01

    A study of the structure of the inertial peak in deep ocean kinetic energy is presented, based on records taken from Polymode arrays deployed in the western North Atlantic Ocean. Results are interpreted in terms of both local sources and turning point effects on internal waves generated at lower latitudes, and it is found that three classes of environment and their corresponding spectra emerge from peak height variations: (1) the 1500-m level near the Mid-Atlantic Ridge, with the greatest peak height of 18 dB; (2) the upper and deep ocean over rough topography and the deep ocean underneath the Gulf Stream, with the intermediate peak height of 11.5 dB; and (3) the deep ocean over smooth topography, with the lowest peak height of 7.5 dB. Using the globally valid wave functions obtained by Munk and Phillips (1968), frequency spectra near f are calculated numerically. The model is latitudinally dependent, with the frequency shift and bandwidth of the inertial peak decreasing with latitude.

  4. Scintillation index of Gaussian waves in weak turbulent ocean

    NASA Astrophysics Data System (ADS)

    Wang, Zhiqiang; Zhang, Pengfei; Qiao, Chunhong; Lu, Lu; Fan, Chengyu; Ji, Xiaoling

    2016-12-01

    The analytical expressions of radial and the longitudinal components of scintillation index are derived in weak oceanic turbulence. The effects of off-axis distance, propagation distance, and three oceanic parameters (i.e., the ratio of temperature to salinity contribution to the refractive index spectrum w, the rate of dissipation of the mean squared temperature χT and the rate of dissipation of the turbulent kinetic energy ε) on radial component of scintillation index are examined. The influences of propagation distance and three oceanic parameters on the longitudinal component of scintillation index are investigated. It is shown that the radial component of scintillation increases as off-axis distance increases. Both radial and longitudinal components of scintillation increase as propagation distance, w and χT increase while decreases as ε increases. Besides, the longitudinal component of scintillation increases more drastically for plane wave than others, which indicates the plane wave is affected the most at the fixed turbulent strength. The longest weak turbulence distance for a plane wave is shorter than that for a Gaussian or spherical wave.

  5. Ocean Surface Wave Optical Roughness - Innovative Measurement and Modeling

    DTIC Science & Technology

    2006-01-01

    S. Guignard, H. Branger, D.R. Thompson, D . Vandemark and B. Chapron, 2003: Time- frequency applications with the Stokes-Woodward technique, IEEE...calibrations. J. Atmos. Ocean Tech., 22, 7, 799-813. [published, refereed] Young, I.R., M.L. Banner M.A., Donelan, A.V. Babanin, W.K. Melville, F. Veron ...refereed] E. J. Walsh, M. L. Banner, C. W. Wright, D . C. Vandemark, B. Chapron, J. Jensen, S. Lee, 2007: The Southern Ocean Waves Experiment, Part

  6. Toward an internal gravity wave spectrum in global ocean models

    NASA Astrophysics Data System (ADS)

    Müller, Malte; Arbic, Brian K.; Richman, James G.; Shriver, Jay F.; Kunze, Eric L.; Scott, Robert B.; Wallcraft, Alan J.; Zamudio, Luis

    2015-05-01

    High-resolution global ocean models forced by atmospheric fields and tides are beginning to display realistic internal gravity wave spectra, especially as model resolution increases. This paper examines internal waves in global simulations with 0.08° and 0.04° (~8 and 4 km) horizontal resolutions, respectively. Frequency spectra of internal wave horizontal kinetic energy in the North Pacific lie closer to observations in the 0.04° simulation than in the 0.08° simulation. The horizontal wave number and frequency (K-ω) kinetic energy spectra contain peaks in the semidiurnal tidal band and near-inertial band, along with a broadband frequency continuum aligned along the linear dispersion relations of low-vertical-mode internal waves. Spectral kinetic energy transfers describe the rate at which nonlinear mechanisms remove or supply kinetic energy in specific K-ω ranges. Energy is transferred out of low-mode inertial and semidiurnal internal waves into a broad continuum of higher-frequency and higher-wave number internal waves.

  7. Starting to Experiment with Wave Power

    ERIC Educational Resources Information Center

    Hare, Jonathan; McCallie, Ellen

    2005-01-01

    Outlined is a simple design for a working wave-powered electrical generator based on one made on the BBC "Rough Science" TV series. The design has been kept deliberately simple to facilitate rapid pupil/student involvement and most importantly so that there is much scope for their own ingenuity and ideas. The generator works on the principle of…

  8. Starting to Experiment with Wave Power

    ERIC Educational Resources Information Center

    Hare, Jonathan; McCallie, Ellen

    2005-01-01

    Outlined is a simple design for a working wave-powered electrical generator based on one made on the BBC "Rough Science" TV series. The design has been kept deliberately simple to facilitate rapid pupil/student involvement and most importantly so that there is much scope for their own ingenuity and ideas. The generator works on the principle of…

  9. Unlocking Electric Power in the Oceans.

    ERIC Educational Resources Information Center

    Hurwood, David L.

    1985-01-01

    Cruising or stationary ocean thermal plants could convert the vast heat energy of the ocean into electricity for islands and underdeveloped countries. This approach to energy conservation is described with suggestions for design and outputs of plants. A model project operating in Hawaii is noted. (DH)

  10. Unlocking Electric Power in the Oceans.

    ERIC Educational Resources Information Center

    Hurwood, David L.

    1985-01-01

    Cruising or stationary ocean thermal plants could convert the vast heat energy of the ocean into electricity for islands and underdeveloped countries. This approach to energy conservation is described with suggestions for design and outputs of plants. A model project operating in Hawaii is noted. (DH)

  11. Generation of internal gravity waves by tidal flow over random oceanic topography

    NASA Astrophysics Data System (ADS)

    Zhao, Jiajun; Zhang, Likun; Swinney, Harry

    2015-03-01

    Internal waves (IWs) are gravity waves that propagate within density-stratified fluids such as the ocean, atmosphere, and protoplanetary disks. IWs generated by tidal flow over oceanic topography provide much of the energy needed to sustain vertical mixing, which plays a critical role in ocean circulation and global climate. Therefore, it is important to determine the amount of energy that is extracted from tidal flow over topography and radiated into IWs. We conduct 2D numerical simulations to determine the IW power generated by tidal flow over random topographies that have the seafloor spectrum. The power is found to saturate with increasing topographic roughness, and to scale linearly with the characteristic height of the topography. The linear dependence on the topographic height is, surprisingly, nearly independent of the value of the exponent characterizing the topographic spectrum. Our results should lead to improved predictions of the IW power generated by tidal flow over global ocean topography. Research supported by the Office of Naval Research and the Texas Advanced Computing Center. JZ is supported also by the President's Graduate Fellowship from the National University of Singapore.

  12. Ocean-atmosphere-wave characterisation of a wind jet (Ebro shelf, NW Mediterranean Sea)

    NASA Astrophysics Data System (ADS)

    Grifoll, Manel; Navarro, Jorge; Pallares, Elena; Ràfols, Laura; Espino, Manuel; Palomares, Ana

    2016-06-01

    In this contribution the wind jet dynamics in the northern margin of the Ebro River shelf (NW Mediterranean Sea) are investigated using coupled numerical models. The study area is characterised by persistent and energetic offshore winds during autumn and winter. During these seasons, a seaward wind jet usually develops in a ˜ 50 km wide band offshore. The COAWST (Coupled Ocean-Atmosphere-Wave-Sediment Transport) modelling system was implemented in the region with a set of downscaling meshes to obtain high-resolution meteo-oceanographic outputs. Wind, waves and water currents were compared with in situ observations and remote-sensing-derived products with an acceptable level of agreement. Focused on an intense offshore wind event, the modelled wind jet appears in a limited area offshore with strong spatial variability. The wave pattern during the wind jet is characterised by the development of bimodal directional spectra, and the ocean circulation tends to present well-defined two-layer flow in the shallower region (i.e. inner shelf). The outer shelf tends to be dominated by mesoscale dynamics such as the slope current. Due to the limited fetch length, ocean surface roughness considering sea state (wave-atmosphere coupling) modifies to a small extent the wind and significant wave height under severe cross-shelf wind events. However, the coupling effect in the wind resource assessment may be relevant due to the cubic relation between the wind intensity and power.

  13. Ocean wave detection and direction measurements with microwave radars

    NASA Technical Reports Server (NTRS)

    Teleki, P. G.; Shuchman, R. A.; Brown, W. E., Jr.; Mcleish, W.; Ross, D.; Mattie, M.

    1978-01-01

    The application of synthetic aperture microwave radar imagery to the measurement of ocean wave direction and wavelength is discussed and an airborne experiment conducted in preparation for the SEASAT-A satellite mission is presented. Models for radar backscattering are examined and it is concluded that the Bragg-Rice model, which represents the ocean surface as a combination of periodic surfaces so that the dominant backscatter matches some portion of the wave spectrum, appears most useful. The experiment was conducted with airborne X-band and L-band synthetic aperture radar (SAR) and data was compared with that obtained from a pitch-and-roll buoy and an instrument package mounted on a sea sled. SAR data was converted to wave spectra and it was found to match data from the buoy, while SAR data on wave direction agrees to within two degrees with the buoy and to within one degree with the sea sled sensors. Wave direction data taken by two real aperture radars is also presented and shown to agree with airborne photographs.

  14. Rayleigh Wave Phase Velocity in the Indian Ocean Upper Mantle

    NASA Astrophysics Data System (ADS)

    Godfrey, K. E.; Dalton, C. A.

    2015-12-01

    Current understanding of the seismic properties of the oceanic upper mantle is heavily weighted toward studies of the Pacific upper mantle. However, global seismic models indicate differences in upper-mantle properties beneath the Pacific, Atlantic, and Indian oceans. Furthermore, factors such as spreading rate, absolute plate motion, and the presence of intraplate volcanism vary between these regions. It is thus important to consider the broad range in parameters when forming ideas about mantle dynamics and lithosphere evolution within ocean basins. We are developing a high-resolution basin-wide seismic model of the Indian Ocean upper mantle. The Indian Ocean contains 16,000 km of mid-ocean ridge, with spreading rates ranging from approximately 14 mm/yr along the Southwest Indian Ridge to 55-75 mm/yr along the Southeast Indian Ridge. It also contains 12 volcanic hotspots, overlies a portion of a large low-shear-velocity province in the lower mantle, and is home to the Australian-Antarctic Discordance and a negative geoid anomaly just south of India, among other features. We measure phase velocity in the period range 30-130 seconds for fundamental-mode Rayleigh waves traversing the Indian Ocean; the data set includes 831 events that occurred between 1992 and 2014 and 769 stations. In order to isolate the signal of the oceanic upper mantle, paths with >30% of their length through continental upper mantle are excluded. Variations in phase velocity in the Indian Ocean upper mantle are explored with two approaches. One, phase velocity is allowed to vary only as a function of seafloor age. Two, a general two-dimensional parameterization is utilized in order to capture perturbations to age-dependent structure. Our preliminary results indicate a strong dependence of phase velocity on seafloor age, with higher velocity associated with older seafloor, and perturbations to the age-dependent trend in the vicinity of the Australian-Antarctic Discordance and the Marion and

  15. Rapid ocean wave teleconnections linking Antarctic salinity anomalies to the equatorial ocean-atmosphere system

    NASA Astrophysics Data System (ADS)

    Atkinson, C. P.; Wells, N. C.; Blaker, A. T.; Sinha, B.; Ivchenko, V. O.

    2009-04-01

    The coupled climate model FORTE is used to investigate rapid ocean teleconnections between the Southern Ocean and equatorial Pacific Ocean. Salinity anomalies located throughout the Southern Ocean generate barotropic signals that propagate along submerged topographic features and result in the growth of baroclinic energy anomalies around Indonesia and the tropical Pacific. Anomalies in the Ross, Bellingshausen and Amundsen Seas exchange the most barotropic kinetic energy between high and low latitudes. In the equatorial Pacific, baroclinic Kelvin waves are excited which propagate eastwards along the thermocline, resulting in SST anomalies in the central and eastern Pacific. SST anomalies are subsequently amplified to magnitudes of 1.25°C by air-sea interaction, which could potentially influence other coupled Pacific phenomena.

  16. Enhancing power generation of floating wave power generators by utilization of nonlinear roll-pitch coupling

    NASA Astrophysics Data System (ADS)

    Yerrapragada, Karthik; Ansari, M. H.; Karami, M. Amin

    2017-09-01

    We propose utilization of the nonlinear coupling between the roll and pitch motions of wave energy harvesting vessels to increase their power generation by orders of magnitude. Unlike linear vessels that exhibit unidirectional motion, our vessel undergoes both pitch and roll motions in response to frontal waves. This significantly magnifies the motion of the vessel and thus improves the power production by several orders of magnitude. The ocean waves result in roll and pitch motions of the vessel, which in turn causes rotation of an onboard pendulum. The pendulum is connected to an electric generator to produce power. The coupled electro-mechanical system is modeled using energy methods. This paper investigates the power generation of the vessel when the ratio between pitch and roll natural frequencies is about 2 to 1. In that case, a nonlinear energy transfer occurs between the roll and pitch motions, causing the vessel to perform coupled pitch and roll motion even though it is only excited in the pitch direction. It is shown that co-existence of pitch and roll motions significantly enhances the pendulum rotation and power generation. A method for tuning the natural frequencies of the vessel is proposed to make the energy generator robust to variations of the frequency of the incident waves. It is shown that the proposed method enhances the power output of the floating wave power generators by multiple orders of magnitude. A small-scale prototype is developed for the proof of concept. The nonlinear energy transfer and the full rotation of the pendulum in the prototype are observed in the experimental tests.

  17. Ocean Surface Wave Optical Roughness - Innovative Measurement and Modeling

    DTIC Science & Technology

    2007-09-30

    Thompson, D . Vandemark and B. Chapron, 2003: Time- frequency applications with the Stokes-Woodward technique, IEEE Geoscience and Remote Sensing Letters...799-813. [published, refereed] Young, I.R., M.L. Banner M.A., Donelan, A.V. Babanin, W.K. Melville, F. Veron and C. McCormick, 2004: An...C. W. Wright, D . C. Vandemark, B. Chapron, J. Jensen, S. Lee, 2007: The Southern Ocean Waves Experiment, Part III. Sea surface slope statistics and

  18. Ocean Surface Wave Optical Roughness: Analysis of Innovative Measurements

    DTIC Science & Technology

    2013-12-16

    relationship of MSS to wind speed, and at times has shown a reversal of the Cox-Munk linear relationship. Furthermore, we observe measurable changes in...1985]. The variable speed allocation method has the effect of aliasing (cb) to slower waves, thereby increasing the exponent –m. Our analysis based ...RaDyO) program. The primary research goals of the program are to (1) examine time -dependent oceanic radiance distribution in relation to dynamic

  19. High Wind Upper Ocean Mixing with Explicit Surface Wave Processes

    DTIC Science & Technology

    2011-09-30

    to Langmuir circulations (Sullivan et al. 2007 ). The equations for the resolved flow compo­ nents are the Craik-Leibovich (CL) theory with crucial...winds and waves are an idealization of Hurricane Frances (Sanford et al., 2011; Zedler 2007 ). In addition to the standard suite of variables output by...Mechanics,334, 1-30. Sanford, T. B., J. F. Price & J. B. Girton, 2007 : Highly resolved observations and simulations of the ocean response to a hurricane

  20. Imaging of converted-wave ocean-bottom seismic data

    NASA Astrophysics Data System (ADS)

    Rosales Roche, Daniel Alejandro

    Converted-wave data can be imaged with several methodologies. The transformation of data into the image space, is defined by an imaging operator, the simplest of which is normal moveout correction plus stack. Most of the converted-wave processing is carried out in the data domain, that is in time, data midpoint location, and data offset, this processing is not ideal for this type of seismic data. The processing should be carried out in the image domain, that is the one composed of depth, image midpoint location and image subsurface offset. Different processing techniques are created for an accurate image of converted wave seismic data. First, in 2-D Ocean-Bottom Seismic (OBC), the image space for converted-wave data is defined in the angle domain to form converted-wave angle-domain common-image gathers (PS-ADCIGs). The PS-ADCIGs can also be mapped into two complementary ADCIGs, the first one is function only of the P-incidence angle, the second ADCIG is function of the S-reflection angle. The method to obtain PS-ADCIGs is independent of the migration algorithm implemented, as long as the migration algorithm is based on wavefield downward-continuation, and the final prestack image is a function of the horizontal subsurface offset. The final process is done for 3-D seismic data, the creation of the converted-wave azimuth moveout operator (PS-AMO) and the converted-wave common-azimuth migration (PS-CAM) allows the definition and accurate image of 3-D prestack ocean-bottom seismic data.

  1. Global Trends in Ocean Wave State and Extremal Storm Events Examined with Microseism Analysis

    NASA Astrophysics Data System (ADS)

    Anthony, R. E.; Aster, R. C.; Rowe, C. A.

    2013-12-01

    The Earth's seismic noise spectrum features two globally ubiquitous peaks near 8 and 16 s periods that arise when storm-generated ocean gravity waves are converted to seismic energy, predominantly as Rayleigh waves. Because of its regionally integrative nature, microseism intensity histories at long running sites can provide useful proxies for wave state. Expanding on an earlier study of global microseism trends (Aster et al., 2010), we analyze up-to-date multi-decadal seismic data from global stations associated with several seismographic networks to characterize the spatiotemporal evolution of wave climate over the past >20 years. Ground motion power spectral density (PSD) is calculated over 3-hour overlapping time series segments to produce a database of PSD statistics at each broadband station between 2 and 100 s. Isolating power in the primary and secondary microseism bands enables regional characterization of spatially-integrated trends in wave states. In addition, specific extremal storm events are detected and are used to assess decadal changes in the location and frequency of oceanic storm activity. The results of these analyses are then interpreted in concert with recognized modes of atmospheric variability (e.g., El Nino-Southern Oscillation, Southern Annular Mode), that can impact storm statistics. We note a number of statistically significant increasing trends in both raw microseism power and storm activity occurring at multiple stations in the Northwest Atlantic and Southeast Pacific suggestive of increased wave heights and storminess in these regions. Additionally, we observe especially strong increases in microseism activity off of the Antarctic Peninsula, with monthly fluctuations strongly correlated to local anomalies in seasonal sea ice concentration. In turn, these reductions in sea ice concentration and extent appear to correlate with recent strengthening of the Southern Annular Mode. Such trends in wave activity have the potential to

  2. Deep Ocean Tsunami Waves off the Sri Lankan Coast

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The initial tsunami waves resulting from the undersea earthquake that occurred at 00:58:53 UTC (Coordinated Universal Time) on December 26, 2004, off the island of Sumatra, Indonesia, took a little over 2 hours to reach the teardrop-shaped island of Sri Lanka. Additional waves continued to arrive for many hours afterward. At approximately 05:15 UTC, as NASA's Terra satellite passed overhead, the Multi-angle Imaging SpectroRadiometer (MISR) captured this image of deep ocean tsunami waves about 30-40 kilometers from Sri Lanka's southwestern coast. The waves are made visible due to the effects of changes in sea-surface slope on the reflected sunglint pattern, shown here in MISR's 46-degree-forward-pointing camera. Sunglint occurs when sunlight reflects off a water surface in much the same way light reflects off a mirror, and the position of the Sun, angle of observation, and orientation of the sea surface determines how bright each part of the ocean appears in the image. These large wave features were invisible to MISR's nadir (vertical-viewing) camera. The image covers an area of 208 kilometers by 207 kilometers. The greatest impact of the tsunami was generally in an east-west direction, so the havoc caused by the tsunami along the southwestern shores of Sri Lanka was not as severe as along the eastern coast. However, substantial damage did occur in this region' as evidenced by the brownish debris in the water' because tsunami waves can diffract around land masses. The ripple-like wave pattern evident in this MISR image roughly correlates with the undersea boundary of the continental shelf. The surface wave pattern is likely to have been caused by interaction of deep waves with the ocean floor, rather than by the more usually observed surface waves, which are driven by winds. It is possible that this semi-concentric pattern represents wave reflection from the continental land mass; however, a combination of wave modeling and detailed bathymetric data is required to

  3. Deep Ocean Tsunami Waves off the Sri Lankan Coast

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The initial tsunami waves resulting from the undersea earthquake that occurred at 00:58:53 UTC (Coordinated Universal Time) on December 26, 2004, off the island of Sumatra, Indonesia, took a little over 2 hours to reach the teardrop-shaped island of Sri Lanka. Additional waves continued to arrive for many hours afterward. At approximately 05:15 UTC, as NASA's Terra satellite passed overhead, the Multi-angle Imaging SpectroRadiometer (MISR) captured this image of deep ocean tsunami waves about 30-40 kilometers from Sri Lanka's southwestern coast. The waves are made visible due to the effects of changes in sea-surface slope on the reflected sunglint pattern, shown here in MISR's 46-degree-forward-pointing camera. Sunglint occurs when sunlight reflects off a water surface in much the same way light reflects off a mirror, and the position of the Sun, angle of observation, and orientation of the sea surface determines how bright each part of the ocean appears in the image. These large wave features were invisible to MISR's nadir (vertical-viewing) camera. The image covers an area of 208 kilometers by 207 kilometers. The greatest impact of the tsunami was generally in an east-west direction, so the havoc caused by the tsunami along the southwestern shores of Sri Lanka was not as severe as along the eastern coast. However, substantial damage did occur in this region' as evidenced by the brownish debris in the water' because tsunami waves can diffract around land masses. The ripple-like wave pattern evident in this MISR image roughly correlates with the undersea boundary of the continental shelf. The surface wave pattern is likely to have been caused by interaction of deep waves with the ocean floor, rather than by the more usually observed surface waves, which are driven by winds. It is possible that this semi-concentric pattern represents wave reflection from the continental land mass; however, a combination of wave modeling and detailed bathymetric data is required to

  4. Some Characteristics of Radioisotope Power Sources in an Ocean Environment

    DTIC Science & Technology

    1974-03-01

    AD/A-002 129 SOME CHARACTERISTICS OF RADIOISOTOPE POWER SOURCES IN AN OCEAN ENVIRONMENT R. C. Erdmann, et al RAND Corporation S.,nta Monica...California March 1974 DISTRIBUTED BY: NItleId Tchinlald I ferrt Svice U. S. DEPARTMENT OF COMMERCE �.j I, ,- SOME CHARACTERISTICS OF RADIOISOTOPE POWER ... SOURCES IN AN OCEAN ENVIRONMENT R. C. ERDMAN3 E. C. GRITTON M. J. OZEROFF March 1974 -DDC, DEC 80 1974 L=-1 B P-5056-1 fotfotrduced by NATIONAL

  5. Ocean Wave Studies with Applications to Ocean Modeling and Improvement of Satellite Altimeter Measurements

    NASA Technical Reports Server (NTRS)

    Glazman, Roman E.

    1999-01-01

    Combining analysis of satellite data (altimeter, scatterometer, high-resolution visible and infrared images, etc.) with mathematical modeling of non-linear wave processes, we investigate various ocean wave fields (on scales from capillary to planetary), their role in ocean dynamics and turbulent transport (of heat and biogeochemical quantities), and their effects on satellite altimeter measuring accuracy. In 1998 my attention was focused on long internal gravity waves (10 to 1000 km), known also as baroclinic inertia-gravity (BIG) waves. We found these waves to be a major factor of altimeter measurements "noise," resulting in a greater uncertainty [up to 10 cm in terms of sea surface height (SSH) amplitude] in the measured SSH signal than that caused by the sea state bias variations (up to 5 cm or so). This effect still remains largely overlooked by the satellite altimeter community. Our studies of BIG waves address not only their influence on altimeter measurements but also their role in global ocean dynamics and in transport and turbulent diffusion of biogeochemical quantities. In particular, in collaboration with Prof Peter Weichman, Caltech, we developed a theory of turbulent diffusion caused by wave motions of most general nature. Applied to the problem of horizontal turbulent diffusion in the ocean, the theory yielded the effective diffusion coefficient as a function of BIG wave parameters obtainable from satellite altimeter data. This effort, begun in 1997, has been successfully completed in 1998. We also developed a theory that relates spatial fluctuations of scalar fields (such as sea surface temperature, chlorophyll concentration, drifting ice concentration, etc.) to statistical characteristics of BIG waves obtainable from altimeter measurements. A manuscript is in the final stages of preparation. In order to verify the theoretical predictions and apply them to observations, we are now analyzing Sea-viewing Wide Field of view Sensor (SeaWiFS) and Field of

  6. Colombian ocean waves and coasts modeled by special functions

    NASA Astrophysics Data System (ADS)

    Duque Tisnés, Simón

    2013-06-01

    Modeling the ocean bottom and surface of both Atlantic and Pacific Oceans near the Colombian coast is a subject of increasing attention due to the possibility of finding oil deposits that haven't been discovered, and as a way of monitoring the ocean limits of Colombia with other countries not only covering the possibility of naval intrusion but as a chance to detect submarine devices that are used by illegal groups for different unwished purposes. In the development of this topic it would be necessary to use Standard Hydrodynamic Equations to model the mathematical shape of ocean waves that will take differential equations forms. Those differential equations will be solved using computer algebra software and methods. The mentioned solutions will involve the use of Special Functions such as Bessel Functions, Whittaker, Heun, and so on. Using the Special Functions mentioned above, the obtained results will be simulated by numerical methods obtaining the typical patterns around the Colombian coasts (both surface and bottom). Using this simulation as a non-perturbed state, any change in the patter could be taken as an external perturbation caused by a strange body or device in an specific area or region modeled, building this simulation as an ocean radar or an unusual object finder. It's worth mentioning that the use of stronger or more rigorous methods and more advanced Special Functions would generate better theoretical results, building a more accurate simulation model that would lead to a finest detection.

  7. Role of south Indian Ocean swells in modulating the north Indian Ocean wave climate through modelling and remote sensing

    NASA Astrophysics Data System (ADS)

    Samiksha, S. V.; Vethamony, P.; Aboobacker, V. M.; Rashmi, R.

    2012-04-01

    Implementation and validation of a third generation wave model, Wavewatch III was used to study the characteristics of the south Indian ocean swells and their propagation in the north Indian Ocean. The NCEP reanalysis wind data (2.5° x 2.5°) has been used to generate the wind waves for the entire Indian Ocean during 2006 - 2007. The modelled wave parameters have been compared with measured buoy data and with merged altimeter data. The model results show good agreement with the buoy and altimeter data. A case study is carried out to study the propagation of the swells generated at the roaring 40°S in the Indian Ocean during May 2007. The "southern swell" occurred during May 2007 has been successfully reproduced in the wave model, which confirmed by the comparison of modelled significant wave heights with the merged altimeter significant wave heights. These swells were generated in the Atlantic ocean near the southern tip of South Africa and propagated towards the north Indian Ocean. These waves touches the Madagascar region and further hits the La Reunion islands after three days thus creating numerous damages near the islands. The magnitude of the swell is around 15m near the generation area and it reduces to around 6m near the La Reunion islands while propagating towards the north Indian Ocean. Further the swell energy is spataially distributed in the northern and southern Indian Ocean. The study reveals that the swells generated in the roaring forties and propagating in the SW/SSW direction influences more to Bay of Bengal than Arabian Sea. This occurs during pre-monsoon season primarily because large scale winds are weak in the north Indian Ocean during this period and hence swells from south Indian Ocean dominates at this time. The case of "southern swell" also happened to be at the same season. Further wave parameters were extracted at few locations in the northern Indian Ocean to study the impact of May 2007 swells on the wave climate. An average of around

  8. Parametric dependence of ocean wave-radar modulation transfer functions

    NASA Technical Reports Server (NTRS)

    Plant, W. J.; Keller, W. C.; Cross, A.

    1983-01-01

    Microwave techniques at X and L band were used to determine the dependence of ocean-wave radar modulation transfer functions (MTFs) on various environmental and radar parameters during the Marine Remote Sensing experiment of 1979 (MARSEN 79). These MIF are presented, as are coherence functions between the AM and FM parts of the backscattered microwave signal. It is shown that they both depend on several of these parameters. Besides confirming many of the properties of transfer functions reported by previous authors, indications are found that MTFs decrease with increasing angle between wave propagation and antenna-look directions but are essentially independent of small changes in air-sea temperature difference. However, coherence functions are much smaller when the antennas are pointed perpendicular to long waves. It is found that X band transfer functions measured with horizontally polarized microwave radiation have larger magnitudes than those obtained by using vertical polarization.

  9. Parametric dependence of ocean wave-radar modulation transfer functions

    NASA Technical Reports Server (NTRS)

    Plant, W. J.; Keller, W. C.; Cross, A.

    1983-01-01

    Microwave techniques at X and L band were used to determine the dependence of ocean-wave radar modulation transfer functions (MTFs) on various environmental and radar parameters during the Marine Remote Sensing experiment of 1979 (MARSEN 79). These MIF are presented, as are coherence functions between the AM and FM parts of the backscattered microwave signal. It is shown that they both depend on several of these parameters. Besides confirming many of the properties of transfer functions reported by previous authors, indications are found that MTFs decrease with increasing angle between wave propagation and antenna-look directions but are essentially independent of small changes in air-sea temperature difference. However, coherence functions are much smaller when the antennas are pointed perpendicular to long waves. It is found that X band transfer functions measured with horizontally polarized microwave radiation have larger magnitudes than those obtained by using vertical polarization.

  10. Long Term Autonomous Ocean Remote Sensing Utilizing the Wave Glider

    NASA Astrophysics Data System (ADS)

    Griffith, J.

    2012-12-01

    Rising costs of ship time and increasing budgetary restrictions make installation and maintenance of fixed ocean buoys a logistical and financial challenge. The cost associated with launch, recovery, and maintenance has resulted in a limited number of deployed buoys, restricting data on oceanic conditions. To address these challenges, Liquid Robotics (LRI) has developed the Wave Glider, an autonomous, mobile remote sensing solution. This system utilizes wave energy for propulsion allowing for long duration deployments of up to one year while providing real-time data on meteorological and oceanographic conditions. In November 2011, LRI deployed four Wave Gliders on a mission to cross the Pacific Ocean (the PacX) from San Francisco to Australia (two vehicles) or Japan (two vehicles) while transmitting data on weather conditions, wave profiles, sea surface temperatures, and biological conditions in real-time. This report evaluates the vehicle's ability to operate as an ocean going data platform by comparing data from the onboard weather sensors with two moored buoys, NDBC 46092 (Monterey Bay) and NDBC 51000 (200 nmi NE of Maui). The report also analyzes data transmitted from all four vehicles as they passed directly through a tropical storm 580 nmi NE of Hawaii. Upon arriving at one of the aforementioned buoys, the gliders continuously circled for a period of two days at a distance of three to eight nautical miles to build a comparative dataset. Data from both platforms were streamed in near real time enabling mid-mission evaluation of the performance of sensors. Overall, results varied from a <0.5% difference in barometric pressure between buoy NDBC 46092 and the gliders to high disagreement in wind speed and direction. While comparisons to moored buoy data can provide valuable insight into the relative accuracy of each platform, differences in agreement on variables such as wind speed and direction were attributed to micro-spatial variability in oceanic conditions

  11. High Power Continuous Wave Semiconductor Injection Laser

    DTIC Science & Technology

    1978-12-01

    hejunction rc~gion can be best accomplished in narro 7/,. laeswt width near 50 micrometers. Further optimization nnf FORM AWN2 AfI,~Jf~~’~ .* .~f’~W...high power CW operation. Trends in output powerwith varying laser length, width, reflectivity, and cavitythickness are presented graphically. LI ,N...J1 I H I I , THSI I ..... IU HIGH POWER CONTINUOUS WAVE ____________ SEMICONDUCTOR INJECTION LASER THESIS ’AIFIT/GEO/PH/78-.Z John1 C. Griffin, XIII

  12. System for generating power from waves

    SciTech Connect

    Gargos, G.

    1987-08-11

    A system is described for generating power from waves in a body of water, comprising floatable vessels; compound bell cranks having a central arm pinned at each end to adjacent the vessels and lateral arms extending outwardly in two opposed directions from each end of the central arm; and hydraulic cylinders pinned to alternate the compound bell cranks at the ends of the lateral arms.

  13. Radiative Efficiencies of Continuously Powered Blast Waves

    NASA Astrophysics Data System (ADS)

    Cohen, Ehud; Piran, Tsvi

    1999-06-01

    We use general arguments to show that a continuously powered radiative blast wave can behave self-similarly if the energy injection and radiation mechanisms are self-similar. In that case, the power-law indices of the blast wave evolution are set by only one of the two constituent physical mechanisms. If the luminosity of the energy source drops fast enough, the radiation mechanisms set the power-law indices; otherwise, they are set by the behavior of the energy source itself. We obtain self-similar solutions for the Newtonian and the ultrarelativistic limits. Both limits behave self-similarly if we assume that the central source supplies energy in the form of a hot wind and that the radiative mechanism is the semiradiative mechanism of Cohen, Piran, and Sari. We calculate the instantaneous radiative efficiencies for both limits and find that a relativistic blast wave has a higher efficiency than a Newtonian one. The instantaneous radiative efficiency depends strongly on the hydrodynamics and cannot be approximated by an estimate of local microscopic radiative efficiencies, since a fraction of the injected energy is deposited in shocked matter. These solutions can be used to calculate gamma-ray-burst afterglows for cases in which the energy is not supplied instantaneously.

  14. Role of Ocean Waves in the Earth system (Fridtjof Nansen Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Janssen, Peter A. E. M.

    2015-04-01

    In this presentation I will start with a brief description of the field of ocean wave forecasting. This will include an introduction to the key quantity of wave forecasting, namely the wave spectrum, and to the role the evolution equation for the wave spectrum, known as the energy balance equation, plays in understanding the role of ocean waves in the earth system. The energy balance equation describes the rate of change of the wave spectrum due to advection and refraction on the one hand and, on the other hand, the rate of change due to physical processes such as wind input, the energy conserving nonlinear four-wave interactions and dissipation by white capping. If the wave spectrum is known at a certain location then all the wave quantities such as wave height, period, energy flux and mean wave direction can be obtained. But knowledge of the wave spectrum also allows to obtain information on the statistics of waves. Just recently it has been shown that the occurrence of extreme events is closely linked to the shape of the wave spectrum. Narrow spectra are, compared to broad spectra, much more prone to extreme events, known as freak waves. Furthermore, for known wave spectrum one may determine, using the wind input source function, how much momentum the atmosphere is transfering to the ocean waves, which, of course slows down the atmospheric flow. On the other hand, using the white capping source function one may determine the energy flux from breaking waves into the upper ocean which enhances the upper ocean mixing of temperature and currents. This suggests that at the sea surface there is a two-interaction between atmosphere and ocean waves, between ocean waves and ocean circulation and between atmosphere and ocean. At ECMWF we are in the process of developing such a coupled system and some interesting results from numerical experiments will be presented.

  15. Wind waves climatology of the Southeast Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Aguirre, Catalina; Rutllant, José; Falvey, Mark

    2017-04-01

    The Southeast Pacific coast still lacks a high-resolution wave hindcast and a detailed description of its wave climatology. Since buoy wave measurements are particularly scarce along the coast of South America, a model hindcast forced with wind information derived from atmospheric Reanalysis seems an attractive way to generate a wave climatology in this poorly studied region, providing far better spatial and temporal coverage than can be achieved using observational data alone. Here, the climatology of wind waves over the Southeast Pacific is analyzed using a 32-year hindcast from the WaveWatch III model, complemented by satellite-derived Significant Wave Height (SWH) and buoy measurements for validation. Using partitioned spectral data, a regional climatology of wind sea and swell parameters was constructed. In general, the simulated SWH shows a good agreement with satellite and in-situ SWH measurements. The spatial pattern of SWH is clearly influenced by the meridional variation of mean surface wind speed, where the stronger winds over the Southern Ocean play a significant role generating higher waves at higher latitudes. Nevertheless, regional features are observed in the annual variability of SWH, which are associated with the existence of atmospheric coastal low-level jets off the coast of Peru and central Chile. In particular, the seasonal variation of these synoptic scale jets shows a direct relationship with the annual variability of SWH. Off the coast of Peru at 15°S the coastal low-level jet is strongest during austral winter, increasing the wind sea SWH. In contrast, off central Chile, there is an important increase of wind sea SWH during summer. The seasonal variation of the wind sea component leads to a contrasting seasonal variation of the total SWH at these locations: off Peru the coastal jet amplifies the annual variability of SWH, while off Central Chile the annual variability of SWH is suppressed by the presence of the coastal jet.

  16. Ocean-Acoustic Solitary Wave Studies and Predictions

    NASA Astrophysics Data System (ADS)

    Warn-Varnas, A. C.; Chin-Bing, S. A.; King, D. B.; Hallock, Z.; Hawkins, J. A.

    Shallow water internal solitary waves have become a major topic of interest to oceanographers and acousticians. In this paper we review the cross-disciplinary status of joint ocean-acoustic solitary wave studies and predictions. We consider the process of acoustical mode coupling in the presence of solitary waves and the corresponding acoustical intensity loss due to increased coupling with the bottom. A study of the interaction of an acoustical field with a train of solitary waves is undertaken at a range of frequencies. At a resonant frequency the acoustic field can interact with the solitary wave packet which results in mode conversions (acoustic energy is redistributed among the modes, often from lower-order to higher-order modes). Higher signal losses can occur in the higher order modes through increased bottom attenuation and result in an anomalous acoustical intensity loss at the resonant frequency. We present some new results of joint ocean-acoustic research, from a dedicated study in the Strait of Messina, where solitary waves are generated by semidiurnal tidal flow over topographic variations. The University of Hamburg weakly nonhydrostatic two layer model is used for simulating the generation and propagation of solitary waves. In particular, the physical states encountered during an October 1995 cruise in the Strait of Messina (between Italy and Sicily) are simulated. Various parameter space sensitivity studies, about the existing cruise conditions, are performed. The modelled solitary wave trains are compared against conductivity-temperature-depth (CTD) chain measurements in terms of amplitudes, wavelengths, phase speeds and correlations with data. Predicted and observed sound speeds are used in acoustical intensity calculations that are conducted with a parabolic equation (PE) model. The differences in the resultant acoustical intensity fields provide a guide for the tuning of the oceanographic model parameters. The tuned oceanographic model shows

  17. Wave-Ice Interaction in the Marginal Ice Zone: Toward a Wave-Ocean-Ice Coupled Modeling System

    DTIC Science & Technology

    2014-09-30

    generated surface gravity waves (WAVEWATCH III®) such that it can accurately predict the attenuation and scattering of waves by interaction with ice in...generated ocean surface wave models at NCEP. Weather and Forecasting (NCEP Notes), 17, 311-333. Wang, R. and H. H. Shen, 2010: Gravity waves

  18. Impact of Parameterized Internal Wave Drag on the Semidiurnal Energy Balancein a Global Ocean Circulation Model

    DTIC Science & Technology

    2016-04-12

    Impact of Parameterized Internal Wave Drag on the Semidiurnal Energy Balance in a Global Ocean Circulation Model* MAARTENC. BUIJSMAN,1 JOSEPHK...of Southern Mississippi, Stennis Space Center, Mississippi #University of Michigan, Ann Arbor, Michigan @Center for Ocean -Atmospheric Prediction...parameterized linear internal wave drag on the semidiurnal barotropic and baroclinic energetics of a realistically forced, three-dimensional global ocean

  19. Studies of Mixing and Internal Waves in the Upper Ocean

    NASA Astrophysics Data System (ADS)

    Wijesekera, Hemantha W.

    Microstructure measurements in the equatorial Pacific at 140^circW in late 1984 show a pronounced diurnal variation in both high-frequency internal wave energy and kinetic energy dissipation rate. Observations indicated that after sunset, internal waves propagate downward and increase turbulence levels in the pycnocline. A wave dissipation model based on the observed turbulent kinetic energy dissipation rate predicts that most of the downward wave momentum flux penetrates through the undercurrent core. It is hypothesized that when the wind stress is strong, the equatorial Pacific ocean responds by generating a westward-travelling internal wave field which transports much of the surface wind stress below the actively mixing surface layer. Several models now exist for predicting the dissipation rate of turbulent kinetic energy, varepsilon , in the oceanic thermocline as a function of the large-scale properties of the internal gravity wave field. These models are based on the transfer of energy towards smaller vertical scales by wave-wave interactions, and their predictions are typically evaluated for a canonical internal wave field as described by Garrett and Munk. Here we use simultaneous measurements of the internal wave field and varepsilon from a drifting ice camp in the eastern Arctic Ocean to evaluate the efficacy of existing models in a region with an anomalous wave field and energetic mixing. We find that, by explicitly retaining the vertical wavenumber bandwidth parameter, beta_*, models can still provide reasonable estimates of the dissipation rate. Statistics of turbulent patches are used to describe the nature of mixing in the pycnocline near abrupt bottom topography. It is found that the turbulent kinetic energy dissipation rate, varepsilon_{r }, averaged over a region of height r has a lognormal distribution consistent with Kolmogorov's third hypothesis: sigma_sp{ln(varepsilon _{r})}{2} = A + mu ln(L_{p}/r) where sigma_sp{ln(varepsilon _{r})}{2} is the

  20. A generalized multivariate regression model for modelling ocean wave heights

    NASA Astrophysics Data System (ADS)

    Wang, X. L.; Feng, Y.; Swail, V. R.

    2012-04-01

    In this study, a generalized multivariate linear regression model is developed to represent the relationship between 6-hourly ocean significant wave heights (Hs) and the corresponding 6-hourly mean sea level pressure (MSLP) fields. The model is calibrated using the ERA-Interim reanalysis of Hs and MSLP fields for 1981-2000, and is validated using the ERA-Interim reanalysis for 2001-2010 and ERA40 reanalysis of Hs and MSLP for 1958-2001. The performance of the fitted model is evaluated in terms of Pierce skill score, frequency bias index, and correlation skill score. Being not normally distributed, wave heights are subjected to a data adaptive Box-Cox transformation before being used in the model fitting. Also, since 6-hourly data are being modelled, lag-1 autocorrelation must be and is accounted for. The models with and without Box-Cox transformation, and with and without accounting for autocorrelation, are inter-compared in terms of their prediction skills. The fitted MSLP-Hs relationship is then used to reconstruct historical wave height climate from the 6-hourly MSLP fields taken from the Twentieth Century Reanalysis (20CR, Compo et al. 2011), and to project possible future wave height climates using CMIP5 model simulations of MSLP fields. The reconstructed and projected wave heights, both seasonal means and maxima, are subject to a trend analysis that allows for non-linear (polynomial) trends.

  1. Modeled dependence of wind and waves on ocean temperature in tropical cyclones

    NASA Astrophysics Data System (ADS)

    Phibbs, S.; Toumi, R.

    2015-12-01

    A coupled ocean-atmosphere-wave model is used to investigate the sensitivity of surface wind speed and significant wave height to ocean temperature for idealized tropical cyclones (TCs). More intense and larger TCs, with higher waves, form when ocean temperature is increased. The maximum significant wave height increases more than the maximum wind speed for TCs up to hurricane force wind. However, above hurricane force wind the change in maximum wind speed is similar or greater than the change in maximum significant wave height. This can be explained by the wind drag coefficient decreasing as wind speed exceeds hurricane force wind, so that the growth of waves is dampened. The areal footprint of wave height grows considerably more than the maximum as ocean temperature is increased. This suggests a large increase in the surface area of damaging waves generated by TCs may be the dominant impact of a future warmer ocean.

  2. Two-frequency /Delta k/ microwave scatterometer measurements of ocean wave spectra from an aircraft

    NASA Technical Reports Server (NTRS)

    Johnson, J. W.; Jones, W. L.; Weissman, D. E.

    1981-01-01

    A technique for remotely sensing the large-scale gravity wave spectrum on the ocean surface using a two frequency (Delta k) microwave scatterometer has been demonstrated from stationary platforms and proposed from moving platforms. This measurement takes advantage of Bragg type resonance matching between the electromagnetic wavelength at the difference frequency and the length of the large-scale surface waves. A prominent resonance appears in the cross product power spectral density (PSD) of the two backscattered signals. Ku-Band aircraft scatterometer measurements were conducted by NASA in the North Sea during the 1979 Maritime Remote Sensing (MARSEN) experiment. Typical examples of cross product PSD's computed from the MARSEN data are presented. They demonstrate strong resonances whose frequency and bandwidth agree with the surface characteristics and the theory. Directional modulation spectra of the surface reflectivity are compared to the gravity wave spectrum derived from surface truth measurements.

  3. A comparison of in situ and airborne radar observations of ocean wave directionality

    NASA Technical Reports Server (NTRS)

    Jackson, F. C.; Walton, W. T.; Peng, C. Y.

    1985-01-01

    The directional spectrum of a fully arisen, about 3 m sea as measured by an experimental airborne radar, the NASA K(u)-band radar ocean wave spectrometer (ROWS), is compared to reference pitch-roll buoy data and to the classical SWOP (stereo wave observations project) spectrum for fully developed conditions. The ROWS spectrum, inferred indirectly from backscattered power measurements at 5-km altitude, is shown to be in excellent agreement with the buoy spectrum. Specifically, excellent agreement is found between the two nondirectional height spectra, and mean wave directions and directional spreads as functions of frequency. A comparison of the ROWS and SWOP spectra shows the two spectra to be very similar, in detailed shape as well as in terms of the gross spreading characteristics. Both spectra are seen to exhibit bimodal structures which accord with the Phillips' (1958) resonance mechanism. This observation is thus seen to support Phillips' contention that the SWOP modes were indeed resonance modes, not statistical artifacts.

  4. Two-frequency /Delta k/ microwave scatterometer measurements of ocean wave spectra from an aircraft

    NASA Technical Reports Server (NTRS)

    Johnson, J. W.; Jones, W. L.; Weissman, D. E.

    1981-01-01

    A technique for remotely sensing the large-scale gravity wave spectrum on the ocean surface using a two frequency (Delta k) microwave scatterometer has been demonstrated from stationary platforms and proposed from moving platforms. This measurement takes advantage of Bragg type resonance matching between the electromagnetic wavelength at the difference frequency and the length of the large-scale surface waves. A prominent resonance appears in the cross product power spectral density (PSD) of the two backscattered signals. Ku-Band aircraft scatterometer measurements were conducted by NASA in the North Sea during the 1979 Maritime Remote Sensing (MARSEN) experiment. Typical examples of cross product PSD's computed from the MARSEN data are presented. They demonstrate strong resonances whose frequency and bandwidth agree with the surface characteristics and the theory. Directional modulation spectra of the surface reflectivity are compared to the gravity wave spectrum derived from surface truth measurements.

  5. A comparison of in situ and airborne radar observations of ocean wave directionality

    NASA Technical Reports Server (NTRS)

    Jackson, F. C.; Walton, W. T.; Peng, C. Y.

    1985-01-01

    The directional spectrum of a fully arisen, about 3 m sea as measured by an experimental airborne radar, the NASA K(u)-band radar ocean wave spectrometer (ROWS), is compared to reference pitch-roll buoy data and to the classical SWOP (stereo wave observations project) spectrum for fully developed conditions. The ROWS spectrum, inferred indirectly from backscattered power measurements at 5-km altitude, is shown to be in excellent agreement with the buoy spectrum. Specifically, excellent agreement is found between the two nondirectional height spectra, and mean wave directions and directional spreads as functions of frequency. A comparison of the ROWS and SWOP spectra shows the two spectra to be very similar, in detailed shape as well as in terms of the gross spreading characteristics. Both spectra are seen to exhibit bimodal structures which accord with the Phillips' (1958) resonance mechanism. This observation is thus seen to support Phillips' contention that the SWOP modes were indeed resonance modes, not statistical artifacts.

  6. Waves and the Equilibrium Range at Ocean Weather Station P

    DTIC Science & Technology

    2013-11-08

    assistance from Alex deKlerk (APL-UW) and Stephanie Downey (APL-UW). Marie Roberts (IOS Canada) and the crew of the R/V Tully deployed the original mooring...frequency spectrum, in Directional Ocean Wave Spectra, edited by Robert Beal, pp. 39–45, Johns Hopkins Univ. Press, Baltimore, MD. Battjes, J., T. Zitman...Oceanogr., 23, 2143–2149. Edson, J. B., A. A. Hinton, K. E. Prada, J. E. Hare , and C. W. Fairall (1998), Direct covariance flux estimates from mobile

  7. Vertical profiles of the wave-coherent airflow over ocean surface waves

    NASA Astrophysics Data System (ADS)

    Grare, L.; Melville, W. K.

    2016-02-01

    Current wind-wave numerical models are largely based on a statistical description of the surface waves and the marine atmospheric boundary layer (MABL) and do not resolve the phase of the waves nor the modulation of the wind by the waves. However, the new generation of LES models provides wave-resolved dynamics, kinematics and the associated wave-coherent air-flow (Sullivan et al., 2014). It is therefore important to provide experimental descriptions of the wave field and the structure of the MABL to test the validity of the numerical simulations. We present an analysis of coherent wind and wave data collected from R/P FLIP off the coast of Southern California in November 2013. The wave-coherent airflow was measured by an array of five sonic anemometers, ranging from 2.5m up to 13.5m above the ocean surface, distributed on a vertical telescopic mast mounted at the end of R/P FLIP's port boom. Results show that, below the critical height zc where the wind speed U(zc) equals the phase speed of the waves c, the normalization of the wave-induced fluctuations by the amplitude of the wave orbital velocities collapses the data from all the anemometers on a curve which follows an exponential decay with the normalized height kz. This experiment also highlighted discrepancies between data measured by Campbell CSAT3 and GILL R3-50 sonic anemometers. The differences between the anemometers depend strongly on the wind direction. The relative error of the mean wind speed can reach 4%, while the relative error of the friction velocity can reach 20% (i.e. 44% for the momentum flux). Several experiments conducted in various environmental conditions confirm these results.

  8. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean

    NASA Technical Reports Server (NTRS)

    Wright, C. W.; Walsh, E. J.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.

    1999-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 deg half-power width (two-way) across the aircraft ground track over a swath equal to 0. 8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The data presented were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Wave heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction and at times there were wave fields traveling at right angles to each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 2-minute animation of the directional wave spectrum spatial variation over this period will be shown.

  9. The Effects of Ice and Currents on Wave-driven Turbulence at the Ocean Surface

    NASA Astrophysics Data System (ADS)

    Zippel, S.; Thomson, J.

    2016-02-01

    In the open ocean, wind driven wave breaking imparts turbulent kinetic energy (TKE) to the ocean surface, which then diffuses downward. Despite the process being wave driven, the flux of TKE is often successfully parameterized from wind measurements by invoking wind-wave equilibrium. In more complex environments, the pathways for mechanical energy and momentum between the atmosphere, waves, and ocean are less direct. We present measurements of wave spectra and near surface turbulent dissipation rates measured from SWIFT drifters at two field sites, one influenced by ice, the other by currents. In partial ice cover, atmospheric momentum is partitioned between ice and ocean, and feedback between waves and ice damps wave breaking, muting exchanges through the air-ocean interface. Measurements from the Beaufort Sea show that surface roughness (as wave mean squared slope) is well correlated with near surface turbulence (as TKE dissipation rate), and both are reduced by two orders of magnitude in partial ice cover. This implies a smaller partition of atmospheric momentum directly to the ocean surface than previously thought. At river inlets, shallow depths and opposing currents enhance wave breaking, increasing the exchange of momentum and energy from the waves to the ocean. Measurements from the mouth of the Columbia River show increased breaking rates at the plume front, where horizontal gradients in currents are large, and over the bar, where waves are shoaling. These breaking locations exhibit increased surface TKE dissipation rates, which are well scaled vertically by wave parameters.

  10. A New Coupled 4DVAR Assimilation System for Coupled Ocean-Wave Models

    NASA Astrophysics Data System (ADS)

    Blain, C. A.; Orzech, M.; Carrier, M.; Ngodock, H.; Souopgui, I.; Smith, S. R.

    2016-02-01

    The coastal ocean environment poses prediction challenges due to shortened time and space scales and highly nonlinear interactions between its wave and circulation dynamics. In-situ observations in such a region can often be scattered and/or incomplete, further stressing our ability to accurately forecast coastal parameters such as currents, wave heights and direction, and density structure. To extend predictability in these coastal environments, we have developed a coupled, four-dimensional, variational (4DVAR) assimilation system for coupled ocean-wave models. Coupling the assimilation systems for the ocean and waves insures dynamical consistency of the assimilation innovations in a highly nonlinear, continuously evolving environment. Coupled assimilation also permits observations of one process to affect the forecast of another, which can maximize our use of limited datasets. The ocean-wave assimilation system is presently coupled through three mechanisms: ocean currents, Stokes' drift, and wave radiation stress gradients, and is incorporated within the Coupled Ocean Atmosphere Mesoscale Prediction System (COAMPS). The coupled assimilation is realized by including each of these coupling terms within the adjoint and tangent linear components of the ocean-wave, 4DVAR assimilation system. The ocean-wave assimilation and forecast system is then applied to a series of twin experiments near the mouth of Chesapeake Bay. These twin experiments are designed to show how information flows from observations assimilated in to either the ocean or wave model through the coupled assimilation to influence both ocean and wave model variables. Inferred corrections from one system to another are demonstrated. As part of the coupled assimilation system, a newly developed formulation for wave error covariances is implemented. Impacts of the wave covariances on predictions from the coupled ocean-wave model system are also assessed.

  11. Long Wave Resonance in Tropical Oceans and Implications on Climate: the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Pinault, Jean-Louis

    2013-11-01

    Kelvin wave, being deflected off the western boundary. The succession of warm and cold waters transferred by baroclinic waves during a cycle leaves the tropical ocean by radiation and contributes to western boundary currents. The main manifestation of the basin modes concerns the variability of the NECC, of the branch of the South Equatorial Current (SEC) along the equator, of the western boundary currents as well as the formation of remote resonances, as will be presented in a future work. Remote resonances occur at midlatitudes, the role of which is suspected of being crucial in the functioning of subtropical gyres and in climate variability.

  12. The Wave Glider°: A New Autonomous Surface Vehicle to Augment MBARI's Growing Fleet of Ocean Observing Systems

    NASA Astrophysics Data System (ADS)

    Tougher, B. B.

    2011-12-01

    Monterey Bay Aquarium Research Institute's (MBARI) evolving fleet of ocean observing systems has made it possible to collect information and data about a wide variety of ocean parameters, enabling researchers to better understand marine ecosystems. In collaboration with Liquid Robotics Inc, the designer of the Wave Glider autonomous surface vehicle (ASV), MBARI is adding a new capability to its suite of ocean observing tools. This new technology will augment MBARI research programs that use satellites, ships, moorings, drifters, autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) to improve data collection of temporally and spatially variable oceanographic features. The Wave Glider ASV derives its propulsion from wave energy, while sensors and communications are powered through the use of two solar panels and batteries, enabling it to remain at sea indefinitely. Wave Gliders are remotely controlled via real-time Iridium burst communications, which also permit real-time data telemetry. MBARI has developed Ocean Acidification (OA) moorings to continuously monitor the chemical and physical changes occurring in the ocean as a result of increased levels of atmospheric carbon dioxide (CO2). The moorings are spatially restricted by being anchored to the seafloor, so during the summer of 2011 the ocean acidification sensor suite designed for moorings was integrated into a Wave Glider ASV to increase both temporal and spatial ocean observation capabilities. The OA sensor package enables the measurement of parameters essential to better understanding the changing acidity of the ocean, specifically pCO2, pH, oxygen, salinity and temperature. The Wave Glider will also be equipped with a meteorological sensor suite that will measure air temperature, air pressure, and wind speed and direction. The OA sensor integration into a Wave Glider was part of MBARI's 2011 summer internship program. This project involved designing a new layout for the OA sensors

  13. Stopping power of charged particles due to ion wave excitations.

    PubMed

    Nitta, H; Muroki, C; Nambu, M

    2002-08-01

    Stopping power due to ion wave excitations is derived for a charged particle moving in a two-component plasma. Unlike previous theories based on ion-acoustic-wave approximation (IAWA), the excitation of short-wavelength ion waves is taken into account. The obtained stopping power has a magnitude larger than that of IAWA. Stopping power at subsonic velocities, where stopping power in IAWA disappears, is even larger than that of supersonic velocities.

  14. Stopping power of charged particles due to ion wave excitations

    NASA Astrophysics Data System (ADS)

    Nitta, H.; Muroki, C.; Nambu, M.

    2002-08-01

    Stopping power due to ion wave excitations is derived for a charged particle moving in a two-component plasma. Unlike previous theories based on ion-acoustic-wave approximation (IAWA), the excitation of short-wavelength ion waves is taken into account. The obtained stopping power has a magnitude larger than that of IAWA. Stopping power at subsonic velocities, where stopping power in IAWA disappears, is even larger than that of supersonic velocities.

  15. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Powell, M. D.; Black, P. G.; Marks, F. D.; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 E half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Individual waves with heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 3-minute animation of the directional wave spectrum spatial variation over this period will be shown as well as summary plots of the wave field spatial variation. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track

  16. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Powell, M. D.; Black, P. G.; Marks, F. D.; Busalacchi, Antonio J. (Technical Monitor)

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1 E half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the incidence angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two-dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving slowly to the north. Individual waves with heights up to 18 m were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye, and made five eye penetrations. A 3-minute animation of the directional wave spectrum spatial variation over this period will be shown as well as summary plots of the wave field spatial variation. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft ground track

  17. Advanced, High Power, Next Scale, Wave Energy Conversion Device

    SciTech Connect

    Hart, Philip R.

    2011-09-27

    This presentation from the Water Peer Review highlights one of the program's marine and hyrokinetics device design projects to scale up the current Ocean Power Technology PowerBuoy from 150kW to 500kW.

  18. On the role of high frequency waves in ocean altimetry

    NASA Astrophysics Data System (ADS)

    Vandemark, Douglas C.

    This work mines a coastal and open ocean air-sea interaction field experiment data set where the goals are to refine satellite retrieval of wind, wind stress, and sea level using a microwave radar altimeter. The data were collected from a low-flying aircraft using a sensor suite designed to measure the surface waves, radar backscatter, the atmospheric flow, and turbulent fluxes within the marine boundary layer. This uncommon ensemble provides the means to address several specific altimeter-related topics. First, we examine and document the impact that non wind-driven gravity wave variability, e.g. swell, has upon the commonly-invoked direct relationship between altimeter backscatter and near surface wind speed. The demonstrated impact is larger in magnitude and more direct than previously suggested. The study also isolates the wind-dependence of short-scale slope variance and suggests its magnitude is somewhat lower than shown elsewhere while a second-order dependence on long waves is also evident. A second study assesses the hypothesis that wind-aligned swell interacts with the atmospheric boundary flow leading to a depressed level of turbulence. Cases of reduced drag coefficient at moderate wind speeds were in evidence within the data set, and buoy observations indicate that swell was present and a likely control during these events. Coincidentally, short-scale wave roughness was also depressed suggesting decreased wind stress. Attempts to confirm the theory failed, however, due to numerous limitations in the quantity and quality of the data in hand. A lesson learned is that decoupling atmospheric stability and wave impacts in field campaigns requires both a very large amount of data as well as vertical resolution of fluxes within the first 10--20 m of the surface.

  19. Observations of Sea Surface Mean Square Slope During the Southern Ocean Waves Experiment

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Vandemark, D. C.; Hines, D. E.; Banner, M. L.; Chen, W.; Swift, R. N.; Scott, J. F.; Jensen, J.; Lee, S.; Fandry, C.

    1999-01-01

    For the Southern Ocean Waves Experiment (SOWEX), conducted in June 1992 out of Hobart, Tasmania, the 36 GHz (8.3 mm) NASA Scanning Radar Altimeter (SRA) was shipped to Australia and installed on a CSIRO Fokker F-27 research aircraft instrumented to make comprehensive surface layer measurements of air-sea interaction fluxes. The sea surface mean square slope (mss), which is predominantly caused by the short waves, was determined from the backscattered power falloff with incidence angle measured by the SRA in the plane normal to the aircraft heading. On each flight, data were acquired at 240 m altitude while the aircraft was in a 7 deg roll attitude, interrogating off-nadir incidence angles from -15 deg through nadir to +29 deg. The aircraft turned azimuthally through 810 deg in this attitude, mapping the azimuthal dependence of the backscattered power falloff with incidence angle. Two sets of turning data were acquired on each day, before and after the aircraft measured wind stress at low altitude (12 m to 65 m). Wave topography and backscattered power for mss were also acquired during those level flight segments whenever the aircraft altitude was above the SRA minimum range of 35 m. A unique feature of this experiment was the use of a nadir-directed low-gain horn antenna (35 deg beamwidth) to acquire azimuthally integrated backscattered power data versus incidence angle before and after the turn data.

  20. Observations of Sea Surface Mean Square Slope During the Southern Ocean Waves Experiment

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Vandemark, D. C.; Hines, D. E.; Banner, M. L.; Chen, W.; Swift, R. N.; Scott, J. F.; Jensen, J.; Lee, S.; Fandry, C.

    1999-01-01

    For the Southern Ocean Waves Experiment (SOWEX), conducted in June 1992 out of Hobart, Tasmania, the 36 GHz (8.3 mm) NASA Scanning Radar Altimeter (SRA) was shipped to Australia and installed on a CSIRO Fokker F-27 research aircraft instrumented to make comprehensive surface layer measurements of air-sea interaction fluxes. The sea surface mean square slope (mss), which is predominantly caused by the short waves, was determined from the backscattered power falloff with incidence angle measured by the SRA in the plane normal to the aircraft heading. On each flight, data were acquired at 240 m altitude while the aircraft was in a 7 deg roll attitude, interrogating off-nadir incidence angles from -15 deg through nadir to +29 deg. The aircraft turned azimuthally through 810 deg in this attitude, mapping the azimuthal dependence of the backscattered power falloff with incidence angle. Two sets of turning data were acquired on each day, before and after the aircraft measured wind stress at low altitude (12 m to 65 m). Wave topography and backscattered power for mss were also acquired during those level flight segments whenever the aircraft altitude was above the SRA minimum range of 35 m. A unique feature of this experiment was the use of a nadir-directed low-gain horn antenna (35 deg beamwidth) to acquire azimuthally integrated backscattered power data versus incidence angle before and after the turn data.

  1. SAR imagery of ocean-wave swell traveling in an arbitrary direction

    NASA Technical Reports Server (NTRS)

    Rufenach, C. L.; Shuchman, R. A.; Lyzenga, D. R.

    1984-01-01

    The intensity wave like patterns observed in Synthetic Aperture Radar (SAR) are known to be caused by two mechanisms: the microwave radar cross sectional amplitude modulation due to tilt and hydrodynamic interaction of the long ocean waves, and intensity modulation due to the motion of the long ocean waves. Two dimensional closed form expressions of intensity wave patterns based on ocean wave swell are developed. They illustrate the relative importance of the amplitude and motion modulations; they also show that velocity bunching and a distortion due to the phase velocity of the ocean wave field are independent of the focus adjustment, provided that the second order temporal effects are neglected. Second order effects are small only over a limited range of ocean/radar parameters.

  2. Can We Use High Frequency Seismic Noise to Infer Local Sea States, Breaking Wave Power, and Sediment Transport?

    NASA Astrophysics Data System (ADS)

    Poppeliers, C.

    2016-12-01

    In the last decade, there has been increased interest in using seismology to characterize, locate, and quantify so-called non-traditional targets. In this talk, I summarize our efforts on attempting to correlate seismic records to the power and direction of breaking ocean waves in the near-shore surf zone. The eventual goal of this work is to determine the efficacy of using seismic monitoring to remotely monitor beach processes such as erosion, accretion, and/or sediment transport. Note that seismic energy generated by breaking waves is not the same as microseism, which is generated by deep water ocean swell and generates energy in a much lower frequency band. Indeed, we observe that breaking waves in the near-shore generate seismic waves in passband of 5-80 Hz. I deployed an eight-station linear array of high frequency seismometers in the dune field immediately adjacent to surf zone and recorded continuously for three weeks. I observed that during elevated sea states, and presumably larger breaking waves in the surf zone, the power spectral density of the wave-generated seismic energy shifts to lower frequencies and higher spectral amplitudes. A loose correlation between the seismic spectral power to the height and period of ocean waves suggests that seismic observations may be used as a proxy for local sea states. However, I found that traditional measures of ocean waves, in the form of significant wave height, Hs, and dominant period, S, misses a wealth of information about the ocean wave field, leading to only very loose correlations between the observed seismic spectrum and Hs and S. Rather, I found that the seismic energy is much more closely correlated to ocean wave spectral energy, suggesting that future work must include higher resolution measurements of ocean waves in the form of water-surface height time series or underwater acoustic monitoring of the surf zone. Also, I observed a significant hysteresis between the sea surface spectral energy the seismic

  3. Numerical simulation and observations of very severe cyclone generated surface wave fields in the north Indian Ocean

    NASA Astrophysics Data System (ADS)

    Sirisha, P.; Remya, P. G.; Balakrishnan Nair, T. M.; Rao, B. Venkateswara

    2015-12-01

    Accurate wave forecast is most needed during tropical cyclones as it has adverse effects on the entire marine activities. The present work evaluates the performance of a wave forecasting system under very severe cyclonic conditions for the Indian Ocean. The wave model results are validated separately for the deep water and shallow water using in-situ observations. Satellite altimeter observations are also utilized for validation purpose. The results show that the model performance is accurate (SI < 26% and correlation > 0.9) and consistent during very severe cyclones (categories 4 and 5). The power of the cyclone waves which hit in the eastern Indian coastal region is also analysed and it reveals that the coastal region which lies on the right side of the cyclone track receives high amount wave energy throughout the cyclone period. The study also says that the abnormal waves mostly present on the right side of the track.

  4. The comparison between the synthetic aperture radar imageries and the surface truth of ocean waves

    NASA Technical Reports Server (NTRS)

    Hsiao, S. V.

    1978-01-01

    Ocean waves measured offshore of Marineland, Florida, by the synthetic aperture radar (SAR) are compared with the surface truth data. The Fourier transform of SAR imageries are taken and the corrections of the wave directions and wave lengths due to the relative velocities between SAR and waves are considered. Favorable comparisons are obtained for the peak frequencies, wave directions, and directional distributions. However, the one-dimensional SAR spectra are quite different from the surface truth wave height spectra.

  5. The comparison between the synthetic aperture radar imageries and the surface truth of ocean waves

    NASA Technical Reports Server (NTRS)

    Hsiao, S. V.

    1978-01-01

    Ocean waves measured offshore of Marineland, Florida, by the synthetic aperture radar (SAR) are compared with the surface truth data. The Fourier transform of SAR imageries are taken and the corrections of the wave directions and wave lengths due to the relative velocities between SAR and waves are considered. Favorable comparisons are obtained for the peak frequencies, wave directions, and directional distributions. However, the one-dimensional SAR spectra are quite different from the surface truth wave height spectra.

  6. CFOSAT: a new Chinese-French satellite for joint observations of ocean wind vector and directional spectra of ocean waves

    NASA Astrophysics Data System (ADS)

    Hauser, D.; Tison, C.; Amiot, T.; Delaye, L.; Mouche, A.; Guitton, G.; Aouf, L.; Castillan, P.

    2016-05-01

    CFOSAT (the China France Oceanography Satellite) is a joint mission from the Chinese and French Space Agencies, devoted to the observation ocean surface wind and waves so as to improve wind and wave forecast for marine meteorology, ocean dynamics modeling and prediction, climate variability knowledge, fundamental knowledge of surface processes. Currently under Phase D (manufacturing phase), the launch is now planned for mid-2018 the later. The CFOSAT will carry two payloads, both Ku-Band radar: the wave scatterometer (SWIM) and the wind scatterometer (SCAT). Both instruments are based on new concepts with respect to existing satellite-borne wind and wave sensors. Indeed, one of the originalities of CFOSAT is that it will provide simultaneously and in the same zone, the directional spectra of ocean waves and the wind vector. The concept used to measure the directional spectra of ocean waves has never been used from space until now: it is based on a near-nadir incidence pointing, rotating fan-beam radar, used in a real-aperture mode. In this paper we present the CFOSAT mission, its objectives and main characteristics. We then focus on the SWIM instrument, the expected geophysical products and performances. Finally, we present ongoing studies based on existing satellite data of directional spectra of ocean waves (Sentinel-1, ..) and carried out in preparation to CAL/VAL activities and to future data exploitation.

  7. Orienting ocean-bottom seismometers from P-wave and Rayleigh wave polarizations

    NASA Astrophysics Data System (ADS)

    Scholz, John-Robert; Barruol, Guilhem; Fontaine, Fabrice R.; Sigloch, Karin; Crawford, Wayne C.; Deen, Martha

    2017-03-01

    We present two independent, automated methods for estimating the absolute horizontal misorientation of seismic sensors. We apply both methods to 44 free-fall ocean-bottom seismometers (OBSs) of the RHUM-RUM experiment (http://www.rhum-rum.net/). The techniques measure the 3-D directions of particle motion of (1) P-waves and (2) Rayleigh waves of earthquake recordings. For P-waves, we used a principal component analysis to determine the directions of particle motions (polarizations) in multiple frequency passbands. We correct for polarization deviations due to seismic anisotropy and dipping discontinuities using a simple fit equation, which yields significantly more accurate OBS orientations. For Rayleigh waves, we evaluated the degree of elliptical polarization in the vertical plane in the time and frequency domain. The results obtained for the RHUM-RUM OBS stations differed, on average, by 3.1° and 3.7° between the methods, using circular mean and median statistics, which is within the methods' estimate uncertainties. Using P-waves, we obtained orientation estimates for 31 ocean-bottom seismometers with an average uncertainty (95 per cent confidence interval) of 11° per station. For 7 of these OBS, data coverage was sufficient to correct polarization measurements for underlying seismic anisotropy and dipping discontinuities, improving their average orientation uncertainty from 11° to 6° per station. Using Rayleigh waves, we obtained misorientation estimates for 40 OBS, with an average uncertainty of 16° per station. The good agreement of results obtained using the two methods indicates that they should also be useful for detecting misorientations of terrestrial seismic stations.

  8. Orienting Ocean-Bottom Seismometers from P-wave and Rayleigh wave polarisations

    NASA Astrophysics Data System (ADS)

    Scholz, John-Robert; Barruol, Guilhem; Fontaine, Fabrice R.; Sigloch, Karin; Crawford, Wayne; Deen, Martha

    2016-11-01

    We present two independent, automated methods for estimating the absolute horizontal misorientation of seismic sensors from their recorded data. We apply both methods to 44 free-fall ocean-bottom seismometers (OBS) of the RHUM-RUM experiment (http://www.rhum-rum.net/). The techniques measure the three-dimensional directions of particle motion of (1) P-waves and (2) Rayleigh waves of earthquake recordings. For P-waves, we used a principal component analysis to determine the directions of particle motions (polarisations) in multiple frequency passbands. We correct for polarisation deviations due to seismic anisotropy and dipping discontinuities using a simple fit equation, which yields significantly more accurate OBS orientations. For Rayleigh waves, we evaluated the degree of elliptical polarisation in the vertical plane in the time and frequency domain. The results obtained for the RUM-RHUM OBS stations differed, on average, by 3.1° and 3.7° between the methods, using circular mean and median statistics, which is within the methods' estimate uncertainties. Using P-waves, we obtained orientation estimates for 31 ocean-bottom seismometers with an average uncertainty (95% confidence interval) of 11° per station. For 7 of these OBS, data coverage was sufficient to correct polarisation measurements for underlying seismic anisotropy and dipping discontinuities, improving their average orientation uncertainty from 11° to 6° per station. Using Rayleigh waves, we obtained misorientation estimates for 40 OBS, with an average uncertainty of 16° per station. The good agreement of results obtained using the two methods indicates that they should also be useful for detecting misorientations of terrestrial seismic stations.

  9. Wave-current interactions at the FloWave Ocean Energy Research Facility

    NASA Astrophysics Data System (ADS)

    Noble, Donald; Davey, Thomas; Steynor, Jeffrey; Bruce, Tom; Smith, Helen; Kaklis, Panagiotis

    2015-04-01

    Physical scale model testing is an important part of the marine renewable energy development process, allowing the study of forces and device behaviour in a controlled environment prior to deployment at sea. FloWave is a new state-of-the-art ocean energy research facility, designed to provide large scale physical modelling services to the tidal and wave sector. It has the unique ability to provide complex multi-directional waves that can be combined with currents from any direction in the 25m diameter circular tank. The facility is optimised for waves around 2s period and 0.4m height, and is capable of generating currents upwards of 1.6m/s. This offers the ability to model metocean conditions suitable for most renewable energy devices at a typical scale of between 1:10 and 1:40. The test section is 2m deep, which can be classed as intermediate-depth for most waves of interest, thus the full dispersion equation must be solved as the asymptotic simplifications do not apply. The interaction between waves and currents has been studied in the tank. This has involved producing in the tank sets of regular waves, focussed wave groups, and random sea spectra including multi-directional sea states. These waves have been both inline-with and opposing the current, as well as investigating waves at arbitrary angles to the current. Changes in wave height and wavelength have been measured, and compared with theoretical results. Using theoretical wave-current interaction models, methods have been explored to "correct" the wave height in the central test area of the tank when combined with a steady current. This allows the wave height with current to be set equal to that without a current. Thus permitting, for example, direct comparison of device motion response between tests with and without current. Alternatively, this would also permit a specific wave height and current combination to be produced in the tank, reproducing recorded conditions at a particular site of interest. The

  10. Interactions of Ocean Fronts with Waves and Turbulence

    NASA Astrophysics Data System (ADS)

    Fox-Kemper, Baylor; Suzuki, Nobuhiro

    2015-11-01

    High resolution simulations and observations of the ocean surface boundary layer have revealed 100m to 10km frontal and filamentary structures in temperature and other properties worldwide. The formation and evolution of these features, through frontogenesis, instability, and frontolysis is an important and often poorly-simulated part of the climate system, yet fronts and filaments strongly affect surface layer dynamics and the transport of energy, momentum, and gasses through this layer. These features also dominate the transport of oil spills and pollutants over a wide range of scales. Analysis of a multi-scale, non-hydrostatic, large eddy simulation spanning 20km fronts to 5m turbulence will be presented. The theory of the interactions of the fronts with turbulence and surface waves will be illustrated, and the consequences of these interactions on frontal strength and tracer transport will be quantified. Supported by NSF 1258907 and BP/The Gulf of Mexico Research Initiative (CARTHE).

  11. Wave-Ice interaction in the Marginal Ice Zone: Toward a Wave-Ocean-Ice Coupled Modeling System

    DTIC Science & Technology

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Wave- Ice interaction in the Marginal Ice Zone: Toward a...Wave-Ocean- Ice Coupled Modeling System W. E. Rogers Naval Research Laboratory, Code 7322 Stennis Space Center, MS 39529 phone: (228) 688-4727...scattering of waves by interaction with ice in the Marginal Ice Zone (MIZ). The wave model physics developed here will later be part of an operational

  12. Numerical Investigations of Wave-Induced Mixing in Upper Ocean Layer

    NASA Astrophysics Data System (ADS)

    Guan, Changlong

    2017-04-01

    The upper ocean layer is playing an important role in ocean-atmosphere interaction. The typical characteristics depicting the upper ocean layer are the sea surface temperature (SST) and the mixed layer depth (MLD). So far, the existing ocean models tend to over-estimate SST and to under-estimate MLD, due to the inadequate mixing in the mixing layer, which is owing to that several processes related mixing in physics are ignored in these ocean models. The mixing induced by surface gravity wave is expected to be able to enhance the mixing in the upper ocean layer, and therefore the over-estimation of SST and the under-estimate of MLD could be improved by including wave-induced mixing. The wave-induced mixing could be accomplished by the physical mechanisms, such as wave breaking (WB), wave-induced Reynolds stress (WR), and wave-turbulence interaction (WT). The General Ocean Turbulence Model (GOTM) is employed to investigate the effects of the three mechanisms concerning wave-induced mixing. The numerical investigation is carried out for three turbulence closure schemes, say, k-epsilon, k-omega and Mellor-Yamada (1982), with the observational data from OSC Papa station and wave data from ECMWF. The mixing enhancement by various waved-induced mixing mechanisms is investigated and verified.

  13. Directional wave climate and power variability along the Southeast Australian shelf

    NASA Astrophysics Data System (ADS)

    Mortlock, Thomas R.; Goodwin, Ian D.

    2015-04-01

    Variability in the modal wave climate is a key process driving large-scale coastal behaviour on moderate- to high-energy sandy coastlines, and is strongly related to variability in synoptic climate drivers. On sub-tropical coasts, shifts in the sub-tropical ridge (STR) modulate the seasonal occurrence of different wave types. However, in semi-enclosed seas, isolating directional wave climates and synoptic drivers is hindered by a complex mixed sea-swell environment. Here we present a directional wave climate typology for the Tasman Sea based on a combined statistical-synoptic approach using mid-shelf wave buoy observations along the Southeast Australian Shelf (SEAS). Five synoptic-scale wave climates exist during winter, and six during summer. These can be clustered into easterly (Tradewind), south-easterly (Tasman Sea) and southerly (Southern Ocean) wave types, each with distinct wave power signatures. We show that a southerly shift in the STR and trade-wind zone, consistent with an observed poleward expansion of the tropics, forces an increase in the total wave energy flux in winter for the central New South Wales shelf of 1.9 GJ m-1 wave-crest-length for 1° southerly shift in the STR, and a reduction of similar magnitude (approximately 1.8 GJ m-1) during summer. In both seasons there is an anti-clockwise rotation of wave power towards the east and south-east at the expense of southerly waves. Reduced obliquity of constructive wave power would promote a general disruption to northward alongshore sediment transport, with the cross-shore component becoming increasingly prevalent. Results are of global relevance to sub-tropical east coasts where the modal wave climate is influenced by the position of the zonal STR.

  14. Wave-Ice and Air-Ice-Ocean Interaction During the Chukchi Sea Ice Edge Advance

    DTIC Science & Technology

    2013-09-30

    Lead Ocean gliders Ahead of ice edge Upper ocean (0-200m) T, S, O2, bio- optics , currents During cruise CU-B UAF Autonomous underwater vehicle...AUV) Under ice, up to 50km transects Ice thickness, floe-size distribution, waves, upper ocean properties ADCP, CTD, camera, multibeam sonar

  15. Turbulence Simulation of Laboratory Wind-Wave Interaction in High Winds and Upscaling to Ocean Conditions

    DTIC Science & Technology

    2016-12-22

    December 2016 Award Number: N00014-12-10184 Turbulence Simulation of Laboratory Wind-Wave Interaction in High Winds and Upscaling to Ocean ...strongly forced ocean conditions where the wave spectral bandwidth is much broader. Overall, the fundamental aerodynamic behavior associated with...between the atmosphere and ocean . This is particularly important at high winds since air-sea fluxes substantially affect tropical cyclone (hurricane

  16. Elastic parabolic equation solutions for oceanic T-wave generation and propagation from deep seismic sources.

    PubMed

    Frank, Scott D; Collis, Jon M; Odom, Robert I

    2015-06-01

    Oceanic T-waves are earthquake signals that originate when elastic waves interact with the fluid-elastic interface at the ocean bottom and are converted to acoustic waves in the ocean. These waves propagate long distances in the Sound Fixing and Ranging (SOFAR) channel and tend to be the largest observed arrivals from seismic events. Thus, an understanding of their generation is important for event detection, localization, and source-type discrimination. Recently benchmarked seismic self-starting fields are used to generate elastic parabolic equation solutions that demonstrate generation and propagation of oceanic T-waves in range-dependent underwater acoustic environments. Both downward sloping and abyssal ocean range-dependent environments are considered, and results demonstrate conversion of elastic waves into water-borne oceanic T-waves. Examples demonstrating long-range broadband T-wave propagation in range-dependent environments are shown. These results confirm that elastic parabolic equation solutions are valuable for characterization of the relationships between T-wave propagation and variations in range-dependent bathymetry or elastic material parameters, as well as for modeling T-wave receptions at hydrophone arrays or coastal receiving stations.

  17. High frequency seismic noise generated from breaking swallow water ocean waves and the link to time-variable sea states

    NASA Astrophysics Data System (ADS)

    Poppeliers, C.; Mallinson, D. J.

    2015-12-01

    Breaking waves in the near-shore are known to generate a significant amount of high frequency (f>5 Hz) energy. We investigate the correlation between the spectrum of seismic energy and the local sea states. We deployed a single three-component broadband seismometer approximately 50 m from the sea shore and recorded continuously for approximately 10 days. Our observations show that during elevated sea states, and presumably larger breaking waves in the surf zone, the power spectral density of the wave-generated seismic energy shifts to lower frequencies and higher spectral amplitudes. The correlation of the seismic spectral power to the height and period of ocean waves suggests that seismic observations can be used as a proxy for local sea states, which may have implications for sea shore sediment transport.

  18. Modeling the Ocean Tide for Tidal Power Generation Applications

    NASA Astrophysics Data System (ADS)

    Kawase, M.; Gedney, M.

    2014-12-01

    Recent years have seen renewed interest in the ocean tide as a source of energy for electrical power generation. Unlike in the 1960s, when the tidal barrage was the predominant method of power extraction considered and implemented, the current methodology favors operation of a free-stream turbine or an array of them in strong tidal currents. As tidal power generation moves from pilot-scale projects to actual array implementations, numerical modeling of tidal currents is expected to play an increasing role in site selection, resource assessment, array design, and environmental impact assessment. In this presentation, a simple, coupled ocean/estuary model designed for research into fundamental aspects of tidal power generation is described. The model consists of a Pacific Ocean-size rectangular basin and a connected fjord-like embayment with dimensions similar to that of Puget Sound, Washington, one of the potential power generation sites in the United States. The model is forced by an idealized lunar tide-generating potential. The study focuses on the energetics of a tidal system including tidal power extraction at both global and regional scales. The hyperbolic nature of the governing shallow water equations means consequence of tidal power extraction cannot be limited to the local waters, but is global in extent. Modeling power extraction with a regional model with standard boundary conditions introduces uncertainties of 3 ~ 25% in the power extraction estimate depending on the level of extraction. Power extraction in the model has a well-defined maximum (~800 MW in a standard case) that is in agreement with previous theoretical studies. Natural energy dissipation and tidal power extraction strongly interact; for a turbine array of a given capacity, the higher the level of natural dissipation the lower the power the array can extract. Conversely, power extraction leads to a decrease in the level of natural dissipation (Figure) as well as the tidal range and the

  19. Surface wave effect on the upper ocean in marine forecast

    NASA Astrophysics Data System (ADS)

    Wang, Guansuo; Qiao, Fangli; Xia, Changshui; Zhao, Chang

    2015-04-01

    An Operational Coupled Forecast System for the seas off China and adjacent (OCFS-C) is constructed based on the paralleled wave-circulation coupled model, which is tested with comprehensive experiments and operational since November 1st, 2007. The main feature of the system is that the wave-induced mixing is considered in circulation model. Daily analyses and three day forecasts of three-dimensional temperature, salinity, currents and wave height are produced. Coverage is global at 1/2 degreed resolution with nested models up to 1/24 degree resolution in China Sea. Daily remote sensing sea surface temperatures (SST) are taken to relax to an analytical product as hot restarting fields for OCFS-C by the Nudging techniques. Forecasting-data inter-comparisons are performed to measure the effectiveness of OCFS-C in predicting upper-ocean quantities including SST, mixed layer depth (MLD) and subsurface temperature. The variety of performance with lead time and real-time is discussed as well using the daily statistic results for SST between forecast and satellite data. Several buoy observations and many Argo profiles are used for this validation. Except the conventional statistical metrics, non-dimension skill scores (SS) is taken to estimate forecast skill. Model SST comparisons with more one year-long SST time series from 2 buoys given a large SS value (more than 0.90). And skill in predicting the seasonal variability of SST is confirmed. Model subsurface temperature comparisons with that from a lot of Argo profiles indicated that OCFS-C has low skill in predicting subsurface temperatures between 80m and 120m. Inter-comparisons of MLD reveal that MLD from model is shallower than that from Argo profiles by about 12m. QCFS-C is successful and steady in predicting MLD. The daily statistic results for SST between 1-d, 2-d and 3-d forecast and data is adopted to describe variability of Skill in predicting SST with lead time or real time. In a word QCFS-C shows reasonable

  20. The local properties of ocean surface waves by the phase-time method

    NASA Technical Reports Server (NTRS)

    Huang, Norden E.; Long, Steven R.; Tung, Chi-Chao; Donelan, Mark A.; Yuan, Yeli; Lai, Ronald J.

    1992-01-01

    A new approach using phase information to view and study the properties of frequency modulation, wave group structures, and wave breaking is presented. The method is applied to ocean wave time series data and a new type of wave group (containing the large 'rogue' waves) is identified. The method also has the capability of broad applications in the analysis of time series data in general.

  1. Freak Waves In The Ocean A~é­ We Need Continuous Measurements!

    NASA Astrophysics Data System (ADS)

    Liu, P.; Teng, C.; Mori, N.

    Freak waves, sometimes also known as rogue waves, are a particular kind of ocean waves that displays a singular, unexpected, and unusually high wave profile with an extraordinarily large and steep trough or crest. The existence of freak waves has be- come widely accepted while it always poses severe hazard to the navy fleets, merchant marines, offshore structures, and virtually all oceanic ventures. Multitudes of seagoing vessels and mariners have encountered freak waves over the years, many had resulted in disasters. The emerging interest in freak waves and the quest to grasp an understand- ing of the phenomenon have inspired numerous theoretical conjectures in recent years. But the practical void of actual field observation on freak waves renders even the well- developed theories remain unverified. Furthermore, the present wave measurement systems, which have been in practice for the last 5 decades, are not at all designed to capture freak waves. We wish therefore to propose and petition to all oceanic scientist and engineers to consider undertaking an unprecedented but technologically feasible practice of making continuous and uninterrupted wave measurements. As freak waves can happen anywhere in the ocean and at anytime, the continuous and uninterrupted measurements at a fixed station would certainly be warranted to document the occur- rence of freak waves, if present, and thus lead to basic realizations of the underlying driving mechanisms.

  2. Propagation and Directional Scattering of Ocean Waves in the Marginal Ice Zone and Neighboring Seas

    DTIC Science & Technology

    2015-09-30

    the spatial and temporal variability of sea state, and improve forecasting of waves on the open ocean and in the marginal ice zone; 2. Develop an...Transition the methodology of Perrie and Hu (1996) to the state-of-the-art for operational wave forecasting , for example WW3, version 4.18. Incorporation... forecasting , specifically, WAVEWATCHIII (WW3), version 4.18. This involves incorporation of the scattering term in modern ocean wave models requires some pre

  3. Sensitivity of Radar Wave Propagation Power to the Marine Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Lentini, N.; Hackett, E. E.

    2014-12-01

    Radar is a remote sensor used for scientific, meteorological, and military applications. Radar waves are affected by the medium through which they propagate, impacting the accuracy of radar measurements. Thus, environmental effects should be understood and quantified. The marine atmospheric boundary layer (MABL) is highly dynamic and turbulent, and affects radar wave propagation. The ocean surface roughness impacts scattering behavior. These effects cause variability in constructive and destructive interference patterns due to reflection from the ocean surface, known as multipath. The atmospheric effects cause radar waves to attenuate and refract; this study focuses on the refractive effects. A high-fidelity, physics-based, parabolic wave equation simulation is used to model the radar propagation and accounts for effects of the rough ocean surface (wind seas and swell) as well as variable refractivity with height and range. We use a robust, variance based, sensitivity analysis method called the Extended Fourier Amplitude Sensitivity Test to quantify which environmental parameters have the most significant effect on the modeled radar wave propagation. In this sensitivity study, the environment is parameterized by 16 variables, 8 ocean surface and 8 atmospheric. Sensitivity analysis is performed for 3 radar frequencies (3, 9, and 15 GHz) and 2 polarizations (horizontal and vertical). Results indicate that radar wave propagation is more sensitive to atmospheric parameters than ocean surface parameters. The mixed layer has the most far-reaching effect over the entire model domain (a range of 60 km and altitudes up to 1 km), characterized by its height and refractivity gradient. The remaining important factors have a predominantly local effect in the region where they occur in the MABL atmospheric structure. At low altitudes, radar wave propagation power is most sensitive to the gradient and curvature of the vertical refractivity profile. This research provides insight

  4. An Analytical Model of Wave-Induced Longshore Current Based on Power Law Wave Height Decay.

    DTIC Science & Technology

    1988-01-01

    34I ANALYtTICAL MODEL OF NAVE-INDUCED LON6SHORE CURRENT BASED ON PONE* LAW.. (U) COASTAL ENG INEERING RESEAKNH CENTER VICKSBURG NS J N SMITH ET AL...j . - .L .V . : ; * AN ANALYTICAL MODEL OF WAVE-INDUCED ~ z * LONGSHORE CURRENT BASED ON POWER LAW * - WAVE HEIGHT DECAY by Jane McKee...I_ I IF 31592 11. TITLE (Include Security Classfication) • An Analytical Model of Wave-Induced Longshore Current Based on Power Law . Wave

  5. Ocean surface waves in Hurricane Ike (2008) and Superstorm Sandy (2012): Coupled model predictions and observations

    NASA Astrophysics Data System (ADS)

    Chen, Shuyi S.; Curcic, Milan

    2016-07-01

    Forecasting hurricane impacts of extreme winds and flooding requires accurate prediction of hurricane structure and storm-induced ocean surface waves days in advance. The waves are complex, especially near landfall when the hurricane winds and water depth varies significantly and the surface waves refract, shoal and dissipate. In this study, we examine the spatial structure, magnitude, and directional spectrum of hurricane-induced ocean waves using a high resolution, fully coupled atmosphere-wave-ocean model and observations. The coupled model predictions of ocean surface waves in Hurricane Ike (2008) over the Gulf of Mexico and Superstorm Sandy (2012) in the northeastern Atlantic and coastal region are evaluated with the NDBC buoy and satellite altimeter observations. Although there are characteristics that are general to ocean waves in both hurricanes as documented in previous studies, wave fields in Ike and Sandy possess unique properties due mostly to the distinct wind fields and coastal bathymetry in the two storms. Several processes are found to significantly modulate hurricane surface waves near landfall. First, the phase speed and group velocities decrease as the waves become shorter and steeper in shallow water, effectively increasing surface roughness and wind stress. Second, the bottom-induced refraction acts to turn the waves toward the coast, increasing the misalignment between the wind and waves. Third, as the hurricane translates over land, the left side of the storm center is characterized by offshore winds over very short fetch, which opposes incoming swell. Landfalling hurricanes produce broader wave spectra overall than that of the open ocean. The front-left quadrant is most complex, where the combination of windsea, swell propagating against the wind, increasing wind-wave stress, and interaction with the coastal topography requires a fully coupled model to meet these challenges in hurricane wave and surge prediction.

  6. Identifying the types of waves: A value adding study on the ocean observing data buoy system

    NASA Astrophysics Data System (ADS)

    Ramakrishnan, B.; Sannasiraj, S.; Sundar, V.

    2007-05-01

    Understanding of the wave climate in a particular place of interest is one of the primary aspects of any ocean observing system. Engineers and scientists working in the area of coastal or offshore engineering require to have knowledge on the types of waves that predominantly prevailing not only for the design of the ocean structures but also to understand the physical behavior of ocean surface. For example, identification of breaking waves is given prime importance as it has potential to answer for many of the water-air interaction or turbulence mixing problems. On the other hand, group of waves in which successive wave heights exceed the significant value could exert tremendous forces on the ocean structures and may lead catastrophic damage to it. Apart from deriving the conventional information such as the significant wave periods, heights and the predominant direction of prevailing, knowledge on the existence of type of waves would certainly help the designers, engineers and researchers. In an attempt to classify the types of waves from the buoy measurements, a detailed experimental program was conducted in the Department of Ocean Engineering, Indian Institute of Technology Madras. The buoy model was subjected to variety of waves such as group and breaking waves. The challenging task of the study is to simulate the group and breaking waves in the controlled laboratory environment. For which, initially, these waves are simulated theoretically, which intern converted into first order wave paddle signals to simulate the waves in the flume. The buoy heave, surge and pitch motions were measured by using potentiometers and the non-contact motion capturing cameras. The experimentally obtained wave elevation and the buoy motions time histories were analyzed by statistical, continuous wavelet transformation and phase-time methods to find the traces of wave types. A careful step by step analysis of the buoy motions yields presence of wave groupiness and breaking events

  7. Altimeter Observations of Baroclinic Oceanic Inertia-Gravity Wave Turbulence

    NASA Technical Reports Server (NTRS)

    Glazman, R. E.; Cheng, B.

    1996-01-01

    For a wide range of nonlinear wave processes - from capillary to planetary waves - theory predicts the existence of Kolmogorov-type spectral cascades of energy and other conserved quantities occuring via nonlinear resonant wave-wave interactions. So far, observations of wave turbulence (WT) have been limited to small-scale processes such as surface gravity and capillary-gravity waves.

  8. Separating Internal Waves and Vortical Structure in the Open Ocean

    NASA Astrophysics Data System (ADS)

    Lauffenburger, N. E.; Sanford, T. B.; Lien, R.

    2012-12-01

    Deviating from past oceanographic surveys, a new, powerful array of profiling floats has been deployed for three weeks in the Sargasso Sea to monitor the evolving sub-mesoscale field. Using 18-20 EM-APEX floats, profiling to 100 m depth simultaneously, velocity (U and V), temperature, salinity and microstructure measurements (χ) were made on horizontal scales between 100 m and 10 km. This strategy provided a 3-D snapshot of the physical properties every half hour, which significantly reduces temporal aliasing. Area-averaged relative vorticity, vortex stretching, non-linear twisting, horizontal divergence and Ertel's potential vorticity have been computed and projected onto isopycnal surfaces. Since vortical modes carry Ertel's potential vorticity (and internal waves do not), this is a useful step in understanding the energetic contribution of vortical motions to the background internal wave field on small scales. In addition, the temporal material conservation law of Ertel's potential vorticity will be tested for the first time by determining the advection of the floats' measurements relative to the motion of the water parcels and by computing the horizontal gradients of the potential vorticity signal. The three deployments provide data to analyze the interaction of inertial waves, vortical processes and barotropic tides in and out of active frontogenesis.

  9. 77 FR 50062 - Safety Zone; Embry-Riddle Wings and Waves, Atlantic Ocean; Daytona Beach, FL

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-20

    ... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Embry-Riddle Wings and Waves, Atlantic... Daytona Beach, Florida during the Embry-Riddle Wings and Waves air show. The event is scheduled to take...: Sec. 165.T07-0653 Safety Zone; Embry Riddle Wings and Waves, Atlantic Ocean, Daytona Beach, FL....

  10. Evidence of Doppler-shifted Bragg scattering in the vertical plane by ocean surface waves.

    PubMed

    Lynch, Stephen D; D'Spain, Gerald L

    2012-03-01

    A set of narrowband tones (280, 370, 535, and 695 Hz) were transmitted by an acoustic source mounted on the ocean floor in 10 m deep water and received by a 64-element hydrophone line array lying on the ocean bottom 1.25 km away. Beamformer output in the vertical plane for the received acoustic tones shows evidence of Doppler-shifted Bragg scattering of the transmitted acoustic signals by the ocean surface waves. The received, scattered signals show dependence on the ocean surface wave frequencies and wavenumber vectors, as well as on acoustic frequencies and acoustic mode wavenumbers. Sidebands in the beamformer output are offset in frequency by amounts corresponding to ocean surface wave frequencies. Deviations in vertical arrival angle from specular reflection agree with those predicted by the Bragg condition through first-order perturbation theory using measured directional surface wave spectra and acoustic modes measured by the horizontal hydrophone array.

  11. Validation Test Report for the Coupled Ocean/Atmosphere MesoscalePrediction System (COAMPS) Version 5.0: Ocean/Wave Component Validation

    DTIC Science & Technology

    2012-12-31

    to ocean model NCOM. The ocean model passes surface currents and water levels to the wave model SWAN . Ocean-wave coupling shows improvement and...NEARSHORE ( SWAN ) MODEL ................................................................................................. 4  2.4  EARTH SYSTEM MODELING...COUPLING AND  SWAN  SENSITIVITY TO WAVE DISSIPATION AND DRAG COEFFICIENT ..................................... 7  2.7  DOCUMENT OVERVIEW

  12. On the focusing issue of synthetic aperture radar imaging of ocean waves

    SciTech Connect

    Bruning, C. ); Alpers, W.R. ); Schroter, J.G. )

    1991-01-01

    It is now widely accepted that the imaging of ocean surface waves by synthetic aperture radar (SAR) can be adequately described by velocity bunching theory in conjunction with the two-scale wave model. However, it has been conjectured that this theory is incapable of explaining why, under certain conditions, the image contrast of airborne SAR imagery of ocean waves can be enhanced by defocusing the SAR processor. It this were true it would raise serious doubts about the validity of the velocity bunching theory to describe the SAR imaging of ocean waves. In this paper the velocity bunching theory is defended. It is shown that image contrast enhancement by defocusing can also be obtained by this theory, which does not require the introduction of the phase or group velocity of the long ocean waves as a basic element of the SAR imaging theory.

  13. 76 FR 63917 - Ocean Renewable Power Company, LLC; Notice of Application Accepted for Filing, Soliciting Motions...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-14

    ... Federal Energy Regulatory Commission Ocean Renewable Power Company, LLC; Notice of Application Accepted.... d. Applicant: Ocean Renewable Power Company, LLC. e. Name of Project: Cobscook Bay Tidal Energy...)-828(c). h. Applicant Contact: Christopher R. Sauer, Ocean Renewable Power Company, LLC, 120...

  14. On Impacts of Ocean Waves in Marginal Ice Zones and their Repercussions for Arctic Ice/Ocean Models (Invited)

    NASA Astrophysics Data System (ADS)

    Squire, V. A.

    2013-12-01

    Associated with a gradual metamorphosis of summer Arctic sea ice -- from a quasi-continuous ice sheet punctuated by pressure ridges and leads to a mélange of ice floes resembling a MIZ, is an augmented presence of sizeable ocean waves that may have propagated into the pack ice from distant storms or have arisen within the MIZ itself due to the larger fetches that are now more common [Francis et al., 2011]. If sufficiently forceful as they pass through the ice field, these waves can break up the ice floes to create a new floe size distribution (FSD), change local concentration by moving floes around, and supplement the melting that is occurring because of ice albedo feedback. In turn, the ocean waves themselves attenuate due to conservative scattering from the randomly-sized, spatially-disordered floes and cakes making up the MIZ that diffuse the waves and return energy to neighboring open water, and lose energy through several prospective dissipative processes. Consequently, the omission of ocean waves from ice/ocean models is unwise, as they can potentially alter atmosphere-ice-ocean coupling appreciably by affecting MIZ morphology so radically. In a series of 3 research projects, involving scientists from Norway, Canada, Australia and NZ, we have systematically investigated how ocean wave interactions with sea ice can be embedded in an ice/ocean model; first at high resolution in the Fram Strait and later in other MIZ around the Arctic Basin. In each case it has been possible to track how the MIZ forms and, on the basis of its FSD or an abrupt change of concentration, how wide it becomes as a result of an inbound wave field provided by a spectral model such as WAM. Initially unidirectional seas were considered [Williams et al., 2013ab] but more sophisticated 2D scattering paradigms are now being developed that allow directionally defined seas to be modeled. Based upon the recognition that a MIZ can be delineated into a number of contiguous bands of ice floes

  15. Wave power focusing due to the Bragg resonance

    NASA Astrophysics Data System (ADS)

    Tao, Ai-feng; Yan, Jin; Wang, Yi; Zheng, Jin-hai; Fan, Jun; Qin, Chuan

    2017-08-01

    Wave energy has drawn much attention as an achievable way to exploit the renewable energy. At present, in order to enhance the wave energy extraction, most efforts have been concentrated on optimizing the wave energy convertor and the power take-off system mechanically and electrically. However, focusing the wave power in specific wave field could also be an alternative to improve the wave energy extraction. In this experimental study, the Bragg resonance effect is applied to focus the wave energy. Because the Bragg resonance effect of the rippled bottom largely amplifies the wave reflection, leading to a significant increase of wave focusing. Achieved with an energy conversion system consisting of a point absorber and a permanent magnet single phase linear motor, the wave energy extracted in the wave flume with and without Bragg resonance effect was measured and compared quantitatively in experiment. It shows that energy extraction by a point absorber from a standing wave field resulted from Bragg resonance effect can be remarkably increased compared with that from a propagating wave field (without Bragg resonance effect).

  16. Diffraction from sharply peaked waves as an ocean surface scattering mechanism

    NASA Technical Reports Server (NTRS)

    Jensen, Glenn A.; Vesecky, John F.; Glazman, Roman E.

    1992-01-01

    The role of sharply peaked waves as a major ocean scattering mechanism for radar is investigated. A prototype three-dimensional wedgelike wave shape was constructed, and its scattering properties were analyzed. Using results from the theory of the statistical geometry of the ocean surface, it is estimated how many such wedges there are per unit area, as a function of sea conditions. Taking into account a directional distribution of the wedges, the total radar cross section due to wedge diffraction effects is estimated. At large incidence angles, wedge diffraction appears to account for a significant amount of the radar cross section on the ocean surface. The wedgelike wave shape used is a more realistic representation of sharplypeaked waves. The scale-size and spatial density of the wedgelike waves are computed directly from the wave-height spectrum.

  17. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, Edward J.; Wright, C. Wayne; Vandemark, Douglas C.; Krabill, William B.; Garcia, Andrew W.; Houston, Samuel H.; Powell, Mark D.; Black, Peter G.; Marks, Frank D.

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1' half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the off-nadir angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving toward 330 deg at about 5 m/s. Individual waves up to 18 m height were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the eye, and made five eye penetrations. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft flight lines included segments near and along the shoreline as well as far offshore. Animations of the directional wave spectrum spatial variation along the aircraft tracks on the two flights

  18. Hurricane Directional Wave Spectrum Spatial Variation in the Open Ocean and at Landfall

    NASA Technical Reports Server (NTRS)

    Walsh, Edward J.; Wright, C. Wayne; Vandemark, Douglas C.; Krabill, William B.; Garcia, Andrew W.; Houston, Samuel H.; Powell, Mark D.; Black, Peter G.; Marks, Frank D.

    2000-01-01

    The sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane hunter aircraft at 1.5 km height. The SRA measures the energetic portion of the directional wave spectrum by generating a topographic map of the sea surface. At 8 Hz, the SRA sweeps a radar beam of 1' half-power width (two-way) across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 positions. These slant ranges are multiplied by the cosine of the off-nadir angles to determine the vertical distances from the aircraft to the sea surface. Subtracting these distances from the aircraft height produces the sea surface elevation map. The sea surface topography is interpolated to a uniform grid, transformed by a two dimensional FFT, and Doppler corrected. The open-ocean data were acquired on 24 August 1998 when hurricane Bonnie was east of the Bahamas and moving toward 330 deg at about 5 m/s. Individual waves up to 18 m height were observed and the spatial variation of the wave field was dramatic. The dominant waves generally propagated at significant angles to the downwind direction. At some positions there were three different wave fields of comparable energy crossing each other. The NOAA aircraft spent over five hours within 180 km of the eye, and made five eye penetrations. On 26 August 1998, the NOAA aircraft flew at 2.2 km height when hurricane Bonnie was making landfall near Wilmington, NC, documenting the directional wave spectrum in the region between Charleston, SC and Cape Hatteras, NC. The aircraft flight lines included segments near and along the shoreline as well as far offshore. Animations of the directional wave spectrum spatial variation along the aircraft tracks on the two flights

  19. Using Seismic Noise Generated by Ocean Waves to Monitor Seasonal and Secular Changes in Antarctic Sea Ice

    NASA Astrophysics Data System (ADS)

    Anthony, R. E.; Aster, R. C.; Thompson, D. W. J.; Reusch, D. B.

    2015-12-01

    The Earth's background seismic noise between ~1-30 seconds period is commonly dominated by microseisms that arise when oceanic wave energy and swell are converted to ground displacement as the waves crash and interact with the continental shelf. Peak power in the microseism bands at high-latitude stations typically coincides with large-scale extratropical cyclonic winter storm activity. However, due to the seasonal formation of sea ice around the continental shelves of polar regions, oceanic waves are impeded from efficiently exciting seismic energy, and annual peak microseism power thus occurs prior to the midwinter storm peak. We utilize recently collected seismic data from across the continent to show that power in three distinct microseism bands is found to be strongly anti-correlated with sea ice extent, with the shorter period signals being exceptionally sensitive to local conditions. Particular focus is given to the Antarctic Peninsula, the strongest source of microseism energy on the continent, where we note a significant increase in primary microseism power attributable to near coastal sources from 1993-2012. This increase correlates with regional sea ice loss driven by large-scale wind changes associated with strengthening of the Southern Annular Mode. Additionally, we use microseism analysis to explore changes in sea ice strength and extent relative to wave state and storminess in the Southern Oceans. Investigation of microseism seasonality, power, and decadal-scale trends in the Antarctic shows promise as a spatially integrated tool for monitoring and interpreting such sea ice strength and extent metrics through time.

  20. Waves and operational oceanography: Toward a coherent description of the upper ocean

    NASA Astrophysics Data System (ADS)

    Ardhuin, Fabrice; Jenkins, Alastair D.; Hauser, Daniéle; Reniers, Ad; Chapron, Bertrand

    The availability of new operational services for ocean circulation modeling presents a unique opportunity to rethink the operational forecasting of ocean waves and how circulation and waves may be combined to provide a better understanding of the upper ocean and enhanced services to society. The largescale oil spill caused by the wreck of the tanker Prestige off the Spanish coast in November 2002, and uncertainties on the fate of that pollution, illustrated the gaps in means of observations and knowledge of relevant processes.The idea of a coupled atmosphere-wavesocean model was proposed by Klaus Hasselmann [Hasselmann, 1991], in the context of climate modeling. As waves are the “gearbox” between the atmosphere and the ocean, a detailed understanding of waves can significantly improve the parameterization of air-sea fluxes and surface processes. Besides, Earth observation systems rely extensively on satellite remote sensing techniques for surface winds, temperature, sea level, ocean color, and sea ice, all affected by surface waves. Hasselmann viewed the future of wave modeling as the development of this central gearbox of a general Earth observation and monitoring system, providing fluxes between ocean and atmosphere in a way consistent with satellite observations. This vision, though slow to materialize, is highly relevant for short-term forecasting in the coastal ocean.

  1. Accuracy of Satellite-Measured Wave Heights in the Australian Region for Wave Power Applications

    ERIC Educational Resources Information Center

    Meath, Sian E.; Aye, Lu; Haritos, Nicholas

    2008-01-01

    This article focuses on the accuracy of satellite data, which may then be used in wave power applications. The satellite data are compared to data from wave buoys, which are currently considered to be the most accurate of the devices available for measuring wave characteristics. This article presents an analysis of satellite- (Topex/Poseidon) and…

  2. Accuracy of Satellite-Measured Wave Heights in the Australian Region for Wave Power Applications

    ERIC Educational Resources Information Center

    Meath, Sian E.; Aye, Lu; Haritos, Nicholas

    2008-01-01

    This article focuses on the accuracy of satellite data, which may then be used in wave power applications. The satellite data are compared to data from wave buoys, which are currently considered to be the most accurate of the devices available for measuring wave characteristics. This article presents an analysis of satellite- (Topex/Poseidon) and…

  3. Observations of Sea Surface Mean Square Slope During the Southern Ocean Waves Experiment

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Vandemark, D. C.; Wright, C. W.; Banner, M. L.; Chen, W.; Swift, R. N.; Scott, J. F.; Hines, D. E.; Jensen, J.; Lee, S.; Gerlach, John C. (Technical Monitor)

    2001-01-01

    For the Southern Ocean Waves Experiment (SOWEX), conducted in June 1992 out of Hobart, Tasmania, the NASA Scanning Radar Altimeter (SRA) was shipped to Australia and installed on a CSIRO Fokker F-27 research aircraft instrumented to make comprehensive surface layer measurements of air-sea interaction fluxes. The SRA sweeps a radar beam of P (two-way) half-power width across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 cross-track positions. In realtime, the slant ranges are multiplied by the cosine of the off-nadir incidence angles (including the effect of aircraft roll attitude) to determine the vertical distances from the aircraft to the sea surface. These distances are subtracted from the aircraft height to produce a sea-surface elevation map, which is displayed on a monitor in the aircraft to enable real-time assessments of data quality and wave properties. The sea surface mean square slope (mss), which is predominantly caused by the short waves, was determined from the backscattered power falloff with incidence angle measured by the SRA in the plane normal to the aircraft heading. On each flight, data were acquired at 240 m altitude while the aircraft was in a 7 degree roll attitude, interrogating off-nadir incidence angles from -15 degrees through nadir to +29 degrees. The aircraft turned azimuthally through 810 degrees in this attitude, mapping the azimuthal dependence of the backscattered power falloff with incidence angle. Two sets of turning data were acquired on each day, before and after the aircraft measured wind stress at low altitude (12 meters to 65 meters). Wave topography and backscattered power for mss were also acquired during those level flight segments whenever the aircraft altitude was above the SRA minimum range of 35 m. Data were collected over a wide range of wind and sea

  4. Observations of Sea Surface Mean Square Slope During the Southern Ocean Waves Experiment

    NASA Technical Reports Server (NTRS)

    Walsh, E. J.; Vandemark, D. C.; Wright, C. W.; Banner, M. L.; Chen, W.; Swift, R. N.; Scott, J. F.; Hines, D. E.; Jensen, J.; Lee, S.; hide

    2001-01-01

    For the Southern Ocean Waves Experiment (SOWEX), conducted in June 1992 out of Hobart, Tasmania, the NASA Scanning Radar Altimeter (SRA) was shipped to Australia and installed on a CSIRO Fokker F-27 research aircraft instrumented to make comprehensive surface layer measurements of air-sea interaction fluxes. The SRA sweeps a radar beam of P (two-way) half-power width across the aircraft ground track over a swath equal to 0.8 of the aircraft height, simultaneously measuring the backscattered power at its 36 GHz (8.3 mm) operating frequency and the range to the sea surface at 64 cross-track positions. In realtime, the slant ranges are multiplied by the cosine of the off-nadir incidence angles (including the effect of aircraft roll attitude) to determine the vertical distances from the aircraft to the sea surface. These distances are subtracted from the aircraft height to produce a sea-surface elevation map, which is displayed on a monitor in the aircraft to enable real-time assessments of data quality and wave properties. The sea surface mean square slope (mss), which is predominantly caused by the short waves, was determined from the backscattered power falloff with incidence angle measured by the SRA in the plane normal to the aircraft heading. On each flight, data were acquired at 240 m altitude while the aircraft was in a 7 degree roll attitude, interrogating off-nadir incidence angles from -15 degrees through nadir to +29 degrees. The aircraft turned azimuthally through 810 degrees in this attitude, mapping the azimuthal dependence of the backscattered power falloff with incidence angle. Two sets of turning data were acquired on each day, before and after the aircraft measured wind stress at low altitude (12 meters to 65 meters). Wave topography and backscattered power for mss were also acquired during those level flight segments whenever the aircraft altitude was above the SRA minimum range of 35 m. Data were collected over a wide range of wind and sea

  5. Towards a coupled ocean-wave-atmosphere four dimensional data assimilation system

    NASA Astrophysics Data System (ADS)

    Ngodock, Hans; Carrier, Matthew; Amerault, Clark; Campbell, Timothy; Holt, Teddy; Xu, Liang; Rowley, Clark

    2015-04-01

    Individual 4dvar systems have been developed at the Naval Research Laboratory (NRL) for the ocean model (Navy coastal ocean model, NCOM), the wave model (simulating waves in the nearshore, SWAN) and the atmospheric component of the coupled ocean-atmosphere mesoscale prediction system (COAMPS). Although the three models within COAPMS are coupled in the forward integration, the initialization of each model is done separately. The coupled system forecast is hindered, however, by the lack of a fully coupled and dynamically balanced ocean-atmosphere analysis. A recent work by Ngodock and Carrier (2013) has highlighted this shortcoming with the NCOM-4DVAR, showing that while the NCOM-4DVAR is able to adjust the ocean state properly, the resulting ocean forecast degrades quickly due to the fact that the atmospheric state has not also been adjusted relative to the ocean observations. Likewise, . Currently, the coupled model is initialized using separate analyses for the ocean and atmosphere that do not account for observations in the adjacent fluid. The lack of a coupled analysis produces shocks in the coupled model in the form of gravity waves that degrade the information gained through DA and increase the error in the coupled forecast. The goal of this presentation is to describe ongoing developments at NRL in building a fully coupled ocean-wave-atmosphere four-dimensional variational (4dvar) data assimilation system using the Earth System Modeling Framework (ESMF).

  6. 2D ocean waves spectra from space: a challenge for validation and synergetic use

    NASA Astrophysics Data System (ADS)

    Mouche, A.; Wang, H.; Husson, R.; Guitton, G.; Chapron, B.; Li, H.

    2016-05-01

    Sentinel-1 A now routinely acquires data over the ocean since 2014. Data are processed by ESA through the Payload Data Ground Segment up to Level-2 for Copernicus users. Level-2 products consist of geo-located geophysical parameters related to wind, waves and ocean current. In particular, Sentinel-1A wave measurements provide 2D ocean swell spectra (2D wave energy distribution as a function of wavelength and direction) as well as integrated parameters such as significant wave height, dominant wavelength and direction for each partition. In 2016, Sentinel-1 B will be launched by ESA and GF-3 by CNSA. Then in 2018, CFOSAT (China France Oceanography Satellite project), a joint mission from the Chinese and French Space Agencies, will be launched. They will also provide 2D Ocean waves spectra. This paper focuses on the techniques used to validate 2D-ocean waves as measured by satellite and the challenges and opportunities of such a program for ocean waves measurements from space.

  7. Quasi-stationary waves and their connection to oceanic and atmospheric anomalies

    NASA Astrophysics Data System (ADS)

    Wolf, Gabriel; Brayshaw, David; Klingaman, Nicholas; Czaja, Arnaud

    2017-04-01

    Strong quasi-stationary atmospheric waves are known to be associated with persistent extreme weather events. We are especially interested in possible oceanic drivers for such quasi-stationary waves over the European-Atlantic region. The existence of such oceanic drivers would suggest potential predictability, or at least a better risk assessment of such events, on a timescale of several weeks or more. We define quasi-stationary waves by the longitudinal envelope of the lowpass filtered meridional wind. For a deeper understanding of these waves and the associated large-scale weather, we created and analysed a climatology of these waves. Besides a clear connection between quasi-stationary waves and persistent extreme temperature and precipitation events, these waves are strongly associated with well-known global pattern indices, especially the Arctic Oscillation/North Atlantic Oscillation and the El Nino-Southern Oscillation. An extensive analysis of the connection between these waves and oceanic anomalies further revealed a connection between Pacific surface heat fluxes and large scale quasi-stationary waves over the Atlantic and Europe. We investigate these connections to better understand the evolution of such quasi-stationary waves and the importance of oceanic anomalies as possible drivers.

  8. Structure and characteristics of submonthly-scale waves along the Indian Ocean ITCZ

    NASA Astrophysics Data System (ADS)

    Fukutomi, Yoshiki; Yasunari, Tetsuzo

    2013-04-01

    This study examines wave disturbances on submonthly (6-30-day) timescales over the tropical Indian Ocean during Southern Hemisphere summer using Japanese Reanalysis (JRA25-JCDAS) products and National Oceanic and Atmospheric Administration outgoing longwave radiation data. The analysis period is December-February for the 29 years from 1979/1980 through 2007/2008. An extended empirical orthogonal function (EEOF) analysis of daily 850-hPa meridional wind anomalies reveals a well-organized wave-train pattern as a dominant mode of variability over the tropical Indian Ocean. Daily lagged composite analyses for various atmospheric variables based on the EEOF result show the structure and evolution of a wave train consisting of meridionally elongated troughs and ridges along the Indian Ocean Intertropical Convergence Zone (ITCZ). The wave train is oriented in a northeast-southwest direction from Sumatra toward Madagascar. The waves have zonal wavelengths of about 3,000-5,000 km and exhibit westward and southwestward phase propagation. Individual troughs and ridges as part of the wave train sequentially travel westward and southwestward from the west of Sumatra into Madagascar. Meanwhile, eastward and northeastward amplification of the wave train occurs associated with the successive growth of new troughs and ridges over the equatorial eastern Indian Ocean. This could be induced by eastward and northeastward wave energy dispersion from the southwestern to eastern Indian Ocean along the mean monsoon westerly flow. In addition, the waves modulate the ITCZ convection. Correlation statistics show the average behavior of the wave disturbances over the tropical Indian Ocean. These statistics and other diagnostic measures are used to characterize the waves obtained from the composite analysis. The waves appear to be connected to the monsoon westerly flow. The waves tend to propagate through a band of the large meridional gradient of absolute vorticity produced by the mean monsoon

  9. Fundamental research on oscillating water column wave power absorbers

    SciTech Connect

    Maeda, H.; Kato, W.; Kinoshita, T.; Masuda, K.

    1985-03-01

    An oscillating water column (OWC) wave power absorber is one of the most promising devices, as well as the Salter Duck and the Clam. This paper presents a simple prediction method, in which the equivalent floating body approximation is used, for absorbing wave power characteristics of an oscillating water column device. The effects of the compressibility of air and inertia of an air turbine and electric generator on absorbed wave power are obtained by using the equivalent electric circuit concept. Both the experimental and theoretical studies are carried out in this paper.

  10. Secondary microseism generation mechanisms and microseism derived ocean wave parameters, NE Atlantic, West of Ireland.

    NASA Astrophysics Data System (ADS)

    Donne, S. E.; Bean, C. J.; Lokmer, I.; Nicolau, M.; O'Neill, M.

    2014-12-01

    Ocean waves, driven by atmospheric processes, generate faint continuous Earth vibrations known as microseisms (Bromirski, 1999). Under certain conditions, ocean waves travelling in opposite directions may interact with one another producing a partial or full standing wave. This wave-wave interaction produces a pressure profile, unattenuated with depth, which exerts a pressure change at the seafloor, resulting in secondary microseisms in the 0.1-0.33 Hz band. There are clear correlations between microseism amplitude and storm and ocean wave intensity. We aim to determine ocean wave heights in the Northeast Atlantic offshore Ireland at individual buoy locations, using terrestrially recorded microseism signals. Two evolutionary approaches are used: Artificial Neural Networks (ANN) and Grammatical Evolution (GE). These systems learn to interpret particular input patterns and corresponding outputs and expose the often complex underlying relationship between them. They learn by example and are therefore entirely data driven so data selection is extremely important for the success of the methods. An analysis and comparison of the performance of these methods for a five month period in 2013 will be presented showing that ocean wave characteristics may be reconstructed using microseism amplitudes, adopting a purely data driven approach. There are periods during the year when the estimations made from both the GE and ANN are delayed in time by 10 to 20 hours when compared to the target buoy measurements. These delays hold important information about the totality of the conditions needed for microseism generation, an analysis of which will be presented.

  11. An idealised experimental model of ocean surface wave transmission by an ice floe

    NASA Astrophysics Data System (ADS)

    Bennetts, L. G.; Alberello, A.; Meylan, M. H.; Cavaliere, C.; Babanin, A. V.; Toffoli, A.

    2015-12-01

    An experimental model of transmission of ocean waves by an ice floe is presented. Thin plastic plates with different material properties and thicknesses are used to model the floe. Regular incident waves with different periods and steepnesses are used, ranging from gently-sloping to storm-like conditions. A wave gauge is used to measure the water surface elevation in the lee of the floe. The depth of wave overwash on the floe is measured by a gauge in the centre of the floe's upper surface. Results show transmitted waves are regular for gently-sloping incident waves but irregular for storm-like incident waves. The proportion of the incident wave transmitted is shown to decrease as incident wave steepness increases, and to be at its minimum for an incident wavelength equal to the floe length. Further, a trend is noted for transmission to decrease as the mean wave height in the overwash region increases.

  12. The Earth's 'hum' is driven by ocean waves over the continental shelves.

    PubMed

    Webb, Spahr C

    2007-02-15

    Observations show that the seismic normal modes of the Earth at frequencies near 10 mHz are excited at a nearly constant level in the absence of large earthquakes. This background level of excitation has been called the 'hum' of the Earth, and is equivalent to the maximum excitation from a magnitude 5.75 earthquake. Its origin is debated, with most studies attributing the forcing to atmospheric turbulence, analogous to the forcing of solar oscillations by solar turbulence. Some reports also predicted that turbulence might excite the planetary modes of Mars to detectable levels. Recent observations on Earth, however, suggest that the predominant excitation source lies under the oceans. Here I show that turbulence is a very weak source, and instead it is interacting ocean waves over the shallow continental shelves that drive the hum of the Earth. Ocean waves couple into seismic waves through the quadratic nonlinearity of the surface boundary condition, which couples pairs of slowly propagating ocean waves of similar frequency to a high phase velocity component at approximately double the frequency. This is the process by which ocean waves generate the well known 'microseism peak' that dominates the seismic spectrum near 140 mHz (refs 11, 12), but at hum frequencies, the mechanism differs significantly in frequency and depth dependence. A calculation of the coupling between ocean waves and seismic modes reproduces the seismic spectrum observed. Measurements of the temporal correlation between ocean wave data and seismic data have confirmed that ocean waves, rather than atmospheric turbulence, are driving the modes of the Earth.

  13. Observation of First and Second Baroclinic Mode Yanai Waves in the Ocean

    DTIC Science & Technology

    2011-01-01

    mode oceanic Yanai waves can be compared with theory separately, and the differences between the two modes can be described explicitly. This is not...tropical instability waves in subsurface observations. /. Phys. Oceanogr. 37: 855-872. Matsuno T. 1966. Quasi - geostrophic motions in the...Group Velocity in the Ocean 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 0601153N 6. AUTHOR(S) Toshiaki Shinoda 5d

  14. Simulation based study of the effect of ocean waves on floating wind farm

    NASA Astrophysics Data System (ADS)

    Yang, Di; Meneveau, Charles; Shen, Lian

    2012-11-01

    A hybrid numerical capability is developed for the simulation of floating wind farm offshore, in which large-eddy simulation is performed for wind turbulence, and a potential flow based method is used for the simulation of ocean wavefield. The wind and wave simulations are coupled through a two-way feedback scheme. The effect of wind turbines on the wind field is represented by an actuator disk model. A variety of fully-developed and fetch-limited wind-sea conditions are considered in the study. The simulation results indicate that the offshore wind farm obtains a higher wind power extraction rate under the fully-developed wind-sea condition compared with the fetch-limited condition. This higher extraction rate is caused by the faster propagating waves and the lower sea-surface resistance on the wind when the wind-seas are fully developed. Such wave effect becomes more prominent when the turbine density of the wind farm increases. DY and LS acknowledge the support of NSF-CBET-1133700. CM acknowledges the support of NSF-CBET-1133800 and NSF-AGS-1045189.

  15. Protective, Modular Wave Power Generation System

    SciTech Connect

    Vvedensky, Jane M.; Park, Robert Y.

    2012-11-27

    The concept of small wave energy conversion modules that can be built into large, scalable arrays, in the same vein as solar panels, has been developed. This innovation lends itself to an organic business and development model, and enables the use of large-run manufacturing technology to reduce system costs. The first prototype module has been built to full-scale, and tested in a laboratory wave channel. The device has been shown to generate electricity and dissipate wave energy. Improvements need to be made to the electrical generator and a demonstration of an array of modules should be made in natural conditions.

  16. Impact of Ocean Surface Waves on Air-Sea Momentum Flux

    NASA Astrophysics Data System (ADS)

    Tamura, H.; Drennan, W. M.; Collins, C. O., III; Graber, H. C.

    2016-02-01

    In this study, we investigated the structure of turbulent air flow over ocean waves. Observations of wind and waves were retrieved by air-sea interaction spar (ASIS) buoys during the shoaling waves experiment (SHOWEX) in Duck, NC in 1999. It is shown that the turbulent velocity spectra and co-spectra for pure wind sea conditions follow the universal forms estimated by Miyake et al [1970]. In the presence of strong swells, the wave boundary layer was extended and the universal spectral scaling of u'w' broke down [Drennan et al, 1999]. On the other hand, the use of the peak wave frequency (fp) to reproduce the "universal spectra" succeeded at explaining the spectral structure of turbulent flow field. The u'w' co-spectra become negative near the fp, which suggests the upward momentum transport (i.e., negative wind stress) induced by ocean waves. Finally, we propose three turbulent flow structures for different wind-wave regimes.

  17. Technical guidance and analytic services in support of SEASAT-A. [radar altimeters for altimetry and ocean wave height

    NASA Technical Reports Server (NTRS)

    Brooks, W. L.; Dooley, R. P.

    1975-01-01

    The design of a high resolution radar for altimetry and ocean wave height estimation was studied. From basic principles, it is shown that a short pulse wide beam radar is the most appropriate and recommended technique for measuring both altitude and ocean wave height. To achieve a topographic resolution of + or - 10 cm RMS at 5.0 meter RMS wave heights, as required for SEASAT-A, it is recommended that the altimeter design include an onboard adaptive processor. The resulting design, which assumes a maximum likelihood estimation (MLE) processor, is shown to satisfy all performance requirements. A design summary is given for the recommended radar altimeter, which includes a full deramp STRETCH pulse compression technique followed by an analog filter bank to separate range returns as well as the assumed MLE processor. The feedback loop implementation of the MLE on a digital computer was examined in detail, and computer size, estimation accuracies, and bias due to range sidelobes are given for the MLE with typical SEASAT-A parameters. The standard deviation of the altitude estimate was developed and evaluated for several adaptive and nonadaptive split-gate trackers. Split-gate tracker biases due to range sidelobes and transmitter noise are examined. An approximate closed form solution for the altimeter power return is derived and evaluated. The feasibility of utilizing the basic radar altimeter design for the measurement of ocean wave spectra was examined.

  18. Satellite Synthetic Aperture Radar Detection of Ocean Internal Waves in the South China Sea

    DTIC Science & Technology

    2008-09-30

    Susanto, R. D., L. Mitnik and Q. Zheng, Ocean internal waves observed in the Lombok Strait, Oceanography, 18,4, 80-87, 2005 Susanto, R.D., A.L. Gordon and...J. Sprintall, 2007: Observations and Proxies of the Surface Layer Throughflow in Lombok Strait, J. Geophys. Res.-Oceans, Vol. 112, No. C3, C03S92

  19. Computationally Efficient Numerical Model for the Evolution of Directional Ocean Surface Waves

    NASA Astrophysics Data System (ADS)

    Malej, M.; Choi, W.; Goullet, A.

    2011-12-01

    The main focus of this work has been the asymptotic and numerical modeling of weakly nonlinear ocean surface wave fields. In particular, a development of an efficient numerical model for the evolution of nonlinear ocean waves, including extreme waves known as Rogue/Freak waves, is of direct interest. Due to their elusive and destructive nature, the media often portrays Rogue waves as unimaginatively huge and unpredictable monsters of the sea. To address some of these concerns, derivations of reduced phase-resolving numerical models, based on the small wave steepness assumption, are presented and their corresponding numerical simulations via Fourier pseudo-spectral methods are discussed. The simulations are initialized with a well-known JONSWAP wave spectrum and different angular distributions are employed. Both deterministic and Monte-Carlo ensemble average simulations were carried out. Furthermore, this work concerns the development of a new computationally efficient numerical model for the short term prediction of evolving weakly nonlinear ocean surface waves. The derivations are originally based on the work of West et al. (1987) and since the waves in the ocean tend to travel primarily in one direction, the aforementioned new numerical model is derived with an additional assumption of a weak transverse dependence. In turn, comparisons of the ensemble averaged randomly initialized spectra, as well as deterministic surface-to-surface correlations are presented. The new model is shown to behave well in various directional wave fields and can potentially be a candidate for computationally efficient prediction and propagation of extreme ocean surface waves - Rogue/Freak waves.

  20. The response of the southwest Western Australian wave climate to Indian Ocean climate variability

    NASA Astrophysics Data System (ADS)

    Wandres, Moritz; Pattiaratchi, Charitha; Hetzel, Yasha; Wijeratne, E. M. S.

    2017-04-01

    Knowledge of regional wave climates is critical for coastal planning, management, and protection. In order to develop a regional wave climate, it is important to understand the atmospheric systems responsible for wave generation. This study examines the variability of the southwest Western Australian (SWWA) shelf and nearshore wind wave climate and its relationship to southern hemisphere climate variability represented by various atmospheric indices: the southern oscillation index (SOI), the Southern Annular Mode (SAM), the Indian Ocean Dipole Mode Index (DMI), the Indian Ocean Subtropical Dipole (IOSD), the latitudinal position of the subtropical high-pressure ridge (STRP), and the corresponding intensity of the subtropical ridge (STRI). A 21-year wave hindcast (1994-2014) of the SWWA continental shelf was created using the third generation wave model Simulating WAves Nearshore (SWAN), to analyse the seasonal and inter-annual wave climate variability and its relationship to the atmospheric regime. Strong relationships between wave heights and the STRP and the STRI, a moderate correlation between the wave climate and the SAM, and no significant correlation between SOI, DMI, and IOSD and the wave climate were found. Strong spatial, seasonal, and inter-annual variability, as well as seasonal longer-term trends in the mean wave climate were studied and linked to the latitudinal changes in the subtropical high-pressure ridge and the Southern Ocean storm belt. As the Southern Ocean storm belt and the subtropical high-pressure ridge shifted southward (northward) wave heights on the SWWA shelf region decreased (increased). The wave height anomalies appear to be driven by the same atmospheric conditions that influence rainfall variability in SWWA.

  1. Energy device powered by the motion of water beneath waves

    SciTech Connect

    Smith, E.J.

    1983-02-01

    A device for extracting both kinetic and potential energy from the motion beneath waves over a considerable depth comprising a power member or sail guided to reciprocate with the movement of the water. The power sail is connected to and operates a power device such as an electric generator or pump. A second member, or sail, is located in geometric position relative to the power sail to reflect energy back to the power sail. Sensors, servo systems, and computers may be used to optimize power output. Multiple units can be arranged in ''farms'' to furnish megawatts of power.

  2. Parameterizing Plasmaspheric Hiss Wave Power by Plasmapause Location

    NASA Astrophysics Data System (ADS)

    Malaspina, D.; Jaynes, A. N.; Boule, C.; Bortnik, J.; Thaller, S. A.; Ergun, R.; Kletzing, C.; Wygant, J. R.

    2016-12-01

    Plasmaspheric hiss is a superposition of electromagnetic whistler-mode waves largely confined within the plasmasphere, the cold plasma torus surrounding Earth. Hiss plays an important role in radiation belt dynamics by pitch angle scattering electrons for a wide range of electron energies (10's of keV to > 1 MeV) which can result in their loss to the atmosphere. This interaction is often included in predictive models of radiation belt dynamics using statistical hiss wave power distributions derived from observations. However, the traditional approach to creating these distributions parameterizes hiss power by L-parameter (e.g. MacIlwain L, dipole L, or L*) and a geomagnetic index (e.g. DST or AE). Such parameterization introduces spatial averaging of dissimilar wave power radial profiles, resulting in heavily smoothed wave power distributions. This work instead parameterizes hiss wave power distributions using plasmapause location and distance from the plasmapause. Using Van Allen Probes data and these new parameterizations, previously unreported and highly repeatable features of the hiss wave power distribution become apparent. These features include: (1) The highest amplitude hiss wave power is concentrated over a narrower range of L than previous studies have indicated, and (2) the location of the peak in hiss wave power is determined by the plasmapause location, occurring at a consistent standoff distance Earthward of the plasmapause. Based on these features, parameterizing hiss using the plasmapause location and distance from the plasmapause may shed new light on hiss generation and propagation physics, as well as serve to improve the parameterization of hiss in predictive models of the radiation belts.

  3. Wave resource variability: Impacts on wave power supply over regional to international scales

    NASA Astrophysics Data System (ADS)

    Smith, Helen; Fairley, Iain; Robertson, Bryson; Abusara, Mohammad; Masters, Ian

    2017-04-01

    The intermittent, irregular and variable nature of the wave energy resource has implications for the supply of wave-generated electricity into the grid. Intermittency of renewable power may lead to frequency and voltage fluctuations in the transmission and distribution networks. A matching supply of electricity must be planned to meet the predicted demand, leading to a need for gas-fired and back-up generating plants to supplement intermittent supplies, and potentially limiting the integration of intermittent power into the grid. Issues relating to resource intermittency and their mitigation through the development of spatially separated sites have been widely researched in the wind industry, but have received little attention to date in the less mature wave industry. This study analyses the wave resource over three different spatial scales to investigate the potential impacts of the temporal and spatial resource variability on the grid supply. The primary focus is the Southwest UK, a region already home to multiple existing and proposed wave energy test sites. Concurrent wave buoy data from six locations, supported by SWAN wave model hindcast data, are analysed to assess the correlation of the resource across the region and the variation in wave power with direction. Power matrices for theoretical nearshore and offshore devices are used to calculate the maximum step change in generated power across the region as the number of deployment sites is increased. The step change analysis is also applied across national and international spatial scales using output from the European Centre for Medium-range Weather Forecasting (ECMWF) ERA-Interim hindcast model. It is found that the deployment of multiple wave energy sites, whether on a regional, national or international scale, results in both a reduction in step changes in power and reduced times of zero generation, leading to an overall smoothing of the wave-generated electrical power. This has implications for the

  4. Ocean wave properties, and implications for seismic noise from 1 to 300 s period

    NASA Astrophysics Data System (ADS)

    Ardhuin, Fabrice; Herbers, Thomas; Stutzmann, Eleonore; Obrebski, Mathias; Gualtieri, Lucia

    2014-05-01

    The Longuet-Higgins and Hasselman theory of seismic and acoustic noise generation has been expanded recently from Rayleigh waves only to body waves, including a strong seismic source reduction for ocean waves in finite water depth, which is very important for periods larger than 30 s (Ardhuin and Herbers 2013). In spite of uncertainties of seismic propagation effects, the theory is very well verified for periods 2 to 10 s. This verification required the improvement of directional wave properties represented in numerical wave models, in particular due to coastal reflection. Efforts are still required to improve the variability of shoreline reflection coefficients. We are now expanding the direct modeling of wave-generated noise towards lower and higher frequencies. At high frequencies, the variability of modeled directional properties are poorly represented, as revealed by new measurements of wave spectra. This results in a poor performance of the direct model compared to ocean bottom acoustic data, and will require an upgrade of wave generation and dissipation parameterizations. For longer periods, the theory for wave propagating over varying water depths (Hasselmann 1963) provides good order of magnitude for the vertical motion recorded from 10 to 300 s. However, some uncertainties remain due to imperfect knowldge of bottom topography and ocean wave coherence properties.

  5. Wave effects on ocean-ice interaction in the marginal ice zone

    NASA Technical Reports Server (NTRS)

    Liu, Antony K.; Hakkinen, Sirpa; Peng, Chih Y.

    1993-01-01

    The effects of wave train on ice-ocean interaction in the marginal ice zone are studied through numerical modeling. A coupled two-dimensional ice-ocean model has been developed to include wave effects and wind stress for the predictions of ice edge dynamics. The sea ice model is coupled to the reduced-gravity ocean model through interfacial stresses. The main dynamic balance in the ice momentum is between water-ice stress, wind stress, and wave radiation stresses. By considering the exchange of momentum between waves and ice pack through radiation stress for decaying waves, a parametric study of the effects of wave stress and wind stress on ice edge dynamics has been performed. The numerical results show significant effects from wave action. The ice edge is sharper, and ice edge meanders form in the marginal ice zone owing to forcing by wave action and refraction of swell system after a couple of days. Upwelling at the ice edge and eddy formation can be enhanced by the nonlinear effects of wave action; wave action sharpens the ice edge and can produce ice meandering, which enhances local Ekman pumping and pycnocline anomalies. The resulting ice concentration, pycnocline changes, and flow velocity field are shown to be consistent with previous observations.

  6. Experimental Investigation of the Power Generation Performance of Floating-Point Absorber Wave Energy Systems: Preprint

    SciTech Connect

    Li, Y.; Yu, Y.; Epler, J.; Previsic, M.

    2012-04-01

    The extraction of energy from ocean waves has gained interest in recent years. The floating-point absorber (FPA) is one of the most promising devices among a wide variety of wave energy conversion technologies. Early theoretical studies mainly focused on understanding the hydrodynamics of the system and on predicting the maximum power that could be extracted by a heaving body. These studies evolve from the investigation of floating-body interactions in offshore engineering and naval architecture disciplines. To our best knowledge, no systematic study has been reported about the investigation of the power generation performance of an FPA with a close-to-commercial design. A series of experimental tests was conducted to investigate the power extraction performance of an FPA system.

  7. TSA - A Two Scale Approximation for Wind-Generated Ocean Surface Waves

    DTIC Science & Technology

    2012-09-30

    The coastal zone involves significant potential future economic development, e.g., residences, recreation, fisheries, aquaculture , coastal...Quality of Life Development of the coastal zone involves residences, recreation, fisheries, aquaculture , coastal transportation. Ocean waves are...11p. [published] 2. Perrie, W., Guo, L ., Long, Z. and Toulany, B., 2011: Impacts of Climate Change on Autumn North Atlantic Wave Climate. 12th

  8. Nonlinearity Role in Long-Term Interaction of the Ocean Gravity Waves

    DTIC Science & Technology

    2012-09-30

    the Nonlinear Schrodinger equation and its exact solutions. Numerical simulations of the fully nonlinear Euler equation have also been performed in... Schrodinger breathers, Proceedings of ECMWF Workshop on "Ocean Waves" - 25 to 27 June 2012 [published] • Onorato, M. and Proment, D.; Approximate rogue wave

  9. Sea State Dependent Air-Sea Fluxes in Coupled Atmosphere-Wave-Ocean Models

    NASA Astrophysics Data System (ADS)

    Meixner, J.; Liu, B.; Kim, H. S. S.; Chawla, A.; Mehra, A.; Reichl, B. G.; Ginis, I.; Hara, T.

    2016-12-01

    Air-sea fluxes of heat and momentum affect hurricane, tropical and extratropical storm intensities. Sea surface waves are an important processes to account for in modeling air-sea fluxes because wind stress and upper ocean mixing, through Langmuir turbulence and Stoke's drift, are sea-state dependent. We present a three-way coupled atmosphere-wave-ocean model which accounts for sea-state dependent air/sea fluxes. The wave model, WAVEWATCH III, calculates the wind stress, which is highly dependent on the high-frequency part of the wave spectrum. The high frequency part of the wave spectrum or tail is chosen so that the drag coefficient is reduced for wind speeds greater than 20 m/s as in the FY2016 operational version of HWRF. To demonstrate the impact of including waves in the coupled model, we show results comparing the two-way coupled atmosphere-ocean model to the three way coupled atmosphere-wave-ocean model for hurricane/tropical/extratropical storms. It is indicated that by including the reduced drag coefficients as well as other surface wave related coupling processes, storm intensities are better predicted in the three-way coupled HWRF system.

  10. River plumes as a source of large-amplitude internal waves in the coastal ocean.

    PubMed

    Nash, Jonathan D; Moum, James N

    2005-09-15

    Satellite images have long revealed the surface expression of large amplitude internal waves that propagate along density interfaces beneath the sea surface. Internal waves are typically the most energetic high-frequency events in the coastal ocean, displacing water parcels by up to 100 m and generating strong currents and turbulence that mix nutrients into near-surface waters for biological utilization. While internal waves are known to be generated by tidal currents over ocean-bottom topography, they have also been observed frequently in the absence of any apparent tide-topography interactions. Here we present repeated measurements of velocity, density and acoustic backscatter across the Columbia River plume front. These show how internal waves can be generated from a river plume that flows as a gravity current into the coastal ocean. We find that the convergence of horizontal velocities at the plume front causes frontal growth and subsequent displacement downward of near-surface waters. Individual freely propagating waves are released from the river plume front when the front's propagation speed decreases below the wave speed in the water ahead of it. This mechanism generates internal waves of similar amplitude and steepness as internal waves from tide-topography interactions observed elsewhere, and is therefore important to the understanding of coastal ocean mixing.

  11. Waves in the Southern Ocean as observed by Sentinel1 synthetic aperture radars

    NASA Astrophysics Data System (ADS)

    Stopa, Justin E.; Sutherland, Peter; Ardhuin, Fabrice

    2017-04-01

    Sea ice plays an important role in the Earth system by regulating air-sea fluxes and moderating the global temperatures. These fluxes can be enhanced by the presence of waves, especially through the breaking of ice into floes which depends on the waves propagating across the ice. The paucity of adequate in-situ wave observations in ice covered seas limits our ability to understand wave-ice interactions. Synthetic Aperture Radar (SAR) imagery over sea ice appears consistent with a dominant modulation of the radar backscatter by velocity bunching (Ardhuin et al. GRL 2015). Because the presence of sea ice generally removes the blurring effects of short wave components, the SAR transformation is more simple than in the open ocean. This property makes it possible to retrieve phase-resolved maps of wave orbital velocities and wave spectra (Ardhuin et al., 2017 RSE). We can thus now use SAR imagery for scientific applications to wave-ice interactions. With the all-weather capabilities and extensive space-time coverage, the Sentinel1 constellation composed of two satellites (S1A & S1B) both equipped with SARs provides the opportunity to extract valuable wave observations in polar regions. Through the high resolution acquisition modes of S1A and S1B which cover the Southern Ocean in 20x20 km images with 4 m spatial resolution we are able to extract an large sample of wave observations. We analyzed more than 35,000 images in the Southern Ocean. Nearly 28% of the images contain wave features and 6% of the images contain well-imaged single wave systems (>2000 wave spectra), with a narrow directional distribution. This dataset of more than 2000 wave spectra is unique in the fact we cover the entire Southern Ocean sea ice with an unprecedented amount of observations. These observations support the idea that the attenuation of waves with periods longer than 10 s is dominated by dissipation processes with a limited effect of scattering. Dissipation rates are estimated from pairs

  12. Impacts of ULF wave power on the Ionosphere

    NASA Astrophysics Data System (ADS)

    Yizengaw, E.; Doherty, P.; Zesta, E.; Moldwin, M.

    2015-12-01

    The impact of the ULF wave power, which is excited by long-lived high solar wind speed streams, in the magnetosphere has been well understood. For example, it has been reported that ULF pulsations may be the likely acceleration mechanism for generating storm-time MeV "killer" electrons in the magnetosphere. However, the impact of this energetic ULF wave power onto the ionosphere is not yet explored very well. In this paper we unequivocally demonstrated that during intense Pc5 ULF wave activity period, distinct pulsations with the same periodicity were found in the TEC data observed by GPS receivers located at different latitudes. The GPS-TEC has been used as a powerful tool to study the propagation pattern of transient ionospheric disturbances generated by seismic or internal gravity waves. Since then the small-scale variations (undulation) of GPS TEC has been associated with either gravity wave or TIDs. However, these small scale undulations of TECs turned out to be sensitive enough to the intense global ULF waves as well. The wavelet analysis of GPS TEC small scale undulations shows a peak value at the frequency of 2-10mHz which is a typical frequency range of Pc5 ULF wave. The typical internal gravity wave frequency is less than 1.6 or 2 mHz, therefore the TEC waves are likely due to ULF waves. At the same time, we detect the ULF activity on the ground using a chain of ground-based magnetometer data, depicting the ULF wave penetration from high latitude to low latitude region. All these observations demonstrate that Pc5 waves with a likely driver in the solar wind can penetrate to the ionosphere and cause small scale undulation on the ionospheric density structures.

  13. Impacts of climate changes on ocean surface gravity waves over the eastern Canadian shelf

    NASA Astrophysics Data System (ADS)

    Guo, Lanli; Sheng, Jinyu

    2017-05-01

    A numerical study is conducted to investigate the impact of climate changes on ocean surface gravity waves over the eastern Canadian shelf (ECS). The "business-as-usual" climate scenario known as Representative Concentration Pathway RCP8.5 is considered in this study. Changes in the ocean surface gravity waves over the study region for the period 1979-2100 are examined based on 3 hourly ocean waves simulated by the third-generation ocean wave model known as WAVEWATCHIII. The wave model is driven by surface winds and ice conditions produced by the Canadian Regional Climate Model (CanRCM4). The whole study period is divided into the present (1979-2008), near future (2021-2050) and far future (2071-2100) periods to quantify possible future changes of ocean waves over the ECS. In comparison with the present ocean wave conditions, the time-mean significant wave heights ( H s ) are expected to increase over most of the ECS in the near future and decrease over this region in the far future period. The time-means of the annual 5% largest H s are projected to increase over the ECS in both near and far future periods due mainly to the changes in surface winds. The future changes in the time-means of the annual 5% largest H s and 10-m wind speeds are projected to be twice as strong as the changes in annual means. An analysis of inverse wave ages suggests that the occurrence of wind seas is projected to increase over the southern Labrador and central Newfoundland Shelves in the near future period, and occurrence of swells is projected to increase over other areas of the ECS in both the near and far future periods.

  14. Impacts of climate changes on ocean surface gravity waves over the eastern Canadian shelf

    NASA Astrophysics Data System (ADS)

    Guo, Lanli; Sheng, Jinyu

    2017-03-01

    A numerical study is conducted to investigate the impact of climate changes on ocean surface gravity waves over the eastern Canadian shelf (ECS). The "business-as-usual" climate scenario known as Representative Concentration Pathway RCP8.5 is considered in this study. Changes in the ocean surface gravity waves over the study region for the period 1979-2100 are examined based on 3 hourly ocean waves simulated by the third-generation ocean wave model known as WAVEWATCHIII. The wave model is driven by surface winds and ice conditions produced by the Canadian Regional Climate Model (CanRCM4). The whole study period is divided into the present (1979-2008), near future (2021-2050) and far future (2071-2100) periods to quantify possible future changes of ocean waves over the ECS. In comparison with the present ocean wave conditions, the time-mean significant wave heights (H s ) are expected to increase over most of the ECS in the near future and decrease over this region in the far future period. The time-means of the annual 5% largest H s are projected to increase over the ECS in both near and far future periods due mainly to the changes in surface winds. The future changes in the time-means of the annual 5% largest H s and 10-m wind speeds are projected to be twice as strong as the changes in annual means. An analysis of inverse wave ages suggests that the occurrence of wind seas is projected to increase over the southern Labrador and central Newfoundland Shelves in the near future period, and occurrence of swells is projected to increase over other areas of the ECS in both the near and far future periods.

  15. Ocean dynamics studies. [of current-wave interactions

    NASA Technical Reports Server (NTRS)

    1974-01-01

    Both the theoretical and experimental investigations into current-wave interactions are discussed. The following three problems were studied: (1) the dispersive relation of a random gravity-capillary wave field; (2) the changes of the statistical properties of surface waves under the influence of currents; and (3) the interaction of capillary-gravity with the nonuniform currents. Wave current interaction was measured and the feasibility of using such measurements for remote sensing of surface currents was considered. A laser probe was developed to measure the surface statistics, and the possibility of using current-wave interaction as a means of current measurement was demonstrated.

  16. Ocean-Wave Coupled Modeling in COAMPS-TC: A Study of Hurricane Ivan (2004)

    DTIC Science & Technology

    2013-08-15

    NCOM to SWAN in high- wind conditions during Hurricane Ivan, near-surface currents in NCOM were first compared to near-surface ADCP observations...Recent modifications to SWAN, including new wind -to-wave energy input and wave-breaking energy dissipation source functions, as well as a new ocean...surface drag coefficient formulation appropriate for high- wind conditions, significantly improved the forecast wave field properties, such as significant

  17. The scientific justification for obtaining ocean wave data of various kinds with Seasat-A

    NASA Technical Reports Server (NTRS)

    Pierson, W. J.

    1974-01-01

    Synthetic aperture radar images of sea surface in deep water as well as two candidate instruments that essentially scan along a line are considered for obtaining spectral wave information with SEASAT-A. An altimeter provides data on wave height for every 50 or 100 kilometers along subsatellite track routine. A combination of these instruments is proposed to obtain wind generated ocean waves and swells.

  18. An Optimal Control Method for Maximizing the Efficiency of Direct Drive Ocean Wave Energy Extraction System

    PubMed Central

    Chen, Zhongxian; Yu, Haitao; Wen, Cheng

    2014-01-01

    The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability. PMID:25152913

  19. An optimal control method for maximizing the efficiency of direct drive ocean wave energy extraction system.

    PubMed

    Chen, Zhongxian; Yu, Haitao; Wen, Cheng

    2014-01-01

    The goal of direct drive ocean wave energy extraction system is to convert ocean wave energy into electricity. The problem explored in this paper is the design and optimal control for the direct drive ocean wave energy extraction system. An optimal control method based on internal model proportion integration differentiation (IM-PID) is proposed in this paper though most of ocean wave energy extraction systems are optimized by the structure, weight, and material. With this control method, the heavy speed of outer heavy buoy of the energy extraction system is in resonance with incident wave, and the system efficiency is largely improved. Validity of the proposed optimal control method is verified in both regular and irregular ocean waves, and it is shown that IM-PID control method is optimal in that it maximizes the energy conversion efficiency. In addition, the anti-interference ability of IM-PID control method has been assessed, and the results show that the IM-PID control method has good robustness, high precision, and strong anti-interference ability.

  20. Jason Tracks Powerful Tropical Cyclone Gonu's High Winds, Waves

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] Wind Speed Wave Height Click on images for larger versions

    This pair of images from the radar altimeter instrument on the U.S./France Jason mission reveals information on wind speeds and wave heights of Tropical Cyclone Gonu, which reached Category 5 strength in the Arabian Sea prior to landfall in early June 2007. Strong winds near 20 meters per second and wave heights of greater than 5 meters were recorded. These high waves are extremely rare in the Arabian Sea and exacerbated heavy flooding from the storm surge over much of the Oman coastline.

    The U.S. portion of the Jason mission is managed by JPL for NASA's Science Mission Directorate, Washington, D.C. Research on Earth's oceans using Jason and other space-based capabilities is conducted by NASA's Science Mission Directorate to better understand and protect our home planet.

  1. WASS: An open-source pipeline for 3D stereo reconstruction of ocean waves

    NASA Astrophysics Data System (ADS)

    Bergamasco, Filippo; Torsello, Andrea; Sclavo, Mauro; Barbariol, Francesco; Benetazzo, Alvise

    2017-10-01

    Stereo 3D reconstruction of ocean waves is gaining more and more popularity in the oceanographic community and industry. Indeed, recent advances of both computer vision algorithms and computer processing power now allow the study of the spatio-temporal wave field with unprecedented accuracy, especially at small scales. Even if simple in theory, multiple details are difficult to be mastered for a practitioner, so that the implementation of a sea-waves 3D reconstruction pipeline is in general considered a complex task. For instance, camera calibration, reliable stereo feature matching and mean sea-plane estimation are all factors for which a well designed implementation can make the difference to obtain valuable results. For this reason, we believe that the open availability of a well tested software package that automates the reconstruction process from stereo images to a 3D point cloud would be a valuable addition for future researches in this area. We present WASS (http://www.dais.unive.it/wass), an Open-Source stereo processing pipeline for sea waves 3D reconstruction. Our tool completely automates all the steps required to estimate dense point clouds from stereo images. Namely, it computes the extrinsic parameters of the stereo rig so that no delicate calibration has to be performed on the field. It implements a fast 3D dense stereo reconstruction procedure based on the consolidated OpenCV library and, lastly, it includes set of filtering techniques both on the disparity map and the produced point cloud to remove the vast majority of erroneous points that can naturally arise while analyzing the optically complex nature of the water surface. In this paper, we describe the architecture of WASS and the internal algorithms involved. The pipeline workflow is shown step-by-step and demonstrated on real datasets acquired at sea.

  2. Simulation of asteroid impact on ocean surfaces, subsequent wave generation and the effect on US shorelines

    SciTech Connect

    Ezzedine, Souheil M.; Lomov, Ilya; Miller, Paul L.; Dennison, Deborah S.; Dearborn, David S.; Antoun, Tarabay H.

    2015-05-19

    As part of a larger effort involving members of several other organizations, we have conducted numerical simulations in support of emergency-response exercises of postulated asteroid ocean impacts. We have addressed the problem from source (asteroid entry) to ocean impact (splash) to wave generation, propagation and interaction with the U.S. shoreline. We simulated three impact sites. The first site is located off the east coast by Maryland's shoreline. The second site is located off of the West coast, the San Francisco bay. The third set of sites are situated in the Gulf of Mexico. Asteroid impacts on the ocean surface are conducted using LLNL's hydrocode GEODYN to create the impact wave source for the shallow water wave propagation code, SWWP, a shallow depth averaged water wave code.

  3. Simulation of asteroid impact on ocean surfaces, subsequent wave generation and the effect on US shorelines

    DOE PAGES

    Ezzedine, Souheil M.; Lomov, Ilya; Miller, Paul L.; ...

    2015-05-19

    As part of a larger effort involving members of several other organizations, we have conducted numerical simulations in support of emergency-response exercises of postulated asteroid ocean impacts. We have addressed the problem from source (asteroid entry) to ocean impact (splash) to wave generation, propagation and interaction with the U.S. shoreline. We simulated three impact sites. The first site is located off the east coast by Maryland's shoreline. The second site is located off of the West coast, the San Francisco bay. The third set of sites are situated in the Gulf of Mexico. Asteroid impacts on the ocean surface aremore » conducted using LLNL's hydrocode GEODYN to create the impact wave source for the shallow water wave propagation code, SWWP, a shallow depth averaged water wave code.« less

  4. Six years of deep ocean infragravity wave measurements on the Mid-Atlantic Ridge, 37°N

    NASA Astrophysics Data System (ADS)

    Crawford, W. C.; Ballu, V.; Bertin, X.; Karpytchev, M.

    2013-12-01

    Ocean infragravity waves are an important part of the deep ocean climate, can be used to measure subsurface elastic properties, and may contribute to the earth's background seismic noise. They are surface gravity waves with periods from 10s of seconds to 10s of minutes and are generated by non-linear wave-wave interactions, with the strongest infragravity waves believed to be generated by storms near coastlines. The first deep ocean observations of infragravity waves suggested that they were much stronger and more constant in the Pacific Ocean than in the North Atlantic Ocean, presumably because the Pacific Ocean has direct wavepaths to more coastline and, in particular, high-latitude coastlines in both the Northern and Southern Oceans [Webb et al., 1991]. However, a recent study of deep ocean infragravity waves, using data from tsunami buoys at a large number of sites in the Pacific and Atlantic Oceans, suggests that infragravity wave energy is much more variable in the Pacific Ocean, and stronger in the Atlantic Ocean, than was assumed [Aucan & Ardhuin, 2013]. We measured seafloor pressure continuously for six years at a deep ocean site using both differential and absolute pressure gauges. We describe the levels and variability of infragravity wave energy and their correlation with coastal storms. We relate the energy observed at Atlantic and Pacific ocean tsunami gauges to the sensitivity of each site to waves from surrounding coastlines, calculated using a tsunami modeling code. We compare the sensitivity of tsunami buoys and differential pressure gauges to deep ocean infragravity waves.

  5. The Future Potential of Wave Power in the US

    NASA Astrophysics Data System (ADS)

    Previsic, M.; Epler, J.; Hand, M.; Heimiller, D.; Short, W.; Eurek, K.

    2012-12-01

    The theoretical ocean wave energy resource potential exceeds 50% of the annual domestic energy demand of the US, is located in close proximity of coastal population centers, and, although variable in nature, may be more consistent and predictable than some other renewable generation technologies. As renewable electricity generation technologies, ocean wave energy offers a low air pollutant option for diversifying the US electricity generation portfolio. Furthermore, the output characteristics of these technologies may complement other renewable technologies. This study addresses: (1) The energy extraction potential from the US wave energy resource, (2) The present cost of wave technology in /kW, (3) The estimated cost of energy in /kWh, and (4) Cost levels at which the technology should see significant deployment. RE Vision Consulting in collaboration with NREL engaged in various analyses to establish present-day and future cost profiles for MHK technologies, compiled existing resource assessments and wave energy supply curves, and developed cost and deployment scenarios using the ReEDS analysis model to estimate the present-day technology cost reductions necessary to facilitate significant technology deployment in the US.

  6. Multi-electrodes in SAW with square wave ac power

    SciTech Connect

    Bunker, T.A.

    1982-07-01

    Examines the feasibility of using AC square wave power for multi-electrode submerged arc welding (SAW) by arranging 2 power sources for weld test using two-electrode submerged arc welding. Presents figures showing phase relationship between lead arc current and trail arc current for Scott connected multi-electrode SAW, and arc deflection vs. electrical degrees. Suggests that Scott connection is preferred because it balances the primary line draw. Concludes that the multielectrode submerged arc process with constant potential square wave power increases travel speed and deposition rates which can be added to the economies obtained from a narrow groove joint configuration and the SAW process.

  7. Extremely Fast Numerical Integration of Ocean Surface Wave Dynamics

    DTIC Science & Technology

    2007-09-30

    1) is a natural two-space-dimension extension of the KdV equation . The periodic KP solutions include directional spreading in the wave field: y η...of the nonlinear preprocessor in the new approach for obtaining numerical solutions to nonlinear wave equations . I will now do so, but without many...analytical study and extremely fast numerical integration of the extended nonlinear Schroedinger equation for fully three dimensional wave motion

  8. Modeling explosion generated Scholte waves in sandy sediments with power law dependent shear wave speed.

    PubMed

    Soloway, Alexander G; Dahl, Peter H; Odom, Robert I

    2015-10-01

    Experimental measurements of Scholte waves from underwater explosions collected off the coast of Virginia Beach, VA in shallow water are presented. It is shown here that the dispersion of these explosion-generated Scholte waves traveling in the sandy seabed can be modeled using a power-law dependent shear wave speed profile and an empirical source model that determines the pressure time-series at 1 m from the source as a function of TNT-equivalent charge weight.

  9. Small-scale open ocean currents have large effects on wind wave heights

    NASA Astrophysics Data System (ADS)

    Ardhuin, Fabrice; Gille, Sarah T.; Menemenlis, Dimitris; Rocha, Cesar B.; Rascle, Nicolas; Chapron, Bertrand; Gula, Jonathan; Molemaker, Jeroen

    2017-06-01

    Tidal currents and large-scale oceanic currents are known to modify ocean wave properties, causing extreme sea states that are a hazard to navigation. Recent advances in the understanding and modeling capability of open ocean currents have revealed the ubiquitous presence of eddies, fronts, and filaments at scales 10-100 km. Based on realistic numerical models, we show that these structures can be the main source of variability in significant wave heights at scales less than 200 km, including important variations down to 10 km. Model results are consistent with wave height variations along satellite altimeter tracks, resolved at scales larger than 50 km. The spectrum of significant wave heights is found to be of the order of 70>>2/>(g2>>2>) times the current spectrum, where >> is the spatially averaged significant wave height, >> is the energy-averaged period, and g is the gravity acceleration. This variability induced by currents has been largely overlooked in spite of its relevance for extreme wave heights and remote sensing.Plain Language SummaryWe show that the variations in currents at scales 10 to 100 km are the main source of variations in <span class="hlt">wave</span> heights at the same scales. Our work uses a combination of realistic numerical models for currents and <span class="hlt">waves</span> and data from the Jason-3 and SARAL/AltiKa satellites. This finding will be of interest for the investigation of extreme <span class="hlt">wave</span> heights, remote sensing, and air-sea interactions. As an immediate application, the present results will help constrain the error budget of the up-coming satellite missions, in particular the Surface Water and <span class="hlt">Ocean</span> Topography (SWOT) mission, and decide how the data will have to be processed to arrive at accurate sea level and <span class="hlt">wave</span> measurements. It will also help in the analysis of <span class="hlt">wave</span> measurements by the CFOSAT satellite.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.4799C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.4799C"><span>Hydroacoustic ray theory-based modeling of T <span class="hlt">wave</span> propagation in the deep <span class="hlt">ocean</span> basin offshore eastern Taiwan</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Chin-Wu; Huang, Chen-Fen; Lin, Chien-Wen; Kuo, Ban-Yuan</p> <p>2017-05-01</p> <p>T <span class="hlt">waves</span> are conventionally defined as seismically generated acoustic energy propagating horizontally over long distances within the minimum sound speed layer in the <span class="hlt">ocean</span> (SOFAR axis minimum). However, T <span class="hlt">waves</span> have also been observed by <span class="hlt">ocean</span>-bottom seismometers in <span class="hlt">ocean</span> basins at depths greater than the SOFAR axis minimum. Previously, nongeometrical processes, such as local scattering at rough seafloor and water-sediment interface coupling, have been proposed as possible mechanisms for deep seafloor detection of T <span class="hlt">waves</span>. Here we employ a new T <span class="hlt">wave</span> modeling approach based on hydroacoustic ray theory to demonstrate that seismoacoustic energy can propagate to reach deep seafloor, previously considered as shadow zone of acoustic propagation. Our new hydroacoustic simulations explain well the observations of T <span class="hlt">waves</span> on <span class="hlt">ocean</span>-bottom seismometers at deep <span class="hlt">ocean</span> basins east of Taiwan and shed new light on the mechanism for deep <span class="hlt">ocean</span> T <span class="hlt">wave</span> propagation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA630870','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA630870"><span>Study of <span class="hlt">Ocean</span> Bottom Interactions with Acoustic <span class="hlt">Waves</span> by a New Elastic <span class="hlt">Wave</span> Propagation Algorithm and an Energy Flow Analysis Technique</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-06-07</p> <p>Study Of <span class="hlt">Ocean</span> Bottom Interactions With Acoustic <span class="hlt">Waves</span> By A New Elastic <span class="hlt">Wave</span> Propagation Algorithm And An Energy Flow Analysis Technique Ru-Shan Wu...imaging to study the <span class="hlt">wave</span>/sea-bottom interaction, energy partitioning, scattering mechanism and other problems that are crucial for many <span class="hlt">ocean</span> bottom...Elastic <span class="hlt">Wave</span> Propagation Algorithm And An Energy Flow Analysis Technique 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA601190','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA601190"><span>An Arctic Ice/<span class="hlt">Ocean</span> Coupled Model with <span class="hlt">Wave</span> Interactions</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-09-30</p> <p>case TOPAZ : a hybrid coordinate <span class="hlt">ocean</span> model of roughly 13 km horizontal resolution forced by ECMWF atmospheric fields, as the platform to construct a...the TOPAZ ice/<span class="hlt">ocean</span> model and WAVEWATCH III, and, for the latter, cross-relate to any viscoelastic parametrization of the sea ice to calibrate the...goal of embedding the 3D WIM described above into the TOPAZ framework, by so doing allowing fully directional seas generated by WAVEWATCH III as</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OcDyn..65.1489G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OcDyn..65.1489G"><span>Statistical estimation of extreme <span class="hlt">ocean</span> <span class="hlt">waves</span> over the eastern Canadian shelf from 30-year numerical <span class="hlt">wave</span> simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, Lanli; Sheng, Jinyu</p> <p>2015-11-01</p> <p>Reliable estimation of extreme <span class="hlt">ocean</span> surface gravity <span class="hlt">waves</span> is important for many scientific and practical issues. In this study, WAVEWATCHIII is used to simulate <span class="hlt">wave</span> conditions over the eastern Canadian shelf (ECS) for the 30-year period, 1979-2008. The <span class="hlt">wave</span> model is forced by the 6-hourly winds and ice cover taken from the Climate Forecast System Reanalysis (CFSR). A parametric vortex is inserted into the CFSR winds to better represent surface winds associated with tropical storms or hurricanes. The model performance in simulating the bulk significant <span class="hlt">wave</span> height is assessed by comparing model results with <span class="hlt">wave</span> observations at 12 buoy stations over the ECS. The peaks-over-threshold method is used to estimate the extreme significant <span class="hlt">wave</span> heights from 30-year <span class="hlt">wave</span> simulations. The estimated extreme <span class="hlt">waves</span> with the 50-year return period over the ECS feature large <span class="hlt">wave</span> heights of more than 12 m in the offshore deep waters and about 8-12 m over the open shelf waters of the ECS. By comparison, the 50-year extreme <span class="hlt">waves</span> are moderate and 7 m or less in the Gulf of St. Lawrence and inner Gulf of Maine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.S52C..06T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.S52C..06T"><span>Seismic Noise Generation by <span class="hlt">Ocean</span> <span class="hlt">Waves</span>: Views from Normal-mode Theory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tanimoto, T.</p> <p>2012-12-01</p> <p>The continuous seismic records (noise) and the cross-correlation techniques are making a huge impact on study for the crust and upper mantle. Such studies rely on microseisms for frequencies about 0.05-0.3 Hz that are excited by <span class="hlt">ocean</span> <span class="hlt">waves</span> but detailed processes for the excitation are still vague. Our views of noise excitation have been influenced by the results in Longuet-Higgins (1950) who showed how colliding <span class="hlt">ocean</span> <span class="hlt">waves</span> generate the dominant secondary microseisms. There are two main points to his results; the first is the generation of pressure at deep <span class="hlt">ocean</span> bottom, even though <span class="hlt">ocean</span> <span class="hlt">waves</span> have energy only in the upper 100-200 meters. This result on deep penetrating pressure was originally derived for an incompressible fluid. The second is the existence of specific <span class="hlt">ocean</span> depths that preferentially excite secondary microseisms (0.15 Hz). This result was derived for a medium with a compressible fluid layer over an elastic half-space. The purpose of this study is to examine these two points from the views of the normal-mode theory. The first point was shown in Tanimoto (2007, GJI). Excitation by the advection term in the Navier-Stokes equation was shown to lead to the equivalent result with Longuet-Higgins (1950). Mathematically, dominant contributions are from colliding <span class="hlt">ocean</span> <span class="hlt">waves</span> and the resulting force exactly matches the Longuet-Higgins pressure formula in the low-frequency range (below 0.05 Hz). It is somewhat surprising that a result in an incompressible fluid emerged in the analysis of elastic medium with compressible <span class="hlt">ocean</span>. However, in the low frequency range, the eigenfunctions of Rayleigh <span class="hlt">waves</span> become (almost) constant in the <span class="hlt">ocean</span>, meaning that the entire fluid layer moves coherently up and down just like an incompressible medium. Then the emergence of the Longuet-Higgins pressure formula is not surprising. However, as Longuet-Higgins (1950) noted, such a situation does not apply to noise at 0.15 Hz as it is above such a frequency range. In a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870051552&hterms=TREATMENT+INSULIN&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DTREATMENT%2BINSULIN','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870051552&hterms=TREATMENT+INSULIN&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DTREATMENT%2BINSULIN"><span>Measuring <span class="hlt">ocean</span> <span class="hlt">waves</span> from space; Proceedings of the Symposium, Johns Hopkins University, Laurel, MD, Apr. 15-17, 1986</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Beal, Robert C. (Editor)</p> <p>1987-01-01</p> <p>Papers are presented on <span class="hlt">ocean-wave</span> prediction; the quasi-universal form of the spectra of wind-generated gravity <span class="hlt">waves</span> at different stages of their development; the limitations of the spectral measurements and observations of the group structure of surface <span class="hlt">waves</span>; the effect of swell on the growth of wind <span class="hlt">wave</span>; operational <span class="hlt">wave</span> forecasting; <span class="hlt">ocean-wave</span> models, and seakeeping using directional <span class="hlt">wave</span> spectra. Consideration is given to microwave measurements of the <span class="hlt">ocean-wave</span> directional spectra; SIR research; estimating <span class="hlt">wave</span> energy spectra from SAR imagery, with the radar <span class="hlt">ocean-wave</span> spectrometer, and SIR-B; the <span class="hlt">wave</span>-measurement capabilities of the surface contour radar and the airborne oceanographic lidar; and SIR-B <span class="hlt">ocean-wave</span> enhancement with fast-Fourier transform techniques. Topics discussed include <span class="hlt">wave</span>-current interaction; the design and applicability of Spectrasat; the need for a global <span class="hlt">wave</span> monitoring system; the age and source of <span class="hlt">ocean</span> swell observed in Hurricane Josephine; and the use of satellite technology for insulin treatment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EPSC....8...54D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EPSC....8...54D"><span>Variations of ULF <span class="hlt">wave</span> <span class="hlt">power</span> throughout the Halloween 2003 superstorm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daglis, I. A.; Balasis, G.; Papadimitriou, C.; Zesta, E.; Georgiou, M.; Mann, I.</p> <p>2013-09-01</p> <p>Focused on the exceptional 2003 Halloween geospace magnetic storm, when Dst reached a minimum of -383 nT, we examine data from topside ionosphere and two magnetospheric missions (CHAMP, Cluster, and Geotail) for signatures of ULF <span class="hlt">waves</span>. We present the overall ULF <span class="hlt">wave</span> activity through the six-day interval from 27 October to 1 November 2003 as observed by the three spacecraft and by the Andenes ground magnetic station of the IMAGE magnetometer array in terms of time variations of the ULF <span class="hlt">wave</span> <span class="hlt">power</span>. The ULF <span class="hlt">wave</span> activity is divided upon Pc3 and Pc5 <span class="hlt">wave</span> <span class="hlt">power</span>. Thus, we provide different ULF <span class="hlt">wave</span> activity indices according to the <span class="hlt">wave</span> frequency (Pc3 and Pc5) and location of observation (Earth's magnetosphere, topside ionosphere and surface). We also look at three specific intervals during different phases of the storm when at least two of the satellites are in good local time (LT) conjunction and examine separately Pc3 and Pc4-5 ULF <span class="hlt">wave</span> activity and its concurrence in the different regions of the magnetosphere and down to the topside ionosphere and on the ground.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013hell.confR..15D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013hell.confR..15D"><span>Variations of ULF <span class="hlt">wave</span> <span class="hlt">power</span> throughout the Halloween 2003 superstorm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daglis, I.; Balasis, G.; Papadimitriou, C.; Zesta, E.; Georgiou, M.; Mann, I.</p> <p>2013-09-01</p> <p>Focused on the exceptional 2003 Halloween geospace magnetic storm, when Dst reached a minimum of -383 nT, we examine data from topside ionosphere and two magnetospheric missions (CHAMP, Cluster, and Geotail) for signatures of ULF <span class="hlt">waves</span>. We present the overall ULF <span class="hlt">wave</span> activity through the six-day interval from 27 October to 1 November 2003 as observed by the three spacecraft and by the Andenes ground magnetic station of the IMAGE magnetometerer array in terms of time variations of the ULF <span class="hlt">wave</span> <span class="hlt">power</span>. The ULF <span class="hlt">wave</span> activity is divided upon Pc3 and Pc5 <span class="hlt">wave</span> <span class="hlt">power</span>. Thus, we provide different ULF <span class="hlt">wave</span> activity indices according to the <span class="hlt">wave</span> frequency (Pc3 and Pc5) and location of observation (Earth’s magnetosphere, topside ionosphere and surface). We also look at three specific intervals during different phases of the storm when at least two of the satellites are in good local time (LT) conjunction and examine separately Pc3 and Pc4-5 ULF <span class="hlt">wave</span> activity and its concurrence in the different regions of the magnetosphere and down to the topside ionosphere and on the ground. This work has received support from the European Community’s Seventh Framework Programme under grant agreement no. 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.9086D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.9086D"><span>Variations of ULF <span class="hlt">wave</span> <span class="hlt">power</span> throughout the Halloween 2003 superstorm</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Daglis, Ioannis; Balasis, Georgios; Papadimitriou, Constantinos; Zesta, Eftyhia; Georgiou, Marina; Mann, Ian</p> <p>2013-04-01</p> <p>Focused on the exceptional 2003 Halloween geospace magnetic storm, when Dst reached a minimum of -383 nT, we examine data from topside ionosphere and two magnetospheric missions (CHAMP, Cluster, and Geotail) for signatures of ULF <span class="hlt">waves</span>. We present the overall ULF <span class="hlt">wave</span> activity through the six-day interval from 27 October to 1 November 2003 as observed by the three spacecraft and by the Andenes ground magnetic station of the IMAGE magnetometerer array in terms of time variations of the ULF <span class="hlt">wave</span> <span class="hlt">power</span>. The ULF <span class="hlt">wave</span> activity is divided upon Pc3 and Pc5 <span class="hlt">wave</span> <span class="hlt">power</span>. Thus, we provide different ULF <span class="hlt">wave</span> activity indices according to the <span class="hlt">wave</span> frequency (Pc3 and Pc5) and location of observation (Earth's magnetosphere, topside ionosphere and surface). We also look at three specific intervals during different phases of the storm when at least two of the satellites are in good local time (LT) conjunction and examine separately Pc3 and Pc4-5 ULF <span class="hlt">wave</span> activity and its concurrence in the different regions of the magnetosphere and down to the topside ionosphere and on the ground. This work has received support from the European Community's Seventh Framework Programme under grant agreement no. 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009OcMod..29..189B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009OcMod..29..189B"><span><span class="hlt">Wave</span>-induced upper-<span class="hlt">ocean</span> mixing in a climate model of intermediate complexity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Babanin, Alexander V.; Ganopolski, Andrey; Phillips, William R. C.</p> <p></p> <p>Climate modelling, to a great extent, is based on simulating air-sea interactions at larger scales. Small-scale interactions and related phenomena, such as wind-generated <span class="hlt">waves</span> and <span class="hlt">wave</span>-induced turbulence are sub-grid processes for such models and therefore cannot be simulated explicitly. In the meantime, the <span class="hlt">waves</span> play the principal role in the upper-<span class="hlt">ocean</span> mixing. This role is usually parameterized, mostly to account for the <span class="hlt">wave</span>-breaking turbulence and to describe downward diffusion of such turbulence. The main purpose of the paper is to demonstrate that an important physical mechanism, that is the <span class="hlt">ocean</span> mixing due to <span class="hlt">waves</span>, is presently missing in the climate models, whereas the effect of this mixing is significant. It is argued that the mixing role of the surface <span class="hlt">waves</span> is not limited to the mere transfer of the wind stress and energy across the <span class="hlt">ocean</span> interface by means of breaking and surface currents. The <span class="hlt">waves</span> facilitate two processes in the upper-<span class="hlt">ocean</span> which can deliver turbulence to the depths of the order of 100 m directly, rather than diffusing it from the surface. The first process is due to capacity of the <span class="hlt">waves</span> to generate turbulence, unrelated to the <span class="hlt">wave</span> breaking, at all depths where the <span class="hlt">wave</span> orbital motion is significant. The second process is Langmuir circulation, triggered by the <span class="hlt">waves</span>. Such <span class="hlt">wave</span>-controlled mixing should cause seasonal variations of the mixed-layer depth, which regulates the thermodynamic balance between the <span class="hlt">ocean</span> and atmosphere. In the present paper, these variations are parameterized in terms of the global winds. The variable mixed-layer depth is then introduced in the climate model of intermediated complexity CLIMBER-2 with a purpose of reproducing the pre-industrial climate. Comparisons are conducted with the NRL global atlas of the mixed layer, and performance of the <span class="hlt">wave</span>-mixing parameterisations was found satisfactory in circumstances where the mixing is expected to be dominated by the wind-generated <span class="hlt">waves</span>. It is shown that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994PApGe.142..319C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PApGe.142..319C"><span>Excitation of T <span class="hlt">waves</span> in the Indian <span class="hlt">Ocean</span> between Srilanka and southern India</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chadha, R. K.</p> <p>1994-06-01</p> <p>T phases of three earthquakes from the Indian <span class="hlt">Ocean</span> region, recorded by a short-period vertical-component seismic station network located in the vicinity of Kanyakumari on the southernmost tip of India, are studied. Two of these earthquakes are located west of 90°E ridge and one in the Nicobar Island region. However, seven other earthquakes which occurred 150 200 km south of Kanyakumari in the <span class="hlt">ocean</span> did not produce T phases. An analysis of T-<span class="hlt">waves</span> (tertiary <span class="hlt">waves</span>) travel time reveals the zone of P-<span class="hlt">wave</span> to T-<span class="hlt">wave</span> conversion (i.e., PT phase) region to coincide with the western continental slope of Srilanka. Further, it is observed that the disposition of the bathymetry between Srilanka and southern India strongly favours the downslope propagation mechanism of T-<span class="hlt">wave</span> travel to the southern coast of India through SOFAR channel. These observations are reported for the first time from India.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23822486','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23822486"><span>On strongly interacting internal <span class="hlt">waves</span> in a rotating <span class="hlt">ocean</span> and coupled Ostrovsky equations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alias, A; Grimshaw, R H J; Khusnutdinova, K R</p> <p>2013-06-01</p> <p>In the weakly nonlinear limit, <span class="hlt">oceanic</span> internal solitary <span class="hlt">waves</span> for a single linear long <span class="hlt">wave</span> mode are described by the KdV equation, extended to the Ostrovsky equation in the presence of background rotation. In this paper we consider the scenario when two different linear long <span class="hlt">wave</span> modes have nearly coincident phase speeds and show that the appropriate model is a system of two coupled Ostrovsky equations. These are systematically derived for a density-stratified <span class="hlt">ocean</span>. Some preliminary numerical simulations are reported which show that, in the generic case, initial solitary-like <span class="hlt">waves</span> are destroyed and replaced by two coupled nonlinear <span class="hlt">wave</span> packets, being the counterpart of the same phenomenon in the single Ostrovsky equation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740022680&hterms=african+american&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dafrican%2Bamerican','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740022680&hterms=african+american&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dafrican%2Bamerican"><span><span class="hlt">Ocean</span> internal <span class="hlt">waves</span> off the North American and African coasts from ERTS-1</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Apel, J. R.; Charnell, R. L.</p> <p>1974-01-01</p> <p>Periodic features observed in the <span class="hlt">ocean</span> portions of certain ERTS-1 images have been identified with reasonable certainty as surface manifestations of <span class="hlt">oceanic</span> internal gravity <span class="hlt">waves</span>. A series of images taken over the New York Bight, commencing with the 16 July 1972 overpass and continuing on into autumn of 1973, has shown the internal <span class="hlt">waves</span> to be present when summer solar heating stratifies the water sufficiently well to support such oscillations. When fall and winter wind action mixes the shelf water down to the bottom, the <span class="hlt">waves</span> no longer appear. In the Bight, the wavelengths range from approximately 400 to 1000 m, with the <span class="hlt">wave</span> field being most sharply delineated near the edges of the continental shelf, at the mouth of the Hudson Canyon. They appear in packets consisting of several <span class="hlt">waves</span> separated by 10-15 km, which propagate up on the shelf and disappear.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1033051','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1033051"><span>Discrete-element model for the interaction between <span class="hlt">ocean</span> <span class="hlt">waves</span> and sea ice</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Xu, Zhijie; Tartakovsky, Alexandre M.; Pan, Wenxiao</p> <p>2012-01-05</p> <p>We present a discrete element method (DEM) model to simulate the mechanical behavior of sea ice in response to <span class="hlt">ocean</span> <span class="hlt">waves</span>. The <span class="hlt">wave</span>/ice interaction can potentially lead to the fracture and fragmentation of sea ice depending on the <span class="hlt">wave</span> amplitude and period. The fracture behavior of sea ice is explicitly modeled by a DEM method, where sea ice is modeled by densely packed spherical particles with finite size. These particles are bonded together at their contact points through mechanical bonds that can sustain both tensile & compressive forces and moments. Fracturing can be naturally represented by the sequential breaking of mechanical bonds. For a given amplitude and period of incident <span class="hlt">ocean</span> <span class="hlt">wave</span>, the model provides information for the spatial distribution and time evolution of stress and micro-fractures and the fragment size distribution. We demonstrate that the fraction of broken bonds,, increases with increasing <span class="hlt">wave</span> amplitude. In contrast, the ice fragment size decreases with increasing amplitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA523865','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA523865"><span><span class="hlt">Ocean</span> Surface <span class="hlt">Wave</span> Optical Roughness: Innovative Polarization Measurement</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2006-01-01</p> <p>whitecap breaking <span class="hlt">waves</span>. * Prof. Michael L . Banner, School of Mathematics, The University of NSW, Sydney, Australia Dr. Bertrand Chapron...breaking <span class="hlt">waves</span> from infrared imagery using a PIV algorithm. Meas. Sci. Technol. 16, 1961-1969. Phillips, O. M., Posner, F. L ., and Hansen , J. P</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986JGR....91.2461G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986JGR....91.2461G"><span><span class="hlt">Ocean</span> <span class="hlt">waves</span> and turbulence as observed with an adaptive coherent multifrequency radar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gjessing, Dag T.; Hjelmstad, Jens</p> <p>1986-02-01</p> <p>An adaptive coherent multifrequency radar system has been developed for several applications. By means of this the velocity distribution (Doppler spectrum) and spectral intensity of 15 different irregularity scales (<span class="hlt">waves</span> and turbulence) can be measured simultaneously. Changing the azimuth angle of the antennas at regular intervals, the direction of the <span class="hlt">wave</span>/turbulence pattern on the sea surface can also be studied. Using this radar system, series of measurements for different air/sea conditions have been carried out from a coast-based platform in southern Norway. Experiments in the Atlantic were also performed with the same equipment, making use of the NASA Electra aircraft. There are many air/sea phenomena that play a role in relation to backscattering of radio <span class="hlt">waves</span> in the microwave region: gravity <span class="hlt">waves</span> "modulate" the capillary <span class="hlt">wave</span> structure, overturning <span class="hlt">wave</span> crests produce focusing effects and also periodic regions of strong turbulence, and the boundary layer wind field with strong turbulence amplified by the <span class="hlt">ocean</span> <span class="hlt">waves</span> will conceivably leave a patchy and even periodic footprint on the sea surface. Internal <span class="hlt">waves</span> originating from density gradients in this <span class="hlt">ocean</span> further complicates the sea surface irregularity pattern. By virtue of the fact that the multifrequency radar allows one to measure the velocity distribution ("coherent and incoherent component") associated with 15 different <span class="hlt">ocean</span> irregularity scales simultaneously for several azimuth directions, it is possible to study the different air/sea mechanisms in some degree of detail.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1711839C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1711839C"><span>Coupled <span class="hlt">wave-ocean</span> modeling system experiments in the Mediterranean Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clementi, Emanuela; Oddo, Paolo; Korres, Gerasimos; Pinardi, Nadia; Drudi, Massimiliano; Tonani, Marina; Grandi, Alessandro; Adani, Mario</p> <p>2015-04-01</p> <p>Wind <span class="hlt">waves</span> and <span class="hlt">oceanic</span> circulation processes are of major interest in determining accurate sea state predictions and their interactions are very important for individual dynamic processes. This work presents a coupled <span class="hlt">wave</span>-current numerical modelling system composed by the <span class="hlt">ocean</span> circulation model NEMO (Nucleus for European Modelling of the <span class="hlt">Ocean</span>) and the third generation <span class="hlt">wave</span> model <span class="hlt">Wave</span>WatchIII (WW3) implemented in the Mediterranean Sea with 1/16° horizontal resolution and forced by ECMWF atmospheric fields. In order to evaluate the performance of the coupled model, two sets of numerical experiments have been performed and described in this work. A first set of experiments has been built by coupling the <span class="hlt">wave</span> and circulation models that hourly exchange the following fields: the sea surface currents and air-sea temperature difference are transferred from NEMO model to WW3 model modifying respectively the mean momentum transfer of <span class="hlt">waves</span> and the wind speed stability parameter; while the neutral drag coefficient computed by WW3 model is passed to NEMO that computes the turbulent component. Five years (2009-2013) numerical experiments have been carried out in both uncoupled and coupled modes. In order to validate the modelling system, numerical results have been compared with coastal and drifting buoys and remote sensing data. Comparison results demonstrate that the WW3 model can fairly reproduce the observed <span class="hlt">wave</span> characteristics and show that the <span class="hlt">wave</span>-current interactions improve the representation of the <span class="hlt">wave</span> spectrum. Minor improvements have been reached by comparing coupled and uncoupled circulation NEMO model results with observations. A second set of numerical experiments has been performed by considering NEMO model one-way coupled with WW3 model. The hydrodynamic model receives from the <span class="hlt">wave</span> model the neutral drag coefficient and a set of <span class="hlt">wave</span> fields used to calculate the <span class="hlt">wave</span>-induced vertical mixing according to Qiao et al. (2010) formulation. Two experiments</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS11B1642W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS11B1642W"><span>Development and applications of a Coupled-<span class="hlt">Ocean-Atmosphere-Wave</span>-Sediment Transport (COAWST) Modeling System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Warner, J. C.; Armstrong, B. N.; He, R.; Zambon, J. B.; Olabarrieta, M.; Voulgaris, G.; Kumar, N.; Haas, K. A.</p> <p>2012-12-01</p> <p>Understanding processes responsible for coastal change is important for managing both our natural and economic coastal resources. Coastal processes respond from both local scale and larger regional scale forcings. Understanding these processes can lead to significant insight into how the coastal zone evolves. Storms are one of the primary driving forces causing coastal change from a coupling of <span class="hlt">wave</span> and wind driven flows. Here we utilize a numerical modeling approach to investigate these dynamics of coastal storm impacts. We use the Coupled <span class="hlt">Ocean</span> - Atmosphere - <span class="hlt">Wave</span> - Sediment Transport (COAWST) Modeling System that utilizes the Model Coupling Toolkit to exchange prognostic variables between the <span class="hlt">ocean</span> model ROMS, atmosphere model WRF, <span class="hlt">wave</span> model SWAN, and the Community Sediment Transport Modeling System (CSTMS) sediment routines. The models exchange fields of sea-surface temperature, <span class="hlt">ocean</span> currents, water levels, bathymetry, <span class="hlt">wave</span> heights, lengths, periods, bottom orbital velocities, and atmospheric surface heat and momentum fluxes, atmospheric pressure, precipitation, and evaporation. Data fields are exchanged using regridded flux conservative sparse matrix interpolation weights computed from the SCRIP spherical coordinate remapping interpolation package. We describe the modeling components and the model field exchange methods. As part of the system, the <span class="hlt">wave</span> and <span class="hlt">ocean</span> models run with cascading, refined, spatial grids to provide increased resolution, scaling down to resolve nearshore <span class="hlt">wave</span> driven flows simulated by the vortex force formulation, all within selected regions of a larger, coarser-scale coastal modeling system. The <span class="hlt">ocean</span> and <span class="hlt">wave</span> models are driven by the atmospheric component, which is affected by <span class="hlt">wave</span> dependent <span class="hlt">ocean</span>-surface roughness and sea surface temperature which modify the heat and momentum fluxes at the <span class="hlt">ocean</span>-atmosphere interface. We describe the application of the modeling system to several regions of multi-scale complexity to identify the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.C21C0695S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.C21C0695S"><span>Observations of <span class="hlt">wave</span>-enhanced mixing in the autumn Arctic <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Smith, M.; Thomson, J. M.; Stammerjohn, S. E.; Persson, O. P. G.; Rainville, L.</p> <p>2016-12-01</p> <p>The mixed layer depth in the Arctic <span class="hlt">Ocean</span> is set primarily by wind-driven mixing, and is generally shallow, compared to other <span class="hlt">oceans</span>, because of ice cover. Recent reductions in sea ice extent have increased not only direct wind forcing, but also <span class="hlt">wave</span> growth (due to increased fetch) and the likelihood for enhanced mixing from <span class="hlt">waves</span>. We present measurements of wind, <span class="hlt">waves</span>, upper-<span class="hlt">ocean</span> velocity profiles, and temperature profiles that indicate significant <span class="hlt">wave</span>-driven mixing during a storm. Measurements were taken as part of the 2015 Sea State program to observe the fall freeze-up period in the Beaufort Sea. Hundreds of kilometers of newly-formed pancake ice melted over the course of a few days, primarily as a result of the substantial loss of heat from the upper <span class="hlt">ocean</span>. The loss of heat cannot be explained solely by wind-driven mixing; an additional contribution via <span class="hlt">wave</span>-driven mixing is necessary to explain the observed deepening of the mixed layer. The observations are well described by a turbulent Langmuir scaling to quantify the <span class="hlt">wave</span>-driven mixing. This scaling compares Stokes shear velocity, which is associated with Langmuir circulations, to wind shear velocity. The overall effect of mixing is to deepen the mixed layer, which mobilizes heat stored in the Near-Surface Temperature Maximum (NSTM), and delays the autumn freeze-up. Such events can have lasting effects by causing a thinner winter ice cover that will retreat faster in the spring.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25430244','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25430244"><span><span class="hlt">Power</span> and polarization monitor development for high <span class="hlt">power</span> millimeter-<span class="hlt">wave</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Makino, R; Kubo, S; Kobayashi, K; Kobayashi, S; Shimozuma, T; Yoshimura, Y; Igami, H; Takahashi, H; Mutoh, T</p> <p>2014-11-01</p> <p>A new type monitor of <span class="hlt">power</span> and polarization states of millimeter-<span class="hlt">waves</span> has been developed to be installed at a miter-bend, which is a part of transmission lines of millimeter-<span class="hlt">waves</span>, for electron cyclotron resonance heating on the Large Helical Device. The monitor measures amplitudes and phase difference of the electric field of the two orthogonal polarizations which are needed for calculation of the <span class="hlt">power</span> and polarization states of <span class="hlt">waves</span>. The <span class="hlt">power</span> and phase differences of two orthogonal polarizations were successfully detected simultaneously.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA556862','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA556862"><span>Modeling the Effects of Anisotropic Turbulence and Dispersive <span class="hlt">Waves</span> on <span class="hlt">Oceanic</span> Circulation and their Incorporation in Navy <span class="hlt">Ocean</span> Models</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2011-09-30</p> <p>anisotropic turbulence and dispersive <span class="hlt">waves</span> in different environments , test them, compare them with data and implement them in <span class="hlt">ocean</span> models. In this project...stratification and/or a solid body rotation. We have also performed computer simulations with an idealized circulation model of quasi-two-dimensional...member of a team on Martian planetary boundary layer at the International Space Science Institute and was responsible for reviewing turbulence models</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMOS21E1548O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMOS21E1548O"><span><span class="hlt">Ocean-Wave</span> Dynamics Analysis during Hurricane Ida and Norida Using a Fully Coupled Modeling System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olabarrieta, M.; Warner, J. C.; Armstrong, B. N.</p> <p>2010-12-01</p> <p>Extreme storms, such as hurricanes and extratropical storms play a dominant role in shaping the beaches of the East and Gulf Coasts of the United States. Future tropical depressions will be more intense than in the present climate (Assessment Report of IPCC, 2007) and therefore coastal areas are likely to become more susceptible to their effects. The major damage caused by these extreme events is associated with the duration of the storm, storm intensity, <span class="hlt">waves</span>, and the total water levels reached during the storm. Numerical models provide a useful approach to study the spatial and temporal distribution of these parameters. However, the correct estimation of the total water levels and wind <span class="hlt">wave</span> heights through numerical modeling requires accurate representation of the air-sea interface dynamics. These processes are highly complex due to the variable interactions between winds, <span class="hlt">ocean</span> <span class="hlt">waves</span> and currents near the sea surface. In the present research we use the COAWST (Coupled <span class="hlt">Ocean-Atmosphere-Wave</span>-Sediment Transport) modeling system (Warner et al., 2010) to address the key role of the atmosphere-<span class="hlt">ocean-wave</span> interactions during Hurricane Ida and its posterior evolution to NorIda, November 2009. This northeastern storm was one of the most costly in the past two decades and likely in the top five of the past century. One interesting aspect of the considered period is that it includes two very different atmospheric extreme conditions, a hurricane and a northeastern storm, developed in regions with very different oceanographic characteristics. By performing a suite of numerical runs we are able to isolate the effect of the interaction terms between the atmosphere (WRF model), the <span class="hlt">ocean</span> (ROMS model) and the <span class="hlt">wave</span> propagation and generation model (SWAN). Special attention is given to the role of the <span class="hlt">ocean</span> surface roughness and high resolution SST fields on the atmospheric boundary layers dynamics and consequently these effects on the wind <span class="hlt">wave</span> generation, surface currents and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19680000152','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19680000152"><span>Mm-<span class="hlt">wave</span> <span class="hlt">power</span> meter mount</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mullen, D. L.; Oltmans, D. A.; Stelzried, C. T.</p> <p>1968-01-01</p> <p>E-band thermistor mount and a technique for adjusting a temperature compensating thermistor to provide an electrically balanced bridge are used for measuring RF <span class="hlt">power</span> in the mm-wavelength. The mount is relatively insensitive to temperature effects that cause measurement errors in single ended circuits.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19884944','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19884944"><span>Reactive <span class="hlt">power</span> in the full Gaussian light <span class="hlt">wave</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Seshadri, S R</p> <p>2009-11-01</p> <p>The electric current sources that are required for the excitation of the fundamental Gaussian beam and the corresponding full Gaussian light <span class="hlt">wave</span> are determined. The current sources are situated on the secondary source plane that forms the boundary between the two half-spaces in which the <span class="hlt">waves</span> are launched. The electromagnetic fields and the complex <span class="hlt">power</span> generated by the current sources are evaluated. For the fundamental Gaussian beam, the reactive <span class="hlt">power</span> vanishes, and the normalization is chosen such that the real <span class="hlt">power</span> is 2 W. The various full Gaussian <span class="hlt">waves</span> are identified by the length parameter b(t) that lies in the range 0 < or = b(t) < or = b, where b is the Rayleigh distance. The other parameters are the wavenumber k, the free-space wavelength lambda, and the beam waist w0 at the input plane. The dependence of the real <span class="hlt">power</span> of the full Gaussian light <span class="hlt">wave</span> on b(t)/b and w0/lambda is examined. For a specified w0/lambda, the reactive <span class="hlt">power</span>, which can be positive or negative, increases as b(t)/b is increased from 0 to 1 and becomes infinite for b(t)/b=1. For a specified b(t)/b, the reactive <span class="hlt">power</span> approaches zero as kw0 is increased and reaches the limiting value of zero of the paraxial beam.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA509170','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA509170"><span><span class="hlt">Ocean</span> Surface <span class="hlt">Wave</span> Transformation Over a Sandy Sea Bed</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2009-09-01</p> <p>coral reefs can dissipate <span class="hlt">wave</span> energy by friction in a magnitude comparable to <span class="hlt">wave</span> breaking. Over sandy bottoms, the size of sand grains is important...Sciences, Prentice Hall, 111–136. Lowe, R.J., et al. (2005). Spectral <span class="hlt">wave</span> dissipation over a barrier reef . J. Phys. Res., 100(C04001), doi:10.1029...thesis are those of the author and do not reflect the official policy or position of the Department of Defense or the U.S. Government. 12a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatCo...814055Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatCo...814055Q"><span>Submesoscale transition from geostrophic flows to internal <span class="hlt">waves</span> in the northwestern Pacific upper <span class="hlt">ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qiu, Bo; Nakano, Toshiya; Chen, Shuiming; Klein, Patrice</p> <p>2017-01-01</p> <p>With radar interferometry, the next-generation Surface Water and <span class="hlt">Ocean</span> Topography satellite mission will improve the measured sea surface height resolution down to 15 km, allowing us to investigate for the first time the global upper <span class="hlt">ocean</span> variability at the submesoscale range. Here, by analysing shipboard Acoustic Doppler Current Profiler measurements along 137°E in the northwest Pacific of 2004-2016, we show that the observed upper <span class="hlt">ocean</span> velocities are comprised of balanced geostrophic flows and unbalanced internal <span class="hlt">waves</span>. The transition length scale, Lt, separating these two motions, is found to depend strongly on the energy level of local mesoscale eddy variability. In the eddy-abundant western boundary current region of Kuroshio, Lt can be shorter than 15 km, whereas Lt exceeds 200 km along the path of relatively stable North Equatorial Current. Judicious separation between the geostrophic and internal <span class="hlt">wave</span> signals represents both a challenge and an opportunity for the Surface Water and <span class="hlt">Ocean</span> Topography mission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA04373.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA04373.html"><span>Deep <span class="hlt">Ocean</span> Tsunami <span class="hlt">Waves</span> off the Sri Lankan Coast</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2005-01-26</p> <p>The initial tsunami <span class="hlt">waves</span> resulting from the undersea earthquake that occurred at 00:58:53 UTC Coordinated Universal Time on 26 December 2004 off the island of Sumatra, Indonesia, as seen by NASA Terra spacecraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21322904','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21322904"><span>On Dissipation Function of <span class="hlt">Ocean</span> <span class="hlt">Waves</span> due to Whitecapping</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zakharov, V. E.; Korotkevich, A. O.; Prokofiev, A. O.</p> <p>2009-09-09</p> <p>The Hasselmann kinetic equation provides a statistical description of <span class="hlt">waves</span> ensemble. Several catastrophic events are beyond statistical model. In the case of gravity <span class="hlt">waves</span> on the surface of the deep fluid may be the most frequent and important events of such kind are whitecapping and <span class="hlt">wave</span> breaking. It was shown earlier that such effects leads to additional dissipation in the energy contaning region around <span class="hlt">waves</span> spectral peak, which can be simulated by means of empiric dissipative term in kinetic equation. In order to find dependence of this term with respect to nonlinearity in the system (steepness of the surface) we preformed two numerical experiments: weakly nonlinear one in the framework of 3D hydrodynamics and fully nonlinear one for 2D hydrodynamic. In spite of significantly different models and initial conditions, both these experiments yielded close results. Obtained data can be used to define analytical formula for dependence of the dissipative term of dissipation coefficient with respect to mean steepness of the surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA521929','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA521929"><span><span class="hlt">Ocean</span> Surface <span class="hlt">Wave</span> Optical Roughness - Innovative Measurement and Modeling</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2006-01-01</p> <p>microsacle breaking <span class="hlt">waves</span> from infrared imagery using a PIV algorithm. Meas. Sci. Technol. 16, 1961-1969. Phillips, O. M., Posner, F. L ., and Hansen , J...small as a millimeter. This characterization includes microscale and whitecap breaking <span class="hlt">waves</span>. * Prof. Michael L . Banner, School of Mathematics...The University of NSW, Sydney, Australia Dr. Bertrand Chapron, Oceanography, IFREMER, Brest, France Dr. Andres Corrada-Emmanuel, Physics Dept</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OcSci..12..601F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OcSci..12..601F"><span>Mapping turbulent diffusivity associated with <span class="hlt">oceanic</span> internal lee <span class="hlt">waves</span> offshore Costa Rica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fortin, Will F. J.; Holbrook, W. Steven; Schmitt, Raymond W.</p> <p>2016-04-01</p> <p>Breaking internal <span class="hlt">waves</span> play a primary role in maintaining the meridional overturning circulation. <span class="hlt">Oceanic</span> lee <span class="hlt">waves</span> are known to be a significant contributor to diapycnal mixing associated with internal <span class="hlt">wave</span> dissipation, but direct measurement is difficult with standard oceanographic sampling methods due to the limited spatial extent of standing lee <span class="hlt">waves</span>. Here, we present an analysis of <span class="hlt">oceanic</span> internal lee <span class="hlt">waves</span> observed offshore eastern Costa Rica using seismic imaging and estimate the turbulent diffusivity via a new seismic slope spectrum method that extracts diffusivities directly from seismic images, using tracked reflections only to scale diffusivity values. The result provides estimates of turbulent diffusivities throughout the water column at scales of a few hundred meters laterally and 10 m vertically. Synthetic tests demonstrate the method's ability to resolve turbulent structures and reproduce accurate diffusivities. A turbulence map of our seismic section in the western Caribbean shows elevated turbulent diffusivities near rough seafloor topography as well as in the mid-water column where observed lee <span class="hlt">wave</span> propagation terminates. Mid-water column hotspots of turbulent diffusivity show levels 5 times higher than surrounding waters and 50 times greater than typical open-<span class="hlt">ocean</span> diffusivities. This site has steady currents that make it an exceptionally accessible laboratory for the study of lee-<span class="hlt">wave</span> generation, propagation, and decay.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840019207','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840019207"><span>Synthetic aperture radar images of <span class="hlt">ocean</span> <span class="hlt">waves</span>, theories of imaging physics and experimental tests</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vesecky, J. F.; Durden, S. L.; Smith, M. P.; Napolitano, D. A.</p> <p>1984-01-01</p> <p>The physical mechanism for the synthetic Aperture Radar (SAR) imaging of <span class="hlt">ocean</span> <span class="hlt">waves</span> is investigated through the use of analytical models. The models are tested by comparison with data sets from the SEASAT mission and airborne SAR's. Dominant <span class="hlt">ocean</span> wavelengths from SAR estimates are biased towards longer wavelengths. The quasispecular scattering mechanism agrees with experimental data. The Doppler shift for ship wakes is that of the mean sea surface.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1980ende....3..165M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1980ende....3..165M"><span>The sea trial of the <span class="hlt">wave</span> <span class="hlt">power</span> generator 'Kaimei'</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masuda, Y.; Miyazaki, T.</p> <p>1980-10-01</p> <p>An experimental Japanese prototype of a <span class="hlt">wave-power</span> electricity generator system is examined. Construction details and experimental data are presented. The ship-type floating structure, 80 meters in length and 500 tons dead weight, used a non-valve Wells turbine of 0.6 m diameter with four wings, whose energy conversion efficiency was found to be greater than 60% with very small <span class="hlt">waves</span>, and whose safety factor was found to be greater than that of the impulse turbine. The 'Kaimei' is concluded to be promising, but some technical problems, including increasing and smoothing the output <span class="hlt">power</span>, remain to be solved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5059714','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5059714"><span><span class="hlt">Ocean</span> rogue <span class="hlt">waves</span> and their phase space dynamics in the limit of a linear interference model</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Birkholz, Simon; Brée, Carsten; Veselić, Ivan; Demircan, Ayhan; Steinmeyer, Günter</p> <p>2016-01-01</p> <p>We reanalyse the probability for formation of extreme <span class="hlt">waves</span> using the simple model of linear interference of a finite number of elementary <span class="hlt">waves</span> with fixed amplitude and random phase fluctuations. Under these model assumptions no rogue <span class="hlt">waves</span> appear when less than 10 elementary <span class="hlt">waves</span> interfere with each other. Above this threshold rogue <span class="hlt">wave</span> formation becomes increasingly likely, with appearance frequencies that may even exceed long-term observations by an order of magnitude. For estimation of the effective number of interfering <span class="hlt">waves</span>, we suggest the Grassberger-Procaccia dimensional analysis of individual time series. For the <span class="hlt">ocean</span> system, it is further shown that the resulting phase space dimension may vary, such that the threshold for rogue <span class="hlt">wave</span> formation is not always reached. Time series analysis as well as the appearance of particular focusing wind conditions may enable an effective forecast of such rogue-<span class="hlt">wave</span> prone situations. In particular, extracting the dimension from <span class="hlt">ocean</span> time series allows much more specific estimation of the rogue <span class="hlt">wave</span> probability. PMID:27731411</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27731411','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27731411"><span><span class="hlt">Ocean</span> rogue <span class="hlt">waves</span> and their phase space dynamics in the limit of a linear interference model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Birkholz, Simon; Brée, Carsten; Veselić, Ivan; Demircan, Ayhan; Steinmeyer, Günter</p> <p>2016-10-12</p> <p>We reanalyse the probability for formation of extreme <span class="hlt">waves</span> using the simple model of linear interference of a finite number of elementary <span class="hlt">waves</span> with fixed amplitude and random phase fluctuations. Under these model assumptions no rogue <span class="hlt">waves</span> appear when less than 10 elementary <span class="hlt">waves</span> interfere with each other. Above this threshold rogue <span class="hlt">wave</span> formation becomes increasingly likely, with appearance frequencies that may even exceed long-term observations by an order of magnitude. For estimation of the effective number of interfering <span class="hlt">waves</span>, we suggest the Grassberger-Procaccia dimensional analysis of individual time series. For the <span class="hlt">ocean</span> system, it is further shown that the resulting phase space dimension may vary, such that the threshold for rogue <span class="hlt">wave</span> formation is not always reached. Time series analysis as well as the appearance of particular focusing wind conditions may enable an effective forecast of such rogue-<span class="hlt">wave</span> prone situations. In particular, extracting the dimension from <span class="hlt">ocean</span> time series allows much more specific estimation of the rogue <span class="hlt">wave</span> probability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...635207B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...635207B"><span><span class="hlt">Ocean</span> rogue <span class="hlt">waves</span> and their phase space dynamics in the limit of a linear interference model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Birkholz, Simon; Brée, Carsten; Veselić, Ivan; Demircan, Ayhan; Steinmeyer, Günter</p> <p>2016-10-01</p> <p>We reanalyse the probability for formation of extreme <span class="hlt">waves</span> using the simple model of linear interference of a finite number of elementary <span class="hlt">waves</span> with fixed amplitude and random phase fluctuations. Under these model assumptions no rogue <span class="hlt">waves</span> appear when less than 10 elementary <span class="hlt">waves</span> interfere with each other. Above this threshold rogue <span class="hlt">wave</span> formation becomes increasingly likely, with appearance frequencies that may even exceed long-term observations by an order of magnitude. For estimation of the effective number of interfering <span class="hlt">waves</span>, we suggest the Grassberger-Procaccia dimensional analysis of individual time series. For the <span class="hlt">ocean</span> system, it is further shown that the resulting phase space dimension may vary, such that the threshold for rogue <span class="hlt">wave</span> formation is not always reached. Time series analysis as well as the appearance of particular focusing wind conditions may enable an effective forecast of such rogue-<span class="hlt">wave</span> prone situations. In particular, extracting the dimension from <span class="hlt">ocean</span> time series allows much more specific estimation of the rogue <span class="hlt">wave</span> probability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S13B2017G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S13B2017G"><span>Modeling microseism generation off Southern California with a numerical <span class="hlt">wave</span> model: Coastal <span class="hlt">wave</span> reflection and open <span class="hlt">ocean</span> interactions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Graham, N.; Clayton, R. W.; Kedar, S.; Webb, F.; Jones, C. E.</p> <p>2010-12-01</p> <p>Application of correlation methods to monitoring temporal variations for relatively short time windows can lead to a violation of the underlying assumption of the technique, that the sources are distributed randomly off either end of the station-station path. If this assumption is not met, the technique estimate can be biased by a favored projection of the Green’s function, which would lead to an incorrect travel time estimate and consequently an incorrect velocity estimate. Since monitoring temporal changes in geological structures of crustal scale is dominated by the <span class="hlt">ocean</span> microseismic band (~3-10 seconds), analysis of the microseisms source distribution is of particular interest. We present the first ever parameterizations of microseism generation by coastal reflection of <span class="hlt">ocean</span> gravity <span class="hlt">waves</span>. The parameterizations have been implemented in a numerical <span class="hlt">wave</span> model covering the waters off Southern California. Using the theory of Longuet-Higgins [1950], we modeled the microseisms generation by computing the <span class="hlt">wave-wave</span> interaction component of the swell with its coastal-reflected component, modified by a depth-dependent resonance term, along the Southern California Coast. Three simulations were conducted covering September 2007 to July 2009. In one simulation, no coastal reflection of <span class="hlt">wave</span> energy was included, with simulated microseism generation only via “open ocean” <span class="hlt">wave-wave</span> interactions. Two other simulations tested simple parameterizations of coastal <span class="hlt">wave</span> reflection based on a) specular, and b) scattered reflection from coastline segments. We compare the time-dependent microseisms amplitude to seismic observations throughout Southern California. We also compare the modeled source locations to those obtained by a location method based on accumulating the zero-lag correlations between data and synthetic surface <span class="hlt">waves</span> generated at a mesh of potential source locations. Preliminary results show good agreement between model results and observations, and indicate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.2262H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.2262H"><span>Inversion to estimate <span class="hlt">ocean</span> <span class="hlt">wave</span> directional spectrum from high-frequency radar</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hisaki, Yukiharu</p> <p>2015-04-01</p> <p>An high-frequency (HF) radar observes <span class="hlt">ocean</span> surface currents and <span class="hlt">waves</span> by radiating HF radio <span class="hlt">waves</span> to the sea surface and analyzing the backscattered signals. <span class="hlt">Ocean</span> <span class="hlt">wave</span> spectrum is estimated from the first- and the second-order scattering of Doppler spectra by the inversion. The estimation of <span class="hlt">ocean</span> surface currents is robust, because the surface currents can be derived from the peak Doppler frequency of the first-order scattering in the Doppler spectrum. The method to estimate <span class="hlt">ocean</span> <span class="hlt">wave</span> spectra is complicated and the second-order scattering in the Doppler spectrum is fragile, which is affected by the noise in the Doppler spectrum. A new method to estimate <span class="hlt">ocean</span> <span class="hlt">wave</span> spectra from HF radar is developed. This method is the extension of Hisaki (1996, 2005, 2006, 2009, 2014). The new method can be applied to both the single radar and dual radar array case, while the previous methods can be applied only the single radar case (Hisaki, 2005, 2006, 2009, 2014) or dual radar case (Hisaki, 1996). <span class="hlt">Ocean</span> <span class="hlt">wave</span> spectra are estimated in the regular grid cells, while <span class="hlt">wave</span> spectra are estimated on the polar grids points with the origin of the radar position in the previous method for single radar case. The governing equations for <span class="hlt">wave</span> estimation are the integral equations which relate the <span class="hlt">wave</span> spectrum to the Doppler spectrum, and the energy balance equation under the assumption of stationarity. The regularization constraints in the horizontal space and the <span class="hlt">wave</span> frequency-direction space are also used for the estimation. The unknowns, which are spectral values, surface wind speeds and directions, are estimated by seeking the minimum of the objective function, which is defined as the sum of weighted squares of the equations. The signal to noise ratio in the Doppler spectrum for <span class="hlt">wave</span> estimation must be high. We selected the Doppler spectra using the SOM (Self organization map ) analysis method. The method will be demonstrated by comparing with in-situ observed data, in which only</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22227974','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22227974"><span>Analysis of the <span class="hlt">power</span> capacity of overmoded slow <span class="hlt">wave</span> structures</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, Dian; Zhang, Jun; Zhong, Huihuang; Jin, Zhenxing</p> <p>2013-07-15</p> <p>As the generated wavelength shortens, overmoded slow <span class="hlt">wave</span> structures (SWSs) with large diameters are employed in O-type Cerenkov high <span class="hlt">power</span> microwave (HPM) generators to achieve high <span class="hlt">power</span> capacity. However, reported experimental results suggest that overmoded slow <span class="hlt">wave</span> HPM generators working at millimeter wavelength output much lower <span class="hlt">power</span> than those working at X-band do, despite the fact that the value of D/λ (here, D is the average diameter of SWSs and λ is the generated wavelength) of the former is much larger than that of the latter. In order to understand this, the characteristics of the <span class="hlt">power</span> capacity of the TM{sub 0n} modes in overmoded SWSs are numerically investigated. Our analysis reveals the following facts. First, the <span class="hlt">power</span> capacity of higher order TM{sub 0n} modes is apparently larger than that of TM{sub 01} mode. This is quite different from the conclusion got in the foregone report, in which the <span class="hlt">power</span> capacity of overmoded SWSs is estimated by that of smooth cylindrical waveguides. Second, the rate at which the <span class="hlt">power</span> capacity of TM{sub 01} mode in overmoded SWSs grows with diameter does not slow down as the TM{sub 01} field transforms from “volume wave” to “surface <span class="hlt">wave</span>.” Third, once the diameter of overmoded SWSs and the beam voltage are fixed, the <span class="hlt">power</span> capacity of TM{sub 01} <span class="hlt">wave</span> drops as periodic length L shortens and the generated frequency rises, although the value of D/λ increases significantly. Therefore, it is necessary to investigate the capability of annular electron beam to interact efficiently with higher order TM{sub 0n} modes in overmoded SWSs if we want to improve the <span class="hlt">power</span> capacity of overmoded O-type Cerenkov HPM generators working at high frequency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.2575Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2575Q"><span><span class="hlt">Wave</span> turbulence interaction induced vertical mixing and its effects in <span class="hlt">ocean</span> and climate models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Qiao, Fangli; Yuan, Yeli; Deng, Jia; Dai, Dejun; Song, Zhenya</p> <p>2017-04-01</p> <p>Heated from above, the <span class="hlt">oceans</span> are stably stratified. Therefore, the performance of the general <span class="hlt">ocean</span> circulation and climate studies through coupled atmosphere-<span class="hlt">ocean</span> models depend critically on vertical mixing of energy and momentum in the water column. Many of the traditional general circulation models are based on Total Kinetic Energy (TKE), in which the roles of <span class="hlt">waves</span> are averaged out. Although theoretical calculations suggest that <span class="hlt">waves</span> could greatly enhance coexisting turbulence, no field measurements on turbulence have ever validated this mechanism directly. To address this problem, a specially designed field experiment has been conducted. The experimental results indicate that the <span class="hlt">wave</span>-turbulence interaction induced enhancement of the background turbulence is indeed the predominant mechanism for turbulence generation and enhancement. Based on this understanding, we propose a new parameterization for vertical mixing as an additive part to the traditional TKE approach. This new result reconfirmed the past theoretical model that had been tested and validated in numerical model experiments and field observations. It firmly establishes the critical role of <span class="hlt">wave</span>-turbulence interaction effects in both the general <span class="hlt">ocean</span> circulation models and atmosphere-<span class="hlt">ocean</span> coupled models, which could greatly improve an understanding of the sea surface temperature and water column properties distributions, and hence the model-based climate forecasting capability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26953182','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26953182"><span><span class="hlt">Wave</span>-turbulence interaction-induced vertical mixing and its effects in <span class="hlt">ocean</span> and climate models.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qiao, Fangli; Yuan, Yeli; Deng, Jia; Dai, Dejun; Song, Zhenya</p> <p>2016-04-13</p> <p>Heated from above, the <span class="hlt">oceans</span> are stably stratified. Therefore, the performance of general <span class="hlt">ocean</span> circulation models and climate studies through coupled atmosphere-<span class="hlt">ocean</span> models depends critically on vertical mixing of energy and momentum in the water column. Many of the traditional general circulation models are based on total kinetic energy (TKE), in which the roles of <span class="hlt">waves</span> are averaged out. Although theoretical calculations suggest that <span class="hlt">waves</span> could greatly enhance coexisting turbulence, no field measurements on turbulence have ever validated this mechanism directly. To address this problem, a specially designed field experiment has been conducted. The experimental results indicate that the <span class="hlt">wave</span>-turbulence interaction-induced enhancement of the background turbulence is indeed the predominant mechanism for turbulence generation and enhancement. Based on this understanding, we propose a new parametrization for vertical mixing as an additive part to the traditional TKE approach. This new result reconfirmed the past theoretical model that had been tested and validated in numerical model experiments and field observations. It firmly establishes the critical role of <span class="hlt">wave</span>-turbulence interaction effects in both general <span class="hlt">ocean</span> circulation models and atmosphere-<span class="hlt">ocean</span> coupled models, which could greatly improve the understanding of the sea surface temperature and water column properties distributions, and hence model-based climate forecasting capability. © 2016 The Authors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750008127','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750008127"><span>Application of monochromatic <span class="hlt">ocean</span> <span class="hlt">wave</span> forecasts to prediction of <span class="hlt">wave</span>-induced currents</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Poole, L. R.</p> <p>1975-01-01</p> <p>The use of monochromatic wind-<span class="hlt">wave</span> forecasts in prediction of wind-<span class="hlt">wave</span>-induced currents was assessed. Currents were computed for selected combinations of wind conditions by using a spectrum approach which was developed by using the Bretschneider <span class="hlt">wave</span> spectrum for partially developed wind seas. These currents were compared with currents computed by using the significant and average monochromatic <span class="hlt">wave</span> parameters related to the Bretschneider spectrum. Results indicate that forecasts of significant <span class="hlt">wave</span> parameters can be used to predict surface wind-<span class="hlt">wave</span>-induced currents. Conversion of these parameters to average <span class="hlt">wave</span> parameters can furnish reasonable estimates of subsurface current values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70032604','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70032604"><span><span class="hlt">Ocean</span>-atmosphere dynamics during Hurricane Ida and Nor'Ida: An application of the coupled <span class="hlt">ocean-atmosphere-wave</span>-sediment transport (COAWST) modeling system</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Olabarrieta, M.; Warner, J.C.; Armstrong, B.; Zambon, J.B.; He, R.</p> <p>2012-01-01</p> <p>The coupled <span class="hlt">ocean-atmosphere-wave</span>-sediment transport (COAWST) modeling system was used to investigate atmosphere-<span class="hlt">ocean-wave</span> interactions in November 2009 during Hurricane Ida and its subsequent evolution to Nor'Ida, which was one of the most costly storm systems of the past two decades. One interesting aspect of this event is that it included two unique atmospheric extreme conditions, a hurricane and a nor'easter storm, which developed in regions with different oceanographic characteristics. Our modeled results were compared with several data sources, including GOES satellite infrared data, JASON-1 and JASON-2 altimeter data, CODAR measurements, and <span class="hlt">wave</span> and tidal information from the National Data Buoy Center (NDBC) and the National Tidal Database. By performing a series of numerical runs, we were able to isolate the effect of the interaction terms between the atmosphere (modeled with Weather Research and Forecasting, the WRF model), the <span class="hlt">ocean</span> (modeled with Regional <span class="hlt">Ocean</span> Modeling System (ROMS)), and the <span class="hlt">wave</span> propagation and generation model (modeled with Simulating <span class="hlt">Waves</span> Nearshore (SWAN)). Special attention was given to the role of the <span class="hlt">ocean</span> surface roughness. Three different <span class="hlt">ocean</span> roughness closure models were analyzed: DGHQ (which is based on <span class="hlt">wave</span> age), TY2001 (which is based on <span class="hlt">wave</span> steepness), and OOST (which considers both the effects of <span class="hlt">wave</span> age and steepness). Including the <span class="hlt">ocean</span> roughness in the atmospheric module improved the wind intensity estimation and therefore also the wind <span class="hlt">waves</span>, surface currents, and storm surge amplitude. For example, during the passage of Hurricane Ida through the Gulf of Mexico, the wind speeds were reduced due to <span class="hlt">wave</span>-induced <span class="hlt">ocean</span> roughness, resulting in better agreement with the measured winds. During Nor'Ida, including the <span class="hlt">wave</span>-induced surface roughness changed the form and dimension of the main low pressure cell, affecting the intensity and direction of the winds. The combined <span class="hlt">wave</span> age- and <span class="hlt">wave</span> steepness</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012OcMod..43..112O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012OcMod..43..112O"><span><span class="hlt">Ocean</span>-atmosphere dynamics during Hurricane Ida and Nor'Ida: An application of the coupled <span class="hlt">ocean-atmosphere-wave</span>-sediment transport (COAWST) modeling system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olabarrieta, Maitane; Warner, John C.; Armstrong, Brandy; Zambon, Joseph B.; He, Ruoying</p> <p></p> <p>The coupled <span class="hlt">ocean-atmosphere-wave</span>-sediment transport (COAWST) modeling system was used to investigate atmosphere-<span class="hlt">ocean-wave</span> interactions in November 2009 during Hurricane Ida and its subsequent evolution to Nor'Ida, which was one of the most costly storm systems of the past two decades. One interesting aspect of this event is that it included two unique atmospheric extreme conditions, a hurricane and a nor'easter storm, which developed in regions with different oceanographic characteristics. Our modeled results were compared with several data sources, including GOES satellite infrared data, JASON-1 and JASON-2 altimeter data, CODAR measurements, and <span class="hlt">wave</span> and tidal information from the National Data Buoy Center (NDBC) and the National Tidal Database. By performing a series of numerical runs, we were able to isolate the effect of the interaction terms between the atmosphere (modeled with Weather Research and Forecasting, the WRF model), the <span class="hlt">ocean</span> (modeled with Regional <span class="hlt">Ocean</span> Modeling System (ROMS)), and the <span class="hlt">wave</span> propagation and generation model (modeled with Simulating <span class="hlt">Waves</span> Nearshore (SWAN)). Special attention was given to the role of the <span class="hlt">ocean</span> surface roughness. Three different <span class="hlt">ocean</span> roughness closure models were analyzed: DGHQ (which is based on <span class="hlt">wave</span> age), TY2001 (which is based on <span class="hlt">wave</span> steepness), and OOST (which considers both the effects of <span class="hlt">wave</span> age and steepness). Including the <span class="hlt">ocean</span> roughness in the atmospheric module improved the wind intensity estimation and therefore also the wind <span class="hlt">waves</span>, surface currents, and storm surge amplitude. For example, during the passage of Hurricane Ida through the Gulf of Mexico, the wind speeds were reduced due to <span class="hlt">wave</span>-induced <span class="hlt">ocean</span> roughness, resulting in better agreement with the measured winds. During Nor'Ida, including the <span class="hlt">wave</span>-induced surface roughness changed the form and dimension of the main low pressure cell, affecting the intensity and direction of the winds. The combined <span class="hlt">wave</span> age- and <span class="hlt">wave</span> steepness</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70129011','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70129011"><span>Investigation of hurricane Ivan using the coupled <span class="hlt">ocean-atmosphere-wave</span>-sediment transport (COAWST) model</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Zambon, Joseph B.; He, Ruoying; Warner, John C.</p> <p>2014-01-01</p> <p>The coupled ocean–atmosphere–wave–sediment transport (COAWST) model is used to hindcast Hurricane Ivan (2004), an extremely intense tropical cyclone (TC) translating through the Gulf of Mexico. Sensitivity experiments with increasing complexity in ocean–atmosphere–<span class="hlt">wave</span> coupled exchange processes are performed to assess the impacts of coupling on the predictions of the atmosphere, <span class="hlt">ocean</span>, and <span class="hlt">wave</span> environments during the occurrence of a TC. Modest improvement in track but significant improvement in intensity are found when using the fully atmosphere–<span class="hlt">ocean-wave</span> coupled configuration versus uncoupled (e.g., standalone atmosphere, <span class="hlt">ocean</span>, or <span class="hlt">wave</span>) model simulations. Surface <span class="hlt">wave</span> fields generated in the fully coupled configuration also demonstrates good agreement with in situ buoy measurements. Coupled and uncoupled model-simulated sea surface temperature (SST) fields are compared with both in situ and remote observations. Detailed heat budget analysis reveals that the mixed layer temperature cooling in the deep <span class="hlt">ocean</span> (on the shelf) is caused primarily by advection (equally by advection and diffusion).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70018602','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70018602"><span>Southern <span class="hlt">Ocean</span> monthly <span class="hlt">wave</span> fields for austral winters 1985-1988 by Geosat radar altimeter</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Josberger, E.G.; Mognard, N.M.</p> <p>1996-01-01</p> <p>Four years of monthly averaged <span class="hlt">wave</span> height fields for the austral winters 19851988 derived from the Geosat altimeter data show a spatial variability of the scale of 500-1000 km that varies monthly and annually. This variability is superimposed on the zonal patterns surrounding the Antarctic continent and characteristic of the climatology derived from the U.S. Navy [1992] Marine Climatic Atlas of the World. The location and the intensity of these large-scale features, which are not found in the climatological fields, exhibit strong monthly and yearly variations. A global underestimation of the climatological mean <span class="hlt">wave</span> heights by more than l m is also found over large regions of the Southern <span class="hlt">Ocean</span>. The largest monthly averaged significant <span class="hlt">wave</span> heights are above 5 m and are found during August of every year in the Indian <span class="hlt">Ocean</span>, south of 40??S. The monthly <span class="hlt">wave</span> fields show more variability in the Atlantic and Pacific <span class="hlt">Oceans</span> than in the Indian <span class="hlt">Ocean</span>. The Seasat data from 1978 and the Geosat data from 1985 and 1988 show an eastward rotation of the largest <span class="hlt">wave</span> heights. However, this rotation is absent in 1986 and 1987; the former was a year of unusually low sea states, and the latter was a year of unusually high sea states, which suggests a link to the El Nin??o-Southern Oscillation event of 1986. Copyright 1996 by the American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JGR...101.6689J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JGR...101.6689J"><span>Southern <span class="hlt">Ocean</span> monthly <span class="hlt">wave</span> fields for austral winters 1985-1988 by Geosat radar altimeter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Josberger, Edward G.; Mognard, Nelly M.</p> <p>1996-03-01</p> <p>Four years of monthly averaged <span class="hlt">wave</span> height fields for the austral winters 1985-1988 derived from the Geosat altimeter data show a spatial variability of the scale of 500-1000 km that varies monthly and annually. This variability is superimposed on the zonal patterns surrounding the Antarctic continent and characteristic of the climatology derived from the U.S. Navy [1992] Marine Climatic Atlas of the World. The location and the intensity of these large-scale features, which are not found in the climatological fields, exhibit strong monthly and yearly variations. A global underestimation of the climatological mean <span class="hlt">wave</span> heights by more than 1 m is also found over large regions of the Southern <span class="hlt">Ocean</span>. The largest monthly averaged significant <span class="hlt">wave</span> heights are above 5 m and are found during August of every year in the Indian <span class="hlt">Ocean</span>, south of 40°S. The monthly <span class="hlt">wave</span> fields show more variability in the Atlantic and Pacific <span class="hlt">Oceans</span> than in the Indian <span class="hlt">Ocean</span>. The Seasat data from 1978 and the Geosat data from 1985 and 1988 show an eastward rotation of the largest <span class="hlt">wave</span> heights. However, this rotation is absent in 1986 and 1987; the former was a year of unusually low sea states, and the latter was a year of unusually high sea states, which suggests a link to the El Niño-Southern Oscillation event of 1986.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S51E..08Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S51E..08Y"><span>Characteristics of Scholte-Rayleigh <span class="hlt">waves</span> and reflected body <span class="hlt">waves</span> recovered by <span class="hlt">ocean</span> bottom ambient noise cross-correlation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yao, H.; Gao, C.; Lin, C.</p> <p>2013-12-01</p> <p>Ambient noise interferometry has been widely used to recover surface <span class="hlt">waves</span> for understanding the crustal and lithospheric structures. Recent studies have shown that body <span class="hlt">wave</span> reflections from deep mantle and core discontinuities can be successfully retrieved by stacking ambient noise cross-correlation functions (CFs) of many different land-station pairs. Here we report that not only surface <span class="hlt">waves</span> but also reflected body <span class="hlt">waves</span> from mantle transition zone discontinuities can be successfully recovered from one-year ambient noise data recorded by <span class="hlt">ocean</span> bottom seismometers near equatorial eastern Pacific Rise. The recovered surface <span class="hlt">waves</span> include Scholte-Rayleigh <span class="hlt">waves</span> on the vertical-vertical (Z-Z) and radial-radial (R-R) component CFs and Love <span class="hlt">waves</span> on the transverse-transverse (T-T) component CFs. On the Z-Z component CFs, we observe both the fundamental mode and the first higher mode Scholte-Rayleigh <span class="hlt">waves</span> in the period band 2 - 10 s; however, on the R-R component CFs, we only observe the first higher mode, which has the same dispersion characteristics of that on the Z-Z component CFs. Synthetic radial component seismograms as the result of a radial-direction point source in the shallow sediment layer explain the missing of fundamental mode Scholte-Rayleigh <span class="hlt">waves</span> on the R-R component CFs, which are primarily sensitive to very low rigidity and high attenuation shallow sedimentary layers below the <span class="hlt">ocean</span> bottom. We also observe clear body <span class="hlt">wave</span> reflections in the period band 5 - 10 s from mantle transition zone discontinuities, e.g., 410 km and 660 km discontinuities, on many single station-pair CFs without stacking over many different station pairs. In particular, these deep reflected signals appear quite stable on almost every daily CF and the amplitude and phase of these reflections show great symmetry on the yearly-stacked CFs. The ambient noise sources to generate these deep reflected signals are probably from <span class="hlt">ocean</span> <span class="hlt">wave</span> pressure exerted on the seafloor, as the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.C21D..05W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.C21D..05W"><span>Two new ways of mapping sea ice thickness using <span class="hlt">ocean</span> <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wadhams, P.</p> <p>2010-12-01</p> <p>TWO NEW METHODS OF MAPPING SEA ICE THICKNESS USING <span class="hlt">OCEAN</span> <span class="hlt">WAVES</span>. P. Wadhams (1,2), Martin Doble (1,2) and F. Parmiggiani (3) (1) Dept. of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, UK. (2) Laboratoire d’Océanographie de Villefranche, Université Pierre et Marie Curie, 06234 Villefranche-sur-Mer, France (2) ISAC-CNR, Bologna, Italy Two new methods of mapping ice thickness have been recently developed and tested, both making use of the dispersion relation of <span class="hlt">ocean</span> <span class="hlt">waves</span> in ice of radically different types. In frazil-pancake ice, a young ice type in which cakes less than 5 m across float in a suspension of individual ice crystals, the propagation of <span class="hlt">waves</span> has been successfully modelled by treating the ice layer as a highly viscous fluid. The model predicts a shortening of wavelengths within the ice. Two-dimensional Fourier analysis of successive SAR subscenes to track the directional spectrum of a <span class="hlt">wave</span> field as it enters an ice edge shows that <span class="hlt">waves</span> do indeed shorten within the ice, and the change has been successfully used to predict the thickness of the frazil-pancake layer. Concurrent shipborne sampling in the Antarctic has shown that the method is accurate, and we now propose its use throughout the important frazil-pancake regimes in the world <span class="hlt">ocean</span> (Antarctic circumpolar ice edge zone, Greenland Sea, Bering Sea and others). A radically different type of dispersion occurs when <span class="hlt">ocean</span> <span class="hlt">waves</span> enter the continuous icefields of the central Arctic, when they couple with the elastic ice cover to propagate as a flexural-gravity <span class="hlt">wave</span>. A two-axis tiltmeter array has been used to measure the resulting change in the dispersion relation for long <span class="hlt">ocean</span> swell (15-30 s) originating from storms in the Greenland Sea. The dispersion relation is slightly different from swell in the open <span class="hlt">ocean</span>, so if two such arrays are placed a substantial distance (100s of km) apart and used to observe the changing <span class="hlt">wave</span> period of arrivals from a given</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhPl...24g3117Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhPl...24g3117Z"><span>Research on the high <span class="hlt">power</span> cyclotron-<span class="hlt">wave</span> rectifier</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Xiaoyun; Tuo, Xianguo; Ge, Qing; Peng, Ying</p> <p>2017-07-01</p> <p>As a key component of a Wireless <span class="hlt">Power</span> Transmission System, a cyclotron-<span class="hlt">wave</span> rectifier, a high <span class="hlt">power</span> microwave to DC converter, has received more attention from scholars. This paper comprehensively analyzes various limiting factors of the output voltage and current. The results show that high frequency breakdown, the external magnetic field, and engineering realization limit the output voltage, and the space charge force limits the beam current. On this basis, by using the equivalent circuit and particle simulation, we design a cyclotron-<span class="hlt">wave</span> rectifier with high <span class="hlt">power</span>. The simulation results demonstrate that working at 2.45 GHz, the rectifier can obtain an output voltage of 113 kV and an output <span class="hlt">power</span> of 791 kW. These conclusions can provide guidance for designing and application of this device.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014OcDyn..64..999L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014OcDyn..64..999L"><span>Marine radar <span class="hlt">ocean</span> <span class="hlt">wave</span> retrieval's dependency on range and azimuth</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lund, Björn; Collins, Clarence O.; Graber, Hans C.; Terrill, Eric; Herbers, Thomas H. C.</p> <p>2014-07-01</p> <p>The strength of the surface <span class="hlt">wave</span> signal in marine X-band radar (MR) images strongly depends on range and azimuth (i.e., the angle between antenna look and peak <span class="hlt">wave</span> direction). Traditionally, MR <span class="hlt">wave</span> analysis is carried out in a set of rectangular windows covering the radar field of view (FOV). The FOV is typically partially obstructed, e.g., due to the coastline or ship superstructures. Especially for ships that are subject to regular course changes, this results in an increased variability or error associated with <span class="hlt">wave</span> parameters. Using MR measurements from R/P FLIP, acquired off California during the 2010 US Office of Naval Research (ONR) high resolution air-sea interaction (Hi-Res) experiment, this study quantifies the dependency of the radar-based 2D <span class="hlt">wave</span> spectrum and parameters on range and azimuth. With the help of reference data from a nearby Datawell Waverider buoy, we propose empirical methods to remove the dependency and we illustrate their efficacy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009GeoRL..36.7601S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009GeoRL..36.7601S"><span>Numerically reproduced internal <span class="hlt">wave</span> spectra in the deep <span class="hlt">ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sugiyama, Yoshifumi; Niwa, Yoshihiro; Hibiya, Toshiyuki</p> <p>2009-04-01</p> <p>A vertically two-dimensional internal <span class="hlt">wave</span> field is forced equally at the near-inertial frequency and the semidiurnal tidal frequency both at the lowest vertical wavenumber. These correspond to wind forcing and internal tide forcing, the main energy sources for the internal <span class="hlt">wave</span> field. After 5 years of spin-up, a quasi-stationary internal <span class="hlt">wave</span> field with characteristics of the Garrett-Munk-like spectrum is successfully reproduced. Furthermore, we carry out additional experiments by changing the strength of the semidiurnal tidal forcing relative to the near-inertial forcing. It is demonstrated that the Garrett-Munk-like spectrum is created and maintained only when energy is supplied both from the near-inertial forcing and the semidiurnal tidal forcing. So long as both energy sources are available, nonlinear interactions among internal <span class="hlt">waves</span> occur such that the resulting internal <span class="hlt">wave</span> spectrum becomes close to the Garrett-Munk-like spectrum irrespective of the ratio of the near-inertial forcing to the semidiurnal tidal forcing.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1097434','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1097434"><span>Advanced, High <span class="hlt">Power</span>, Next Scale, <span class="hlt">Wave</span> Energy Conversion Device</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mekhiche, Mike; Dufera, Hiz; Montagna, Deb</p> <p>2012-10-29</p> <p>The project conducted under DOE contract DE‐EE0002649 is defined as the Advanced, High <span class="hlt">Power</span>, Next Scale, <span class="hlt">Wave</span> Energy Converter. The overall project is split into a seven‐stage, gated development program. The work conducted under the DOE contract is OPT Stage Gate III work and a portion of Stage Gate IV work of the seven stage product development process. The project effort includes Full Concept Design & Prototype Assembly Testing building on our existing <span class="hlt">Power</span>Buoy technology to deliver a device with much increased <span class="hlt">power</span> delivery. Scaling‐up from 150kW to 500kW <span class="hlt">power</span> generating capacity required changes in the <span class="hlt">Power</span>Buoy design that addressed cost reduction and mass manufacturing by implementing a Design for Manufacturing (DFM) approach. The design changes also focused on reducing <span class="hlt">Power</span>Buoy Installation, Operation and Maintenance (IO&M) costs which are essential to reducing the overall cost of energy. In this design, changes to the core <span class="hlt">Power</span>Buoy technology were implemented to increase capability and reduce both CAPEX and OPEX costs. OPT conceptually envisaged moving from a floating structure to a seabed structure. The design change from a floating structure to seabed structure would provide the implementation of stroke‐ unlimited <span class="hlt">Power</span> Take‐Off (PTO) which has a potential to provide significant <span class="hlt">power</span> delivery improvement and transform the <span class="hlt">wave</span> energy industry if proven feasible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOS.A34C2669K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOS.A34C2669K"><span>Radar and Laser Sensors for High Frequency <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Measurement.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kennedy, C. R.</p> <p>2016-02-01</p> <p>Experimental measurement of air-sea fluxes invariably take place using shipbourne instrumentation and simultaneous measurement of <span class="hlt">wave</span> height and direction is desired. A number of researchers have shown that range measuring sensors combined with inertial motion compensation can be successful on board stationary or very slowly moving ships. In order to measure <span class="hlt">wave</span> characteristics from ships moving at moderate to full speed the sensors are required to operate at higher frequency so as to overcome the Doppler shift caused by ship motion. This work presents results from some preliminary testing of laser, radar and ultrasonic range sensors in the laboratory and on board ship. The characteristics of the individual sensors are discussed and comparison of the <span class="hlt">wave</span> spectra produced by each is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790027754&hterms=radio+caroline&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dradio%2Bcaroline','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790027754&hterms=radio+caroline&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dradio%2Bcaroline"><span>Measurement of <span class="hlt">ocean</span> <span class="hlt">wave</span> heights using the Geos 3 altimeter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rufenach, C. L.; Alpers, W. R.</p> <p>1978-01-01</p> <p>Radar altimeter signals transmitted from the low-orbiting satellite Geos 3 were analyzed for two selected orbits over high seas associated with hurricane 'Caroline' in the Gulf of Mexico and a North Atlantic storm. The measured values of significant <span class="hlt">wave</span> height are in reasonable agreement with surface measurements, provided that the altimeter data are properly edited. The internal consistency of estimated <span class="hlt">wave</span> heights for the North Atlantic storm, a standard deviation of 0.6 m or less, and the good agreement with surface truth lend credence to the method. A statistical analysis of the pulse slope variation gives estimated values of significant <span class="hlt">wave</span> height within + or - 1 m of the true values 75% of the time for spatial averaging over 70 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA479627','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA479627"><span>Measurements of <span class="hlt">Ocean</span> Surface Turbulence and <span class="hlt">Wave</span>-Turbulence Interactions (PREPRINT)</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2008-02-19</p> <p>SUBTITLE Measurements of <span class="hlt">ocean</span> surface turbulence and <span class="hlt">wave</span>-turbulence interactions 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...corrects the directional spreading caused by the conventional MLM technique (Isobe et al., 1984, Capon, 1969), and the Maximum Entropy Method (MEM, Lygre...5245-5248 (1998). Isobe, M., Kondo, K. & Horikawa, K. Extension of MLM for estimating directional <span class="hlt">wave</span> spec- trum. Symposium on description and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800023544','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800023544"><span>The Seasat SAR Wind and <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Monitoring Capabilities: A case study for pass 1339m</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Beal, R. C.</p> <p>1980-01-01</p> <p>A well organized low energy 11 sec. swell system off the East Coast of the U.S. was detected with the Seasat Synthetic Aperture Radar and successfully tracked from deep water, across the continental shelf, and into shallow water. In addition, a less organized 7 sec. system was tentatively identified in the imagery. Both systems were independently confirmed with simultaneous <span class="hlt">wave</span> spectral measurements from a research pier, aircraft laser profilometer data, and Fleet Numerical Spectral <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830005273','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830005273"><span>Aircraft and satellite measurement of <span class="hlt">ocean</span> <span class="hlt">wave</span> directional spectra using scanning-beam microwave radars</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jackson, F. C.; Walton, W. T.; Baker, P. L.</p> <p>1982-01-01</p> <p>A microwave radar technique for remotely measuring the vector <span class="hlt">wave</span> number spectrum of the <span class="hlt">ocean</span> surface is described. The technique, which employs short-pulse, noncoherent radars in a conical scan mode near vertical incidence, is shown to be suitable for both aircraft and satellite application, the technique was validated at 10 km aircraft altitude, where we have found excellent agreement between buoy and radar-inferred absolute <span class="hlt">wave</span> height spectra.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA118688','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA118688"><span>The Spectral <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Model (SOWM), a Northern Hemisphere Computer Model for Specifying and Forecasting <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Spectra</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1982-07-01</p> <p>and incorporates them into the interpretation of the accuracy of the model specifications. In addition, rapid spatial and temporal variations of...rapid spatial and temporal variations of actual <span class="hlt">waves</span> that are not reproduced by the model are documented; and possible errors in the specification of...<span class="hlt">wave</span> clima - tology without incurring prohibitive costs. "The indexing algorithm, which is the heart of the retrival system, uses sub- projection</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-02-06/pdf/2012-2571.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-02-06/pdf/2012-2571.pdf"><span>77 FR 5791 - <span class="hlt">Ocean</span> Renewable <span class="hlt">Power</span> Company Maine, LLC; Notice of Staff Participation in Meeting</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-02-06</p> <p>... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission <span class="hlt">Ocean</span> Renewable <span class="hlt">Power</span> Company Maine, LLC; Notice of Staff Participation in... representatives from <span class="hlt">Ocean</span> Renewable <span class="hlt">Power</span> Company Maine, LLC at the Federal Energy Regulatory...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2011-04-05/pdf/2011-7984.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2011-04-05/pdf/2011-7984.pdf"><span>76 FR 18750 - <span class="hlt">Ocean</span> Renewable <span class="hlt">Power</span> Company, LLC; Notice of Change in Docket Number</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2011-04-05</p> <p>... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission <span class="hlt">Ocean</span> Renewable <span class="hlt">Power</span> Company, LLC; Notice of Change in Docket Number On July 24, 2009, <span class="hlt">Ocean</span> Renewable <span class="hlt">Power</span> Company, LLC (ORPC) filed a draft hydrokinetic pilot...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1810509H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810509H"><span>Tracking <span class="hlt">Ocean</span> Gravity <span class="hlt">Waves</span> in Real-time: Highlights of Bottom Pressure Data Recorded on <span class="hlt">Ocean</span> Networks Canada's NEPTUNE observatory</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heesemann, Martin; Mihaly, Steve; Gemmrich, Johannes; Davis, Earl; Thomson, Richard; Dewey, Richard</p> <p>2016-04-01</p> <p><span class="hlt">Ocean</span> Networks Canada operates two cabled <span class="hlt">ocean</span> observatories off Vancouver Island on Canada's west coast. The regional NEPTUNE observatory spans the entire Juan de Fuca tectonic plate from the coast across the subduction zone to the hydrothermally active Endeavour Segment of the Juan de Fuca Ridge Segment while the VENUS observatory focuses on coastal processes. Both observatories collect data on physical, chemical, biological, and geological aspects of the <span class="hlt">ocean</span> over long time periods, supporting research on complex earth processes. High-precision bottom pressure recorders (BPR) deployed on the NEPTUNE observatory are capable of detecting a wide range of phenomena related to sea level variations. The observatory BPRs provide observations of nano-resolution (with respect to full scale of the instrument) pressure variations which correspond to sub-millimeter scale surface water displacements in several kilometers of water. Detected signals include tides, tsunamis, infragravity <span class="hlt">waves</span>, swell, <span class="hlt">wave</span>-induced microseisms, storm surge, and seismic signals. Spectral analysis reveals many of these phenomena with periods ranging from a few seconds to many hours. Dispersion patterns from distant swells are prominent in the swell and microseism bands. By comparing the difference of arrival times between longer period <span class="hlt">waves</span>, which arrive first, and shorter period <span class="hlt">waves</span> we can estimate the distance the swells travelled since they were generated. Using this information, swell can be tracked back to specific storms across the Pacific. The presentation will high-light some examples of the mentioned phenomena in the continuous time-series that in some instances are more than seven years long.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006APS..MAR.Y8011G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006APS..MAR.Y8011G"><span>Energy from <span class="hlt">Ocean</span> <span class="hlt">Waves</span>, River Currents, and Wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guha, Shyamal</p> <p>2006-03-01</p> <p>The Earth we live in is surrounded by fluids, which are in perpetual motion. The air in the atmosphere and water found in lakes, <span class="hlt">ocean</span>, and rivers form our natural environment. Much of the fluid medium is in constant motion. The kinetic energy of this moving fluid is astronomical in magnitude. Over the years, I have considered methods of converting a fraction of the vast reserve of this kinetic energy into electro-mechanical energy. I have conceived a few schemes of such conversions. The fluids whose kinetic energy can be converted into electro-mechanical energy are the following: <span class="hlt">ocean</span> waters, river currents and atmospheric air. In a book to be published in the spring of 2006, I have described different techniques of energy conversion. In the upcoming APS meeting, I plan to discuss some of these techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006APS..NWS.G3007G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006APS..NWS.G3007G"><span>Energy from <span class="hlt">Ocean</span> <span class="hlt">Waves</span>, River Currents, and Wind</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guha, Shyamal</p> <p>2006-05-01</p> <p>The earth we live in is surrounded by fluids, which are in perpetual motion. There is air in the atmosphere, water in lakes, <span class="hlt">oceans</span> and rivers. The air and water around us form our natural environment. Much of the fluid medium is in constant motion. The kinetic energy of this moving fluid is astronomical in magnitude. Over the years, I considered methods of converting a fraction of the vast reserve of this kinetic energy into electro-mechanical energy. I conceived a few schemes of such conversion. The fluids whose kinetic energy can be converted into electro-mechanical energy are: <span class="hlt">ocean</span> waters, river current and atmospheric air. In a book to be published in 2006, I have described different techniques of energy conversion. In the APS meeting, I plan to discuss some of these techniques.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA598263','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA598263"><span><span class="hlt">Ocean</span> Surface <span class="hlt">Wave</span> Optical Roughness - Analysis of Innovative Measurements</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-09-30</p> <p><span class="hlt">Oceanic</span> Technol., 26, 1663-1671. 8 Zappa, C. J., J. R. Gemmrich, R. P. Morison, H. Schultz, M . L . Banner, D. A. LeBel, and T. Dickey (2012), An...Innovative Measurements Michael L . Banner School of Mathematics and Statistics The University of New South Wales Sydney 2052, Australia Tel...Phillips et al., 2001] and microscale breaker crest length spectral density [e.g., Jessup and Phadnis, 2005] have been reported. Our effort seeks</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA573139','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA573139"><span><span class="hlt">Ocean</span> Surface <span class="hlt">Wave</span> Optical Roughness - Analysis of Innovative Measurements</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2012-09-30</p> <p>goals of the program are to (1) examine time -dependent <span class="hlt">oceanic</span> radiance distribution in relation to dynamic surface boundary layer (SBL) processes; (2... Analysis of Innovative Measurements 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER...RESULTS An overview of results is provided by Zappa et al. [2012] and Dickey et al. [2012]. TOGA-COARE and Air-sea fluxes Time series</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.A42B0762K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.A42B0762K"><span>Parallel Computation of <span class="hlt">Ocean-Atmosphere-Wave</span> Coupled Storm Surge Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, K.; Yamashita, T.</p> <p>2003-12-01</p> <p><span class="hlt">Ocean</span>-atmosphere interactions are very important in the formation and development of tropical storms. These interactions are dominant in exchanging heat, momentum, and moisture fluxes. Heat flux is usually computed using a bulk equation. In this equation air-sea interface supplies heat energy to the atmosphere and to the storm. Dynamical interaction is most often one way in which it is the atmosphere that drives the <span class="hlt">ocean</span>. The winds transfer momentum to both <span class="hlt">ocean</span> surface <span class="hlt">waves</span> and <span class="hlt">ocean</span> current. The wind <span class="hlt">wave</span> makes an important role in the exchange of the quantities of motion, heat and a substance between the atmosphere and the <span class="hlt">ocean</span>. Storm surges can be considered as the phenomena of mean sea-level changes, which are the result of the frictional stresses of strong winds blowing toward the land and causing the set level and the low atmospheric pressure at the centre of the cyclone can additionally raise the sea level. In addition to the rise in water level itself, another <span class="hlt">wave</span> factor must be considered. A rise of mean sea level due to white-cap <span class="hlt">wave</span> dissipation should be considered. In bounded bodies of water, such as small seas, wind driven sea level set up is much serious than inverted barometer effects, in which the effects of wind <span class="hlt">waves</span> on wind-driven current play an important role. It is necessary to develop the coupled system of the full spectral third-generation wind-<span class="hlt">wave</span> model (WAM or WAVEWATCH III), the meso-scale atmosphere model (MM5) and the coastal <span class="hlt">ocean</span> model (POM) for simulating these physical interactions. As the component of coupled system is so heavy for personal usage, the parallel computing system should be developed. In this study, first, we developed the coupling system of the atmosphere model, <span class="hlt">ocean</span> <span class="hlt">wave</span> model and the coastal <span class="hlt">ocean</span> model, in the Beowulf System, for the simulation of the storm surge. It was applied to the storm surge simulation caused by Typhoon Bart (T9918) in the Yatsushiro Sea. The atmosphere model and the <span class="hlt">ocean</span> model have</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OcMod.107...21Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OcMod.107...21Z"><span>A diffusion approximation for <span class="hlt">ocean</span> <span class="hlt">wave</span> scatterings by randomly distributed ice floes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Xin; Shen, Hayley</p> <p>2016-11-01</p> <p>This study presents a continuum approach using a diffusion approximation method to solve the scattering of <span class="hlt">ocean</span> <span class="hlt">waves</span> by randomly distributed ice floes. In order to model both strong and weak scattering, the proposed method decomposes the <span class="hlt">wave</span> action density function into two parts: the transmitted part and the scattered part. For a given <span class="hlt">wave</span> direction, the transmitted part of the <span class="hlt">wave</span> action density is defined as the part of <span class="hlt">wave</span> action density in the same direction before the scattering; and the scattered part is a first order Fourier series approximation for the directional spreading caused by scattering. An additional approximation is also adopted for simplification, in which the net directional redistribution of <span class="hlt">wave</span> action by a single scatterer is assumed to be the reflected <span class="hlt">wave</span> action of a normally incident <span class="hlt">wave</span> into a semi-infinite ice cover. Other required input includes the mean shear modulus, diameter and thickness of ice floes, and the ice concentration. The directional spreading of <span class="hlt">wave</span> energy from the diffusion approximation is found to be in reasonable agreement with the previous solution using the Boltzmann equation. The diffusion model provides an alternative method to implement <span class="hlt">wave</span> scattering into an operational <span class="hlt">wave</span> model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005JGRC..11011006V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005JGRC..11011006V"><span>Impact of high-frequency <span class="hlt">waves</span> on the <span class="hlt">ocean</span> altimeter range bias</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vandemark, D.; Chapron, B.; Elfouhaily, T.; Campbell, J. W.</p> <p>2005-11-01</p> <p>New aircraft observations are presented on the range determination error in satellite altimetry associated with <span class="hlt">ocean</span> <span class="hlt">waves</span>. Laser-based measurements of the cross correlation between the gravity <span class="hlt">wave</span> slope and elevation are reported for the first time. These observations provide direct access to a long, O(10 m), gravity <span class="hlt">wave</span> statistic central to nonlinear <span class="hlt">wave</span> theory prediction of the altimeter sea state bias. Coincident Ka-band radar scattering data are used to estimate an electromagnetic (EM) range bias analogous to that in satellite altimetry. These data, along with ancillary wind and <span class="hlt">wave</span> slope variance estimates, are used alongside existing theory to evaluate the extent of long- versus short-<span class="hlt">wave</span>, O(cm), control of the bias. The longer <span class="hlt">wave</span> bias contribution to the total EM bias is shown to range from 25 to as much as 100%. Moreover, on average the term is linearly related to wind speed and to the gravity <span class="hlt">wave</span> slope variance, consistent with WNL theory. The EM bias associated with interactions between long and short <span class="hlt">waves</span> is obtained assuming the effect is additive to the independently observed long-<span class="hlt">wave</span> factor. This second component is also a substantial contributor, is observed to be quadratic in wind speed or <span class="hlt">wave</span> slope, and dominates at moderate wind speeds. The behavior is shown to be consistent with EM bias prediction based in hydrodynamic modulation theory. Study implications for improved correction of the on-orbit satellite sea state bias are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPGI3005B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPGI3005B"><span>Electron Acceleration by High <span class="hlt">Power</span> Radio <span class="hlt">Waves</span> in the Ionosphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bernhardt, Paul</p> <p>2012-10-01</p> <p>At the highest ERP of the High Altitude Auroral Research Program (HAARP) facility in Alaska, high frequency (HF) electromagnetic (EM) <span class="hlt">waves</span> in the ionosphere produce artificial aurora and electron-ion plasma layers. Using HAARP, electrons are accelerated by high <span class="hlt">power</span> electrostatic (ES) <span class="hlt">waves</span> to energies >100 times the thermal temperature of the ambient plasma. These ES <span class="hlt">waves</span> are driven by decay of the pump EM <span class="hlt">wave</span> tuned to plasma resonances. The most efficient acceleration process occurs near the harmonics of the electron cyclotron frequency in earth's magnetic field. Mode conversion plays a role in transforming the ES <span class="hlt">waves</span> into EM signals that are recorded with ground receivers. These diagnostic <span class="hlt">waves</span>, called stimulated EM emissions (SEE), show unique resonant signatures of the strongest electron acceleration. This SEE also provides clues about the ES <span class="hlt">waves</span> responsible for electron acceleration. The electron gas is accelerated by high frequency modes including Langmuir (electron plasma), upper hybrid, and electron Bernstein <span class="hlt">waves</span>. All of these <span class="hlt">waves</span> have been identified in the scattered EM spectra as downshifted sidebands of the EM pump frequency. Parametric decay is responsible low frequency companion modes such as ion acoustic, lower hybrid, and ion Bernstein <span class="hlt">waves</span>. The temporal evolution of the scattered EM spectrum indicates development of field aligned irregularities that aid the mode conversion process. The onset of certain spectral features is strongly correlated with glow plasma discharge structures that are both visible with the unaided eye and detectable using radio backscatter techniques at HF and UHF frequencies. The primary goals are to understand natural plasma layers, to study basic plasma physics in a unique ``laboratory with walls,'' and to create artificial plasma structures that can aid radio communications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1818108S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1818108S"><span>Artificial <span class="hlt">ocean</span> upwelling utilizing the energy of surface <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Soloviev, Alexander</p> <p>2016-04-01</p> <p>Artificial upwelling can bring cold water from below the thermocline to the sea surface. Vershinsky, Pshenichnyy, and Soloviev (1987) developed a prototype device, utilizing the energy of surface <span class="hlt">waves</span> to create an upward flow of water in the tube. This is a <span class="hlt">wave</span>-inertia pump consisting of a vertical tube, a valve, and a buoy to keep the device afloat. An outlet valve at the top of the unit synchronizes the operation of the device with surface <span class="hlt">waves</span> and prevents back-splashing. A single device with a 100 m long and 1.2 m diameter tube is able to produce up to 1 m3s-1 flow of deep water to the surface. With a 10 oC temperature difference over 100 m depth, the negative heat supply rate to the sea surface is 42 MW, which is equivalent to a 42 Wm-2 heat flux, if distributed over 1 km2 area. Such flux is comparable to the average net air-sea flux. A system of artificial upwelling devices can cool down the sea surface, modify climate on a regional scale and possibly help mitigate hurricanes. The cold water brought from a deeper layer, however, has a larger density than the surface water and therefore has a tendency to sink back down. In this work, the efficiency of <span class="hlt">wave</span>-inertia pumps and climatic consequences are estimated for different environmental conditions using a computational fluid dynamics model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1031039','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1031039"><span>Toward An Internal Gravity <span class="hlt">Wave</span> Spectrum In Global <span class="hlt">Ocean</span> Models</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2015-05-14</p> <p><span class="hlt">wave</span> Sturm- Liouville problem. Stratification profiles N2(z), computed from time-averaged temperatures and salinities at individual grid points from the...HYCOM25 output, are taken as inputs to the Sturm- Liouville problem. The dispersion relation for a particular vertical mode is given by ω2 ¼ f2 þ c2n K2</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18..275S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18..275S"><span>El Nino as an element of a global-scale <span class="hlt">wave</span> in the atmosphere-<span class="hlt">ocean</span> system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Serykh, Ilya; Sonechkin, Dmitry</p> <p>2016-04-01</p> <p>The analyses of the real meteorological and oceanographical data, and long runs of the coupled atmosphere-<span class="hlt">ocean</span> hydro- thermodynamical models identify a spatial-temporal structure of the main mode of the interannual to decadal climatic variations. This mode looks like a global-scale <span class="hlt">wave</span> that extends from West to East around the Earth, and varies rhythmically. In fact, the establishment of this <span class="hlt">wave</span> is a generalization and development of the well-known structures of the so-called "teleconnections" in the <span class="hlt">ocean</span>-atmosphere system. The known regional structures like ENSO, IOD, PDO, IPO, PNA, NAO, AO, ACW and other can be considered as parts of this global-scale <span class="hlt">wave</span>. Moving eastward around the Earth, this <span class="hlt">wave</span> triggers El Nino - Southern oscillation events. An index of this <span class="hlt">wave</span> is proposed as a sum of normalized anomalies of the sea level pressure and the near-surface temperature in 20 locations around the globe. It is proven that the <span class="hlt">power</span> spectrum of this index is not continuous but discrete in its character. Thus, one can suppose that the dynamics of the global-scale <span class="hlt">wave</span> is nonchaotic, and so predictable with no limit in principle. The index <span class="hlt">power</span> spectrum reveals statistically significant peaks at the same periods that are inherent to the <span class="hlt">power</span> spectra of the traditional ENSO indices. The main peaks are at the sub-harmonics of the well-known Chandler wobble (of the ~1.2 year period) in the Earth's pole motion: 3.6; 4.8; 2.4 years. Some other statistically significant peaks also are seen at the super-harmonics of the Luni-Solar nutation (of the ~18.6 year period), and combinational harmonics of the Schwabe's and Hale's solar activity cycles. Based on the eastward propagation of the global-scale <span class="hlt">wave</span>, a predictor of ENSO events was suggested. It has high correlation (about 0.7) with Nino indices but leads them on about 12 months. The use of this predictor opens a possibility to overcome the Spring Predictability Barrier in ENSO forecasting.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1987PrOce..19..177H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1987PrOce..19..177H"><span>Effects of longshore shelf variations on barotropic continental shelf <span class="hlt">waves</span>, slope currents and <span class="hlt">ocean</span> modes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huthnance, J. M.</p> <p></p> <p>Effects of continental shelf bends, converging depth contours and changing depth profiles are discussed. Some analysis is carried out for previously unstudied cases. Separate <span class="hlt">oceanic</span> interior and shelf flow problems are formulated for a sufficiently narrow shelf. The <span class="hlt">ocean</span> interior ‘sees’ only an integrated shelf effect, typically increasing shelf-edge amplitudes, retarding longshore Kelvin-<span class="hlt">wave</span> propagation and increasing natural mode periods by 0 (10%). On the local shelf, the flow matches to the <span class="hlt">ocean</span> interior and is nondivergent. Effects on shelf <span class="hlt">waves</span> and slope currents depend subtly on the nature of the longshore variations. Curvature and contour convergence do not per se imply scaterring or generation of shelf <span class="hlt">waves</span>. Indeed, any depth h(ξ) where ▽ 2ξ(x,y) = 0 (a condition approximating longshelf uniformity in the topography's convexity) supports essentially the same shelf <span class="hlt">waves</span> as do straight depth contours (DAVIS, 1983), and slope currents follow depth contours. Scattering results rather from breaks in analyticity of the depth profile. Hence calculations for small isolated features (necessarily highly convex or concave) may overestimate scattering, and superposition for realistic topography may lead to much self-cancellation among scattered <span class="hlt">waves</span>. Otherwise, examples show a strong preference for scattering into adjacent mode numbers and into any shelf <span class="hlt">wave</span> mode near to its maximum frequency. A shelf sector, where the maximum shelf <span class="hlt">wave</span> frequency maxω is less than the frequency ω of an incident shelf <span class="hlt">wave</span>, causes substantial scattering unless maxω and ω are very close. Adjustment of slope currents to changed conditions takes place through (and over the decay distance of) scattered shelf <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2281F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2281F"><span>Effects of <span class="hlt">ocean</span> surface gravity <span class="hlt">waves</span>: on turbulence, climate, and frontogenesis</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fox-Kemper, Baylor; Suzuki, Nobuhiro</p> <p>2016-04-01</p> <p>Surface <span class="hlt">waves</span> affect turbulence of the upper <span class="hlt">ocean</span> on a variety of scales, with impacts from the meter scale to the global. This talk will review simulations and theory quantifying and elucidating these effects. This presentation will first touch upon the best understood <span class="hlt">wave</span> influence-Langmuir turbulence-concluding with a quantification of the importance of Langmuir turbulence on global climate. This quantification is based on prognosis of <span class="hlt">wave</span> statistics using <span class="hlt">Wave</span>Watch-III as a component of the Community Earth System Model. These statistics are used to enhance mixing in the K-Profile Parameterization consistently with scalings based on Large Eddy Simulations of the <span class="hlt">Wave</span>-Averaged, or Craik-Leibovich, equations. In this system, all of the <span class="hlt">wave</span> effects arrive via Stokes forces-rectified forces proportional to the Stokes drift which exchange properties between <span class="hlt">waves</span> and turbulence. The second major portion of the talk will address the importance of Stokes forces on <span class="hlt">oceanic</span> fronts. High resolution simulations and observations of the <span class="hlt">ocean</span> surface boundary layer have revealed 100m to 10km frontal structures in temperature and other properties worldwide. The formation and evolution of these features, through frontogenesis, instability, and frontolysis is an important and often poorly-simulated part of the climate system, yet fronts and filaments dominate the transport of energy, momentum, dissolved gasses, oil, and pollutants over a wide range of scales. Large Eddy Simulations of the the <span class="hlt">Wave</span>-Averaged Equations spanning the scales from 5m to 20km will illustrate the theory of frontogenesis-including the leading order effects of Langmuir turbulence and surface <span class="hlt">waves</span> which imbue the fronts with ageostrophic and nonhydrostatic character.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNG13B..07V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNG13B..07V"><span>A model to simulate nonhydrostatic internal gravity <span class="hlt">waves</span> in the <span class="hlt">ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vitousek, S.; Fringer, O. B.; Zhang, Y.</p> <p>2015-12-01</p> <p>Internal gravity <span class="hlt">waves</span> in the <span class="hlt">ocean</span> are primarily generated due to tidal flow over topography that generates internal tides, or internal <span class="hlt">waves</span> of tidal frequency. As they propagate, internal tides steepen into trains of internal solitary <span class="hlt">waves</span> that eventually break upon interacting with shallow coastal topography. Modeling internal solitary <span class="hlt">waves</span> is difficult because they have length scales that are short relative to the internal tide, and so many grid points in three dimensions are needed to accurately resolve their evolution. Because internal solitary <span class="hlt">waves</span> arise from a balance between nonlinear advection of momentum and nonhydrostatic dispersion, they must be simulated with nonhydrostatic <span class="hlt">ocean</span> models. Such models are expensive because computation of the nonhydrostatic pressure requires solution of a three-dimensional Poisson equation that can incur an order of magnitude increase in the computational cost. Finally, because internal solitary <span class="hlt">waves</span> can propagate over long distances with little to no dissipation or mixing of the thermocline upon which they propagate, the numerical model must minimize spurious vertical numerical diffusion of the density field. We will discuss development of a new <span class="hlt">ocean</span> model designed to accurately simulate internal solitary <span class="hlt">waves</span>. Horizontally unstructured, finite-volume grids are employed to enable resolution of the multiscale nature of internal solitary <span class="hlt">waves</span> by refining the grid where they are likely to form. To resolve the nonlinear-nonhydrostatic balance in the <span class="hlt">waves</span>, the model computes the nonhydrostatic pressure, but with a preconditioner that ensures minimal overhead where the nonhydrotatic pressure is not needed. Finally, to minimize spurious numerical diffusion, we employ an Arbitrary-Lagrangian-Eulerian (ALE), or hybrid, vertical coordinate system in which the vertical direction is discretized with boundary-following (sigma or s), Cartesian (z), or density-following (isopycnal) coordinates. Because isopycnal coordinates</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830005504','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830005504"><span>Exploitation of SAR data for measurement of <span class="hlt">ocean</span> currents and <span class="hlt">wave</span> velocities</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shuchman, R. A.; Lyzenga, D. R.; Klooster, A., Jr.</p> <p>1981-01-01</p> <p>Methods of extracting information on <span class="hlt">ocean</span> currents and <span class="hlt">wave</span> orbital velocities from SAR data by an analysis of the Doppler frequency content of the data are discussed. The theory and data analysis methods are discussed, and results are presented for both aircraft and satellite (SEASAT) data sets. A method of measuring the phase velocity of a gravity <span class="hlt">wave</span> field is also described. This method uses the shift in position of the <span class="hlt">wave</span> crests on two images generated from the same data set using two separate Doppler bands. Results of the current measurements are pesented for 11 aircraft data sets and 4 SEASAT data sets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA542499','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA542499"><span>Physics, Nonlinear Time Series Analysis, Data Assimilation and Hyperfast Modeling of Nonlinear <span class="hlt">Ocean</span> <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-09-30</p> <p>Hyperfast Modeling of Nonlinear <span class="hlt">Ocean</span> <span class="hlt">Waves</span> A. R. Osborne Dipartimento di Fisica Generale, Università di Torino Via Pietro Giuria 1, 10125...PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Universit?i Torino,Dipartimento di Fisica Generale,Via Pietro Giuria 1,10125 Torino, Italy, 8. PERFORMING</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA629945','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA629945"><span>Satellite Synthetic Aperture Radar Detection of <span class="hlt">Ocean</span> Internal <span class="hlt">Waves</span> in the South China Sea</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2006-09-30</p> <p><span class="hlt">waves</span> will occur and what effects they will have on the hydrodynamic and acoustic environment. This project focuses on the use of remotely sensed...variability of the ITF and its associated heat and freshwater flux exported into the Indian <span class="hlt">Ocean</span>. REFERENCES Boyer, T., and S. Levites , Quality</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19830043081&hterms=doldrums&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Ddoldrums','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19830043081&hterms=doldrums&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Ddoldrums"><span>Southern <span class="hlt">ocean</span> mean monthly <span class="hlt">waves</span> and surface winds for winter 1978 by Seasat radar altimeter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mognard, N. M.; Campbell, W. J.; Cheney, R. E.; Marsh, J. G.</p> <p>1983-01-01</p> <p>Data acquired by the SEASAT radar altimeter during the 3 month satellite lifetime are analyzed in a study of the sea state of the southern hemisphere <span class="hlt">oceans</span>. The lifetime of the SEASAT satellite, July 7 to October 10, 1978, corresponds to the Antarctic winter. Mean monthly maps of wind speed, significant <span class="hlt">wave</span> height, and swell have been generated from the altimeter measurements along the satellite tracks. These maps delineate spatial and temporal differences of these parameters in the Atlantic, Indian, and Pacific <span class="hlt">oceans</span>. Several features of the Southern <span class="hlt">Ocean</span> wind and <span class="hlt">wave</span> fields agree with conventional descriptions. For example, the principle zonal wind regimes established by the Southeast Trades and Westerlies are clearly evident in the monthly averages. Significant <span class="hlt">wave</span> height and swell also exhibit minima near the Doldrums at low latitudes with steady increases southward to the latitudes of the Westerlies. However, superimposed on these general patterns is significant variability with horizontal scales as small as 1000 km. The maps also document a gradual migration of the region of absolute maximum wind and <span class="hlt">wave</span> from the Atlantic eastward to the Indian <span class="hlt">Ocean</span> and finally into the Pacific.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983JGR....88.1736M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983JGR....88.1736M"><span>Southern <span class="hlt">ocean</span> mean monthly <span class="hlt">waves</span> and surface winds for winter 1978 by Seasat radar altimeter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mognard, Nelly M.; Campbell, William J.; Cheney, Robert E.; Marsh, James G.</p> <p>1983-02-01</p> <p>Data acquired by the SEASAT radar altimeter during the 3 month satellite lifetime are analyzed in a study of the sea state of the southern hemisphere <span class="hlt">oceans</span>. The lifetime of the SEASAT satellite, July 7 to October 10, 1978, corresponds to the Antarctic winter. Mean monthly maps of wind speed, significant <span class="hlt">wave</span> height, and swell have been generated from the altimeter measurements along the satellite tracks. These maps delineate spatial and temporal differences of these parameters in the Atlantic, Indian, and Pacific <span class="hlt">oceans</span>. Several features of the Southern <span class="hlt">Ocean</span> wind and <span class="hlt">wave</span> fields agree with conventional descriptions. For example, the principle zonal wind regimes established by the Southeast Trades and Westerlies are clearly evident in the monthly averages. Significant <span class="hlt">wave</span> height and swell also exhibit minima near the Doldrums at low latitudes with steady increases southward to the latitudes of the Westerlies. However, superimposed on these general patterns is significant variability with horizontal scales as small as 1000 km. The maps also document a gradual migration of the region of absolute maximum wind and <span class="hlt">wave</span> from the Atlantic eastward to the Indian <span class="hlt">Ocean</span> and finally into the Pacific.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OcMod.107...97B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OcMod.107...97B"><span>A fully-coupled atmosphere-<span class="hlt">ocean-wave</span> model of the Caspian Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bruneau, Nicolas; Toumi, Ralf</p> <p>2016-11-01</p> <p>Located in the mid-latitudes, the Caspian Sea is the largest enclosed basin in the world. A fully-coupled atmosphere-<span class="hlt">ocean-wave</span> model of the Caspian Sea at high resolution (8 km) for a period of three years is presented. After validating each component of the modelling platform, the <span class="hlt">wave</span> state of the Caspian Sea is studied. Results show very different <span class="hlt">wave</span> regimes between the three different basins, a strong seasonality and an almost swell-free state. It is shown here that <span class="hlt">waves</span> modify the horizontal eddy viscosity and vertical heat diffusion. However, due to a reasonably weak annual <span class="hlt">wave</span> state, these effects are restricted to the upper-<span class="hlt">ocean</span> layer (< 30 m) except during the most severe events (100 m). Three main experiments are conducted: 1) the ROMS <span class="hlt">ocean</span> model forced by atmospheric reanalysis (CFSR), 2) ROMS coupled with the atmospheric model WRF and 3) the impact of <span class="hlt">wave</span>-induced processes. The seasonality of the Caspian Sea is accurately captured in each experiment which highlights a rapid warming of the sea surface temperature (SST) in spring while the mixed layer depths (MLD) become very rapidly shallow (shifting from over 100 m to 15 m in two months). Contrarily, a gentle cooling of the SST accompanied with a deepening of the MLD is modelled during autumn and winter. The results also show a significant improvement of the model skill in the representation of the dynamics when ROMS is coupled to WRF. Finally, as <span class="hlt">ocean</span> surface <span class="hlt">waves</span> imply feedback at the interface atmosphere-<span class="hlt">ocean</span> through the transfer of momentum, mass and heat, we investigate their potential effects on the Caspian Sea dynamics. Results are mixed and show a reasonably weak impact of <span class="hlt">wave</span>-induced processes. While <span class="hlt">waves</span> have a negligible effect during the winter as <span class="hlt">wave</span>-induced mixing is confined to the MLD, the summer global SST are less accurately modelled due to the enhancement of mixing in shallow MLDs. However the SST bias, temperature at a subsurface location are improved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFMGC11A0144B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFMGC11A0144B"><span>Hurricane <span class="hlt">Wave</span> <span class="hlt">Power</span> Extremes Along the U.S. Atlantic and Gulf Coasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bromirski, P. D.; Kossin, J. P.</p> <p>2007-12-01</p> <p>Extremes in <span class="hlt">wave</span> <span class="hlt">power</span> generated by tropical cyclones (TCs) will have an increasingly greater coastal impact as mean sea level rises. The Gulf 98th percentile (3 m) deep-water significant <span class="hlt">wave</span> height, HS, measured at four open <span class="hlt">ocean</span> NOAA buoys along the U.S. Atlantic coast and three Gulf buoys identifies extreme TC-generated <span class="hlt">wave</span> events during the June-November hurricane season. Since 1978, there were substantially more significant HS events along the Atlantic coast than in the Gulf, with almost three times as many extreme <span class="hlt">wave</span> events during September. The monthly distribution along both coasts peaks in September, with an equally likely chance of a significant TC <span class="hlt">wave</span> event occurring during October as during August over the 1978-2006 data record. However, no clear trend in TC-generated extreme <span class="hlt">wave</span> heights is observed. In general, the Atlantic buoys show a significant increase in seasonal <span class="hlt">wave</span> <span class="hlt">power</span>, PW, since 1995. PW during six of the hurricane seasons since 1995 exceeds all prior years at at least one of the Atlantic group buoys. In contrast to the Atlantic buoys, the Gulf buoys show exceptional seasonal PW levels only during the 2005 hurricane season when major Hurricanes Dennis, Emily, Katrina, Rita, and Wilma tracked trough the Gulf. The exceptional PW levels observed in the Gulf during 2005 were exceeded in the Atlantic during 1999, and approached during 1995 and 1996, attesting to a greater frequency of extreme TC-associated extreme <span class="hlt">wave</span> events along the East Coast compared to the Gulf during the last four decades. A TC <span class="hlt">wave</span> <span class="hlt">power</span> index (WPI) increases significantly in the Atlantic during the mid-1990s, resulting largely from an increase in mid-to-late hurricane season TCs. The WPI is related to TC strength, size, duration, and frequency, and is highly correlated with the TC <span class="hlt">power</span> dissipation index (PDI, Emanuel 2005). The close association of the WPI to hurricane activity implies that significant coastal impacts will increase as the PDI increases</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750020587','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750020587"><span>Dual frequency scatterometer measurement of <span class="hlt">ocean</span> <span class="hlt">wave</span> height</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Johnson, J. W.; Jones, W. L.; Swift, C. T.; Grantham, W. L.; Weissman, D. E.</p> <p>1975-01-01</p> <p>A technique for remotely measuring <span class="hlt">wave</span> height averaged over an area of the sea surface was developed and verified with a series of aircraft flight experiments. The measurement concept involves the cross correlation of the amplitude fluctuations of two monochromatic reflected signals with variable frequency separation. The signal reflected by the randomly distributed specular points on the surface is observed in the backscatter direction at nadir incidence angle. The measured correlation coefficient is equal to the square of the magnitude of the characteristic function of the specular point height from which RMS <span class="hlt">wave</span> height can be determined. The flight scatterometer operates at 13.9 GHz and 13.9 - delta f GHz with a maximum delta f of 40 MHz. Measurements were conducted for low and moderate sea states at altitudes of 2, 5, and 10 thousand feet. The experimental results agree with the predicted decorrelation with frequency separation and with off-nadir incidence angle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22894188','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22894188"><span>Acoustic-gravity <span class="hlt">waves</span> in atmospheric and <span class="hlt">oceanic</span> waveguides.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Godin, Oleg A</p> <p>2012-08-01</p> <p>A theory of guided propagation of sound in layered, moving fluids is extended to include acoustic-gravity <span class="hlt">waves</span> (AGWs) in waveguides with piecewise continuous parameters. The orthogonality of AGW normal modes is established in moving and motionless media. A perturbation theory is developed to quantify the relative significance of the gravity and fluid compressibility as well as sensitivity of the normal modes to variations in sound speed, flow velocity, and density profiles and in boundary conditions. Phase and group speeds of the normal modes are found to have certain universal properties which are valid for waveguides with arbitrary stratification. The Lamb <span class="hlt">wave</span> is shown to be the only AGW normal mode that can propagate without dispersion in a layered medium.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA623415','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA623415"><span>Internal <span class="hlt">Wave</span> Driven Mixing and Transport in the Coastal <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2014-09-30</p> <p>driven mixing in global circulation models where such small-scale processes are not resolved (i.e. occur as subgrid-scale processes). OBJECTIVES ...The main objectives are: (1) to perform a series of high-resolution “numerical” microstructure profile studies using representative field scale...oriented study since they allow for specific internal <span class="hlt">wave</span> induced turbulent mixing processes to be isolated and examined. Furthermore, they will also</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OcMod..96..161P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OcMod..96..161P"><span>Statistical multi-model climate projections of surface <span class="hlt">ocean</span> <span class="hlt">waves</span> in Europe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perez, Jorge; Menendez, Melisa; Camus, Paula; Mendez, Fernando J.; Losada, Inigo J.</p> <p>2015-12-01</p> <p>In recent years, the impact of climate change on sea surface <span class="hlt">waves</span> has received increasingly more attention by the climate community. Indeed, <span class="hlt">ocean</span> <span class="hlt">waves</span> reaching the coast play an important role in several processes concerning coastal communities, such as inundation and erosion. However, regional downscaling at the high spatial resolution necessary for coastal studies has received less attention. Here, we present a novel framework for regional <span class="hlt">wave</span> climate projections and its application in the European region. Changes in the <span class="hlt">wave</span> dynamics under different scenarios in the Northeast Atlantic <span class="hlt">Ocean</span> and the Mediterranean are analyzed. The multi-model projection methodology is based on a statistical downscaling approach. The statistical relation between the predictor (atmospheric conditions) and the predictand (multivariate <span class="hlt">wave</span> climate) is based on a weather type (WT) classification. This atmospheric classification is developed by applying the k-means clustering technique over historical offshore sea level pressure (SLP) fields. Each WT is linked to sea <span class="hlt">wave</span> conditions from a <span class="hlt">wave</span> hindcast. This link is developed by associating atmospheric conditions from reanalysis with multivariate local <span class="hlt">waves</span>. This predictor-predictand relationship is applied to the daily SLP fields from global climate models (GCMs) in order to project future changes in regional <span class="hlt">wave</span> conditions. The GCMs used in the multi-model projection are selected according to skill criteria. The application of this framework uses CMIP5-based <span class="hlt">wave</span> climate projections in Europe. The low computational requirements of the statistical approach allow a large number of GCMs and climate change scenarios to be studied. Consistent with previous works on global <span class="hlt">wave</span> climate projections, the estimated changes from the regional <span class="hlt">wave</span> climate projections show a general decrease in <span class="hlt">wave</span> heights and periods in the Atlantic Europe for the late twenty-first century. The regional projections, however, allow a more detailed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PApGe.173.2119P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PApGe.173.2119P"><span>Long <span class="hlt">Wave</span> Resonance in Tropical <span class="hlt">Oceans</span> and Implications on Climate: The Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pinault, Jean-Louis</p> <p>2016-06-01</p> <p>The dynamics of the tropical Pacific can be understood satisfactorily by invoking the coupling between the basin modes of 1-, 4- and 8-year average periods. The annual quasi-stationary <span class="hlt">wave</span> (QSW) is a first baroclinic-mode, fourth meridional-mode Rossby <span class="hlt">wave</span> resonantly forced by easterlies. The quadrennial QSW is built up from a first baroclinic-mode Kelvin <span class="hlt">wave</span> and a first baroclinic-mode, first meridional-mode Rossby <span class="hlt">wave</span> equatorially trapped and two off-equatorial Rossby <span class="hlt">waves</span>, their dovetailing forming a resonantly forced <span class="hlt">wave</span> (RFW). The 8-year period QSW is a replica of the quadrennial QSW for the second-baroclinic mode. The coupling between basin modes results from the merging of modulated currents both in the western part of the North Equatorial Counter Current and along the South Equatorial Current. Consequently, a sub-harmonic mode locking occurs, which means that the average period of QSWs is 1-, 4- and 8-year exactly. The quadrennial sub-harmonic is subject to two modes of forcing. One results from coupling with the annual QSW that produces a Kelvin <span class="hlt">wave</span> at the origin of transfer of the warm waters from the western part of the basin to the central-eastern Pacific. The other is induced by El Niño and La Niña that self-sustain the sub-harmonic by stimulating the Rossby <span class="hlt">wave</span> accompanying the westward recession of the QSW at a critical stage of its evolution. The interpretation of ENSO from the coupling of different basin modes allows predicting and estimating the amplitude of El Niño events a few months before they become mature from the accelerations of the geostrophic component of the North Equatorial Counter Current.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820044061&hterms=transfer+functions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dtransfer%2Bfunctions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820044061&hterms=transfer+functions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dtransfer%2Bfunctions"><span>Optimal spatial filtering and transfer function for SAR <span class="hlt">ocean</span> <span class="hlt">wave</span> spectra</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goldfinger, A. D.; Beal, R. C.; Tilley, D. G.</p> <p>1981-01-01</p> <p>The Seasat Synthetic Aperture Radar (SAR) has proved to be an instrument of great utility in the sensing of <span class="hlt">ocean</span> conditions on a global scale. An analysis of oceanographic and atmospheric aspects of Seasat data has shown that the features observed in the imagery are linked to <span class="hlt">ocean</span> phenomena such as storm sources and their resulting swell systems. However, there remains one central problem which has not been satisfactorily solved to date. This problem is related to the accurate measurement of wind-generated <span class="hlt">ocean</span> <span class="hlt">wave</span> spectra. Investigations addressing this problem are currently being conducted. The problem has two parts, including the accurate measurement of the image spectra and the inference of actual surface <span class="hlt">wave</span> spectra from these measurements. A description is presented of the progress made towards solving the first part of the problem, taking into account a digital rather than optical computation of the image transforms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860043880&hterms=transfer+functions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtransfer%2Bfunctions','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860043880&hterms=transfer+functions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dtransfer%2Bfunctions"><span>Measurements of <span class="hlt">ocean</span> <span class="hlt">wave</span> spectra and modulation transfer function with the airborne two-frequency scatterometer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Weissman, D. E.; Johnson, J. W.</p> <p>1986-01-01</p> <p>The directional spectrum and the microwave modulation transfer function of <span class="hlt">ocean</span> <span class="hlt">waves</span> can be measured with the airborne two frequency scatterometer technique. Similar to tower based observations, the aircraft measurements of the Modulation Transfer Function (MTF) show that it is strongly affected by both wind speed and sea state. Also detected are small differences in the magnitudes of the MTF between downwind and upwind radar look directions, and variations with <span class="hlt">ocean</span> wavenumber. The MTF inferred from the two frequency radar is larger than that measured using single frequency, <span class="hlt">wave</span> orbital velocity techniques such as tower based radars or ROWS measurements from low altitude aircraft. Possible reasons for this are discussed. The ability to measure the <span class="hlt">ocean</span> directional spectrum with the two frequency scatterometer, with supporting MTF data, is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840019214','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840019214"><span>Measurements of <span class="hlt">ocean</span> <span class="hlt">wave</span> spectra and modulation transfer function with the airborne two frequency scatterometer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Weissman, D. E.; Johnson, J. W.</p> <p>1984-01-01</p> <p>The directional spectrum and the microwave modulation transfer function of <span class="hlt">ocean</span> <span class="hlt">waves</span> can be measured with the airborne two frequency scatterometer technique. Similar to tower based observations, the aircraft measurements of the Modulation Transfer Function (MTF) show that it is strongly affected by both wind speed and sea state. Also detected are small differences in the magnitudes of the MTF between downwind and upwind radar look directions, and variations with <span class="hlt">ocean</span> wavenumber. The MTF inferred from the two frequency radar is larger than that measured using single frequency, <span class="hlt">wave</span> orbital velocity techniques such as tower based radars or ROWS measurements from low altitude aircraft. Possible reasons for this are discussed. The ability to measure the <span class="hlt">ocean</span> directional spectrum with the two frequency scatterometer, with supporting MTF data, is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22003323','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22003323"><span>Delta <span class="hlt">wave</span> <span class="hlt">power</span>: an independent sleep phenotype or epiphenomenon?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Davis, Christopher J; Clinton, James M; Jewett, Kathryn A; Zielinski, Mark R; Krueger, James M</p> <p>2011-10-15</p> <p>Electroencephalographic (EEG) δ <span class="hlt">waves</span> during non-rapid eye movement sleep (NREMS) after sleep deprivation are enhanced. That observation eventually led to the use of EEG δ <span class="hlt">power</span> as a parameter to model process S in the two-process model of sleep. It works remarkably well as a model parameter because it often co-varies with sleep duration and intensity. Nevertheless there is a large volume of literature indicating that EEG δ <span class="hlt">power</span> is regulated independently of sleep duration. For example, high amplitude EEG δ <span class="hlt">waves</span> occur in wakefulness after systemic atropine administration or after hyperventilation in children. Human neonates have periods of sleep with an almost flat EEG. Similarly, elderly people have reduced EEG δ <span class="hlt">power</span>, yet retain substantial NREMS. Rats provided with a cafeteria diet have excess duration of NREMS but simultaneously decreased EEG δ <span class="hlt">power</span> for days. Mice challenged with influenza virus have excessive EEG δ <span class="hlt">power</span> and NREMS. In contrast, if mice lacking TNF receptors are infected, they still sleep more but have reduced EEG δ <span class="hlt">power</span>. Sleep regulatory substances, e.g., IL1, TNF, and GHRH, directly injected unilaterally onto the cortex induce state-dependent ipsilateral enhancement of EEG δ <span class="hlt">power</span> without changing duration of organism sleep. IL1 given systemically enhances duration of NREMS but reduces EEG δ <span class="hlt">power</span> in mice. Benzodiazepines enhance NREMS but inhibit EEG δ <span class="hlt">power</span>. If duration of NREMS is an indicator of prior sleepiness then simultaneous EEG δ <span class="hlt">power</span> may or may not be a useful index of sleepiness. Finally, most sleep regulatory substances are cerebral vasodilators and blood flow affects EEG δ <span class="hlt">power</span>. In conclusion, it seems unlikely that a single EEG measure will be reliable as a marker of sleepiness for all conditions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25480048','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25480048"><span>Shock <span class="hlt">wave</span> propagation along constant sloped <span class="hlt">ocean</span> bottoms.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Maestas, Joseph T; Taylor, Larissa F; Collis, Jon M</p> <p>2014-12-01</p> <p>The nonlinear progressive <span class="hlt">wave</span> equation (NPE) is a time-domain model used to calculate long-range shock propagation using a <span class="hlt">wave</span>-following computational domain. Current models are capable of treating smoothly spatially varying medium properties, and fluid-fluid interfaces that align horizontally with a computational grid that can be handled by enforcing appropriate interface conditions. However, sloping interfaces that do not align with a horizontal grid present a computational challenge as application of interface conditions to vertical contacts is non-trivial. In this work, range-dependent environments, characterized by sloping bathymetry, are treated using a rotated coordinate system approach where the irregular interface is aligned with the coordinate axes. The coordinate rotation does not change the governing equation due to the narrow-angle assumption adopted in its derivation, but care is taken with applying initial, interface, and boundary conditions. Additionally, sound pressure level influences on nonlinear steepening for range-independent and range-dependent domains are used to quantify the pressures for which linear acoustic models suffice. A study is also performed to investigate the effects of thin sediment layers on the propagation of blast <span class="hlt">waves</span> generated by explosives buried beneath mud line.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OcMod..92....1Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OcMod..92....1Z"><span><span class="hlt">Ocean</span> <span class="hlt">wave</span> transmission and reflection by viscoelastic ice covers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Xin; Shen, Hayley H.</p> <p>2015-08-01</p> <p>Modeling ice covers as viscoelastic continua, Zhao and Shen, (2013) applied a two-mode approximate method to determine the transmission and reflection between two different ice covers. This approximate solution considered only two modes of the dispersion relation. In addition, the horizontal boundary conditions were simplified by matching mean values over the interfaces. In this study, we employ a variational method (Fox and Squire, (1990)) to calculate the <span class="hlt">wave</span> transmission and reflection from two connecting viscoelastic ice covers of different properties. The variational approach minimizes the overall error function at the interface of two ice covers, hence is more rigorous than the previous approximate method that minimized the difference between mean values at the interface. The effect of additional travelling and evanescent modes are also investigated. We compare results from different matching methods, as well as the effects of including additional modes. From this study, we find that additional modes do not always improve the results for our model. For all cases tested, two modes appear to be sufficient. These two modes represent the open-water-like and the elastic-pressure <span class="hlt">wave</span>-like behavior. The two-mode approximate method and the variational method have similar results except at very short <span class="hlt">wave</span> periods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcMod.116..146G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcMod.116..146G"><span>Modelling and observations of <span class="hlt">oceanic</span> nonlinear internal <span class="hlt">wave</span> packets affected by the Earth's rotation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grimshaw, Roger; da Silva, Jose C. B.; Magalhaes, Jorge M.</p> <p>2017-08-01</p> <p>The large-amplitude internal solitary <span class="hlt">waves</span> commonly observed in the coastal <span class="hlt">ocean</span> can propagate for long distances for long times, so that it may be necessary to take account of the effects of the Earth's background rotation. In this case an appropriate model <span class="hlt">wave</span> evolution equation is the Ostrovsky equation, whose typical solutions indicate that internal solitary <span class="hlt">waves</span> will evolve into envelope <span class="hlt">wave</span> packets. Unlike the more usual Korteweg-de Vries solutions which are typically rank-ordered <span class="hlt">wave</span> packets, these are centred with the largest <span class="hlt">waves</span> in the middle. This qualitative feature, together with certain key quantitative parameters such as the envelope carrier wavenumber and speed, can be sought in <span class="hlt">oceanic</span> observations. Hence we have examined many SAR images of internal solitary <span class="hlt">waves</span> with the general aim of finding features indicating that rotational effects have become significant. From these we report in detail on six typical cases of which four give indications of rotational effects. In addition we use a two-layer fluid model to estimate how the rotational parameters depend on the background stratification and topography.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3928955','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3928955"><span>Modelling rogue <span class="hlt">waves</span> through exact dynamical lump soliton controlled by <span class="hlt">ocean</span> currents</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kundu, Anjan; Mukherjee, Abhik; Naskar, Tapan</p> <p>2014-01-01</p> <p>Rogue <span class="hlt">waves</span> are extraordinarily high and steep isolated <span class="hlt">waves</span>, which appear suddenly in a calm sea and disappear equally fast. However, though the rogue <span class="hlt">waves</span> are localized surface <span class="hlt">waves</span>, their theoretical models and experimental observations are available mostly in one dimension, with the majority of them admitting only limited and fixed amplitude and modular inclination of the <span class="hlt">wave</span>. We propose two dimensions, exactly solvable nonlinear Schrödinger (NLS) equation derivable from the basic hydrodynamic equations and endowed with integrable structures. The proposed two-dimensional equation exhibits modulation instability and frequency correction induced by the nonlinear effect, with a directional preference, all of which can be determined through precise analytic result. The two-dimensional NLS equation allows also an exact lump soliton which can model a full-grown surface rogue <span class="hlt">wave</span> with adjustable height and modular inclination. The lump soliton under the influence of an <span class="hlt">ocean</span> current appears and disappears preceded by a hole state, with its dynamics controlled by the current term. These desirable properties make our exact model promising for describing <span class="hlt">ocean</span> rogue <span class="hlt">waves</span>. PMID:24711719</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12736682','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12736682"><span>Redistribution of energy available for <span class="hlt">ocean</span> mixing by long-range propagation of internal <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alford, Matthew H</p> <p>2003-05-08</p> <p><span class="hlt">Ocean</span> mixing, which affects pollutant dispersal, marine productivity and global climate, largely results from the breaking of internal gravity <span class="hlt">waves</span>--disturbances propagating along the <span class="hlt">ocean</span>'s internal stratification. A global map of internal-<span class="hlt">wave</span> dissipation would be useful in improving climate models, but would require knowledge of the sources of internal gravity <span class="hlt">waves</span> and their propagation. Towards this goal, I present here computations of horizontal internal-<span class="hlt">wave</span> propagation from 60 historical moorings and relate them to the source terms of internal <span class="hlt">waves</span> as computed previously. Analysis of the two most energetic frequency ranges--near-inertial frequencies and semidiurnal tidal frequencies--reveals that the fluxes in both frequency bands are of the order of 1 kW x m(-1) (that is, 15-50% of the energy input) and are directed away from their respective source regions. However, the energy flux due to near-inertial <span class="hlt">waves</span> is stronger in winter, whereas the tidal fluxes are uniform throughout the year. Both varieties of internal <span class="hlt">waves</span> can thus significantly affect the space-time distribution of energy available for global mixing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24711719','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24711719"><span>Modelling rogue <span class="hlt">waves</span> through exact dynamical lump soliton controlled by <span class="hlt">ocean</span> currents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kundu, Anjan; Mukherjee, Abhik; Naskar, Tapan</p> <p>2014-04-08</p> <p>Rogue <span class="hlt">waves</span> are extraordinarily high and steep isolated <span class="hlt">waves</span>, which appear suddenly in a calm sea and disappear equally fast. However, though the rogue <span class="hlt">waves</span> are localized surface <span class="hlt">waves</span>, their theoretical models and experimental observations are available mostly in one dimension, with the majority of them admitting only limited and fixed amplitude and modular inclination of the <span class="hlt">wave</span>. We propose two dimensions, exactly solvable nonlinear Schrödinger (NLS) equation derivable from the basic hydrodynamic equations and endowed with integrable structures. The proposed two-dimensional equation exhibits modulation instability and frequency correction induced by the nonlinear effect, with a directional preference, all of which can be determined through precise analytic result. The two-dimensional NLS equation allows also an exact lump soliton which can model a full-grown surface rogue <span class="hlt">wave</span> with adjustable height and modular inclination. The lump soliton under the influence of an <span class="hlt">ocean</span> current appears and disappears preceded by a hole state, with its dynamics controlled by the current term. These desirable properties make our exact model promising for describing <span class="hlt">ocean</span> rogue <span class="hlt">waves</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/1335573','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/1335573"><span>Balancing <span class="hlt">Power</span> Absorption and Fatigue Loads in Irregular <span class="hlt">Waves</span> for an Oscillating Surge <span class="hlt">Wave</span> Energy Converter</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Tom, Nathan M.; Yu, Yi-Hsiang; Wright, Alan D.; Lawson, Michael</p> <p>2016-06-24</p> <p>The aim of this paper is to describe how to control the <span class="hlt">power</span>-to-load ratio of a novel <span class="hlt">wave</span> energy converter (WEC) in irregular <span class="hlt">waves</span>. The novel WEC that is being developed at the National Renewable Energy Laboratory combines an oscillating surge <span class="hlt">wave</span> energy converter (OSWEC) with control surfaces as part of the structure; however, this work only considers one fixed geometric configuration. This work extends the optimal control problem so as to not solely maximize the time-averaged <span class="hlt">power</span>, but to also consider the <span class="hlt">power</span>-take-off (PTO) torque and foundation forces that arise because of WEC motion. The objective function of the controller will include competing terms that force the controller to balance <span class="hlt">power</span> capture with structural loading. Separate penalty weights were placed on the surge-foundation force and PTO torque magnitude, which allows the controller to be tuned to emphasize either <span class="hlt">power</span> absorption or load shedding. Results of this study found that, with proper selection of penalty weights, gains in time-averaged <span class="hlt">power</span> would exceed the gains in structural loading while minimizing the reactive <span class="hlt">power</span> requirement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.S52B..03R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.S52B..03R"><span>Constraints from Satellite <span class="hlt">Ocean</span> Altimetry and <span class="hlt">Wave</span> Dynamics on Splay Faulting in the 2004 Indian <span class="hlt">Ocean</span> Earthquake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rice, J. R.; Dedontney, N.</p> <p>2010-12-01</p> <p>Coseismic slip on a subduction zone splay fault has large implications for the resulting local tsunami and on assessing tsunami hazard. Splay faults are steeply dipping so only a small amount of slip is needed to produce a large vertical uplift, and since the splay fault reaches the seafloor closer to the coast than the subduction interface, the local tsunami arrival time is significantly earlier if the splay fault is activated. We have therefore sought (DeDontney and Rice, subm. to JGR, 2010) to determine if the signature of coseismic activation of a subduction zone splay fault will be preserved and recognizable in the <span class="hlt">ocean</span> bound tsunami waveform. The Jason-1 satellite altimetry measurements of the 2004 Indian <span class="hlt">Ocean</span> tsunami recorded a lead <span class="hlt">wave</span> with two peaks of similar amplitude and wavelength, whereas the later-passing TOPEX/Poseidon satellite recorded just a single broad peak. We seek, through analysis of <span class="hlt">ocean</span> gravity <span class="hlt">wave</span> dynamics, an explanation compatible with both observations. First, we determine that coseismic activation of both a splay fault and the updip portion of the subduction interface will result in two areas of uplifted seafloor, and is capable of generating two peaks in the leadwave. We model the seafloor deformation, and resulting tsunami, in 1D and 2D, albeit for a model with uniform sea depth, to determine under what conditions the resulting waveform will approximate that observed by Jason-1. In addition to looking at the role of slip partitioning between the subduction interface and a splay fault, we include the effects of updip rupture velocity, finite rise times, and slip distributions that terminate beneath the accretionary prism. The role of <span class="hlt">wave</span> dispersion is studied and standard shallow water <span class="hlt">wave</span> theory is shown to be inadequate for some the issues being addressed. It is only with the inclusion of dispersion that the waveform can evolve with distance traveled, and accurately represent the lead <span class="hlt">wave</span> structure. Additionally, we back</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/49319','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/49319"><span>Directional <span class="hlt">ocean</span> <span class="hlt">wave</span> measurements in a coastal setting using a focused array imaging radar</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Frasier, S.J.; Liu, Y.; Moller, D.; McIntosh, R.E.; Long, C.</p> <p>1995-03-01</p> <p>A unique focused array imaging Doppler radar was used to measure directional spectra of <span class="hlt">ocean</span> surface <span class="hlt">waves</span> in a nearshore experiment performed on the North Carolina Outer Banks. Radar images of the <span class="hlt">ocean</span> surface`s Doppler velocity were used to generate two dimensional spectra of the radial component of the <span class="hlt">ocean</span> surface velocity field. These are compared to simultaneous in-situ measurements made by a nearby array of submerged pressure sensors. Analysis of the resulting two-dimensional spectra include comparisons of dominant <span class="hlt">wave</span> lengths, <span class="hlt">wave</span> directions, and <span class="hlt">wave</span> energy accounting for relative differences in water depth at the measurement locations. Limited estimates of the two-dimensional surface displacement spectrum are derived from the radar data. The radar measurements are analogous to those of interferometric synthetic aperture radars (INSAR), and the equivalent INSAR parameters are shown. The agreement between the remote and in-situ measurements suggests that an imaging Doppler radar is effective for these <span class="hlt">wave</span> measurements at near grazing incidence angles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22400697','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22400697"><span>Discrete-element model for the interaction between <span class="hlt">ocean</span> <span class="hlt">waves</span> and sea ice.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Zhijie; Tartakovsky, Alexandre M; Pan, Wenxiao</p> <p>2012-01-01</p> <p>We present a discrete-element method (DEM) model to simulate the mechanical behavior of sea ice in response to <span class="hlt">ocean</span> <span class="hlt">waves</span>. The interaction of <span class="hlt">ocean</span> <span class="hlt">waves</span> and sea ice potentially can lead to the fracture and fragmentation of sea ice depending on the <span class="hlt">wave</span> amplitude and period. The fracture behavior of sea ice explicitly is modeled by a DEM method where sea ice is modeled by densely packed spherical particles with finite sizes. These particles are bonded together at their contact points through mechanical bonds that can sustain both tensile and compressive forces and moments. Fracturing naturally can be represented by the sequential breaking of mechanical bonds. For a given amplitude and period of incident <span class="hlt">ocean</span> <span class="hlt">waves</span>, the model provides information for the spatial distribution and time evolution of stress and microfractures and the fragment size distribution. We demonstrate that the fraction of broken bonds α increases with increasing <span class="hlt">wave</span> amplitude. In contrast, the ice fragment size l decreases with increasing amplitude. This information is important for the understanding of the breakup of individual ice floes and floe fragment size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFD.A5004C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFD.A5004C"><span>Observations of Equatorial Kelvin <span class="hlt">Waves</span> and their Convective Coupling with the Atmosphere/<span class="hlt">Ocean</span> Surface Layer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Conry, Patrick; Fernando, H. J. S.; Leo, Laura; Blomquist, Byron; Amelie, Vincent; Lalande, Nelson; Creegan, Ed; Hocut, Chris; MacCall, Ben; Wang, Yansen; Jinadasa, S. U. P.; Wang, Chien; Yeo, Lik-Khian</p> <p>2016-11-01</p> <p>Intraseasonal disturbances with their genesis in the equatorial Indian <span class="hlt">Ocean</span> (IO) are an important component of global climate. The disturbances, which include Madden-Julian Oscillation and equatorial Kelvin and Rossby <span class="hlt">waves</span> in the atmosphere and <span class="hlt">ocean</span>, carry energy which affects El Niño, cyclogenesis, and monsoons. A recent field experiment in IO (ASIRI-RAWI) observed disturbances at three sites across IO with arrays of instruments probing from surface layer to lower stratosphere. During the field campaign the most pronounced planetary-scale disturbances were Kelvin <span class="hlt">waves</span> in tropical tropopause layer. In Seychelles, quasi-biweekly westerly wind bursts were documented and linked to the Kelvin <span class="hlt">waves</span> aloft, which breakdown in the upper troposphere due to internal shear instabilities. Convective coupling between <span class="hlt">waves</span>' phase in upper troposphere and surface initiates rapid (turbulent) vertical transport and resultant wind bursts at surface. Such phenomena reveal linkages between planetary-scale <span class="hlt">waves</span> and small-scale turbulence in the surface layer that can affect air-sea property exchanges and should be parameterized in atmosphere-<span class="hlt">ocean</span> general circulation models. Funded by ONR Grants N00014-14-1-0279 and N00014-13-1-0199.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130010928','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130010928"><span>Calibration of <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Measurements by the TOPEX, Jason-1, and Jason-2 Satellites</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ray, Richard D.; Beckley, B. D.</p> <p>2012-01-01</p> <p>The calibration and validation of <span class="hlt">ocean</span> <span class="hlt">wave</span> height measurements by the TOPEX, Jason-1, and Jason-2 satellite altimeters is addressed by comparing the measurements internally among them- selves and against independent <span class="hlt">wave</span> measurements at moored buoys. The two six-month verification campaigns, when two of the satellites made near-simultaneous measurements along the same ground track, are invaluable for such work and reveal subtle aspects that otherwise might go undetected. The two Jason satellites are remarkably consistent; Topex reports <span class="hlt">waves</span> generally 1-2% larger. External calibration is complicated by some systematic errors in the buoy data. We confirm a recent report by Durrant et al. that Canadian buoys underestimate significant <span class="hlt">wave</span> heights by about 10% relative to U.S. buoys. <span class="hlt">Wave</span> heights from all three altimetric satellites require scaling upwards by 5 6% to be consistent with U.S. buoys.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007NPGeo..14..757F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007NPGeo..14..757F"><span>On a spectrum of nonlinear internal <span class="hlt">waves</span> in the <span class="hlt">oceanic</span> coastal zone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Filonov, A.; Novotryasov, V.</p> <p>2007-11-01</p> <p>This paper studies the internal <span class="hlt">wave</span> band of temperature fluctuation spectra in the coastal zone of Pacific <span class="hlt">ocean</span>. It is observed that on the central Mexican Pacific Shelf in the high-frequency band of temperature spectra the spectral exponent tends to ~ω-1 at the time of spring tide and ω-2 at the time of neap tide. On the western shelf of the Japan/East Sea, in the Ω<<ω<< N* range, where N* is the representative buoyancy frequency and Ω is the inertial frequency, the rate tends to ~ω-3. These features of spectra are simulated by the model spectrum of nonlinear internal <span class="hlt">waves</span> in the shallow water. Interaction of high-frequency internal <span class="hlt">waves</span> with an internal <span class="hlt">wave</span> of semidiurnal frequency is considered. It is shown that as a result of the interaction the spectrum of high-frequency internal <span class="hlt">waves</span> take the universal form and the spectral exponent tends to ~ω-1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFMSA31C..02B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFMSA31C..02B"><span>Ground Detection of Gyro Resonant Plasma <span class="hlt">Waves</span> During High <span class="hlt">Power</span> Radio <span class="hlt">Waves</span> Experiments at HAARP (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bernhardt, P. A.; Pedersen, T. R.; Kendall, E. A.</p> <p>2010-12-01</p> <p>High <span class="hlt">power</span> radio <span class="hlt">waves</span> transmitted from the ground can enter the ionosphere and become transformed into electrostatic <span class="hlt">waves</span> by mode coupling or parametric decay. The decay products may be electromagnetic (EM) <span class="hlt">waves</span> that propagate to the ground and are detected by ground receivers. The decay products may also be electrostatic <span class="hlt">waves</span> that are mode converted to EM <span class="hlt">waves</span> for propagation to ground receivers. The EM signals have frequency offsets from the EM pump <span class="hlt">wave</span> and are called stimulated electromagnetic emissions (SEE). The production of SEE requires five factors for excitation. First, the EM pump <span class="hlt">wave</span> must have sufficient amplitude in the ionosphere to excite the parametric decay process. Second, the EM pump <span class="hlt">wave</span> must propagate to a region where it can couple into a resonant mode of the plasma. Third, the large amplitude EM or ES resonant mode drives a parametric decay instability to generate two other resonant modes in the plasma. Fourth, at least one resonant mode in the plasma must be weakly damped. Fifth, the high frequency daughter <span class="hlt">wave</span> of the parametric decay process may need to be converted into an electromagnetic <span class="hlt">wave</span> to be received on the ground. In the framework of these five criteria, the production of stimulated ion Bernstein (SIB) emissions is considered for an electromagnetic pump <span class="hlt">wave</span> tuned to the second harmonic of the electron cyclotron frequency. For maximum pump amplitude, the plasma frequency should be nearly equal to the pump frequency. This double resonance occurs if the EM pump frequency is tuned to match the frequency at the altitude where the plasma frequency in the plasma layer is equal to twice the electron gyro frequency. The double resonance of pump frequency equals plasma frequency equals twice the electron gyro frequency insures that a large amplitude standing <span class="hlt">wave</span> is formed at the point where the pump electric field can couple into the electron Bernstein resonance at twice the electron cyclotron frequency. The theory for generation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22825159','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22825159"><span>High <span class="hlt">power</span> single frequency solid state master oscillator <span class="hlt">power</span> amplifier for gravitational <span class="hlt">wave</span> detection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Basu, Chandrajit; Wessels, Peter; Neumann, Jörg; Kracht, Dietmar</p> <p>2012-07-15</p> <p>High <span class="hlt">power</span> single frequency, single mode, linearly polarized laser output at the 1 μm regime is in demand for the interferometric gravitational <span class="hlt">wave</span> detectors (GWDs). A robust single frequency solid state master oscillator <span class="hlt">power</span> amplifier (MOPA) is a promising candidate for such applications. We present a single frequency solid state multistage MOPA system delivering 177 W of linearly polarized output <span class="hlt">power</span> at 1 μm with 83.5% TEM(00) mode content.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840019213','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840019213"><span>An improved dual-frequency technique for the remote sensing of <span class="hlt">ocean</span> currents and <span class="hlt">wave</span> spectra</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schuler, D. L.; Eng, W. P.</p> <p>1984-01-01</p> <p>A two frequency microwave radar technique for the remote sensing of directional <span class="hlt">ocean</span> <span class="hlt">wave</span> spectra and surface currents is investigated. This technique is conceptually attractive because its operational physical principle involves a spatial electromagnetic scattering resonance with a single, but selectable, long gravity <span class="hlt">wave</span>. Multiplexing of signals having different spacing of the two transmitted frequencies allows measurements of the entire long <span class="hlt">wave</span> <span class="hlt">ocean</span> spectrum to be carried out. A new scatterometer is developed and experimentally tested which is capable of making measurements having much larger signal/background values than previously possible. This instrument couples the resonance technique with coherent, frequency agility radar capabilities. This scatterometer is presently configured for supporting a program of surface current measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OcMod..97..109T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OcMod..97..109T"><span>Impact of topographic internal lee <span class="hlt">wave</span> drag on an eddying global <span class="hlt">ocean</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trossman, David S.; Arbic, Brian K.; Richman, James G.; Garner, Stephen T.; Jayne, Steven R.; Wallcraft, Alan J.</p> <p>2016-01-01</p> <p>The impact of topographic internal lee <span class="hlt">wave</span> drag (<span class="hlt">wave</span> drag hereafter) on several aspects of the low-frequency circulation in a high-resolution global <span class="hlt">ocean</span> model forced by winds and air-sea buoyancy fluxes is examined here. The HYbrid Coordinate <span class="hlt">Ocean</span> Model (HYCOM) is run at two different horizontal resolutions (one nominally 1/12° and the other 1/25°). <span class="hlt">Wave</span> drag, which parameterizes both topographic blocking and the generation of lee <span class="hlt">waves</span> arising from geostrophic flow impinging upon rough topography, is inserted into the simulations as they run. The parameterization used here affects the momentum equations and hence the structure of eddy kinetic energy. Lee <span class="hlt">waves</span> also have implications for diapycnal mixing in the <span class="hlt">ocean</span>, though the parameterization does not directly modify the density. Total near-bottom energy dissipation due to <span class="hlt">wave</span> drag and quadratic bottom boundary layer drag is nearly doubled, and the energy dissipation due to quadratic bottom drag is reduced by about a factor of two, in simulations with an inserted <span class="hlt">wave</span> drag compared to simulations having only quadratic bottom drag. With the insertion of <span class="hlt">wave</span> drag, the kinetic energy is reduced in the abyss and in a three-dimensional global integral. Deflection by partial topographic blocking is inferred to be one reason why the near-bottom kinetic energy can increase in locations where there is little change in dissipation by quadratic bottom drag. Despite large changes seen in the abyss, the changes that occur near the sea surface are relatively small upon insertion of <span class="hlt">wave</span> drag into the simulations. Both the sea surface height variance and geostrophic surface kinetic energy are reduced on global average by more than twice the seasonal variability in these diagnostics. Alterations in the intensified jet positions brought about by inserting <span class="hlt">wave</span> drag are not distinguishable from the temporal variability of jet positions. Various statistical measures suggest that applying <span class="hlt">wave</span> drag only within a fixed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020022890&hterms=Hurricane+Size&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHurricane%2BSize','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020022890&hterms=Hurricane+Size&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DHurricane%2BSize"><span>Hurricane Directional <span class="hlt">Wave</span> Spectrum Spatial Variation in the Open <span class="hlt">Ocean</span> and at Landfall</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Walsh, E. J.; Wright, C. W.; Vandemark, D.; Krabill, W. B.; Garcia, A. W.; Houston, S. H.; Murillo, S. T.; Powell, M. D.; Black, P. G.; Marks, F. D.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20020022890'); toggleEditAbsImage('author_20020022890_show'); toggleEditAbsImage('author_20020022890_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20020022890_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20020022890_hide"></p> <p>2001-01-01</p> <p>The sea surface directional <span class="hlt">wave</span> spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA scanning radar altimeter (SRA) carried aboard one of the NOAA WP-3D hurricane research aircraft at 1.5 kilometer height. The SRA measures the energetic portion of the directional <span class="hlt">wave</span> spectrum by generating a topographic map of the sea surface. The data were acquired on 24 August 1998 when Hurricane Bonnie was 400 km east of Abaco Island, Bahamas. Individual <span class="hlt">waves</span> with heights up to 19 meters were observed and the spatial variation of the <span class="hlt">wave</span> field was dramatic. The dominant <span class="hlt">waves</span> generally propagated at significant angles to the downwind direction. At one position, three different <span class="hlt">wave</span> systems of comparable energy and wavelength crossed each other. The aircraft spent over five hours within 180 kilometers of the Hurricane Bonnie eye and made five eye penetrations. On 26 August 1998, the SRA at 2.2 kilometer height documented the directional <span class="hlt">wave</span> spectrum in the region between Charleston, SC, and Cape Hatteras, NC, as Hurricane Bonnie was making landfall near Wilmington, NC. The storm was similar in size during the two flights, but the maximum speed in the NOAA Hurricane Research Division surface wind analysis was 15% lower prior to landfall (39 meters per second) than it had been in the open <span class="hlt">ocean</span> (46 meters per second). This was compensated for by its faster movement prior to landfall (9.5 meters per second) than when it was encountered in the open <span class="hlt">ocean</span> (5 meters per second), significantly increasing the effective fetch and duration of <span class="hlt">waves</span> near the peak of the spectrum which propagated in the direction of the storm track. The open <span class="hlt">ocean</span> <span class="hlt">wave</span> height variation indicated that Hurricane Bonnie would have produced <span class="hlt">waves</span> of 11 meters significant <span class="hlt">wave</span> height on the shore northeast of Wilmington had it not been for the continental shelf. The bathymetry distributed the steepening and breaking process across the shelf so that the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21811131','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21811131"><span>Watching television: a previously unrecognized <span class="hlt">powerful</span> trigger of λ <span class="hlt">waves</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alvarez, Vincent; Maeder-Ingvar, Malin; Rossetti, Andrea O</p> <p>2011-08-01</p> <p>To assess whether lambda <span class="hlt">waves</span> are elicited by watching television (TV) and their association with demographical and EEG features. We retrospectively compared lambda <span class="hlt">wave</span> occurrence in prolonged EEG monitorings of outpatients who were allowed to watch TV and in standard EEGs recorded in TV-free rooms. All EEGs were interpreted by the same two electroencephalographers. Of 2,072 standard EEG reports, 36 (1.7 %) mentioned lambda <span class="hlt">waves</span> versus 46 (32.2%) of 143 prolonged EEG monitoring reports (P < 0.001). Multivariable comparison of prolonged EEG monitorings and standard EEGs disclosed that recordings performed in rooms with a TV (odds ratio, 20.6; 95% confidence interval, 4.8-88.0) and normal EEGs (odds ratio, 3.03; 95% confidence interval, 1.5-6.25) were independently associated with lambda <span class="hlt">waves</span>. In the prolonged EEG monitoring group, all recordings with lambda <span class="hlt">waves</span> also had positive occipital sharp transients of sleep. Watching TV likely represents a <span class="hlt">powerful</span> and previously unrecognized stimulus for lambda <span class="hlt">waves</span>. Furthermore, this study confirms the benign nature of this EEG variant and its strong association with positive occipital sharp transients of sleep.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.er.usgs.gov/publication/70041533','USGSPUBS'); return false;" href="http://pubs.er.usgs.gov/publication/70041533"><span>The observed relationship between <span class="hlt">wave</span> conditions and beach response, <span class="hlt">Ocean</span> Beach, San Francisco, CA</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Hansen, J.E.; Barnard, P.L.</p> <p>2009-01-01</p> <p>Understanding how sandy beaches respond to storms is critical for effective sediment management and developing successful erosion mitigation efforts. However, only limited progress has been made in relating observed beach changes to <span class="hlt">wave</span> conditions, with one of the major limiting factors being the lack of temporally dense beach topography and nearshore <span class="hlt">wave</span> data in most studies. This study uses temporally dense beach topographic and offshore <span class="hlt">wave</span> data to directly link beach response and <span class="hlt">wave</span> forcing with generally good results. <span class="hlt">Ocean</span> Beach is an open coast high-energy sandy beach located in San Francisco, CA, USA. From April 2004 through the end of 2008, 60 three-dimensional topographic beach surveys were conducted on approximately a monthly basis, with more frequent “short-term surveys during the winters of 2005-06 and 2006-07. Shoreline position data from the short-term surveys show good correlation with offshore <span class="hlt">wave</span> height, period, and direction averaged over several days prior to the survey (mean R*=0.54 for entire beach). There is, however, considerable alongshore variation in model performance, with R- values ranging from 0.81 to 0.19 for individual sections of the beach. After <span class="hlt">wave</span> height, the direction of <span class="hlt">wave</span> approach was the most important factor in determining the response of the shoreline, followed by <span class="hlt">wave</span> period. Our results indicate that an empirical predictive model of beach response to <span class="hlt">wave</span> conditions at <span class="hlt">Ocean</span> Beach is possible with frequent beach mapping and <span class="hlt">wave</span> data, and that such a model could be useful to coastal managers. </p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA276165','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA276165"><span><span class="hlt">Ocean</span> Acoustic Propagation Measurements and <span class="hlt">Wave</span> Propagation in Random Media</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1993-04-01</p> <p>medium focus follows closely the prediction of Spivack and Uscinski3 5 . Using numerical solutions to the 4th moment equation, the (I’, Z) dependence...32(1), 71-89 (1985). 13. B.J. Uscinski, C. Macaskill and M. Spivack , "Path integrals for <span class="hlt">wave</span> intensity fluctuations in random media," J. Sound and...intensity in a turbulent atmosphere-- the distribution function," Soy. Phys. JETP 47(6), 1028-1030 (1978). 35. M. Spivack and BJ. Uscinski, "Accurate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DPPGO6012P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DPPGO6012P"><span>Fast <span class="hlt">wave</span> <span class="hlt">power</span> flow along SOL field lines in NSTX</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Perkins, R. J.; Bell, R. E.; Diallo, A.; Gerhardt, S.; Hosea, J. C.; Jaworski, M. A.; Leblanc, B. P.; Kramer, G. J.; Phillips, C. K.; Roquemore, L.; Taylor, G.; Wilson, J. R.; Ahn, J.-W.; Gray, T. K.; Green, D. L.; McLean, A.; Maingi, R.; Ryan, P. M.; Jaeger, E. F.; Sabbagh, S.</p> <p>2012-10-01</p> <p>On NSTX, a major loss of high-harmonic fast <span class="hlt">wave</span> (HHFW) <span class="hlt">power</span> can occur along open field lines passing in front of the antenna over the width of the scrape-off layer (SOL). Up to 60% of the RF <span class="hlt">power</span> can be lost and at least partially deposited in bright spirals on the divertor floor and ceiling [1,2]. The flow of HHFW <span class="hlt">power</span> from the antenna region to the divertor is mostly aligned along the SOL magnetic field [3], which explains the pattern of heat deposition as measured with infrared (IR) cameras. By tracing field lines from the divertor back to the midplane, the IR data can be used to estimate the profile of HHFW <span class="hlt">power</span> coupled to SOL field lines. We hypothesize that surface <span class="hlt">waves</span> are being excited in the SOL, and these results should benchmark advanced simulations of the RF <span class="hlt">power</span> deposition in the SOL (e.g., [4]). Minimizing this loss is critical optimal high-<span class="hlt">power</span> long-pulse ICRF heating on ITER while guarding against excessive divertor erosion.[4pt] [1] J.C. Hosea et al., AIP Conf Proceedings 1187 (2009) 105. [0pt] [2] G. Taylor et al., Phys. Plasmas 17 (2010) 056114. [0pt] [3] R.J. Perkins et al., to appear in Phys. Rev. Lett. [0pt] [4] D.L. Green et al., Phys. Rev. Lett. 107 (2011) 145001.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JIEIB.tmp...38K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JIEIB.tmp...38K"><span>Electronic <span class="hlt">Power</span> Conditioner for Ku-band Travelling <span class="hlt">Wave</span> Tube</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kowstubha, Palle; Krishnaveni, K.; Ramesh Reddy, K.</p> <p>2016-07-01</p> <p>A highly sophisticated regulated <span class="hlt">power</span> supply is known as electronic <span class="hlt">power</span> conditioner (EPC) is required to energise travelling <span class="hlt">wave</span> tubes (TWTs), which are used as RF signal amplifiers in satellite payloads. The assembly consisting of TWT and EPC together is known as travelling <span class="hlt">wave</span> tube amplifier (TWTA). EPC is used to provide isolated and conditioned voltage rails with tight regulation to various electrodes of TWT and makes its RF performance independent of solar bus variations which are caused due to varying conditions of eclipse and sunlit. The payload mass and their <span class="hlt">power</span> consumption is mainly due to the existence of TWTAs that represent about 35 % of total mass and about 70-90 % (based on the type of satellite application) of overall dc <span class="hlt">power</span> consumption. This situation ensures a continuous improvement in the design of TWTAs and their associated EPCs to realize more efficient and light products. Critical technologies involved in EPCs are design and configuration, closed loop regulation, component and material selection, energy limiting of high voltage (HV) outputs and potting of HV card etc. This work addresses some of these critical technologies evolved in realizing and testing the state of art of EPC and it focuses on the design of HV supply with a HV and high <span class="hlt">power</span> capability, up to 6 kV and 170 WRF, respectively required for a space TWTA. Finally, an experimental prototype of EPC with a dc <span class="hlt">power</span> of 320 W provides different voltages required by Ku-band TWT in open loop configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JIEIB..98..213K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JIEIB..98..213K"><span>Electronic <span class="hlt">Power</span> Conditioner for Ku-band Travelling <span class="hlt">Wave</span> Tube</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kowstubha, Palle; Krishnaveni, K.; Ramesh Reddy, K.</p> <p>2017-04-01</p> <p>A highly sophisticated regulated <span class="hlt">power</span> supply is known as electronic <span class="hlt">power</span> conditioner (EPC) is required to energise travelling <span class="hlt">wave</span> tubes (TWTs), which are used as RF signal amplifiers in satellite payloads. The assembly consisting of TWT and EPC together is known as travelling <span class="hlt">wave</span> tube amplifier (TWTA). EPC is used to provide isolated and conditioned voltage rails with tight regulation to various electrodes of TWT and makes its RF performance independent of solar bus variations which are caused due to varying conditions of eclipse and sunlit. The payload mass and their <span class="hlt">power</span> consumption is mainly due to the existence of TWTAs that represent about 35 % of total mass and about 70-90 % (based on the type of satellite application) of overall dc <span class="hlt">power</span> consumption. This situation ensures a continuous improvement in the design of TWTAs and their associated EPCs to realize more efficient and light products. Critical technologies involved in EPCs are design and configuration, closed loop regulation, component and material selection, energy limiting of high voltage (HV) outputs and potting of HV card etc. This work addresses some of these critical technologies evolved in realizing and testing the state of art of EPC and it focuses on the design of HV supply with a HV and high <span class="hlt">power</span> capability, up to 6 kV and 170 WRF, respectively required for a space TWTA. Finally, an experimental prototype of EPC with a dc <span class="hlt">power</span> of 320 W provides different voltages required by Ku-band TWT in open loop configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..1411981L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..1411981L"><span>On a set of 20th century monumental events that shaped the modern discipline of <span class="hlt">ocean</span> wind <span class="hlt">wave</span>'s research</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, P.</p> <p>2012-04-01</p> <p>History is made up of individual events. The modern <span class="hlt">ocean</span> wind <span class="hlt">waves</span> research has been active for nearly 70 years since the early years of the decade of 1940's while the World War II was still fighting in earnest and Sverdrup and Munk were embarked on an unprecedented attempt to make <span class="hlt">wave</span> condition prediction for Navy Amphibious forces carrying out landing operation. That was certainly a monumental event that started the modern <span class="hlt">ocean</span> wind <span class="hlt">wave</span>'s research. Here I wish to present a set of other monumental events in the intervening years which, in my personal view, are vital to the formation of our present day conventional <span class="hlt">ocean</span> wind <span class="hlt">wave</span>'s research: • Circa 1945: The war time invention of underwater pressure <span class="hlt">wave</span> gage that measures pressure fluctuations induced by surface <span class="hlt">waves</span> and also marked as the start of single-point <span class="hlt">wave</span> measurements prevalent today. • Circa 1950: When oceanographer Pierson met statistician Tukey and <span class="hlt">ocean</span> <span class="hlt">wave</span> spectrum analysis was thereby born. • Circa 1952: Something old something new - Longuet-Higgins introduced the distribution function of Load Rayleigh to the emerging <span class="hlt">ocean</span> <span class="hlt">wave</span> data analysis and Rayleigh distribution has been the mainstay of <span class="hlt">ocean</span> wind <span class="hlt">wave</span>'s research ever since. • Circa 1953: Neumann started the quest to formulate a wind <span class="hlt">wave</span> spectrum with his impressive first empirical spectrum before spectrum was widely measured. • Circa 1957: Phillips worked out the resonance theory for wind <span class="hlt">wave</span>'s generation. • Circa 1957: Miles simultaneously developed the shear flow model for wind <span class="hlt">wave</span>'s generation, complementary to Phillips theory. • Circa 1959: Hasselmann formulated the source function to start the first framework of comprehensive wind <span class="hlt">wave</span> modeling. These are all the basic innovative milestones that the bulk of the conventional <span class="hlt">ocean</span> wind <span class="hlt">wave</span> research studies today were evolved from. While the monumental status of these works may represent merely the personal opinion of a single aficionado, I do feel that they</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991PhDT........46Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991PhDT........46Y"><span>Millimeter-<span class="hlt">Wave</span> <span class="hlt">Power</span>-Combining with Radiating Oscillator Arrays.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>York, Robert Armstrong</p> <p></p> <p>The next generation of communications and radar systems will soon begin to exploit the millimeter-<span class="hlt">wave</span> portion of the electromagnetic spectrum. Such systems will require a high-<span class="hlt">power</span> source of millimeter-<span class="hlt">wave</span> energy, ideally small, lightweight, highly efficient, and failure -proof over a span of decades. Circuits using semiconductor devices have proved useful for this purpose at lower frequencies, but unfortunately the <span class="hlt">power</span> generating capacity of solid -state devices diminishes quickly as frequencies approach 100 GHz. This has forced designers to use bulky, inefficient, and unreliable (but high-<span class="hlt">power</span>) vacuum-tube sources. Combining the <span class="hlt">power</span> produced by a large number of individual solid-state devices has been suggested as a means of overcoming the inherent limitations of millimeter -<span class="hlt">wave</span> devices. In order to compete with vacuum-tube sources, <span class="hlt">power</span>-combiners would require up to 1000 devices, presenting a difficult engineering challenge. This thesis introduces one possible solution to this problem. The proposed concept uses arrays of millimeter-<span class="hlt">wave</span> oscillators, where each oscillator contains one or more active devices in a planar radiating structure. The oscillators are weakly coupled to synchronize frequency and phase relationships, and the <span class="hlt">power</span> produced by each oscillator is radiatively combined in free-space, which gives rise to very high combining efficiencies. The array concept has been demonstrated at microwave frequencies using both Gunn and MESFET devices in a 4 x 4 patch antenna configuration. The Gunn array produced 22 Watts Equivalent Radiated <span class="hlt">Power</span> (ERP), and the MESFET array produced 10 Watts ERP. A new theory has been developed which describes the coupled-oscillator dynamics, and has been shown to accurately predict experimentally observed effects. In addition to strict CW <span class="hlt">power</span>-combining, a new mode of operation has been discovered which enables the same arrays to generate high-<span class="hlt">power</span> pulses of energy. This new effect involves a "mode</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA....11995C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA....11995C"><span>Impact of rossby <span class="hlt">waves</span> on surface chlorophyll patterns in the north atlantic <span class="hlt">ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Charria, G.; Dadou, I.; Sudre, J.; Garçon, V.</p> <p>2003-04-01</p> <p>In situ measurements (Price and Magaard, 1986 ; Spall, 1992) and sea surface height anomaly measured by Topex/Poseidon and ERS2 (Cromwell, 2001 ; Cipollini et al. , 1997, 1998) have allowed to detect baroclinic Rossby <span class="hlt">waves</span> in the North Atlantic and to study their features (wavelength, group and phase speed and period). Enhancement of surface chlorophyll-a by Rossby <span class="hlt">waves</span> has been recently detected by several authors in <span class="hlt">ocean</span> color data (Uz et al., 2001 ; Cipollini et al., 2001; Charria et al., 2002). The monthly SeaWiFS data and combined TOPEX/ERS2 data over the 5 years 1998-2002 are used. Detecting this <span class="hlt">wave</span> in altimetry and <span class="hlt">ocean</span> color data is difficult due to the weak signal compared to the seasonal cycle and the mesoscale activity. A spatial filter, based on a wavelet analysis, has been used to highlight this <span class="hlt">wave</span> in the North Atlantic. We will discuss, in space and time, the link between Rossby <span class="hlt">waves</span> and mesoscale activity as well as the interannuality of these <span class="hlt">waves</span>, both on the physical signal (sea surface anomaly) and the biological signal (surface chlorophyll). The zonal "waveguide" at 34°N will be specially investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000075209&hterms=Hurricane+Categories&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHurricane%2BCategories','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000075209&hterms=Hurricane+Categories&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DHurricane%2BCategories"><span>Open <span class="hlt">Ocean</span> and Landfalling Hurricane Directional <span class="hlt">Wave</span> Spectra from a Scanning Radar Altimeter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wright, C. Wayne; Busalacchi, Antonio J. (Technical Monitor)</p> <p>2000-01-01</p> <p>The sea surface directional <span class="hlt">wave</span> spectrum was measured for the first time in all quadrants of a hurricane in open water using the NASA airborne scanning radar altimeter (SRA) carried aboard one of the National <span class="hlt">Oceanic</span> and Atmospheric Administration (NOAA) WP-3D hurricane research aircraft at 1.5 km height. The open-<span class="hlt">ocean</span> data were acquired on 24 August 1998 when Bonnie, a large category 3 hurricane, was east of the Bahamas and moving about 5 meters per second toward 330. The NOAA aircraft spent over five hours within 180 km of the hurricane Bonnie eye and made five eye penetrations. Individual <span class="hlt">waves</span> with heights up to 18 m were observed and the spatial variation of the <span class="hlt">wave</span> field was dramatic. The dominant <span class="hlt">waves</span> generally propagated at significant angles to the downwind direction. At some positions there were three different <span class="hlt">wave</span> fields of comparable energy crossing each other. On 26 August 1998, the SRA documented the <span class="hlt">wave</span> spectrum spatial variation while Bonnie was making landfall near Wilmington, NC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1991PhFlA...3.1458D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1991PhFlA...3.1458D"><span>Application of the principle of breaking <span class="hlt">ocean</span> <span class="hlt">waves</span> to mixing technology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doman, Michael</p> <p>1991-05-01</p> <p>Turbulent mixing in the multiphase system of breaking <span class="hlt">ocean</span> <span class="hlt">waves</span> and whitecaps is known to play an important role in the mass exchange between <span class="hlt">ocean</span> and atmosphere. Thus engineering applications to this naturally occurring dynamic exchange process appear to be of interest in various areas of applied mixing technology. Starting from the fact that <span class="hlt">ocean</span> <span class="hlt">waves</span> break after having reached their point of instability, a three-dimensional collapsible swivel mechanism (CSM) was developed for simulating by mechanical means the highly dynamic movement of breaking <span class="hlt">ocean</span> <span class="hlt">waves</span>. The CSM, employing reversion kinematics of a six-link spatial kinematic chain, has been realized in the construction of a new mixing technology (called swing mixer) that can either move the fluid by the use of mixing tools in a vessel (stirrer principle) or by moving the entire vessel (shaker principle). A first description of swing mixers has recently been given.1 A special characteristic of swing mixers is their three-dimensional reversing motion, the forward and backward paths being nonsuperimposable mirror images of one another. During the mixing process in swing mixers, the efficient mixing principle of repeated stretching and folding2 also takes place in the third dimension. Details of the mixing technology of swing mixers will be discussed together with some suggestions as to how spatial and temporal changes in the concentration may be determined with the help of CCD cameras in a given multiphase system agitated by swing mixers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvC..95e4001V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvC..95e4001V"><span><span class="hlt">Power</span> counting in peripheral partial <span class="hlt">waves</span>: The singlet channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Valderrama, M. Pavón; Sánchez, M. Sánchez; Yang, C.-J.; Long, Bingwei; Carbonell, J.; van Kolck, U.</p> <p>2017-05-01</p> <p>We analyze the <span class="hlt">power</span> counting of the peripheral singlet partial <span class="hlt">waves</span> in nucleon-nucleon scattering. In agreement with conventional wisdom, we find that pion exchanges are perturbative in the peripheral singlets. We quantify from the effective field theory perspective the well-known suppression induced by the centrifugal barrier in the pion-exchange interactions. By exploring perturbation theory up to fourth order, we find that the one-pion-exchange potential in these channels is demoted from leading to subleading order by a given <span class="hlt">power</span> of the expansion parameter that grows with the orbital angular momentum. We discuss the implications of these demotions for few-body calculations: though higher partial <span class="hlt">waves</span> have been known for a long time to be irrelevant in these calculations (and are hence ignored), here we explain how to systematize the procedure in a way that is compatible with the effective field theory expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22303655','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22303655"><span>A <span class="hlt">powerful</span> reflector in relativistic backward <span class="hlt">wave</span> oscillator</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cao, Yibing Sun, Jun; Teng, Yan; Zhang, Yuchuan; Zhang, Lijun; Shi, Yanchao; Ye, Hu; Chen, Changhua</p> <p>2014-09-15</p> <p>An improved TM{sub 021} resonant reflector is put forward. Similarly with most of the slow <span class="hlt">wave</span> structures used in relativistic backward <span class="hlt">wave</span> oscillator, the section plane of the proposed reflector is designed to be trapezoidal. Compared with the rectangular TM{sub 021} resonant reflector, such a structure can depress RF breakdown more effectively by weakening the localized field convergence and realizing good electrostatic insulation. As shown in the high <span class="hlt">power</span> microwave (HPM) generation experiments, with almost the same output <span class="hlt">power</span> obtained by the previous structure, the improved structure can increase the pulse width from 25 ns to over 27 ns and no obvious surface damage is observed even if the generated HPM pulses exceed 1000 shots.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6522065','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6522065"><span>Ionospheric modification by high-<span class="hlt">power</span> radio <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Duncan, L.M.</p> <p>1981-04-01</p> <p><span class="hlt">Powerful</span>, high-frequency radio <span class="hlt">waves</span> have been used to temporarily modify the ionosphere. Thermal and parametric interactions have led to a diverse range of observed phenomena, including generation of density striations and artificial spread-F, enhancements of electron plasma <span class="hlt">waves</span>, production of extrathermal electron fluxes and enhanced airglow, modification of the D-region temperature and densities, wideband signal attenuation, and self-focusing and scattering of the electromagnetic <span class="hlt">waves</span>. The physics of ionospheric modification by high-<span class="hlt">power</span> radio <span class="hlt">waves</span> is reviewed in the context of our current theoretical understanding; disturbance generation mechanisms are qualitatively described. In addition, results of recent experiments are summarized in which ionospheric irregularities are generated and their evolution and decay processes investigated in detail. The effects and potential controlled applications of these HF ionospheric modifications for various RF systems studies are discussed. The C/sup 3/I scientific community provides an important motivation for these ionospheric modification studies; their increased interaction and active participation in experimental design and interpretation are encouraged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LaPhy..26g5001G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LaPhy..26g5001G"><span>High <span class="hlt">power</span> continuous-<span class="hlt">wave</span> Alexandrite laser with green pump</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ghanbari, Shirin; Major, Arkady</p> <p>2016-07-01</p> <p>We report on a continuous-<span class="hlt">wave</span> (CW) Alexandrite (Cr:BeAl2O4) laser, pumped by a high <span class="hlt">power</span> green source at 532 nm with a diffraction limited beam. An output <span class="hlt">power</span> of 2.6 W at 755 nm, a slope efficiency of 26%, and wavelength tunability of 85 nm have been achieved using 11 W of green pump. To the best of our knowledge, this is the highest CW output <span class="hlt">power</span> of a high brightness laser pumped Alexandrite laser reported to date. The results obtained in this experiment can lead to the development of a high <span class="hlt">power</span> tunable CW and ultrafast sources of the near-infrared or ultraviolet radiation through frequency conversion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1033670','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1033670"><span>A low-<span class="hlt">power</span> <span class="hlt">wave</span> union TDC implemented in FPGA</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wu, Jinyuan; Shi, Yanchen; Zhu, Douglas; /Illinois Math. Sci. Acad.</p> <p>2011-10-01</p> <p>A low-<span class="hlt">power</span> time-to-digital convertor (TDC) for an application inside a vacuum has been implemented based on the <span class="hlt">Wave</span> Union TDC scheme in a low-cost field programmable gate array (FPGA) device. Bench top tests have shown that a time measurement resolution better than 30 ps (standard deviation of time differences between two channels) is achieved. Special firmware design practices are taken to reduce <span class="hlt">power</span> consumption. The measurements indicate that with 32 channels fitting in the FPGA device, the <span class="hlt">power</span> consumption on the FPGA core voltage is approximately 9.3 mW/channel and the total <span class="hlt">power</span> consumption including both core and I/O banks is less than 27 mW/channel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1184169-location-high-frequency-wave-microseismic-noise-pacific-ocean-using-multiple-small-aperture-arrays','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1184169-location-high-frequency-wave-microseismic-noise-pacific-ocean-using-multiple-small-aperture-arrays"><span>Location of high-frequency P <span class="hlt">wave</span> microseismic noise in the Pacific <span class="hlt">Ocean</span> using multiple small aperture arrays</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Pyle, Moira L.; Koper, Keith D.; Euler, Garrett G.; ...</p> <p>2015-04-20</p> <p>We investigate source locations of P-<span class="hlt">wave</span> microseisms within a narrow frequency band (0.67–1.33 Hz) that is significantly higher than the classic microseism band (~0.05–0.3 Hz). Employing a backprojection method, we analyze data recorded during January 2010 from five International Monitoring System arrays that border the Pacific <span class="hlt">Ocean</span>. We develop a ranking scheme that allows us to combine beam <span class="hlt">power</span> from multiple arrays to obtain robust locations of the microseisms. Some individual arrays exhibit a strong regional component, but results from the combination of all arrays show high-frequency P <span class="hlt">wave</span> energy emanating from the North Pacific basin, in general agreement withmore » previous observations in the double-frequency (DF) microseism band (~0.1–0.3 Hz). This suggests that the North Pacific source of ambient P noise covers a broad range of frequencies and that the <span class="hlt">wave-wave</span> interaction model is likely valid at shorter periods.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5857T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5857T"><span>Finite frequency P-<span class="hlt">wave</span> traveltime measurements on <span class="hlt">ocean</span> bottom seismometers and hydrophones in the western Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsekhmistrenko, Maria; Sigloch, Karin; Hosseini, Kasra; Barruol, Guilhem</p> <p>2016-04-01</p> <p>From 2011 to 2014, the RHUM-RUM project (Reunion Hotspot Upper Mantle - Reunions Unterer Mantel) instrumented a 2000x2000km2 area of Indian <span class="hlt">Ocean</span> seafloor, islands and Madagascar with broadband seismometers and hydrophones. The central component was a 13-month deployment of 57 German and French <span class="hlt">Ocean</span> Bottom Seismometers (OBS) in 2300-5600 m depth. This was supplemented by 2-3 year deployments of 37 island stations on Reunion, Mauritius, Rodrigues, the southern Seychelles, the Iles Eparses and southern Madagascar. Two partner projects contributed another 30+ stations on Madagascar. Our ultimate objective is multifrequency waveform tomography of the entire mantle column beneath the Reunion hotspot. Ideally we would use all passbands that efficiently transmit body <span class="hlt">waves</span> but this meets practical limits in the noise characteristics of <span class="hlt">ocean</span>-bottom recordings in particular. Here we present the preliminary data set of frequency-dependent P-<span class="hlt">wave</span> traveltime measurements on seismometers and hydrophones, obtained by cross-correlation of observed with predicted waveforms. The latter are synthesized from fully numerical Green's functions and carefully estimated, broadband source time functions. More than 200 teleseismic events during the 13-month long deployment yielded usable P-waveform measurements. We present our methods and discuss data yield and quality of <span class="hlt">ocean</span>-bottom versus land seismometers, and of OBS versus broadband hydrophones. Above and below the microseismic noise band, data yields are higher than within it, especially for OBS. The 48 German OBS, equipped with Guralp 60 s sensors, were afflicted by relatively high self-noise compared to the 9 French instruments equipped with Nanometrics Trillium 240 s sensors. The HighTechInc (model HTI-01 and HTI-04-PCA/ULF) hydrophones (100 s corner period) functioned particularly reliably but their waveforms are relatively more challenging to model due to reverberations in the water column. We obtain ~15000 combined cross</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22047437','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22047437"><span>Millimeter-<span class="hlt">wave</span> spectral line radiation from a <span class="hlt">powerful</span> explosion</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kotov, Yu. B.; Popov, V. D.; Semenova, T. A.; Fedorov, V. F.</p> <p>2012-01-15</p> <p>Millimeter-<span class="hlt">wave</span> spectral line radiation from a <span class="hlt">powerful</span> air explosion accompanied by neutron, X-ray, and gamma emission is considered. It is shown that the main contribution to the line radiation in the frequency window of air near the wavelength of 2.3 mm is made by nitric oxide molecules. The set of kinetic equations for a partially ionized plasma near the explosion is solved by the Runge-Kutta method. It is shown that the density of nitrogen oxide molecules increases in time to a certain steady-state level. The spectral <span class="hlt">power</span> of radiation in the NO lines is estimated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6745270','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6745270"><span>High <span class="hlt">power</span> millimeter <span class="hlt">wave</span> ECRH source needs for fusion program</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Not Available</p> <p>1984-06-01</p> <p>This document stems from the four-day Gyrotron Symposium held at the US Department of Energy (DOE) Headquarters on June 13-16, 1983, and serves as a position paper for the Office of Fusion Energy, DOE, on high-<span class="hlt">power</span> millimeter <span class="hlt">wave</span> source development for Electron Cyclotron Heating (ECH) of plasmas. It describes the fusion program needs for gyrotron as ECH sources, their current status, and desirable development strategies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130012646','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130012646"><span>Wind, <span class="hlt">Wave</span>, and Tidal Energy Without <span class="hlt">Power</span> Conditioning</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Jones, Jack A.</p> <p>2013-01-01</p> <p>Most present wind, <span class="hlt">wave</span>, and tidal energy systems require expensive <span class="hlt">power</span> conditioning systems that reduce overall efficiency. This new design eliminates <span class="hlt">power</span> conditioning all, or nearly all, of the time. Wind, <span class="hlt">wave</span>, and tidal energy systems can transmit their energy to pumps that send high-pressure fluid to a central <span class="hlt">power</span> production area. The central <span class="hlt">power</span> production area can consist of a series of hydraulic generators. The hydraulic generators can be variable displacement generators such that the RPM, and thus the voltage, remains constant, eliminating the need for further <span class="hlt">power</span> conditioning. A series of wind blades is attached to a series of radial piston pumps, which pump fluid to a series of axial piston motors attached to generators. As the wind is reduced, the amount of energy is reduced, and the number of active hydraulic generators can be reduced to maintain a nearly constant RPM. If the axial piston motors have variable displacement, an exact RPM can be maintained for all, or nearly all, wind speeds. Analyses have been performed that show over 20% performance improvements with this technique over conventional wind turbines</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002CG.....28..547W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002CG.....28..547W"><span>Teaching <span class="hlt">ocean</span> <span class="hlt">wave</span> forecasting using computer-generated visualization and animation—Part 2: swell forecasting</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Whitford, Dennis J.</p> <p>2002-05-01</p> <p>This paper, the second of a two-part series, introduces undergraduate students to <span class="hlt">ocean</span> <span class="hlt">wave</span> forecasting using interactive computer-generated visualization and animation. Verbal descriptions and two-dimensional illustrations are often insufficient for student comprehension. Fortunately, the introduction of computers in the geosciences provides a tool for addressing this problem. Computer-generated visualization and animation, accompanied by oral explanation, have been shown to be a pedagogical improvement to more traditional methods of instruction. Cartographic science and other disciplines using geographical information systems have been especially aggressive in pioneering the use of visualization and animation, whereas oceanography has not. This paper will focus on the teaching of <span class="hlt">ocean</span> swell <span class="hlt">wave</span> forecasting, often considered a difficult oceanographic topic due to the mathematics and physics required, as well as its interdependence on time and space. Several MATLAB ® software programs are described and offered to visualize and animate group speed, frequency dispersion, angular dispersion, propagation, and <span class="hlt">wave</span> height forecasting of deep water <span class="hlt">ocean</span> swell <span class="hlt">waves</span>. Teachers may use these interactive visualizations and animations without requiring an extensive background in computer programming.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006OcScD...3.1825J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006OcScD...3.1825J"><span>Assessment of the importance of the current-<span class="hlt">wave</span> coupling in the shelf <span class="hlt">ocean</span> forecasts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jordà, G.; Bolaños, R.; Espino, M.; Sánchez-Arcilla, A.</p> <p>2006-10-01</p> <p>The effects of <span class="hlt">wave</span>-current interactions on shelf <span class="hlt">ocean</span> forecasts is investigated in the framework of the MFSTEP (Mediterranean Forecasting System Project Towards Enviromental Predictions) project. A one way sequential coupling approach is adopted to link the <span class="hlt">wave</span> model (WAM) to the circulation model (SYMPHONIE). The coupling of <span class="hlt">waves</span> and currents has been done considering four main processes: <span class="hlt">wave</span> refraction due to currents, surface wind drag and bo€ttom drag modifications due to <span class="hlt">waves</span>, and the <span class="hlt">wave</span> induced mass flux. The coupled modelling system is implemented in the southern Catalan shelf (NW Mediterranean), a region with characteristics similar to most of the Mediterranean shelves. The sensitivity experiments are run in a typical operational configuration. The <span class="hlt">wave</span> refraction by currents seems to be not very relevant in a microtidal context such as the western Mediterranean. The main effect of <span class="hlt">waves</span> on current forecasts is through the modification of the wind drag. The Stokes drift also plays a significant role due to its spatial and temporal characteristics. Finally, the enhanced bottom friction is just noticeable in the inner shelf.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030093729','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030093729"><span>Simultaneous <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Measurements by the Jason and Topex Satellites, With Buoy and Model Comparisons</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ray, Richard D.; Beckley, B. D.</p> <p>2003-01-01</p> <p>The verification phase of the Jason-1 satellite altimeter mission presents a unique opportunity for comparing near-simultaneous, independent satellite measurements. We here examine simultaneous significant <span class="hlt">wave</span> height measurements by the Jason-1 and Topex/Poseidon altimeters. These data are also compared with in-situ measurements from deep-<span class="hlt">ocean</span> buoys and with predicted <span class="hlt">wave</span> heights from the <span class="hlt">Wave</span> Watch 111 operational model. The rms difference between Jason and Topex <span class="hlt">wave</span> heights is 21 cm, and this can be further lowered by application of median filters to reduce high-frequency noise. This noise is slightly larger in the Jason dataset, amounting to about 7 cm rms for frequencies above 0.05 Hz, which is the frequency at which the coherence between Topex and Jason measurements drops to zero. The probability density function for Jason shows a dearth of small <span class="hlt">waves</span> relative to Topex. Buoy comparisons confirm that this problem lies with the Jason measurements. The buoy comparisons confirm previous reports that Topex <span class="hlt">wave</span> heights are roughly 5% smaller than buoy measurements for <span class="hlt">waves</span> between 2 and 5m; Jason heights in general are 2.7% smaller than Topex. Spurious dips in the Topex density function for 3- and 6-meter <span class="hlt">waves</span>, a problem that has existed since the beginning of the mission, can be solved by waveform retracking..</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040040120&hterms=phase+noise+satellite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dphase%2Bnoise%2Bsatellite','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040040120&hterms=phase+noise+satellite&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dphase%2Bnoise%2Bsatellite"><span>Simultaneous <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Measurements by the JASON and TOPEX Satellites, With Buoy and Model Comparisons</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ray, R. D.; Beckley, B. D.</p> <p>2003-01-01</p> <p>The verification phase of the Jason-1 satellite altimeter mission presents a unique opportunity for comparing near-simultaneous, independent satellite measurements. We here examine simultaneous significant <span class="hlt">wave</span> height measurements by the Jason-1 and Topex/Poseidon altimeters. These data are also compared with in-situ measurements from deep-<span class="hlt">ocean</span> buoys and with predicted <span class="hlt">wave</span> heights from the <span class="hlt">Wave</span>Watch 111 operational model. The rms difference between Jason and Topex <span class="hlt">wave</span> heights is 28 cm, and this can be lowered by half through improved outlier editing and filtering of high-frequency noise. Noise is slightly larger in the Jason dataset, exceeding Topex by about 7 cm rms at frequencies above 0.05 Hz, which is the frequency at which the coherence between Topex and Jason measurements drops to zero. Jason <span class="hlt">wave</span> heights are more prone to outliers, especially during periods of moderate to high backscatter. Buoy comparisons confirm previous reports that Topex <span class="hlt">wave</span> heights are roughly 5% smaller than buoy measurements for <span class="hlt">waves</span> between 2 and 5m; Jason heights in general are 3% smaller than Topex. Spurious dips in the Topex density function for 3- and 6-meter <span class="hlt">waves</span>, a problem that has existed since the beginning of the mission, can be solved by waveform retracking.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/FR-2012-02-06/pdf/2012-2547.pdf','FEDREG'); return false;" href="https://www.gpo.gov/fdsys/pkg/FR-2012-02-06/pdf/2012-2547.pdf"><span>77 FR 5817 - <span class="hlt">Ocean</span> Renewable <span class="hlt">Power</span> Company, Tidal Energy Project, Cobscook Bay, ME</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR">Federal Register 2010, 2011, 2012, 2013, 2014</a></p> <p></p> <p>2012-02-06</p> <p>... SECURITY Coast Guard <span class="hlt">Ocean</span> Renewable <span class="hlt">Power</span> Company, Tidal Energy Project, Cobscook Bay, ME AGENCY: Coast... five turbine generator units secured to the <span class="hlt">ocean</span> floor, used for generating electricity from tidal...: Background and Purpose ORPC's tidal energy project involves installation of five underwater turbines on the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1060943','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1060943"><span>Mapping and Assessment of the United States <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Energy Resource</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jacobson, Paul T; Hagerman, George; Scott, George</p> <p>2011-12-01</p> <p>This project estimates the naturally available and technically recoverable U.S. <span class="hlt">wave</span> energy resources, using a 51-month Wavewatch III hindcast database developed especially for this study by National Oceanographic and Atmospheric Administration's (NOAA's) National Centers for Environmental Prediction. For total resource estimation, <span class="hlt">wave</span> <span class="hlt">power</span> density in terms of kilowatts per meter is aggregated across a unit diameter circle. This approach is fully consistent with accepted global practice and includes the resource made available by the lateral transfer of <span class="hlt">wave</span> energy along <span class="hlt">wave</span> crests, which enables <span class="hlt">wave</span> diffraction to substantially reestablish <span class="hlt">wave</span> <span class="hlt">power</span> densities within a few kilometers of a linear array, even for fixed terminator devices. The total available <span class="hlt">wave</span> energy resource along the U.S. continental shelf edge, based on accumulating unit circle <span class="hlt">wave</span> <span class="hlt">power</span> densities, is estimated to be 2,640 TWh/yr, broken down as follows: 590 TWh/yr for the West Coast, 240 TWh/yr for the East Coast, 80 TWh/yr for the Gulf of Mexico, 1570 TWh/yr for Alaska, 130 TWh/yr for Hawaii, and 30 TWh/yr for Puerto Rico. The total recoverable <span class="hlt">wave</span> energy resource, as constrained by an array capacity packing density of 15 megawatts per kilometer of coastline, with a 100-fold operating range between threshold and maximum operating conditions in terms of input <span class="hlt">wave</span> <span class="hlt">power</span> density available to such arrays, yields a total recoverable resource along the U.S. continental shelf edge of 1,170 TWh/yr, broken down as follows: 250 TWh/yr for the West Coast, 160 TWh/yr for the East Coast, 60 TWh/yr for the Gulf of Mexico, 620 TWh/yr for Alaska, 80 TWh/yr for Hawaii, and 20 TWh/yr for Puerto Rico.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.A53J0270F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.A53J0270F"><span>Structure and Evolution of Tropical Synoptic-Scale <span class="hlt">Wave</span> Disturbances and Extratropical—Tropical Interactions over the Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fukutomi, Y.; Yasunari, T.</p> <p>2012-12-01</p> <p>The structure and behavior of synoptic-scale <span class="hlt">wave</span> disturbances over the tropical Indian <span class="hlt">Ocean</span> are examined using the 30 years of the JRA-25 products and NOAA outgoing long <span class="hlt">wave</span> radiation data. Two types of the tropical synoptic-scale <span class="hlt">waves</span> are identified by an extended EOF (EEOF) analysis on 2—7-day filtered daily 850-hPa meridional wind anomalies during December—February 1979/80—2008/09. Composite analyses based on the resulting EEOF time coefficients reveal structure and evolution of these <span class="hlt">waves</span>. One type has an east—west dipole structure traversing tropical Indian <span class="hlt">Ocean</span> (Type 1) and the other type exhibits a southwest—northeast oriented <span class="hlt">wave</span> train structure extending from the southwest to the eastern Indian <span class="hlt">Ocean</span> (Type 2). Both types of the <span class="hlt">waves</span> occur in conjunction with convective activity along the Indian <span class="hlt">Ocean</span> ITCZ, and have a westward phase speed around 7—9 m/s. Type 1 <span class="hlt">wave</span> is regarded as a mixed Rossby-gravity (MRG) type <span class="hlt">wave</span>. Individual circulation centers of the <span class="hlt">waves</span> are shifted southward to 2—3S. The MRG-type <span class="hlt">waves</span> of about 8000—9000 km wavelengths propagate westward from the west of Sumatra into East Africa. The <span class="hlt">waves</span> are amplified when low-level northerly monsoon surges over the Arabian Sea and the Bay of Bengal reaches the equatorial Indian <span class="hlt">Ocean</span>. The northerly surges are originated in the midlatitude Asian continent, and they are caused by synoptic-scale baroclinic <span class="hlt">waves</span> propagating along the Asian subtropical westerly jet. Type 2 <span class="hlt">wave</span> is assumed to be a MRG-tropical depression (TD) type <span class="hlt">wave</span>. The MRG-TD type <span class="hlt">waves</span> of wavelengths of about 6000—7000 km propagate westward and southwestward from the west of Sumatra into the southwest Indian <span class="hlt">Ocean</span>. As a MRG <span class="hlt">wave</span>-like equatorial gyre at the eastern end of the MRG-TD <span class="hlt">wave</span> train moves westward, the gyre is translated to an off-equatorial Rossby-type gyre which then moves southwestward toward the southwest Indian <span class="hlt">Ocean</span>. The northerly surges over the Bay of Bengal appear to enhance the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ChPhB..25l8401W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ChPhB..25l8401W"><span>A high-<span class="hlt">power</span> subterahertz surface <span class="hlt">wave</span> oscillator with separated overmoded slow <span class="hlt">wave</span> structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Guang-Qiang; Wang, Jian-Guo; Zeng, Peng; Wang, Dong-Yang; Li, Shuang</p> <p>2016-12-01</p> <p>A megawatt-level subterahertz surface <span class="hlt">wave</span> oscillator (SWO) is proposed to obtain high conversion efficiency by using separated overmoded slow <span class="hlt">wave</span> structures (SWSs). Aiming at the repetitive operation and practical applications, the device driven by electron beam with modest energy and current is theoretically analyzed and verified. Then, the functions of the two SWS sections and the effect of the drift tube are investigated by using a particle-in-cell code to reveal how the proposed device achieves high efficiency. The mode analysis of the beam-<span class="hlt">wave</span> interaction region in the device is also carried out, and the results indicate that multi-modes participate in the premodulation of the electron beam in the first SWS section, while the TM01 mode surface <span class="hlt">wave</span> is successfully and dominantly excited and amplified in the second SWS section. Finally, a typical simulation result demonstrates that at a beam energy of 313 keV, beam current of 1.13 kA, and guiding magnetic field of above 3.5 T, a high-<span class="hlt">power</span> subterahertz <span class="hlt">wave</span> is obtained with an output <span class="hlt">power</span> of about 70 MW at frequency 146.3 GHz, corresponding to the conversion efficiency of 20%. Compared with the results of the previous subterahertz overmoded SWOs with integral SWS and similar beam parameters, the efficiency increases almost 50% in the proposed device. Project supported by the National Natural Science Foundation of China (Grant No. 61231003).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.7377K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.7377K"><span>Development of a GPS buoy system for monitoring tsunami, sea <span class="hlt">waves</span>, <span class="hlt">ocean</span> bottom crustal deformation and atmospheric water vapor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kato, Teruyuki; Terada, Yukihiro; Nagai, Toshihiko; Koshimura, Shun'ichi</p> <p>2010-05-01</p> <p>We have developed a GPS buoy system for monitoring tsunami for over 12 years. The idea was that a buoy equipped with a GPS antenna and placed offshore may be an effective way of monitoring tsunami before its arrival to the coast and to give warning to the coastal residents. The key technology for the system is real-time kinematic (RTK) GPS technology. We have successfully developed the system; we have detected tsunamis of about 10cm in height for three large earthquakes, namely, the 23 June 2001 Peru earthquake (Mw8.4), the 26 September 2003 Tokachi earthquake (Mw8.3) and the 5 September 2004 earthquake (Mw7.4). The developed GPS buoy system is also capable of monitoring sea <span class="hlt">waves</span> that are mainly caused by winds. Only the difference between tsunami and sea <span class="hlt">waves</span> is their frequency range and can be segregated each other by a simple filtering technique. Given the success of GPS buoy experiments, the system has been adopted as a part of the Nationwide <span class="hlt">Ocean</span> <span class="hlt">Wave</span> information system for Port and HArborS (NOWPHAS) by the Ministry of Land, Infrastructure, Transport and Tourism of Japan. They have established more than eight GPS buoys along the Japanese coasts and the system has been operated by the Port and Airport Research Institute. As a future scope, we are now planning to implement some other additional facilities for the GPS buoy system. The first application is a so-called GPS/Acoustic system for monitoring <span class="hlt">ocean</span> bottom crustal deformation. The system requires acoustic <span class="hlt">waves</span> to detect <span class="hlt">ocean</span> bottom reference position, which is the geometrical center of an array of transponders, by measuring distances between a position at the sea surface (vessel) and <span class="hlt">ocean</span> bottom equipments to return the received sonic <span class="hlt">wave</span>. The position of the vessel is measured using GPS. The system was first proposed by a research group at the Scripps Institution of Oceanography in early 1980's. The system was extensively developed by Japanese researchers and is now capable of detecting <span class="hlt">ocean</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12501587','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12501587"><span>Tracking the drift of a human body in the coastal <span class="hlt">ocean</span> using numerical prediction models of the <span class="hlt">oceanic</span>, atmospheric and <span class="hlt">wave</span> conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carniel, S; Umgiesser, G; Sclavo, M; Kantha, L H; Monti, S</p> <p>2002-01-01</p> <p>This paper describes the use of numerical models to infer the path of a floating human body in the Ligurian Sea (north-west Mediterranean) during the month of January 2001. The prevailing <span class="hlt">oceanic</span> currents were obtained from a state-of-the-art real-time nowcast/forecast <span class="hlt">ocean</span> circulation model, while the sea state was inferred from a numerical model of the surface gravity <span class="hlt">waves</span>, both driven by regional atmospheric models. The surface currents (from the <span class="hlt">ocean</span> model) and the drift ones at the <span class="hlt">ocean</span> surface, as inferred from the <span class="hlt">wave</span> model, were used to drive a Lagrangian model of the drifting body to deduce its plausible trajectory along the Ligurian coast. The inferred path is reasonably consistent with location and time of the discovery on the French coast. This note illustrates the utility of numerical prediction models at the disposal of modern forensic science in the fields of <span class="hlt">ocean</span> sciences.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013APS..DFDA36004B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013APS..DFDA36004B"><span>Characterization of the Vertical Energy Distribution of the Internal <span class="hlt">Wave</span> Field in the Upper <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bruch, Jeremy</p> <p>2013-11-01</p> <p>A method to simulate internal <span class="hlt">waves</span> in the upper <span class="hlt">ocean</span> is proposed by defining the vertical energy distribution as a function of mode number with the associated vertical structure functions as an appropriate set of orthogonal basis functions. An internal <span class="hlt">wave</span> simulation is shown for a case with a stylized BV peak profile, using the Garrett and Munk internal <span class="hlt">wave</span> model (GM) as the input energy distribution. The resulting simulated spectra are shown to be self-consistent with the proposed definition of the vertical energy distribution. Application of the GM model requires many assumptions, including the requirement that the internal <span class="hlt">waves</span> are modeled strictly in deep water where there is little variation in the stratification. Given the typical non-uniformity of the stratification profile in the upper <span class="hlt">ocean</span>, it may be of interest to relax this restriction of the GM model but the obvious non-stationary properties near the thermocline are incompatible with the calculation of the vertical spectrum of the internal <span class="hlt">wave</span> field. The method described in this presentation suggests a means to reconcile this incompatibility. Membership pending.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1714576T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1714576T"><span>Vertical Kinetic Energy of Internal Gravity <span class="hlt">Waves</span> and Turbulent Dissipation in the <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thurnherr, Andreas; St. Laurent, Louis; Richards, Kelvin; Toole, John</p> <p>2015-04-01</p> <p>Internal gravity <span class="hlt">waves</span> in the <span class="hlt">ocean</span> are closely associated with turbulence and mixing. The relationship between IGWs and turbulence is usually interpreted in the framework of the Garret-Munk model, a prescription for open-<span class="hlt">ocean</span> internal-<span class="hlt">wave</span> energy as a function of several environmental parameters. Here, we evaluate the relationship between internal-<span class="hlt">wave</span> energy and turbulence directly, using more than 250 joint profiles of turbulent dissipation from microstructure, and vertical velocity from CTD/LADCP measurements. The observations include profiles from a wide variety of dynamical regimes and latitudes between the equator and 60°. In most profiles, finescale vertical kinetic energy (VKE) varies as kz-2, where kz is the vertical <span class="hlt">wave</span> number. Scaling VKE with dissipation collapses all off-equatorial data-set average spectra to within √2 or better. The dissipation-normalized spectrum can be interpreted as a new single-parameter (dissipation) model for internal-<span class="hlt">wave</span> VKE, which is considerably simpler and more accurate than the corresponding Garrett-Munk model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JSV...332.5559D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JSV...332.5559D"><span>The impulsive effects of momentum transfer on the dynamics of a novel <span class="hlt">ocean</span> <span class="hlt">wave</span> energy converter</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Diamond, Christopher A.; O'Reilly, Oliver M.; Savaş, Ömer</p> <p>2013-10-01</p> <p>In a recent paper by Orazov et al. [On the dynamics of a novel <span class="hlt">ocean</span> <span class="hlt">wave</span> energy converter. Journal of Sound and Vibration329 (24) (2010) 5058-5069], a <span class="hlt">wave</span> energy converter (WEC) was proposed. The converter features a mass modulation scheme and a simple model was used to examine its efficacy. The simple model did not adequately account for the momentum transfer which takes place during the mass modulation. The purpose of the present paper is to account for this transfer and to show that the WEC equipped with a novel and more general mass modulation scheme has the potential to improve its energy harvesting capabilities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA522765','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA522765"><span>Observed Dispersion Relation of Yanai <span class="hlt">Waves</span> and 17-Day Tropical Instability <span class="hlt">Waves</span> in the Pacific <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-01-01</p> <p>day TIWs. 1. Introduction Mixed Rossby-Gravity <span class="hlt">waves</span> (often referred to as Yanai <span class="hlt">waves</span>) play an important role in a variety of phenomena in the...significant role in the SST and SSH variability caused by 17-day TIWs especially in the northern hemisphere. 3. Cross-correlation analysis The phase...penetrating from the upper troposphere into the lower strato - sphere. J. Meteor. Soc. Japan, 47, 167–182. Zangvil, A., 1975: Temporal and spatial</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170000013&hterms=oceans&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Doceans','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170000013&hterms=oceans&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Doceans"><span>Tsunami <span class="hlt">Waves</span> Extensively Resurfaced the Shorelines of an Early Martian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rodriguez, J. A. P.; Fairen, A. G.; Linares, R.; Zarroca, M.; Platz, T.; Komatsu, G.; Kargel, J. S.; Gulick, V.; Jianguo, Y.; Higuchi, K.; Miyamoto, H.; Baker, V. R.; Glines, N.</p> <p>2016-01-01</p> <p>Viking image-based mapping of a widespread deposit covering most of the northern low-lands of Mars led to the proposal by Parker et al. that the deposit represents the vestiges of an enormous <span class="hlt">ocean</span> that existed approx. 3.4 Ga. Later identified as the Vastitas Borealis Formation, the latest geologic map of Mars identifies this deposit as the Late Hesperian lowland unit (lHl). This deposit is typically bounded by raised lobate margins. In addition, some margins have associated rille channels, which could have been produced sub-aerially by the back-wash of high-energy tsunami <span class="hlt">waves</span>. Radar-sounding data indicate that the deposit is ice-rich. However, until now, the lack of <span class="hlt">wave</span>-cut shoreline features and the presence of lobate margins have remained an im-pediment to the acceptance of the paleo-<span class="hlt">ocean</span> hypothesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820015568','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820015568"><span>Size distribution of <span class="hlt">oceanic</span> air bubbles entrained in sea-water by <span class="hlt">wave</span>-breaking</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Resch, F.; Avellan, F.</p> <p>1982-01-01</p> <p>The size of <span class="hlt">oceanic</span> air bubbles produced by whitecaps and <span class="hlt">wave</span>-breaking is determined. The production of liquid aerosols at the sea surface is predicted. These liquid aerosols are at the origin of most of the particulate materials exchanged between the <span class="hlt">ocean</span> and the atmosphere. A prototype was designed and built using an optical technique based on the principle of light scattering at an angle of ninety degrees from the incident light beam. The output voltage is a direct function of the bubble diameter. Calibration of the probe was carried out within a range of 300 microns to 1.2 mm. Bubbles produced by <span class="hlt">wave</span>-breaking in a large air-sea interaction simulating facility. Experimental results are given in the form of size spectrum.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170000013&hterms=Ocean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DOcean','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170000013&hterms=Ocean&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DOcean"><span>Tsunami <span class="hlt">Waves</span> Extensively Resurfaced the Shorelines of an Early Martian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rodriguez, J. A. P.; Fairen, A. G.; Linares, R.; Zarroca, M.; Platz, T.; Komatsu, G.; Kargel, J. S.; Gulick, V.; Jianguo, Y.; Higuchi, K.; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20170000013'); toggleEditAbsImage('author_20170000013_show'); toggleEditAbsImage('author_20170000013_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20170000013_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20170000013_hide"></p> <p>2016-01-01</p> <p>Viking image-based mapping of a widespread deposit covering most of the northern low-lands of Mars led to the proposal by Parker et al. that the deposit represents the vestiges of an enormous <span class="hlt">ocean</span> that existed approx. 3.4 Ga. Later identified as the Vastitas Borealis Formation, the latest geologic map of Mars identifies this deposit as the Late Hesperian lowland unit (lHl). This deposit is typically bounded by raised lobate margins. In addition, some margins have associated rille channels, which could have been produced sub-aerially by the back-wash of high-energy tsunami <span class="hlt">waves</span>. Radar-sounding data indicate that the deposit is ice-rich. However, until now, the lack of <span class="hlt">wave</span>-cut shoreline features and the presence of lobate margins have remained an im-pediment to the acceptance of the paleo-<span class="hlt">ocean</span> hypothesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JMiMi..19i4014T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JMiMi..19i4014T"><span>A radioisotope-<span class="hlt">powered</span> surface acoustic <span class="hlt">wave</span> transponder</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tin, S.; Lal, A.</p> <p>2009-09-01</p> <p>We demonstrate a 63Ni radioisotope-<span class="hlt">powered</span> pulse transponder that has a SAW (surface acoustic <span class="hlt">wave</span>) device as the frequency transmission frequency selector. Because the frequency is determined by a SAW device, narrowband detection with an identical SAW device enables the possibility for a long-distance RF-link. The SAW transponders can be buried deep into structural constructs such as steel and concrete, where changing batteries or harvesting vibration or EM energy is not a reliable option. RF-released <span class="hlt">power</span> to radioisotope- released <span class="hlt">power</span> amplification is 108, even when regulatory safe amounts of 63Ni are used. Here we have achieved an 800 µW pulse (315 MHz, 10 µs pause) across a 50 Ω load every 3 min, using a 1.5 milli-Ci 63Ni source.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1911528H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1911528H"><span><span class="hlt">Oceanic</span> Internal Variability, Tropical Instability <span class="hlt">Waves</span> and the El Nino-Southern Oscillation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Holmes, Ryan; McGregor, Shayne; Santoso, Agus; England, Matthew</p> <p>2017-04-01</p> <p>Tropical instability <span class="hlt">waves</span> (TIWs) are a major source of internally-generated <span class="hlt">oceanic</span> variability in the central and eastern equatorial Pacific <span class="hlt">Ocean</span>. These non-linear processes play an important role in the heat and momentum budgets and influence the sea surface temperature (SST) in a region critical for low-frequency coupled modes of variability such as the El Nino-Southern Oscillation (ENSO). However, their direct contribution to this type of interannual variability has received little attention. Previous studies using <span class="hlt">ocean</span>- or atmosphere-only models suggest that TIW rectification may drive low-frequency SST and wind stress variability in the eastern Pacific that is comparable in magnitude to that driven by the Madden-Julian Oscillation (MJO) in the western Pacific. Other work suggests that TIWs can interact with equatorial Kelvin <span class="hlt">waves</span>, limiting the magnitude of the associated thermocline depth and SST anomalies. In this study, we investigate the influence of TIWs on coupled variability using a 1/4-degree <span class="hlt">ocean</span> model of the equatorial Pacific coupled to a simple atmosphere. The use of a simple atmosphere, in which a large portion of complex intrinsic atmospheric variability is absent, is intended to facilitate an examination of the first-order TIW effect on coupled variability. This setup allows the dominant mode of air-sea coupling, represented as a statistical relationship between SST and wind stress anomalies, while also permitting the effects of TIW-rectification on the variability of thermodynamic fields near the air-sea interface. Using this model setup, we perform two ensembles of idealised coupled model forecast experiments which are initiated with either downwelling or upwelling Kelvin <span class="hlt">waves</span> in the western Pacific. By examining the results of these ensemble experiments, which only differ due to internal <span class="hlt">oceanic</span> variability, we quantify the impact of TIWs on the characteristics of subsequent coupled events. The results have implications for our</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA623768','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA623768"><span>TSA - a Two Scale Approximation for Wind-generated <span class="hlt">Ocean</span> Surface <span class="hlt">Waves</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2013-01-01</p> <p>aquaculture , coastal transportation. Better forecasts, with longer lead-time, and better accuracy can help reduce potential risk to these economic...developments, due to <span class="hlt">ocean</span> <span class="hlt">waves</span>. Quality of Life Development of the coastal zone involves residences, recreation, fisheries, aquaculture , coastal...Babanin, J. F. Filipot, R. Magne, A. Roland, A. van der Westhuysen, P. Queffeulou, J. M. Lefevre, L . Aouf, and F. Collard (2010), Semiempirical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005mmmp.book.....B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005mmmp.book.....B"><span>Modern Microwave and Millimeter-<span class="hlt">Wave</span> <span class="hlt">Power</span> Electronics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barker, Robert J.; Luhmann, Neville C.; Booske, John H.; Nusinovich, Gregory S.</p> <p>2005-04-01</p> <p>A comprehensive study of microwave vacuum electronic devices and their current and future applications While both vacuum and solid-state electronics continue to evolve and provide unique solutions, emerging commercial and military applications that call for higher <span class="hlt">power</span> and higher frequencies to accommodate massive volumes of transmitted data are the natural domain of vacuum electronics technology. Modern Microwave and Millimeter-<span class="hlt">Wave</span> <span class="hlt">Power</span> Electronics provides systems designers, engineers, and researchers-especially those with primarily solid-state training-with a thoroughly up-to-date survey of the rich field of microwave vacuum electronic device (MVED) technology. This book familiarizes the R&D and academic communities with the capabilities and limitations of MVED and highlights the exciting scientific breakthroughs of the past decade that are dramatically increasing the compactness, efficiency, cost-effectiveness, and reliability of this entire class of devices. This comprehensive text explores a wide range of topics: * Traveling-<span class="hlt">wave</span> tubes, which form the backbone of satellite and airborne communications, as well as of military electronic countermeasures systems * Microfabricated MVEDs and advanced electron beam sources * Klystrons, gyro-amplifiers, and crossed-field devices * "Virtual prototyping" of MVEDs via advanced 3-D computational models * High-<span class="hlt">Power</span> Microwave (HPM) sources * Next-generation microwave structures and circuits * How to achieve linear amplification * Advanced materials technologies for MVEDs * A Web site appendix providing a step-by-step walk-through of a typical MVED design process Concluding with an in-depth examination of emerging applications and future possibilities for MVEDs, Modern Microwave and Millimeter-<span class="hlt">Wave</span> <span class="hlt">Power</span> Electronics ensures that systems designers and engineers understand and utilize the significant potential of this mature, yet continually developing technology. SPECIAL NOTE: All of the editors' royalties realized from</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006ESASP.614E.112C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006ESASP.614E.112C"><span>Altimetry, Sea Surface Temperature and <span class="hlt">Ocean</span> Colour Unveil the Effects of Planetary <span class="hlt">Waves</span> on Phytoplankton</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cipollini, P.</p> <p>2006-07-01</p> <p>In the present paper w e discuss the manifestation of planetary w aves in sea surface temper atur e (SST) and <span class="hlt">ocean</span> co lour, and the insigh t that can be gain ed by comparing those observations w ith altimetry. We focus in particular on the discovery of planetary <span class="hlt">waves</span> in <span class="hlt">ocean</span> co lour, which implies some eff ects of the wav es on phytoplankton. A critical assessment of the v arious mech anisms th at may be r esponsib le for th e formation of a signal in <span class="hlt">ocean</span> colour h ighligh ts the importan t role played by horizon tal adv ection of phytoplankton. However, v ertical mechanisms su ch as upw elling of nutrien ts cannot b e ruled out comp letely at this stage, and there remains ample scope for a systematic global study of th e w ave signature in h eigh t, colour and SST.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.S41A2750G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.S41A2750G"><span>Rayleigh <span class="hlt">Wave</span> Phase Velocity in the Upper Mantle Beneath the Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Godfrey, K. E.; Dalton, C. A.; Ritsema, J.</p> <p>2016-12-01</p> <p>Most of what is currently understood about the seismic properties of <span class="hlt">oceanic</span> upper mantle is based on either global studies or regional studies of the upper mantle beneath the Pacific <span class="hlt">Ocean</span>. However, global seismic models and geochemical studies of mid-<span class="hlt">ocean</span> ridge basalts indicate differences in the properties of the upper mantle beneath the Pacific, Atlantic, and Indian <span class="hlt">oceans</span>. Though the Indian <span class="hlt">Ocean</span> is not as well studied seismically, it is host to a number of geologically interesting features including 16,000 km of mid-<span class="hlt">ocean</span> ridge with a range of spreading rates from 14 mm/yr along the Southwest Indian Ridge to 55-75 mm/yr along the Southeast Indian Ridge. The Indian <span class="hlt">Ocean</span> also contains multiple volcanic hotspots, the Australian-Antarctic Discordance, and a low geoid anomaly south of India, and it overlies a portion of a large low-shear-velocity province. We are using Rayleigh <span class="hlt">waves</span> to construct a high-resolution seismic velocity model of the Indian <span class="hlt">Ocean</span> upper mantle. We utilize a global dataset of phase delays measured at 20 periods, between 37 and 375 seconds; the dataset includes between 700 and 20,000 that traverse our study region exclusively, with a larger number of paths at shorter periods. We explore variations in phase velocity using two separate approaches. One, we allow phase velocity to vary only as a function of seafloor age. Two, we perform a damped least-squares inversion to solve for 2-D phase velocity maps at each period. Preliminary results indicate low velocities along the Southeast Indian Ridge and Central Indian Ridge, but the expected low velocities are less apparent along the slow-spreading Southwest Indian Ridge. We observe a region of fast velocities extending from Antarctica northward between the Kerguelen and Crozet hotspots, and lower than expected velocities beneath the Reunion hotspot. Additionally, we find low velocities associated with a region of extinct seafloor spreading in the Wharton basin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5228030','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5228030"><span>Submesoscale transition from geostrophic flows to internal <span class="hlt">waves</span> in the northwestern Pacific upper <span class="hlt">ocean</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Qiu, Bo; Nakano, Toshiya; Chen, Shuiming; Klein, Patrice</p> <p>2017-01-01</p> <p>With radar interferometry, the next-generation Surface Water and <span class="hlt">Ocean</span> Topography satellite mission will improve the measured sea surface height resolution down to 15 km, allowing us to investigate for the first time the global upper <span class="hlt">ocean</span> variability at the submesoscale range. Here, by analysing shipboard Acoustic Doppler Current Profiler measurements along 137°E in the northwest Pacific of 2004–2016, we show that the observed upper <span class="hlt">ocean</span> velocities are comprised of balanced geostrophic flows and unbalanced internal <span class="hlt">waves</span>. The transition length scale, Lt, separating these two motions, is found to depend strongly on the energy level of local mesoscale eddy variability. In the eddy-abundant western boundary current region of Kuroshio, Lt can be shorter than 15 km, whereas Lt exceeds 200 km along the path of relatively stable North Equatorial Current. Judicious separation between the geostrophic and internal <span class="hlt">wave</span> signals represents both a challenge and an opportunity for the Surface Water and <span class="hlt">Ocean</span> Topography mission. PMID:28067242</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28067242','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28067242"><span>Submesoscale transition from geostrophic flows to internal <span class="hlt">waves</span> in the northwestern Pacific upper <span class="hlt">ocean</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Qiu, Bo; Nakano, Toshiya; Chen, Shuiming; Klein, Patrice</p> <p>2017-01-09</p> <p>With radar interferometry, the next-generation Surface Water and <span class="hlt">Ocean</span> Topography satellite mission will improve the measured sea surface height resolution down to 15 km, allowing us to investigate for the first time the global upper <span class="hlt">ocean</span> variability at the submesoscale range. Here, by analysing shipboard Acoustic Doppler Current Profiler measurements along 137°E in the northwest Pacific of 2004-2016, we show that the observed upper <span class="hlt">ocean</span> velocities are comprised of balanced geostrophic flows and unbalanced internal <span class="hlt">waves</span>. The transition length scale, Lt, separating these two motions, is found to depend strongly on the energy level of local mesoscale eddy variability. In the eddy-abundant western boundary current region of Kuroshio, Lt can be shorter than 15 km, whereas Lt exceeds 200 km along the path of relatively stable North Equatorial Current. Judicious separation between the geostrophic and internal <span class="hlt">wave</span> signals represents both a challenge and an opportunity for the Surface Water and <span class="hlt">Ocean</span> Topography mission.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950049301&hterms=photograph&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dphotograph','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950049301&hterms=photograph&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dphotograph"><span>Dynamic interpretation of space shuttle photographs: Deepwater internal <span class="hlt">waves</span> in the western equatorial Indian <span class="hlt">Ocean</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zheng, Quanan; Klemas, Vic; Yan, Xiao-Hai</p> <p>1995-01-01</p> <p>Visible images of deep-<span class="hlt">ocean</span> internal <span class="hlt">waves</span> in the western equatorial Indian <span class="hlt">Ocean</span> taken by the space shuttle Atlantis during mission STS 44 in 1991 are interpreted and analyzed. The internal <span class="hlt">waves</span> occurred in the form of a multisoliton packet in which there are about a dozen solitons. The average wavelength of the solitons is 1.8 +/- 0.5 km, ranging from 1.1 to 2.6 km. The crest lines are mostly straight and reach as long as 100 km. The distance between two adjacent packets is about 66 km. Using the deepwater soliton theory, we derived that the mean amplitude of the solitons is 25 m, the nonlinear phase speed is 1.7 m/s, and the average period is 18 min. The internal semidiurnal tides are the principal generating mechanism. The oblique collision of two multisoliton packets shown on photograph STS 44-93-103 is examined. The results show that the deep-<span class="hlt">ocean</span> internal <span class="hlt">waves</span> obey the general properties of soliton collision. The leading solitons and a few followers exhibit some properties of inelastic collision characterized by a phase shift, and the rest of the solitons exhibits properties of elastic collision under resonance conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRD..121.2045B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRD..121.2045B"><span>Impact of atmospheric convectively coupled equatorial Kelvin <span class="hlt">waves</span> on upper <span class="hlt">ocean</span> variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baranowski, Dariusz B.; Flatau, Maria K.; Flatau, Piotr J.; Matthews, Adrian J.</p> <p>2016-03-01</p> <p>Convectively coupled Kelvin <span class="hlt">waves</span> (CCKWs) are atmospheric weather systems that propagate eastward along the equatorial <span class="hlt">wave</span> guide with phase speeds between 11 and 14 m s-1. They are an important constituent of the convective envelope of the Madden-Julian oscillation (MJO), for which <span class="hlt">ocean</span>-atmosphere interactions play a vital role. Hence, <span class="hlt">ocean</span>-atmosphere interactions within CCKWs may be important for MJO development and prediction and for tropical climate, in general. Although the atmospheric structure of CCKWs has been well studied, their impact on the underlying <span class="hlt">ocean</span> is unknown. In this paper, the <span class="hlt">ocean</span>-atmosphere interactions in CCKWs are investigated by a case study from November 2011 during the CINDY/DYNAMO field experiment, using in situ oceanographic measurements from an <span class="hlt">ocean</span> glider. The analysis is then extended to a 15 year period using precipitation data from the Tropical Rainfall Measuring Mission and surface fluxes from the TropFlux analysis. A methodology is developed to calculate trajectories of CCKWs. CCKW events are strongly controlled by the MJO, with twice as many CCKWs observed during the convectively active phase of the MJO compared to the suppressed phase. Coherent <span class="hlt">ocean</span>-atmosphere interaction is observed during the passage of a CCKW, which lasts approximately 4 days at any given longitude. Surface wind speed and latent heat flux are enhanced, leading to a transient suppression of the diurnal cycle of sea surface temperature (SST) and a sustained decrease in bulk SST of 0.1°C. Given that a typical composite mean MJO SST anomaly is of the order of 0.3°C, and more than one CCKW can occur during the active phase of a single MJO event, the oceanographic impact of CCKWs is of major importance to the MJO cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JSV...381..192M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JSV...381..192M"><span>Repulsive magnetic levitation-based <span class="hlt">ocean</span> <span class="hlt">wave</span> energy harvester with variable resonance: Modeling, simulation and experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Masoumi, Masoud; Wang, Ya</p> <p>2016-10-01</p> <p>This paper investigates a magnetic levitation characteristic used in a vibration based energy harvester, called repulsive magnetic scavenger (RMS). The RMS is capable of harvesting <span class="hlt">ocean</span> <span class="hlt">wave</span> energy with a unique repelling permanent magnet array, which provides a stronger and more uniform magnetic field, compared to its attracting magnetic counterparts. The levitating magnets are stacked together around a threaded rod so that the same pole is facing each other. Two fixed magnets placed with one at each end of the RMS provides a collocated harvesting and braking mechanism in the face of high amplitude vibrations. Magnets in the levitated magnet stack are separated by pole pieces which are made of metals to intensify the magnetic field strength. The effect of the thickness and the use of different materials with different permeability for pole pieces is also studied to obtain an optimal energy harvesting efficiency. Moreover, the procedure to find the restoring force applied to the levitating magnet stack is demonstrated. Then, the Duffing vibration equation of the harvester is solved and the frequency response function is calculated for various force amplitudes and electrical damping so as to investigate the effect of these parameters on the response of the system. Furthermore, the effect of the maximum displacement of the moving magnet stack on the natural frequency of the device is studied. And finally, Faraday's law is employed to estimate the output voltage and <span class="hlt">power</span> of the system under the specified input excitation force. Experiments show that the output emf voltage of the manufactured prototype reaches up to 42 V for an excitation force with the frequency of 9 Hz and the maximum amplitude of 3.4 g.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998GeoJI.132..227H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998GeoJI.132..227H"><span>RESEARCH NOTE : Shear-<span class="hlt">wave</span> velocity in marine sediments on young <span class="hlt">oceanic</span> crust: constraints from dispersion analysis of Scholte <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Heinz-Essen, H.; Grevemeyer, Ingo; Herber, Rolf; Weigel, Wilfried</p> <p>1998-01-01</p> <p>An experiment with a newly developed implosive source, located about 1 m above the seafloor at 3665 m depth, revealed a slow interface <span class="hlt">wave</span>. This <span class="hlt">wave</span> is attributed to S <span class="hlt">waves</span> in a soft sediment layer covering the hard rock sub-bottom. Dispersion analysis by means of the multiple-filter technique yields the group velocity as a function of frequency. Model calculations showed that the observed dispersion curve can be reproduced by considering a steep gradient of S velocity within the sediment layer. Nearly perfect agreement of experimental and model data could be achieved with a sediment layer thickness of 21.5 m, an S speed of 225 m s- 1 at the water-sediment interface and an increase by 23 s- 1 within the layer. These values are relatively high compared to data from the literature. However, previous estimates of in situ S-<span class="hlt">wave</span> velocity have been obtained on old <span class="hlt">oceanic</span> crust in the vicinity of continents or islands, while our experiment was carried out on young Pacific crust. Therefore, we suggest two mechanisms which could support a relatively high S speed in sediments: (1) the input of hydrothermally generated metalliferous sediments from the adjacent spreading axis; and (2) post-depositional diagenesis which has accelerated the induration of sediments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26ES...73a2010R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26ES...73a2010R"><span>Model Predictive Control-based <span class="hlt">Power</span> take-off Control of an Oscillating Water Column <span class="hlt">Wave</span> Energy Conversion System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rajapakse, G.; Jayasinghe, S. G.; Fleming, A.; Shahnia, F.</p> <p>2017-07-01</p> <p>Australia’s extended coastline asserts abundance of <span class="hlt">wave</span> and tidal <span class="hlt">power</span>. The predictability of these energy sources and their proximity to cities and towns make them more desirable. Several tidal current turbine and <span class="hlt">ocean</span> <span class="hlt">wave</span> energy conversion projects have already been planned in the coastline of southern Australia. Some of these projects use air turbine technology with air driven turbines to harvest the energy from an oscillating water column. This study focuses on the <span class="hlt">power</span> take-off control of a single stage unidirectional oscillating water column air turbine generator system, and proposes a model predictive control-based speed controller for the generator-turbine assembly. The proposed method is verified with simulation results that show the efficacy of the controller in extracting <span class="hlt">power</span> from the turbine while maintaining the speed at the desired level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=ocean+AND+power&pg=3&id=EJ422472','ERIC'); return false;" href="https://eric.ed.gov/?q=ocean+AND+power&pg=3&id=EJ422472"><span>The <span class="hlt">Power</span> of the "<span class="hlt">OCEAN</span>": Another Way to Diagnose Clients.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Miller, Mark J.</p> <p>1990-01-01</p> <p>Outlines the <span class="hlt">OCEAN</span> model of personality which includes the domains of Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism. Provides a detailed explanation of each factor and a case study to illustrate how the model can be used to diagnose clients. Discusses advantages of this diagnostic approach and implications for usage.…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/51855','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/51855"><span>Propulsion of small launch vehicles using high <span class="hlt">power</span> millimeter <span class="hlt">waves</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Benford, J.; Myrabo, L.</p> <p>1994-12-31</p> <p>The use of microwave and millimeter <span class="hlt">wave</span> beamed energy for propulsion of vehicles in the atmosphere and in space has been under study for at least 35 years. The need for improved propulsion technology is clear: chemical rockets orbit only a few percent of the liftoff mass at a cost of over $3,000/lb. The key advantage of the beamed <span class="hlt">power</span> approach is to place the heavy and expensive components on the ground or in space, not in the vehicle. This paper, following upon the high <span class="hlt">power</span> laser propulsion programs, uses a multi-cycle propulsion engine in which the first phase of ascent is based on the air breathing ramjet principle, a repetitive Pulsed Detonation Engine (PDE) which uses a microwave-supported detonation to heat the air working fluid, i.e., propellant. The second phase is a pure beam-heated rocket. The key factor is that high peak <span class="hlt">power</span> is essential to this pulsed engine. This paper explores this propulsion concept using millimeter <span class="hlt">waves</span>, the most advantageous part of the spectrum. The authors find that efficient system concepts can be developed for the beam <span class="hlt">powered</span> launch system and that, while the capital cost may be as high as the earlier orbital transfer concepts, the operating cost is much lower. The vehicle can have payload-to-mass ratios on the order of one and cost (per pound to orbit) two orders of magnitudes less than for chemical rockets. This allows the weight of microwave <span class="hlt">powered</span> vehicles to be very small, as low as {approximately}100 kg for test devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10955617','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10955617"><span>Calculations of internal-<span class="hlt">wave</span>-induced fluctuations in <span class="hlt">ocean</span>-acoustic propagation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Flatté, S M; Rovner, G</p> <p>2000-08-01</p> <p>Variability in the <span class="hlt">ocean</span> sound-speed field on time scales of a few hours and horizontal spatial scales of a few kilometers is often dominated by the random, anisotropic fluctuations caused by the internal-<span class="hlt">wave</span> field. Results have been compiled from analytical approaches and from numerical simulations using the parabolic approximation into an efficient set of algorithms for calculating approximations to internal-<span class="hlt">wave</span> effects on temporal and spatial coherences, coherent bandwidths, and regimes of acoustic fluctuation behavior. These approximate formulas account for the background, deterministic, sound-speed profile and the anisotropy of the internal-<span class="hlt">wave</span> field, and they also allow for the incorporation of experimentally determined profiles of sound speed, buoyancy frequency, and sound-speed variance. The algorithms start from the geometrical-acoustics approximation, in which the field transmitted from a source can be described completely in terms of rays whose characteristics are determined by the sound speed as a function of position. Ordinary integrals along these rays provide approximations to acoustic-fluctuation quantities due to the statistical effects of internal <span class="hlt">waves</span>, including diffraction. The results from the algorithms are compared with numerical simulations and with experimental results for long-range propagation in the deep <span class="hlt">ocean</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFD.E9006P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFD.E9006P"><span>A 3D MPI-Parallel GPU-accelerated framework for simulating <span class="hlt">ocean</span> <span class="hlt">wave</span> energy converters</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pathak, Ashish; Raessi, Mehdi</p> <p>2015-11-01</p> <p>We present an MPI-parallel GPU-accelerated computational framework for studying the interaction between <span class="hlt">ocean</span> <span class="hlt">waves</span> and <span class="hlt">wave</span> energy converters (WECs). The computational framework captures the viscous effects, nonlinear fluid-structure interaction (FSI), and breaking of <span class="hlt">waves</span> around the structure, which cannot be captured in many potential flow solvers commonly used for WEC simulations. The full Navier-Stokes equations are solved using the two-step projection method, which is accelerated by porting the pressure Poisson equation to GPUs. The FSI is captured using the numerically stable fictitious domain method. A novel three-phase interface reconstruction algorithm is used to resolve three phases in a VOF-PLIC context. A consistent mass and momentum transport approach enables simulations at high density ratios. The accuracy of the overall framework is demonstrated via an array of test cases. Numerical simulations of the interaction between <span class="hlt">ocean</span> <span class="hlt">waves</span> and WECs are presented. Funding from the National Science Foundation CBET-1236462 grant is gratefully acknowledged.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780016832','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780016832"><span>Verification results for the Spectral <span class="hlt">Ocean</span> <span class="hlt">Wave</span> Model (SOWM) by means of significant <span class="hlt">wave</span> height measurements made by the GEOS-3 spacecraft</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pierson, W. J.; Salfi, R. E.</p> <p>1978-01-01</p> <p>Significant <span class="hlt">wave</span> heights estimated from the shape of the return pulse <span class="hlt">wave</span> form of the altimeter on GEOS-3 for forty-four orbit segments obtained during 1975 and 1976 are compared with the significant <span class="hlt">wave</span> heights specified by the spectral <span class="hlt">ocean</span> <span class="hlt">wave</span> model (SOWM), which is the presently operational numerical <span class="hlt">wave</span> forecasting model at the Fleet Numerical Weather Central. Except for a number of orbit segments with poor agreement and larger errors, the SOWM specifications tended to be biased from 0.5 to 1.0 meters too low and to have RMS errors of 1.0 to 1.4 meters. The much fewer larger errors can be attributed to poor wind data for some parts of the Northern Hemisphere <span class="hlt">oceans</span>. The bias can be attributed to the somewhat too light winds used to generate the <span class="hlt">waves</span> in the model. Other sources of error are identified in the equatorial and trade wind areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.C13E..04V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.C13E..04V"><span>Calving Signature in <span class="hlt">Ocean</span> <span class="hlt">Waves</span>: Helheim Glacier and Sermilik Fjord Dynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vankova, I.; Holland, D.</p> <p>2015-12-01</p> <p>In this work, we investigate the characteristics of calving on Helheim glacier from data recorded on an array of five high frequency pressure meters placed along Sermilik fjord. Calving generated tsunami <span class="hlt">waves</span> were recorded and used to construct a calving event catalog and to characterize the post-calving <span class="hlt">ocean</span> state. Calving on Helheim is highly seasonal: it onsets after months of inactivity in early spring, immediately following the rise of daily average temperatures above freezing point, which indicates the potentially dominant role of meltwater in the calving mechanism. Tidal phase and amplitude, <span class="hlt">ocean</span> temperature variations or surges did not seem to be significant calving factors. In the <span class="hlt">ocean</span> spectra, we observe discrete peaks between 0.4 to 6 mHz associated with calving events. These peak frequencies are consistent among all the events and they travel as propagating modes up and down the fjord for several hours while being slowly radiated away to the open <span class="hlt">ocean</span>, an observation which we support with a model. Large part of the spectrum is trapped in evanescent modes or is quickly dissipated. These observations are relevant for our understanding of the time scale and rate of mixing in glacier fjords, and eventually for improving boundary conditions for <span class="hlt">ocean</span> models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFM.A23B0798M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFM.A23B0798M"><span>Antarctic Circumpolar <span class="hlt">Wave</span> dynamics in a simplified <span class="hlt">ocean</span>- atmosphere coupled model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maze, G.; D'Andrea, F.; Colin de Verdiere, A.</p> <p>2004-12-01</p> <p>The Antarctic Circumpolar <span class="hlt">Wave</span> (ACW) is one of the main pattern of variability in the <span class="hlt">Ocean</span>-Atmosphere system in the southern Hemisphere extratropics. It involves sea surface temperature (SST), sea level pressure (SLP) and other variables, and consists of a <span class="hlt">wave</span> train of zonal number 2, travelling around Antarctica at the speed of 6-8 cm s-1, hence taking around 8 years to complete a circle. A fundamental feature of this observed pattern is that anomalies are eastward propagating and seem to be phase locked: for example SST and SLP are in quadrature (high downstream of warm SST). Nevertheless the atmospheric part of the <span class="hlt">wave</span> has been questioned by some observational studies. Different analytical and numerical studies have veen proposed, but a convincing theoretical explanation for the ACW is still missing. In this work we study the ACW as simulated by a simple dynamical model, in order to determine the basic physical processes that characterize it. The model used is an atmospheric quasi-geostrophic tridimensional model coupled to an <span class="hlt">ocean</span> "slab" mixed layer, which includes mean geostrophic advection by the antarctic circumpolar current (ACC). The atmosphere-<span class="hlt">ocean</span> coupling is obtained via surface sensible heat fluxes. We analyse three configuration of the model, a "passive <span class="hlt">ocean</span>" one, where the <span class="hlt">ocean</span> responds to the atmopheric forcing but does not feeds back to the atmosphere; a "passive atmosphere" one, where the stationary reponse of the atmosphere to prescribed SST anomalies; and a fully coupled one. The two forced experiment show separately a positive feedback in the coupled system.The passive <span class="hlt">ocean</span> experiment shows an ACW-type low frequency variability in the <span class="hlt">ocean</span>, ie a propagating SST anomaly with 4 years period. SSTa amplitude created were around 0.5C wich is less than observed anomalies (1.5oC). This means that the stochastic focing of the atmosphere is sufficient to substain a variability of the SST whose periodicity is set by the mean advection</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760017773','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760017773"><span>Transformation of apparent <span class="hlt">ocean</span> <span class="hlt">wave</span> spectra observed from an aircraft sensor platform</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Poole, L. R.</p> <p>1976-01-01</p> <p>The problem considered was transformation of a unidirectional apparent <span class="hlt">ocean</span> <span class="hlt">wave</span> spectrum observed from an aircraft sensor platform into the true spectrum that would be observed from a stationary platform. Spectral transformation equations were developed in terms of the linear <span class="hlt">wave</span> dispersion relationship and the <span class="hlt">wave</span> group speed. An iterative solution to the equations was outlined and used to transform reference theoretical apparent spectra for several assumed values of average water depth. Results show that changing the average water depth leads to a redistribution of energy density among the various frequency bands of the transformed spectrum. This redistribution is most severe when much of the energy density is expected, a priori, to reside at relatively low true frequencies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SPIE.9046E..16D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SPIE.9046E..16D"><span>Design of stabilization system for medium <span class="hlt">wave</span> infrared laser <span class="hlt