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Sample records for wasa wave hindcast

  1. The wave climate of the Northeast Atlantic over the period 1955-1994: the WASA wave hindcast

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, H.; Rosenthal, W.; Stawarz, M. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Gewaesserphysik; Carretero, J.C.; Gomez, M.; Lozano, I.; Serrano, O. [Programa de Clima Maritimo (Puertos del Estado), Madrid (Spain); Reistad, M. [Det Norske Meteorologiske Inst., Bergen (Norway)

    1997-12-31

    The European project ``waves and storms in the North Atlantic`` (WASA) has been set up to prove, or to disprove, hypotheses of a worsening storm and wave climate in the Northeast Atlantic and adjacent seas in the present century. A major obstacle for assessing changes in storm and wave conditions are inhomogeneities in the observational records, both in the local observations and in the analysed products, which usually produce an artificial increase of extreme winds and waves. Therefore, changes in the wave climate were assessed with a state-of-the-art wave model using wind analyses. Within the scope of the WASA project, a 40 year reconstruction (1955-1994) of the wave climate in the North Atlantic was completed using the WAM wave model. The input wind fields were assumed to be reasonably homogeneous with time in the area south of 70 N and east of 20 W, and it was expected that the hindcast wave data would reliably describe the space-time evolution of wave conditions in this area. The results of the hindcast experiment are presented in this article. The main conclusion was that the wave climate in most of the Northeast Atlantic and in the North Sea has undergone significant variations on time scales of decades. Part of variability was found to be related to the North Atlantic oscillation. As a general result we noted an increase of the maximum annual significant wave height over the last 40 years of about 5 to 10 cm/year for large parts of the Northeast Atlantic, north of the North Sea. There was also a slight increase of probabilities of high waves derived from conventional extreme value statistics in northwest approaches to the North Sea. Similar trends of the extreme waves were found in a scenario of future wave climate at a time of doubled C0{sub 2} concentration in the atmosphere. (orig.) 28 refs.

  2. Wave influence on polar mesosphere summer echoes above Wasa: experimental and model studies

    Directory of Open Access Journals (Sweden)

    P. Dalin

    2012-08-01

    Full Text Available Comprehensive analysis of the wave activity in the Antarctic summer mesopause is performed using polar mesospheric summer echoes (PMSE measurements for December 2010–January 2011. The 2-day planetary wave is a statistically significant periodic oscillation in the power spectrum density of PMSE power. The strongest periodic oscillation in the power spectrum belongs to the diurnal solar tide; the semi-diurnal solar tide is found to be a highly significant harmonic oscillation as well. The inertial-gravity waves are extensively studied by means of PMSE power and wind components. The strongest gravity waves are observed at periods of about 1, 1.4, 2.5 and 4 h, with characteristic horizontal wavelengths of 28, 36, 157 and 252 km, respectively. The gravity waves propagate approximately in the west-east direction over Wasa (Antarctica. A detailed comparison between theoretical and experimental volume reflectivity of PMSE, measured at Wasa, is made. It is demonstrated that a new expression for PMSE reflectivity derived by Varney et al. (2011 is able to adequately describe PMSE profiles both in the magnitude and in height variations. The best agreement, within 30%, is achieved when mean values of neutral atmospheric parameters are utilized. The largest contribution to the formation and variability of the PMSE layer is explained by the ice number density and its height gradient, followed by wave-induced perturbations in buoyancy period and the turbulent energy dissipation rate.

  3. Wave influence on polar mesosphere summer echoes above Wasa: experimental and model studies

    Science.gov (United States)

    Dalin, P.; Kirkwood, S.; Hervig, M.; Mihalikova, M.; Mikhaylova, D.; Wolf, I.; Osepian, A.

    2012-08-01

    Comprehensive analysis of the wave activity in the Antarctic summer mesopause is performed using polar mesospheric summer echoes (PMSE) measurements for December 2010-January 2011. The 2-day planetary wave is a statistically significant periodic oscillation in the power spectrum density of PMSE power. The strongest periodic oscillation in the power spectrum belongs to the diurnal solar tide; the semi-diurnal solar tide is found to be a highly significant harmonic oscillation as well. The inertial-gravity waves are extensively studied by means of PMSE power and wind components. The strongest gravity waves are observed at periods of about 1, 1.4, 2.5 and 4 h, with characteristic horizontal wavelengths of 28, 36, 157 and 252 km, respectively. The gravity waves propagate approximately in the west-east direction over Wasa (Antarctica). A detailed comparison between theoretical and experimental volume reflectivity of PMSE, measured at Wasa, is made. It is demonstrated that a new expression for PMSE reflectivity derived by Varney et al. (2011) is able to adequately describe PMSE profiles both in the magnitude and in height variations. The best agreement, within 30%, is achieved when mean values of neutral atmospheric parameters are utilized. The largest contribution to the formation and variability of the PMSE layer is explained by the ice number density and its height gradient, followed by wave-induced perturbations in buoyancy period and the turbulent energy dissipation rate.

  4. Wave influence on polar mesosphere summer echoes above Wasa. Experimental and model studies

    Energy Technology Data Exchange (ETDEWEB)

    Dalin, P.; Kirkwood, S.; Mihalikova, M.; Mikhaylova, D.; Wolf, I. [Swedish Institute of Space Physics, Kiruna (Sweden); Hervig, M. [GATS Inc., Driggs, ID (United States); Osepian, A. [Polar Geophysical Institute, Murmansk (Russian Federation)

    2012-11-01

    Comprehensive analysis of the wave activity in the Antarctic summer mesopause is performed using polar mesospheric summer echoes (PMSE) measurements for December 2010-January 2011. The 2-day planetary wave is a statistically significant periodic oscillation in the power spectrum density of PMSE power. The strongest periodic oscillation in the power spectrum belongs to the diurnal solar tide; the semi-diurnal solar tide is found to be a highly significant harmonic oscillation as well. The inertial-gravity waves are extensively studied by means of PMSE power and wind components. The strongest gravity waves are observed at periods of about 1, 1.4, 2.5 and 4 h, with characteristic horizontal wavelengths of 28, 36, 157 and 252 km, respectively. The gravity waves propagate approximately in the west-east direction over Wasa (Antarctica). A detailed comparison between theoretical and experimental volume reflectivity of PMSE, measured at Wasa, is made. It is demonstrated that a new expression for PMSE reflectivity derived by Varney et al. (2011) is able to adequately describe PMSE profiles both in the magnitude and in height variations. The best agreement, within 30 %, is achieved when mean values of neutral atmospheric parameters are utilized. The largest contribution to the formation and variability of the PMSE layer is explained by the ice number density and its height gradient, followed by waveinduced perturbations in buoyancy period and the turbulent energy dissipation rate. (orig.)

  5. Extended Long Wave Hindcast inside Port Solutions to Minimize Resonance

    Directory of Open Access Journals (Sweden)

    Gabriel Diaz-Hernandez

    2016-02-01

    Full Text Available The present study shows a methodology to carry out a comprehensive study of port agitation and resonance analysis in Geraldton Harbor (Western Australia. The methodology described and applied here extends the short and long wave hindcast outside the harbor and towards the main basin. To perform such an analysis, and as the first stage of the methodology, it is necessary to determine, in detail, both the long and short wave characteristics, through a comprehensive methodology to obtain and to hindcast the full spectral data (short waves + long waves, for frequencies between 0.005 and 1 Hz. Twelve-year spectral hindcast wave data, at a location before the reef, have been modified analytically to include the energy input associated with infragravity waves. A decomposition technique based on the energy balance of the radiation stress of short waves is followed. Predictions for long wave heights and periods at different harbor locations are predicted and validated with data recorded during 2004 to 2009. This new database will ensure an accurate and reliable assessment of long wave hourly data (height, period and currents in any area within the main basin of the Port of Geraldton, for its present geometry. With this information, two main task will be completed: (1 undertake a forensic diagnosis of the present response of the harbor, identifying those forcing characteristics related to inoperability events; and (2 propose any layout solutions to minimize, change, dissipate/fade/vanish or positively modify the effects of long waves in the harbor, proposing different harbor geometry modifications. The goal is to identify all possible combinations of solutions that would minimize the current inoperability in the harbor. Different pre-designs are assessed in this preliminary study in order to exemplify the potential of the methodology.

  6. Boulder-based wave hindcasting underestimates storm size

    Science.gov (United States)

    Kennedy, David; Woods, Joesphine; Rosser, Nick; Hansom, James; Naylor, Larissa

    2017-04-01

    Large boulder-size clasts represent an important archive of erosion and wave activity on the coast. From tropical coral reefs to eroding cliffs in the high-latitudes, boulders have been used to hindcast the frequency and magnitude of cyclones and tsunami. Such reconstructions are based on the balance between the hydrodynamic forces acting on individual clasts and the counteracting resistive forces of friction and gravity. Here we test the three principle hindcasting relationships on nearly 1000 intertidal boulders in North Yorkshire, U.K using a combination of field and airborne terrestrial LiDAR data. We quantify the predicted versus actual rates of movement and the degree to which local geomorphology can retard or accelerate transport. Actual clast movement is significantly less than predicted values, regardless of boulder volume, shape or location. In situ cementation of clasts to the substrate by marine organisms and clustering of clasts increases friction thereby preventing transport. The implication is that boulders do not always provide a reliable estimation of wave height on the coast and reliance solely on hindcasting relationships leads to an under prediction of the frequency and magnitude of past storm wave activity. The crucial need for process field studies to refine boulder transport models is thus demonstrated.

  7. Wave hindcast experiments in the Indian Ocean using MIKE 21 SW ...

    Indian Academy of Sciences (India)

    Wave prediction and hindcast studies are important in ocean engineering, coastal infrastructure development and management. In view of sparse and infrequent in-situ observations, model derived hindcast wave data can be used for the assessment of wave climate in offshore and coastal areas. In the present study, MIKE ...

  8. Real time wave measurements and wave hindcasting in deep waters

    Digital Repository Service at National Institute of Oceanography (India)

    Anand, N.M.; Mandal, S.; SanilKumar, V.; Nayak, B.U.

    Deep water waves off Karwar (lat. 14~'45.1'N, long. 73~'34.8'E) at 75 m water depth pertaining to peak monsoon period have been measured using a Datawell waverider buoy. Measured wave data show that the significant wave height (Hs) predominantly...

  9. Selection and formulation of a numerical shallow water wave hindcast model

    NARCIS (Netherlands)

    Herbers, T.; Holthuijsen, L.H.; Booij, N.

    1983-01-01

    Formulate a numerical wave hindcast model which can be used to obtain realistic estimates of wave conditions in the Oosterschelde as input to a numerical geomorphological model. A directionally decoupled, parametric wave hindeast model is recommended that includes parameterized versions of

  10. Improving coastal wave hindcasts by combining offshore buoy observations with global wave models.

    Science.gov (United States)

    Crosby, S. C.; O'Reilly, W. C.; Guza, R. T.

    2014-12-01

    Waves conditions in southern California are sensitive to offshore wave directions. Due to blocking by coastal islands and refraction across complex bathymetry, a transform incident offshore swell-spectra to shallow water buoy locations. A nearly continuous 10 yr data set of approximately 14 buoys is used. Comparisons include standard bulk parameters (e.g. significant wave height, peak period), the frequency-dependent energy spectrum (needed for run-up estimation) and radiation stress component Sxy (needed for alongshore current and sediment transport estimation). Global wave model uncertainties are unknown, complicating the formulation of optimum assimilation constraints. Several plausible models for estimating offshore waves are tested. Future work includes assimilating nearshore buoy observations, with the long-term objective of accurate regional wave hindcasts using an efficient mix of global wave models and buoys. This work is supported by the California Department of Parks and Recreation, Division of Boating and Waterways Oceanography Program.

  11. Thirty-four years of Hawaii wave hindcast from downscaling of climate forecast system reanalysis

    Science.gov (United States)

    Li, Ning; Cheung, Kwok Fai; Stopa, Justin E.; Hsiao, Feng; Chen, Yi-Leng; Vega, Luis; Cross, Patrick

    2016-04-01

    The complex wave climate of Hawaii includes a mix of seasonal swells and wind waves from all directions across the Pacific. Numerical hindcasting from surface winds provides essential space-time information to complement buoy and satellite observations for studies of the marine environment. We utilize WAVEWATCH III and SWAN (Simulating WAves Nearshore) in a nested grid system to model basin-wide processes as well as high-resolution wave conditions around the Hawaiian Islands from 1979 to 2013. The wind forcing includes the Climate Forecast System Reanalysis (CFSR) for the globe and downscaled regional winds from the Weather Research and Forecasting (WRF) model. Long-term in-situ buoy measurements and remotely-sensed wind speeds and wave heights allow thorough assessment of the modeling approach and data products for practical application. The high-resolution WRF winds, which include orographic and land-surface effects, are validated with QuickSCAT observations from 2000 to 2009. The wave hindcast reproduces the spatial patterns of swell and wind wave events detected by altimeters on multiple platforms between 1991 and 2009 as well as the seasonal variations recorded at 16 offshore and nearshore buoys around the Hawaiian Islands from 1979 to 2013. The hindcast captures heightened seas in interisland channels and around prominent headlands, but tends to overestimate the heights of approaching northwest swells and give lower estimates in sheltered areas. The validated high-resolution hindcast sets a baseline for future improvement of spectral wave models.

  12. Thirty-four years of Hawaii wave hindcast from downscaling of climate forecast system reanalysis

    OpenAIRE

    Li, Ning; Cheung, Kwok Fai; Stopa, Justin E.; Hsiao, Feng; Chen, Yi-Leng; Vega, Luis; Cross, Patrick

    2016-01-01

    The complex wave climate of Hawaii includes a mix of seasonal swells and wind waves from all directions across the Pacific. Numerical hindcasting from surface winds provides essential space-time information to complement buoy and satellite observations for studies of the marine environment. We utilize WAVEWATCH III and SWAN (Simulating WAves Nearshore) in a nested grid system to model basin-wide processes as well as high-resolution wave conditions around the Hawaiian Islands from 1979 to 2013...

  13. Steps towards a consistent Climate Forecast System Reanalysis wave hindcast (1979-2016)

    Science.gov (United States)

    Stopa, Justin E.; Ardhuin, Fabrice; Huchet, Marion; Accensi, Mickael

    2017-04-01

    Surface gravity waves are being increasingly recognized as playing an important role within the climate system. Wave hindcasts and reanalysis products of long time series (>30 years) have been instrumental in understanding and describing the wave climate for the past several decades and have allowed a better understanding of extreme waves and inter-annual variability. Wave hindcasts have the advantage of covering the oceans in higher space-time resolution than possible with conventional observations from satellites and buoys. Wave reanalysis systems like ECWMF's ERA-Interim directly included a wave model that is coupled to the ocean and atmosphere, otherwise reanalysis wind fields are used to drive a wave model to reproduce the wave field in long time series. The ERA Interim dataset is consistent in time, but cannot adequately resolve extreme waves. On the other hand, the NCEP Climate Forecast System (CFSR) wind field better resolves the extreme wind speeds, but suffers from discontinuous features in time which are due to the quantity and quality of the remote sensing data incorporated into the product. Therefore, a consistent hindcast that resolves the extreme waves still alludes us limiting our understanding of the wave climate. In this study, we systematically correct the CFSR wind field to reproduce a homogeneous wave field in time. To verify the homogeneity of our hindcast we compute error metrics on a monthly basis using the observations from a merged altimeter wave database which has been calibrated and quality controlled from 1985-2016. Before 1985 only few wave observations exist and are limited to a select number of wave buoys mostly in the North Hemisphere. Therefore we supplement our wave observations with seismic data which responds to nonlinear wave interactions created by opposing waves with nearly equal wavenumbers. Within the CFSR wave hindcast, we find both spatial and temporal discontinuities in the error metrics. The Southern Hemisphere often

  14. A multi-decadal wind-wave hindcast for the North Sea 1949-2014: coastDat2

    Science.gov (United States)

    Groll, Nikolaus; Weisse, Ralf

    2017-12-01

    Long and consistent wave data are important for analysing wave climate variability and change. Moreover, such wave data are also needed in coastal and offshore design and for addressing safety-related issues at sea. Using the third-generation spectral wave model WAM a multi-decadal wind-wave hindcast for the North Sea covering the period 1949-2014 was produced. The hindcast is part of the coastDat database representing a consistent and homogeneous met-ocean data set. It is shown that despite not being perfect, data from the wave hindcast are generally suitable for wave climate analysis. In particular, comparisons of hindcast data with in situ and satellite observations show on average a reasonable agreement, while a tendency towards overestimation of the highest waves could be inferred. Despite these limitations, the wave hindcast still provides useful data for assessing wave climate variability and change as well as for risk analysis, in particular when conservative estimates are needed. Hindcast data are stored at the World Data Center for Climate (WDCC) and can be freely accessed using the https://doi.org/10.1594/WDCC/coastDat-2_WAM-North_Sea" target="_blank">doi:10.1594/WDCC/coastDat-2_WAM-North_Sea Groll and Weisse(2016) or via the coastDat web-page http://www.coastdat.de.

  15. Locally calibrated wave hindcasts in the Estonian coastal sea in 1966–2011

    Directory of Open Access Journals (Sweden)

    Ülo Suursaar

    2013-02-01

    Full Text Available Wave parameters were studied in four differently exposed fetch-limited Estonian coastal sea locations: the Harilaid Peninsula facing W–NW, Letipea N–NE, Matsi SW and Kõiguste SE. Based on high-quality measurements of waves with the bottom-mounted Recording Doppler Current Profiler in 2006–2011, a model for significant wave height was calibrated separately for those locations. Using wind forcing data from Estonian coastal meteorological stations, a set of hindcasts was obtained over the period of 1966–2011. The wave heights showed some quasi-periodic cycles with a high stage in 1980–1995, and probably also from 2007; a prevailing overall decrease in the mean wave height; an increase in high wave events at the windward coasts of West Estonia but a decrease at the northern and southeastern coasts. The spatially contrasting results for differently exposed coasts reflect the corresponding variations in local wind, which are probably caused by changes in large-scale atmospheric pressure patterns above Northern Europe and a poleward shift of cyclones’ trajectories. Although featuring outstanding calibration results, the long-term wave hindcast may be impacted by possible inhomogeneities in the older wind data.

  16. The International Workshop on Wave Hindcasting and Forecasting and the Coastal Hazards Symposium

    CERN Document Server

    Breivik, Øyvind; Babanin, Alexander; Horsburgh, Kevin

    2015-01-01

    Following the 13th International Workshop on Wave Hindcasting and Forecasting and 4th Coastal Hazards Symposium in October 2013 in Banff, Canada, a topical collection has appeared in recent issues of Ocean Dynamics. Here we give a brief overview of the history of the conference since its inception in 1986 and of the progress made in the fields of wind-generated ocean waves and the modelling of coastal hazards before we summarize the main results of the papers that have appeared in the topical collection.

  17. Nearshore waves in southern California: Hindcast, and modeled historical and 21st-century projected time series

    Science.gov (United States)

    Hegermiller, Christie; Erikson, Li; Barnard, Patrick

    2016-01-01

    As part of the Coastal Storm Modeling System (CoSMoS), time series of hindcast, historical, and 21st-century nearshore wave parameters (wave height, period, and direction) were simulated for the southern California coast from Point Conception to the Mexican border. The hindcast (1980-2010) time series represents reanalysis-forced offshore waves propagated to the nearshore, whereas the historical (1976-2005) and 21st-century (2012-2100) time series represent global climate model-forced offshore waves propagated to the nearshore. Changes in deep-water wave conditions directly regulate the energy driving coastal processes. However, a number of physical processes, for example, refraction on continental shelves and/or diffraction by islands, transform deep-water waves as they propagate to the coast, which complicates large-scale modeling efforts. In this work, a hindcast of nearshore waves was simulated by forcing a numerical wave model with hindcasted intermediate-water waves and reanalysis winds. A lookup table was created by relating corresponding offshore winds and waves with nearshore wave conditions. Using the lookup table, historical and 21st-century nearshore wave time series were generated for global climate model-forced offshore winds and waves.

  18. GOW2.0: A global wave hindcast of high resolution

    Science.gov (United States)

    Menendez, Melisa; Perez, Jorge; Losada, Inigo

    2016-04-01

    The information provided by reconstructions of historical wind generated waves is of paramount importance for a variety of coastal and offshore purposes (e.g. risk assessment, design of costal structures and coastal management). Here, a new global wave hindcast (GOW2.0) is presented. This hindcast is an update of GOW1.0 (Reguero et al. 2012) motivated by the emergence of new settings and atmospheric information from reanalysis during recent years. GOW2.0 is based on version 4.18 of WaveWatch III numerical model (Tolman, 2014). Main features of the model set-up are the analysis and selection of recent source terms concerning wave generation and dissipation (Ardhuin et al. 2010, Zieger et al., 2015) and the implementation of obstruction grids to improve the modeling of wave shadowing effects in line with the approach described in Chawla and Tolman (2007). This has been complemented by a multigrid system and the use of the hourly wind and ice coverage from the Climate Forecast System Reanalysis, CFSR (30km spatial resolution approximately). The multigrid scheme consists of a series of "two-way" nested domains covering the whole ocean basins at a 0.5° spatial resolution and continental shelfs worldwide at a 0.25° spatial resolution. In addition, a technique to reconstruct wave 3D spectra for any grid-point is implemented from spectral partitioning information. A validation analysis of GOW2.0 outcomes has been undertaken considering wave spectral information from surface buoy stations and multi-mission satellite data for a spatial validation. GOW2.0 shows a substantial improvement over its predecessor for all the analyzed variables. In summary, GOW2.0 reconstructs historical wave spectral data and climate information from 1979 to present at hourly resolution providing higher spatial resolution over regions where local generated wind seas, bimodal-spectral behaviour and relevant swell transformations across the continental shelf are important. Ardhuin F, Rogers E

  19. Identifying the Optimal Offshore Areas for Wave Energy Converter Deployments in Taiwanese Waters Based on 12-Year Model Hindcasts

    Directory of Open Access Journals (Sweden)

    Hung-Ju Shih

    2018-02-01

    Full Text Available A 12-year sea-state hindcast for Taiwanese waters, covering the period from 2005 to 2016, was conducted using a fully coupled tide-surge-wave model. The hindcasts of significant wave height and peak period were employed to estimate the wave power resources in the waters surrounding Taiwan. Numerical simulations based on unstructured grids were converted to structured grids with a resolution of 25 × 25 km. The spatial distribution maps of offshore annual mean wave power were created for each year and for the 12-year period. Waters with higher wave power density were observed off the northern, northeastern, southeastern (south of Green Island and southeast of Lanyu and southern coasts of Taiwan. Five energetic sea areas with spatial average annual total wave energy density of 60–90 MWh/m were selected for further analysis. The 25 × 25 km square grids were then downscaled to resolutions of 5 × 5 km, and five 5 × 5 km optimal areas were identified for wave energy converter deployments. The spatial average annual total wave energy yields at the five optimal areas (S1–(S5 were estimated to be 64.3, 84.1, 84.5, 111.0 and 99.3 MWh/m, respectively. The prevailing wave directions for these five areas lie between east and northeast.

  20. A QGIS Plugin for Offshore Wave Hindcasting Based on Geographic Transposition of Wave Gauge Data

    National Research Council Canada - National Science Library

    F. Pasanisi; C. Tebano

    2016-01-01

    The paper presents a first experimental version of the original QGIS plugin QWaveTransposition that numerically implements the geographic transposition of wave gauge data method proposed by Contini and De Girolamo (1998...

  1. Long Term Wave Climate at the Danish Test Site DanWEC Based on 35 Years Hindcast Data

    DEFF Research Database (Denmark)

    Tetu, Amélie; Jensen, Palle Martin; Kramer, Morten Mejlhede

    2017-01-01

    , Forecasts and wave energy converters (WECs) operation and maintenance (O&M) strategies at DanWEC and beyond” which has been initiated to deliver detailed information on the environmental conditions at DanWEC and to review implementation of O&M procedures, which will ultimately improve WEC’s operation...... of the test site, such as scatter tables in terms of wave height and energy period (Hm0, Te) and weather window characteristics will be given. Based on 35 years of data gathered so far, an analysis of extreme events at the DanWEC test site is also included in this work.......This paper presents an analysis of the wave climate of the DanWEC test site based on the 35 years hindcast data. This includes monthly and annual variation of the wave climate at the site together with an analysis of extreme events. This work includees results from the project “Resource Assessment...

  2. Abnormal storm waves in the winter East/Japan Sea: generation process and hindcasting using an atmosphere-wind wave modelling system

    Directory of Open Access Journals (Sweden)

    H. S. Lee

    2010-04-01

    Full Text Available Abnormal storm waves cause coastal disasters along the coasts of Korean Peninsula and Japan in the East/Japan Sea (EJS in winter, arising due to developed low pressures during the East Asia winter monsoon. The generation of these abnormal storm waves during rough sea states were studied and hindcast using an atmosphere-wave coupled modelling system. Wind waves and swell due to developed low pressures were found to be the main components of abnormal storm waves. The meteorological conditions that generate these waves are classified into three patterns based on past literature that describes historical events as well as on numerical modelling. In hindcasting the abnormal storm waves, a bogussing scheme originally designed to simulate a tropical storm in a mesoscale meteorological model was introduced into the modelling system to enhance the resolution of developed low pressures. The modelling results with a bogussing scheme showed improvements in terms of resolved low pressure, surface wind field, and wave characteristics obtained with the wind field as an input.

  3. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2011-07 (NODC Accession 0089885)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  4. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2009-01 (NODC Accession 0089855)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  5. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2006-02 (NODC Accession 0089820)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  6. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2005-08 (NODC Accession 0089814)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  7. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2013-06 (NODC Accession 0110318)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  8. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2007-04 (NODC Accession 0089834)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  9. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2010-03 (NODC Accession 0089869)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  10. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2008-03 (NODC Accession 0089845)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  11. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2008-08 (NODC Accession 0089850)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  12. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2012-08 (NODC Accession 0098973)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  13. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2007-06 (NODC Accession 0089836)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  14. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2012-12 (NODC Accession 0104257)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  15. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2009-05 (NODC Accession 0089859)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  16. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2014-10 (NODC Accession 0126373)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  17. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2007-12 (NODC Accession 0089842)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  18. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2014-09 (NODC Accession 0125935)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  19. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2014-01 (NODC Accession 0117477)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  20. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2012-10 (NODC Accession 0104207)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  1. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2006-08 (NODC Accession 0089826)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  2. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2010-10 (NODC Accession 0089876)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  3. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2010-12 (NODC Accession 0089878)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  4. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2006-12 (NODC Accession 0089830)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  5. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2009-07 (NODC Accession 0089861)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  6. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2014-11 (NODC Accession 0126391)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  7. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2009-12 (NODC Accession 0089866)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  8. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2013-10 (NODC Accession 0115066)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  9. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2015-07 (NCEI Accession 0130763)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  10. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2013-07 (NODC Accession 0114816)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  11. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2012-05 (NODC Accession 0098970)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  12. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2008-06 (NODC Accession 0089848)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  13. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2007-09 (NODC Accession 0089839)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  14. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2011-05 (NODC Accession 0089883)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  15. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2008-09 (NODC Accession 0089851)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  16. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2009-09 (NODC Accession 0089863)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  17. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2011-01 (NODC Accession 0089879)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  18. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2006-07 (NODC Accession 0089825)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  19. Output fields from the NOAA WAVEWATCH III® wave model monthly hindcasts for 2012-02 (NODC Accession 0089892)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA WAVEWATCH III® hindcast dataset comprises output fields from the monthly WAVEWATCH III® hindcast model runs conducted at the National Centers for...

  20. A long-term nearshore wave hindcast for Ireland: Atlantic and Irish Sea coasts (1979-2012). Present wave climate and energy resource assessment

    Science.gov (United States)

    Gallagher, Sarah; Tiron, Roxana; Dias, Frédéric

    2014-08-01

    The Northeast Atlantic possesses some of the highest wave energy levels in the world. The recent years have witnessed a renewed interest in harnessing this vast energy potential. Due to the complicated geomorphology of the Irish coast, there can be a significant variation in both the wave and wind climate. Long-term hindcasts with high spatial resolution, properly calibrated against available measurements, provide vital information for future deployments of ocean renewable energy installations. These can aid in the selection of adequate locations for potential deployment and for the planning and design of those marine operations. A 34-year (from 1979 to 2012), high-resolution wave hindcast was performed for Ireland including both the Atlantic and Irish Sea coasts, with a particular focus on the wave energy resource. The wave climate was estimated using the third-generation spectral wave model WAVEWATCH III®; version 4.11, the unstructured grid formulation. The wave model was forced with directional wave spectral data and 10-m winds from the European Centre for Medium Range Weather Forecasts (ECMWF) ERA-Interim reanalysis, which is available from 1979 to the present. The model was validated against available observed satellite altimeter and buoy data, particularly in the nearshore, and was found to be excellent. A strong spatial and seasonal variability was found for both significant wave heights, and the wave energy flux, particularly on the north and west coasts. A strong correlation between the North Atlantic Oscillation (NAO) teleconnection pattern and wave heights, wave periods, and peak direction in winter and also, to a lesser extent, in spring was identified.

  1. U.S. Navy Hindcast Spectral Ocean Wave Model Climatic Atlas: Mediterranean Sea

    Science.gov (United States)

    1990-01-01

    8217 (total) were obtained by summing the percent frequencies across each row. Rounding may cause minor differences between printed totals and total cell counts...26 81IN L54 F 4’+ .51 82 tt -b3- 42 A & - 414 rt4 ’𔃾- 𔃼 𔄂 4 3036 4248 46b0 166 8494 ’ )t 3 11’ 644,48 4 6t 4’ 4 4 , 4 HOURS DURATION OP EVENTS HOURS...The SOWM generates ’en-.!rgy ’ariaLLcb’ cell within the 180 element matrix f The output from a SOWM hindcast includes a wind fields. There is a

  2. Wave hindcast experiments in the Indian Ocean using MIKE 21 SW ...

    Indian Academy of Sciences (India)

    derived ocean wave period using genetic algorithm; IEEE. Geosci. Rem. Sens. Lett. 8 354–358. IOC 2003 Centenary Edition of the GEBCO Digital Atlas, published on CD-ROM on behalf of the Intergovern- mental Oceanographic Commission and the International. Hydrographic Centre, Organization as part of the General.

  3. Hindcast and validation of Hurricane Ike waves, forerunner, and storm surge

    NARCIS (Netherlands)

    Hope, M.E.; Westerink, J.J.; Kennedy, A.B.; Kerr, P.C.; Dietrich, J.C.; Dawson, C.; Bender, C.J.; Smith, J.M.; Jensen, R.E.; Zijlema, M.; Holthuijsen, L.H.; Luettich, R.A.; Powell, M.D.; Cardone, V.J.; Cox, A.T.; Pourtaheri, H.; Roberts, H.J.; Atkinson, J.H.; Tanaka, S.; Westerink, H.J.; Westerink, L.G.

    2013-01-01

    Hurricane Ike (2008) made landfall near Galveston, Texas, as a moderate intensity storm. Its large wind field in conjunction with the Louisiana-Texas coastline's broad shelf and large scale concave geometry generated waves and surge that impacted over 1000 km of coastline. Ike's complex and varied

  4. Can we predict the growth of sand waves? Hindcast of a field experiment in the Bisanseto Sea, Japane

    NARCIS (Netherlands)

    Knaapen, Michiel; Hulscher, Suzanne J.M.H.; Scholl, O.; Scholl, Olaf; Edge, Billy L.

    2001-01-01

    To optimise the dredging of sand waves in navigation channels, it is important to predict the regeneration of the sand waves. For this purpose, the authors combine a morphodynamic evolution model, based on the Landau equation, with data measured in a field experiment in the Bisanseto sea in Japan. A

  5. The WASA detector facility at CELSIUS

    Science.gov (United States)

    Bargholtz, Chr.; Bashkanov, M.; Berłowski, M.; Bondar, A.; Bogoslawsky, D.; Brodowski, W.; Brudvik, J.; Calén, H.; Capellaro, F.; Chilingarov, A.; Clement, H.; Comfort, J.; Demirörs, L.; Ekström, C.; Fransson, K.; Fridén, C.-J.; Gerén, L.; Gornov, M.; Grebenev, V.; Greiff, J.; Gurov, Y.; Gustafsson, L.; Höistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, A.; Johansson, T.; Keleta, S.; Khakimova, O.; Khoukaz, A.; Kilian, K.; Kimura, N.; Koch, I.; Kolachev, G.; Kren, F.; Kullander, S.; Kupść, A.; Kuzmin, A.; Kuznetsov, A.; Lindberg, K.; Marciniewski, P.; Meier, R.; Messner, O.; Morosov, B.; Nawrot, A.; Nefkens, B. M. K.; Norman, G.; Oelert, W.; Pauly, C.; Pettersson, H.; Pivovarov, A.; Pätzold, J.; Petukhov, Y.; Povtorejko, A.; Reistad, D.; Ruber, R. J. M. Y.; Sandukovsky, S.; Schönning, K.; Scobel, W.; Sefzick, T.; Shafigullin, R.; Shwartz, B.; Sidorov, V.; Skorodko, T.; Sopov, V.; Starostin, A.; Stepaniak, J.; Sukhanov, A.; Sukhanov, A.; Tchernyshev, V.; Tegnér, P.-E.; Thörngren Engblom, P.; Tikhomirov, V.; Toki, H.; Turowiecki, A.; Wagner, G. J.; Wiedner, U.; Wilhelmi, Z.; Wolke, M.; Yamamoto, A.; Yamaoka, H.; Zabierowski, J.; Zartova, I.; Złomańczuk, J.; Celsius/Wasa Collaboration

    2008-09-01

    The WASA 4π multidetector system, aimed at investigating light meson production in light ion collisions and η meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique feature of the system is the use of hydrogen pellets as internal targets for the first time. A detailed description of the design, together with the anticipated and achieved performance parameters are given.

  6. The WASA detector facility at CELSIUS

    Energy Technology Data Exchange (ETDEWEB)

    Bargholtz, Chr. [Stockholm University, Stockholm (Sweden); Bashkanov, M. [Physikalisches Institut der Universitaet Tuebingen, Tuebingen (Germany); Berlowski, M. [Soltan Institute of Nuclear Studies, Warsaw and Lodz (Poland); Bondar, A. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Bogoslawsky, D. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Brodowski, W. [Physikalisches Institut der Universitaet Tuebingen, Tuebingen (Germany); Brudvik, J. [University of California Los Angeles, Los Angeles, CA (United States); Calen, H.; Capellaro, F. [Uppsala University, Uppsala (Sweden); Chilingarov, A. [Budker Institute of Nuclear Physics, Novosibirsk (Russian Federation); Clement, H. [Physikalisches Institut der Universitaet Tuebingen, Tuebingen (Germany); Comfort, J. [Arizona State University, Tempe (United States); Demiroers, L. [Institut fuer Experimentalphysik der Universitaet Hamburg, Hamburg (Germany); Ekstroem, C. [Svedberg Laboratory, Uppsala (Sweden); Fransson, K. [Uppsala University, Uppsala (Sweden); Friden, C.-J. [Svedberg Laboratory, Uppsala (Sweden); Geren, L. [Stockholm University, Stockholm (Sweden); Gornov, M.; Grebenev, V. [Moscow Engineering Physics Institute, Moscow (Russian Federation); Greiff, J. [Institut fuer Experimentalphysik der Universitaet Hamburg, Hamburg (Germany)] (and others)

    2008-09-11

    The WASA 4{pi} multidetector system, aimed at investigating light meson production in light ion collisions and {eta} meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique feature of the system is the use of hydrogen pellets as internal targets for the first time. A detailed description of the design, together with the anticipated and achieved performance parameters are given.

  7. Nearshore waves in southern California: hindcast, and modeled historical and 21st-century projected time series

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Abstract: This data release presents modeled time series of nearshore waves along the southern California coast, from Point Conception to the Mexican border,...

  8. Wave hindcast studies using SWAN nested in WAVEWATCH III - comparison with measured nearshore buoy data off Karwar, eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Amrutha, M.M.; SanilKumar, V.; Sandhya, K.G.; Nair, T.M.B.; Rathod, J.L.

    for the tropical Indian Ocean are 0.8 m/s, 0.57, 2.6 m/s and 52.5, respectively (Harikumar et al., 2013). The earlier studies have shown that bathymetry is also an important factor (Chawla, 2007; Brown and Wolf, 2009). Hence, both bathymetry and wind field.... J. Geophysical Res. 104 (4), 7649- 7666. Brown, Jennifer M., and Judith Wolf., 2009. Coupled wave and surge modellingfor the easern Irish sea and implications for model wind-stress. Continental shelf Res. 29(10), 1329-1342. Cavaleri, L., 1994...

  9. Report on the Charged Decay Products Identification Possibilities in WASA

    Science.gov (United States)

    Jacewicz, M.; Bargholtz, C.; Bogoslawsky, D.; Bondar, A.; Calén, H.; Cappellaro, F.; Clement, H.; Comfort, J.; Demirörs, L.; Dorochkevitch, E.; Ekström, C.; Fransson, K.; Fridén, C. J.; Chernyshev, B.; Gerén, L.; Grebenev, V.; Greiff, J.; Gurov, Y.; Gustafsson, L.; Höistad, B.; Ivanov, G.; Koch, I.; Jiganov, E.; Johansson, A.; Johansson, T.; Keleta, S.; Kilian, K.; Kimura, N.; Kullander, S.; Kupść, A.; Kurdadze, L.; Kuzmin, A.; Kuznetsov, A.; Lindberg, K.; Marciniewski, P.; Martemyanov, B.; Meier, R.; Morosov, B.; Nawrot, A.; Nefkens, B. M. K.; Oelert, W.; Oreshkin, S.; Pauly, C.; Pawlowski, Z.; Petukhov, Y.; Povtorejko, A.; Pätzold, J.; Reistad, D.; Ruber, R. J. M. Y.; Sandukovsky, V.; Scobel, W.; Sefzick, T.; Shafigullin, R.; Shepkin, M.; Sidorov, V.; Schwartz, B.; Skorodko, T.; Sopov, V.; Starostin, A.; Stepaniak, J.; Sukhanov, A.; Tchernychev, V.; Tegnér, P.-E.; Thörngren Engblom, P.; Tikhomirov, V.; Turowiecki, A.; Wagner, G.; Wiedner, U.; Wilhelmsen, K.; Wilhelmi, Z.; Yamamoto, A.; Yamaoka, H.; Zabierowski, J.; Zlomańczuk, J.

    The WASA detector located at the CELSIUS storage ring of the The Svedberg Laboratory in Uppsala has recently finished its commissioning phase and is in full operation. An unique internal pellet-target system together with a detector covering a solid angle close to 4π steradians gives opportunities to study the rare decays of the π0 and the eta; meson in high-luminosity experiments. Another unique feature of the WASA setup is the thin-walled superconducting solenoid which provides the magnetic field for a mini drift chamber allowing highly efficient measurements of charged particles and minimal interference for particles entering the external electromagnetic calorimeter. The WASA setup is presented in this report with an emphasis on the ability to detect charged decay products. The results from the first experiments and performance of the detector are discussed together with the initial physics programme for charged decays of η mesons.

  10. Prototyping a Focussing Lightguide Disc DIRC at WASA for PANDA

    Energy Technology Data Exchange (ETDEWEB)

    Foehl, Klaus; Brodski, Irina; Dueren, Michael; Hayrapetyan, Avetik; Kroeck, Benno; Koch, Peter; Merle, Oliver; Sporleder, Michael; Stenzel, Hasko; Zuehlsdorf, M. [II. Physikalisches Institut, Universitaet Giessen, Heinrich-Buff-Ring 16, D-35392 Giessen (Germany)

    2009-07-01

    For the future PANDA experiment at the FAIR laboratory particle identification is a crucial capability, and the space constraints favour the use of compact DIRC detectors. For the Endcap area in the PANDA Target Spectrometer a novel Focussing Lightguides Disc DIRC is being investigated. The talk will focus on how a prototype could be placed into the existing WASA experiment at COSY, which would improve the WASA energy resolution for high-energy particles as well as provide proof-of-concept for the PANDA DIRC detector developments.

  11. WASA detector: Towards rare pion and eta decays

    Science.gov (United States)

    Calén, H.; Bilger, R.; Blom, M.; Bogoslawsky, D.; Bondar, A.; Brodowski, W.; Chuvilo, I.; Clement, H.; Dunin, V.; Dyring, J.; Ekström, C.; Fransson, K.; Friden, C.-J.; Greiff, J.; Gustafsson, L.; Häggström, S.; Höistad, B.; Jacewicz, M.; Johanson, J.; Johansson, A.; Johansson, T.; Khoukaz, A.; Kilian, K.; Kimura, N.; Koch, I.; Kolachev, G.; Komogorov, M.; Kullander, S.; Kupsc, A.; Kurdadze, L.; Kuzmin, A.; Kuznetsov, A.; Marciniewski, P.; Martemyanov, A.; Martemyanov, B.; Morosov, B.; Mörtsell, A.; Nawrot, A.; Oelert, W.; Oreshkin, S.; Petukhov, Y.; Povtorejko, A.; Przestrzelska, K.; Pätzold, J.; Reistad, D.; Ruber, R. J. M. Y.; Sandukovsky, V.; Schuberth, U.; Sefzick, T.; Sidorov, V.; Shwartz, B.; Sopov, V.; Stepaniak, J.; Sukhanov, A.; Sukhanov, A.; Sundberg, P.; Tchernychev, V.; Thörngren, P.; Tikhomirov, V.; Turowiecki, A.; Wagner, G.; Wilhelmi, Z.; Yamamoto, A.; Yamaoka, H.; Zabierowski, J.; Zernov, A.; Celsius/Wasa Collaboration

    2000-06-01

    The WASA 4π detector at the The Svedberg Laboratory in Uppsala is now being commissioned. This detector will make possible new detailed studies of many interesting rare processes in intermediate energy light-ion physics. WASA is built around a new target system, providing well defined internal hydrogen (and deuterium) targets of high density. It has a detection coverage of close to 4π sr for high energy photons and charged particles and it includes a strong magnetic field provided by an extremely thin-walled superconducting solenoid.

  12. customary land tenure and land documentation in the wasa amenfi ...

    African Journals Online (AJOL)

    administration including customary land tenure lo reduce land conflicts and enhance producti,·ity or land. ... a pool or human resources necessary for vibrant development. These unique advantages ... 1 The District Chief Executive of the Wasa J\\mcnli District and other dislricl administration sources indicate thal preliminary ...

  13. Wind Atlas for South Africa (WASA). Report on Measurements

    DEFF Research Database (Denmark)

    Mabille, Eugéne; Prinsloo, Eric; Mortensen, Niels Gylling

    The key to any good and accurate wind atlas is good quality data. To this end the 1st Verified Numerical Wind Atlas South Africa, for parts of the Northern and Eastern Capes as well as the Western Cape makes use of meteorological data from ten sites, distributed throughout the modelling domain......, to verify the results of the meso-scale modelling. The Measurements work package (WP2) is one of six work packages that collectively make up the Wind Atlas for South Africa (WASA) project. The measurements also provide observed wind climates at the measurement sites, which can be used by micrositing...

  14. The Present Performance of the CELSIUS\\WASA Experiment

    Science.gov (United States)

    Greiff, Jan; CELSIUS/WASA Collaboration

    The CELSIUS\\WASA experiment is now finishing its commissioning phase and has started with data taking in autumn 2001. The results from a first analysis of data samples from an experimental run in September 2001 are presented. They demonstrate some of the capabilities of the detector subsystems that will be exploited for a continued program of studies of light meson production. The results also show the ability to tag η and πo production events, which is crucial for the anticipated studies of rare decays.

  15. The CELSIUS/WASA 4π Detector Facility

    Science.gov (United States)

    Bargholtz, C.; Bilger, R.; Blom, M.; Bogoslawsky, D.; Bondar, A.; Brodowski, W.; Calen, H.; Clement, H.; Demiroers, L.; Dunin, V.; Ekstroem, C.; Fransson, K.; Friden, C.-J.; Greiff, J.; Gustafsson, L.; Hoeistad, B.; Jacewicz, M.; Johanson, J.; Johansson, A.; Johansson, T.; Khoukaz, A.; Kilian, K.; Kimura, N.; Koch, I.; Kolachev, G.; Komogorov, M.; Kullander, S.; Kupsc, A.; Kurdadze, L.; Kuzmin, A.; Kuznetsov, A.; Lundstroem, B.; Marciniewski, P.; Martemyanov, B.; Morosov, B.; Nawrot, A.; Nefkens, B. M. K.; Norman, G.; Oelert, W.; Oreshkin, S.; Petukhov, Y.; Pomp, S.; Povtorejko, A.; Przestrzelska, K.; Paetzold, J.; Reistad, D.; Ruber, R. J. M. Y.; Sandukovsky, V.; Scobel, W.; Sefzick, T.; Sewerin, S.; Sidorov, V.; Shwartz, B.; Sopov, V.; Stepaniak, J.; Sukhanov, A.; Sundberg, P.; Tchernychev, V.; Tegner, P.-E.; Thoerngren Engblom, P.; Tikhomirov, V.; Turowiecki, A.; Wagner, G.; Wiedner, U.; Wilhelmi, Z.; Yamamoto, A.; Yamaoka, H.; Zabierowski, J.; Zernov, A.; Zlomanczuk, J.

    2000-10-01

    A new experimental setup for light-ion physics located at the CELSIUS storage ring of The Svedberg Laboratory in Uppsala is now in the commissioning phase. It consists of an internal pellet target station and the WASA detector covering a solid angle close to 4π steradians. Its central part is optimized to measure energies of electrons and photons for energies up to 600 MeV. The setup and the initial physics programme is presented as well as the status of the commissioning.

  16. The Present Performance of the CELSIUS/WASA Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Greiff, Jan [The Svedberg Laboratory, Uppsala (Sweden)

    2002-08-01

    The CELSIUS/WASA experiment is now finishing its commissioning phase and has started with data taking in autumn 2001.The results from a first analysis of data samples from an experimental run in September 2001 are presented. They demonstrate some of the capabilities of the detector subsystems that will be exploited for a continued program of studies of light meson production. The results also show the ability to tag {eta} and {pi}{sup 0} production events, which is crucial for the anticipated studies of rare decays.

  17. Hindcasting cyclonic waves using neural networks

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.; Rao, S.; Chakravarty, N.V.

    the backpropagation networks with updated algorithms are used in this paper. A brief description about the working of a back propagation neural network and three updated algorithms is given below. Backpropagation learning: Backpropagation is the most widely used... algorithm for supervised learning with multi layer feed forward networks. The idea of the backpropagation learning algorithm is the repeated application of the chain rule to compute the influence of each weight in the network with respect to an arbitrary...

  18. Hindcasting of storm waves using neural networks

    Digital Repository Service at National Institute of Oceanography (India)

    Rao, S.; Mandal, S.

    of any exogenous input requirement makes the network attractive. A neural network is an information processing system modeled on the structure of the human brain. Its merit is the ability to deal with fuzzy information whose interrelation is ambiguous...

  19. First Results of the CELSIUS/WASA Experiment

    Science.gov (United States)

    Koch, I.; Bargholtz, C.; Bogoslawsky, D.; Bondar, A.; Calén, H.; Cappellaro, F.; Clement, H.; Comfort, J.; Demirörs, L.; Dorochkevitch, E.; Ekström, C.; Fransson, K.; Fridén, C. J.; Chernyshev, B.; Gerén, L.; Grebenev, V.; Greiff, J.; Gurov, Y.; Gustafsson, L.; Höistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, A.; Johansson, T.; Keleta, S.; Kilian, K.; Kimura, N.; Kullander, S.; Kupść, A.; Kurdadze, L.; Kuzmin, A.; Kuznetsov, A.; Lindberg, K.; Marciniewski, P.; Martemyanov, B.; Meier, R.; Morosov, B.; Nawrot, A.; Nefkens, B. M. K.; Oelert, W.; Oreshkin, S.; Pauly, C.; Pawlowski, Z.; Petukhov, Y.; Povtorejko, A.; Pätzold, J.; Reistad, D.; Ruber, R. J. M. Y.; Sandukovsky, V.; Scobel, W.; Sefzick, T.; Shafigullin, R.; Shepkin, M.; Sidorov, V.; Schwartz, B.; Skorodko, T.; Sopov, V.; Starostin, A.; Stepaniak, J.; Sukhanov, A.; Tchernychev, V.; Tegnér, P.-E.; Thörngren Engblom, P.; Tikhomirov, V.; Turowiecki, A.; Wagner, G.; Wiedner, U.; Wilhelmsen, K.; Wilhelmi, Z.; Yamamoto, A.; Yamaoka, H.; Zabierowski, J.; Zlomańczuk, J.

    The CELSIUS/WASA experiment is now finishing its commissioning phase and has started regular data taking in autumn 2001. Results from a first analysis of data samples from an experimental run at a beam energy of Tp = 1360 MeV in September 2001 are presented. The results show the ability to tag π0 and η production events. For 2π0 production a large data sample exists. The 2π0 and 3π0 production processes will be important sources of background for the η decays. They have until now been poorly measured, if at all, at this energy. The decay η → γγ will be used for normalization of all other η decays and the eta; → 3π0 decay will test the light quark mass ratio predicted by Chiral Perturbation Theory.

  20. Study of light mesons with WASA-at-COSY

    Directory of Open Access Journals (Sweden)

    Prencipe Elisabetta

    2014-06-01

    Full Text Available The WASA detector, operating at the COSY facility in Jülich (Germany has been collecting data since 2007. The experiment allows to perform studies of light mesons, such as π0, η and ω rare decay processes, in order to perform precise measurements of branching ratios, determine Dalitz plot parameters, test symmetry and symmetry breaking, and evaluate transition form factors. In the experiments a proton or deuteron beam impinged on a pellet target of hydrogen or deuterium, which allows the reactions proton-proton (pp or proton-deuteron (pd. A high-statistics sample of η mesons has been collected: in the reaction pd →3He η, 3×107η mesons were tagged at a beam energy of 1.0 GeV, while 5×108η mesons were produced in the reaction pp → ppη at 1.4 GeV. This corresponds to the production of 10 η/s and 100 η/s, respectively, for the two reaction processes. In the pp dataset a higher background level is found compared to the pd data set. In both cases, we identify the η mesons by means of the missing mass derived from the recoil particles. A kinematic fit largely rejects the background in our analysis. The advantage in using the pp dataset is that the production of η mesons is almost a factor of 10 higher than in the pd fusion to 3He. As we plan to measure the branching ratios of very rare processes, high statistics is needed. A summary of the recent activity on the study of light mesons with WASA-at-COSY here is given.

  1. Mesoscale modeling for the Wind Atlas of South Africa (WASA) project

    DEFF Research Database (Denmark)

    Hahmann, Andrea N.; Lennard, Chris; Badger, Jake

    This document reports on the methods used to create and the results of the two numerical wind atlases developed for the Wind Atlas for South Africa (WASA) project. The wind atlases were created using the KAMM-WAsP method and from the output of climate-type simulations of the Weather, Research...

  2. Spectator tagging in quasi-free pn-reactions on deuterium at PROMICE/WASA, CELSIUS

    Science.gov (United States)

    Bilger, R.; Brodowski, W.; Calen, H.; Clement, H.; Dunin, V.; Dyring, J.; Ekström, C.; Fransson, K.; Greiff, J.; Gustafsson, L.; Häggström, S.; Höistad, B.; Johanson, J.; Johansson, A.; Johansson, T.; Khoukaz, A.; Kilian, K.; Koch, I.; Kullander, S.; Kupsc, A.; Marciniewski, P.; Morosov, B.; Neubauer, T.; Oelert, W.; Ruber, R.; Shwartz, B.; Stepaniak, J.; Sukhanov, A.; Sukhanov, A.; Sundberg, P.; Turowiecki, A.; Wagner, G.; Wilhelmi, Z.; Wilkin, C.; Zabierowski, J.; Zernov, A.; Zlomanczuk, J.

    2000-01-01

    A set of silicon detectors has been added to the PROMICE/WASA (P/W) experiment at CELSIUS. These detectors have been used for spectator-proton tagging in proton deuteron collisions to investigate proton-neutron reactions at intermediate energies. The performance of the setup has been tested by measuring the pd -> dπopspectator reaction

  3. Spectator tagging in quasi-free pn-reactions on deuterium at PROMICE/WASA, CELSIUS

    Energy Technology Data Exchange (ETDEWEB)

    Bilger, R.; Brodowski, W.; Calen, H.; Clement, H.; Dunin, V.; Dyring, J.; Ekstroem, C.; Fransson, K.; Greiff, J.; Gustafsson, L.; Haeggstroem, S.; Hoeistad, B.; Johanson, J.; Johansson, A.; Johansson, T.; Khoukaz, A.; Kilian, K.; Koch, I.; Kullander, S.; Kupsc, A.; Marciniewski, P.; Morosov, B.; Neubauer, T.; Oelert, W; Ruber, R.; Shwartz, B.; Stepaniak, J.; Sukhanov, A.; Sundberg, P.; Turowiecki, A.; Wagner, G.; Wilhelmi, Z.; Wilkin, C.; Zabierowski, J.; Zernov, A.; Zlomanczuk, J

    2000-01-31

    A set of silicon detectors has been added to the PROMICE/WASA (P/W) experiment at CELSIUS. These detectors have been used for spectator-proton tagging in proton deuteron collisions to investigate proton-neutron reactions at intermediate energies. The performance of the setup has been tested by measuring the pd {yields} d{pi}{sup o}p{sub spectator} reaction.

  4. Spectator tagging in quasi-free pn-reactions on deuterium at PROMICE/WASA, CELSIUS

    CERN Document Server

    Bilger, R; Calén, H; Clement, H; Dunin, V; Dyring, J; Ekström, C; Fransson, K; Greiff, J; Gustafsson, L; Häggström, S; Hoeistad, B; Johanson, J; Johansson, A; Johansson, T; Khoukaz, A; Kilian, K; Koch, I; Kullander, Sven; Kupsc, A; Marciniewski, P; Morosov, B; Neubauer, T; Oelert, W; Ruber, Roger J M Y; Shwartz, B A; Stepaniak, J; Sukhanov, A; Sukhanov, A; Sundberg, P; Turowiecki, A; Wagner, G; Wilhelmi, Z; Wilkin, C; Zabierowski, J; Zernov, A; Zlomanczuk, Yu

    2000-01-01

    A set of silicon detectors has been added to the PROMICE/WASA (P/W) experiment at CELSIUS. These detectors have been used for spectator-proton tagging in proton deuteron collisions to investigate proton-neutron reactions at intermediate energies. The performance of the setup has been tested by measuring the pd -> d pi sup o p sub s sub p sub e sub c sub t sub a sub t sub o sub r reaction

  5. Surge hindcast in the East China sea

    Science.gov (United States)

    Choi, B. H.

    Two typhoon surges generated during July-August 1978 are investigated numerically with the use of a vertically-integrated finite-difference model of the Yellow Sea and the East China Sea. The hindcast scheme involves processing pressure data from weather charts to provide the necessary meteorological forcing to a sea model that computes the response in terms of water levels and currents. Computed residuals are compared with hourly records from selected tide gauges (Inchon, Kunsan, Mokpo, Jeju and Yeosu) along the coast of Korea. Some of the preliminary results are presented and discussed.

  6. Application of Bayesian Networks to hindcast barrier island morphodynamics

    Science.gov (United States)

    Wilson, Kathleen E.; Adams, Peter N.; Hapke, Cheryl J.; Lentz, Erika E.; Brenner, Owen T.

    2015-01-01

    Prediction of coastal vulnerability is of increasing concern to policy makers, coastal managers and other stakeholders. Coastal regions and barrier islands along the Atlantic and Gulf coasts are subject to frequent, large storms, whose waves and storm surge can dramatically alter beach morphology, threaten infrastructure, and impact local economies. Given that precise forecasts of regional hazards are challenging, because of the complex interactions between processes on many scales, a range of probable geomorphic change in response to storm conditions is often more helpful than deterministic predictions. Site-specific probabilistic models of coastal change are reliable because they are formulated with observations so that local factors, of potentially high influence, are inherent in the model. The development and use of predictive tools such as Bayesian Networks in response to future storms has the potential to better inform management decisions and hazard preparation in coastal communities. We present several Bayesian Networks designed to hindcast distinct morphologic changes attributable to the Nor'Ida storm of 2009, at Fire Island, New York. Model predictions are informed with historical system behavior, initial morphologic conditions, and a parameterized treatment of wave climate.

  7. Monte Carlo studies of η → 4π0 CP symmetry violating decay with WASA-at-COSY detector

    Directory of Open Access Journals (Sweden)

    Bednarski Tomasz

    2012-12-01

    Full Text Available We present feasibility studies of the measurement of η meson decay into a 4π0 system using the WASA-at-COSY detector. Kinematics of the pp → ppη → pp4π0 → pp8γ reactions and response of the WASA-at-COSY detector were simulated. The identification of the η → 4π0 → 8γ decay was based on the invariant mass method for both π0 and η mesons. As a result, the resolution of the invariant mass determination of the η meson was established to σ = 31 MeV/c2. The efficiency of the WASA-at-COSY detector for the measurement and reconstruction of the pp → ppη → pp4π0 → pp8γ reaction was determined to be 1.5%.

  8. Towards the Electromagnetic Transition Form Factor of the η Meson with WASA-at-COSY

    Science.gov (United States)

    Goswami, Ankita

    We present a study of the Dalitz decay η to γ e+e-. The aim is to determine the transition form factor of the η meson. The transition form factor describes the electromagnetic structure of the meson. The transition form factor is determined by comparing the experimental e+e- invariant mass distribution with the QED calculation. The analysis uses the proton-proton collision reaction at 1.4 GeV. The data has been collected with the WASA detector at COSY (Forschungszentrum Juelich, Germany). The preliminary results of the analysis will be shown.

  9. Wind Atlas for South Africa (WASA): Project overview and status - Wind Power Africa Conference 2010

    CSIR Research Space (South Africa)

    Szewczuk, S

    2010-05-01

    Full Text Available • Activities ongoing – Mast transport to site and erection – Instrumentation • Data acquisition from all masts expected to start July 2010 • RODEO, web and data availability for public access expected to start September 2010 WP2 method overview Wind... via GSM • Acquisition, QA, calibration and database organisation and web publishing by RODEO at CSIR • Web www.wasa.csir.co.za • Graphs daily • Data files monthly The wind measurement stations were designed with a view to • Meeting IEC...

  10. Search for a new light boson in η decays using the WASA detector

    Directory of Open Access Journals (Sweden)

    Stepaniak Joanna

    2014-01-01

    Full Text Available Some dark matter scenarios predict a light scalar boson that couples to charged leptons. Present experiments do not exclude the existence of a new light (M<1GeV particle(s with small coupling to leptons. It can manifest itself in η meson decays with electron-positron pair(sin the final state. We present preliminary results from the search for η → π0 + (X → e+e− decay in a total of 5 × 107 η mesons produced in the pp → ppη reaction, a fraction of the data collected in the WASA experiment.

  11. Prototyping a DIRC detector for the WASA-at-COSY experiment

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, Adrian; Eyrich, Wolfgang; Heimlich, Julia; Adolph, Christoph; Teufel, Andreas; Li, Liwen [Universitaet Erlangen, Erlangen (Germany); Collaboration: WASA-at-COSY-Collaboration

    2011-07-01

    The WASA-at-COSY experiment at the Forschungszentrum Juelich provides a nearly 4{pi} detector including a forward spectrometer especially for studies on {eta} and {eta}' meson decays in proton-proton collisions. Simulations have shown that an additional Detector of Internally Reflected Cherenkov light (DIRC) in front of the Forward Range Hodoscope improves the particle identification and energy resolution significantly. As a first prototype test has shown the feasibility, a large scale prototype is under construction. We report on the status of the prototyping. Optical performance studies and main characteristics of the favoured photomultiplier tubes will be presented.

  12. Statistical analysis on extreme wave height

    Digital Repository Service at National Institute of Oceanography (India)

    Teena, N.V.; SanilKumar, V.; Sudheesh, K.; Sajeev, R.

    The classical extreme value theory based on generalized extreme value (GEV) distribution and generalized Pareto distribution (GPD) is applied to the wave height estimate based on wave hindcast data covering a period of 31 years for a location...

  13. Ocean wave prediction using numerical and neural network models

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.; Prabaharan, N.

    This paper presents an overview of the development of the numerical wave prediction models and recently used neural networks for ocean wave hindcasting and forecasting. The numerical wave models express the physical concepts of the phenomena...

  14. Atlantic Coast Hindcast, Shallow-Water, Significant Wave Information.

    Science.gov (United States)

    1983-01-01

    Virginia 77 36.92’ 75.99’ 342 Cape Henry, Virginia 711 36. 73’ 75.94’ 339 Rand Bridge, Virginia 79 36.57’ 75.87’ 348 Pale Cape, Virginia 80 36.41...1411 2n5 0107 117 (r)-d Rech, Plrida 142 20.*20’ 81.00’* 114 Soahreec rlurida 141 20 .05’ 60.00 111 Nlv ayn Rench, Florida 14 20.0 0.1’ 310 Flda-, Florid

  15. Wind fields of storms from surface isobars for wave hindcasting

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.; Vaithiyanathan, R.; Santanam, K.

    stream_size 5 stream_content_type text/plain stream_name Proc_Int_Conf_Ocean_Eng_1996_502.pdf.txt stream_source_info Proc_Int_Conf_Ocean_Eng_1996_502.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  16. Modelling sediment export, retention and reservoir sedimentation in drylands with the WASA-SED model

    Directory of Open Access Journals (Sweden)

    E. N. Mueller

    2010-04-01

    Full Text Available Current soil erosion and reservoir sedimentation modelling at the meso-scale is still faced with intrinsic problems with regard to open scaling questions, data demand, computational efficiency and deficient implementations of retention and re-mobilisation processes for the river and reservoir networks. To overcome some limitations of current modelling approaches, the semi-process-based, spatially semi-distributed modelling framework WASA-SED (Vers. 1 was developed for water and sediment transport in large dryland catchments. The WASA-SED model simulates the runoff and erosion processes at the hillslope scale, the transport and retention processes of suspended and bedload fluxes in the river reaches and the retention and remobilisation processes of sediments in reservoirs. The modelling tool enables the evaluation of management options both for sustainable land-use change scenarios to reduce erosion in the headwater catchments as well as adequate reservoir management options to lessen sedimentation in large reservoirs and reservoir networks. The model concept, its spatial discretisation scheme and the numerical components of the hillslope, river and reservoir processes are described and a model application for the meso-scale dryland catchment Isábena in the Spanish Pre-Pyrenees (445 km2 is presented to demonstrate the capabilities, strengths and limits of the model framework. The example application showed that the model was able to reproduce runoff and sediment transport dynamics of highly erodible headwater badlands, the transient storage of sediments in the dryland river system, the bed elevation changes of the 93 hm3 Barasona reservoir due to sedimentation as well as the life expectancy of the reservoir under different management options.

  17. Hindcasting coastal flooding in Scituate (MA) during the Dec. 27, 2010 Nor'easter

    Science.gov (United States)

    Beardsley, R. C.; Chen, C.; Xu, Q.; Qi, J.; Lin, H.

    2012-12-01

    As part of the Northeast Coastal Ocean Forecast System (NECOFS) and in collaboration with the Taunton NWS Weather Forecast Office, we have built a nested inundation forecast model system for Scituate (MA). Here we have used this system to hindcast the coastal flooding in Scituate during the Dec. 26-27 2010 Nor'easter. This classic storm started as a large extratropical low pressure system centered off North Carolina on Dec. 26 and strengthen into a gale as it approached Cape Cod and southeastern Massachusetts the next day. By 06 GMT Dec. 27, barometric pressure in Scituate had dropped 42 mb in 21 hrs, northeast winds had increased to 22 m/s, and waves offshore increased to 7.5 m. NECOFS uses a regional mesoscale weather model (WRF) to drive an unstructured-grid ocean model (FVCOM) and surface wave model (SWAVE) to produce hindcast/forecasts of total water level, currents, and waves on a Northeast regional (GOM3) grid. The Scituate FVCOM inundation model includes flooding/drying, seawall/dike, and wave-current interaction capabilities, and is driven by one-way nesting with NECOFS. Hindcasts were made with two grids, a base grid with resolution varying from 10 m to 100 m within the harbor and a second more refined grid with resolution down to 2 m. The Dec. 27 Nor'easter simulations made with a base grid indicate that inundation predicted within the harbor was realistic and agreed well with tidal measurements. Increasing the grid resolution within the harbor produced greater flooding in several shallow areas but did not change the maximum water level in the main harbor significantly. The inundation model system did not predict significant flooding caused by the wind-wave-current-driven overtopping of the exposed northern seawall. This "splash-over" process is not included in the Scituate inundation forecast system at present but work has started on including this in the future. The computational effort and efficiency to product timely inundation forecasts with this

  18. An overview of the numerical and neural network accosts of ocean wave prediction

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.; Prabaharan, N.

    This paper presents an overview of the development of the numerical wave prediction models and recently used neural networks for wave hindcasting and forecasting. The numerical wave models express the physical concepts of the phenomena...

  19. Encounter Probability of Significant Wave Height

    DEFF Research Database (Denmark)

    Liu, Z.; Burcharth, H. F.

    The determination of the design wave height (often given as the significant wave height) is usually based on statistical analysis of long-term extreme wave height measurement or hindcast. The result of such extreme wave height analysis is often given as the design wave height corresponding to a c...

  20. Improvement of wind field hindcasts for tropical cyclones

    Directory of Open Access Journals (Sweden)

    Yi Pan

    2016-01-01

    Full Text Available This paper presents a study on the improvement of wind field hindcasts for two typical tropical cyclones, i.e., Fanapi and Meranti, which occurred in 2010. The performance of the three existing models for the hindcasting of cyclone wind fields is first examined, and then two modification methods are proposed to improve the hindcasted results. The first one is the superposition method, which superposes the wind field calculated from the parametric cyclone model on that obtained from the cross-calibrated multi-platform (CCMP reanalysis data. The radius used for the superposition is based on an analysis of the minimum difference between the two wind fields. The other one is the direct modification method, which directly modifies the CCMP reanalysis data according to the ratio of the measured maximum wind speed to the reanalyzed value as well as the distance from the cyclone center. Using these two methods, the problem of underestimation of strong winds in reanalysis data can be overcome. Both methods show considerable improvements in the hindcasting of tropical cyclone wind fields, compared with the cyclone wind model and the reanalysis data.

  1. Improvement of wind field hindcasts for tropical cyclones

    Directory of Open Access Journals (Sweden)

    Yi Pan

    2016-01-01

    Full Text Available This paper presents a study on the improvement of wind field hindcasts for two typical tropical cyclones, i.e., Fanapi and Meranti, which occurred in 2010. The performance of the three existing models for the hindcasting of cyclone wind fields is first examined, and then two modification methods are proposed to improve the hindcasted results. The first one is the superposition method, which superposes the wind field calculated from the parametric cyclone model on that obtained from the Cross-Calibrated Multi-Platform (CCMP reanalysis data. The radius used for the superposition is based on an analysis of the minimum difference between the two wind fields. The other one is the direct modification method, which directly modifies the CCMP reanalysis data according to the ratio of the measured maximum wind speed to the reanalyzed value as well as the distance from the cyclone center. Using these two methods, the problem of underestimation of strong winds in reanalysis data can be overcome. Both methods show considerable improvements in the hindcasting of tropical cyclone wind fields, compared with the cyclone wind model and the reanalysis data.

  2. Investigation of the charge symmetry breaking reaction dd → {sup 4}Heπ{sup 0} with the WASA-at-COSY facility

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Maria Katarzyna

    2017-07-01

    Probing elementary symmetries and symmetry breaking tests our understanding of the theory of strong forces, Quantum Chromodynamics. The presented study concentrates on the charge symmetry forbidden reaction dd → {sup 4}Heπ{sup 0}. The aim is to provide experimental results for comparison with predictions from Chiral Perturbation Theory (χ{sub PT}) to study effects induced by quark masses on the hadronic level, e.g., the proton-neutron mass difference. First calculations showed that in addition to the existing high-precision data from TRIUMF and IUCF, more data are required for a precise determination of the parameters of χ{sub PT}. These new data should comprise the measurement of the charge symmetry forbidden dd → {sup 4}Heπ{sup 0} reaction at sufficiently high energy, where the p-wave contribution becomes important. A first measurement with the WASA-at-COSY experiment at an excess energy of ε = 60 MeV was performed, but the results did not allow for a decisive interpretation because of limited statistics. This thesis reports on a second measurement of the dd → {sup 4}Heπ{sup 0} reaction at ε = 60 MeV using an improved WASA detector setup aiming at higher statistics. A sample of 336 ± 43 event candidates have been extracted using a data set from an eight-week long beamtime, and total and differential cross sections have been determined. The angular distribution has been described with a function of the form dσ/dΩ = a + b cos{sup 2}θ*, where θ* is the scattering angle of the pion in the c.m. coordinate system. The obtained parameters a and b and the total cross section are: a = (1.75 ± 0.46(stat.){sup +0.31}{sub -0.8}(syst.)) pb/sr, b = (13.6 ± 2.2(stat.){sup +0.9}{sub -2.7}(syst.)) pb/sr, σ{sub tot} = (79.1 ± 7.3(stat.){sup +1.2}{sub -10.5}(syst.) ± 8.1(norm.) ± 2.0(lumi. syst.)) pb. For this experiment a modified detector setup optimized for a time-of-flight measurement of the forward going particles has been used. After detector

  3. Search for the He-η bound states with the WASA-at-COSY facility

    Directory of Open Access Journals (Sweden)

    Krzemien W.

    2012-12-01

    Full Text Available The η-mesic nuclei in which the η meson is bound with nucleus via strong interaction was postulated already in 1986, however till now no experiment confirmed empirically its existence. The discovery of this new kind of an exotic nuclear matter would be very important for better understanding of the η meson structure and its interaction with nucleons. The search for η-mesic helium is carried out with high statistic and high acceptance with the WASA-at-COSY detection setup in the Research Center Jülich. The search is conducted via the measurement of the excitation function for the chosen decay channels of the 4He-η system. Till now two reactions dd → (4He-ηbs → 3Hepπ− and dd → (4He-ηbs → 3Henπ0 were measured with the beam momentum ramped around the η production threshold. This report includes the description of experimental method and status of the analysis.

  4. Time dependency of the prediction skill for the North Atlantic subpolar gyre in initialized decadal hindcasts

    Science.gov (United States)

    Brune, Sebastian; Düsterhus, André; Pohlmann, Holger; Müller, Wolfgang A.; Baehr, Johanna

    2017-11-01

    We analyze the time dependency of decadal hindcast skill in the North Atlantic subpolar gyre within the time period 1961-2013. We compare anomaly correlation coefficients and temporal interquartile ranges of total upper ocean heat content and sea surface temperature for three differently initialized sets of hindcast simulations with the global coupled model MPI-ESM. All initializations use weakly coupled assimilation with the same full value nudging in the atmospheric component and different assimilation techniques for oceanic temperature and salinity: (1) ensemble Kalman filter assimilating EN4 observations and HadISST data, (2) nudging of anomalies to ORAS4 reanalysis, (3) nudging of full values to ORAS4 reanalysis. We find that hindcast skill depends strongly on the evaluation time period, with higher hindcast skill during strong multiyear trends, especially during the warming in the 1990s and lower hindcast skill in the absence of such trends. Differences between the prediction systems are more pronounced when investigating any 20-year subperiod within the entire hindcast period. In the ensemble Kalman filter initialized hindcasts, we find significant correlation skill for up to 5-8 lead years, albeit along with an overestimation of the temporal interquartile range. In the hindcasts initialized by anomaly nudging, significant correlation skill for lead years greater than two is only found in the 1980s and 1990s. In the hindcasts initialized by full value nudging, correlation skill is consistently lower than in the hindcasts initialized by anomaly nudging in the first lead years with re-emerging skill thereafter. The Atlantic meridional overturning circulation reacts on the density changes introduced by oceanic nudging, this limits the predictability in the subpolar gyre in the first lead years. Overall, we find that a model-consistent assimilation technique can improve hindcast skill. Further, the evaluation of 20 year subperiods within the full hindcast period

  5. Min resa med Fantomen : En receptionsanalys av studiematerialet till Wasa Teaters pjäs Fantomens lillasyster

    OpenAIRE

    Sigfrids, Amanda

    2013-01-01

    Examensarbetet behandlar ämnena dramapedagogik, publikarbete och mobbning. Syftet med examensarbetet är att undersöka hur publikarbetet till Wasa Teaters föreställning, Fantomens lillasyster, påverkat elevernas uppfattning om mobbning och trakasserier. Publikarbetets målgrupp var grundskolan åk 7-9 samt andra stadiets elever. Publikarbetet består av ett studiematerial. Studiematerialet gav lärare möjligheten att tillsammans med sin klass bearbeta tematiken före och efter föreställningen. Stud...

  6. Pion Production in Deuteron Proton Collisions Between the 3N and 2N Thresholds Using the PROMICE/WASA Detector at CELSIUS

    Science.gov (United States)

    Greiff, J.; Koch, I.; Rohdjess, H.; Scobel, W.

    2000-10-01

    The reaction {dp→ dpπ 0} has been measured with the PROMICE/WASA detector setup at CELSIUS with deuteron beam energies between 436 MeV and 558 MeV. The observed energy and angular distributions allow to determine contributions from a quasi-free {np→ dπ 0 } and a coherent 3-nucleon production mechanism.

  7. Hindcasting to measure ice sheet model sensitivity to initial states

    Directory of Open Access Journals (Sweden)

    A. Aschwanden

    2013-07-01

    Full Text Available Validation is a critical component of model development, yet notoriously challenging in ice sheet modeling. Here we evaluate how an ice sheet system model responds to a given forcing. We show that hindcasting, i.e. forcing a model with known or closely estimated inputs for past events to see how well the output matches observations, is a viable method of assessing model performance. By simulating the recent past of Greenland, and comparing to observations of ice thickness, ice discharge, surface speeds, mass loss and surface elevation changes for validation, we find that the short term model response is strongly influenced by the initial state. We show that the thermal and dynamical states (i.e. the distribution of internal energy and momentum can be misrepresented despite a good agreement with some observations, stressing the importance of using multiple observations. In particular we identify rates of change of spatially dense observations as preferred validation metrics. Hindcasting enables a qualitative assessment of model performance relative to observed rates of change. It thereby reduces the number of admissible initial states more rigorously than validation efforts that do not take advantage of observed rates of change.

  8. On the Extreme Wave Height Analysis

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Liu, Zhou

    1994-01-01

    The determination of the design wave height is usually based on the statistical analysis of long-term extreme wave height measurements. After an introduction to the procedure of the extreme wave height analysis, the paper presents new development concerning various aspects of the extreme wave...... height analysis. Finally, the paper gives a practical example based on a data set of the hindcasted wave heights for a deep water location in the Mediterranean Sea....

  9. 8000 Ways to Model a Vortex: A Review of Hindcast Wind Field Methodologies

    Science.gov (United States)

    Sweeney, J.

    2014-12-01

    Hindcasts of cyclonic wind fields are crucial for extreme analysis in the oil and gas industry. Recent scientific developments have increased the number of parameterization options for tropical cyclone vortices, leading to well over 8000 permutations of model choices. Which is best? Also problematic is how best to blend modelled vortex winds into a global wind model (such as the Climate Forecast System Reanalysis (CFSR)) in order to resolve tropical cyclones to sufficient detail for wave modelling. Standard blending schemes can leave a 'moat' between the vortex and the CFSR circulation (see Figure 1 from TC Olivia 1996). Using a 35-year track database from the Australian Bureau of Meteorology, this study assesses model configurations and blending schemes against the most extensive measured meteorological dataset in the north-east Indian Ocean (largely commercial-in-confidence). The Holland profile models of 1980 and 2008 are two starting points, with other options examined for radius to maximum wind calculations, pressure-wind relationships, averaging periods, atmospheric profiles, gust factors, and asymmetry methods. Once a vortex is modelled, the winds are then fitted to the radius of gales and blended into the CFSR before further verification. Initial results support recent theoretical developments by Hu et al (2012), with additional results that call for a new asymmetry method and the separation of pressure and wind field modelling.

  10. Process-based, morphodynamic hindcast of decadal deposition patterns in San Pablo Bay, California, 1856-1887

    Science.gov (United States)

    van der Wegen, M.; Jaffe, B.E.; Roelvink, J.A.

    2011-01-01

    This study investigates the possibility of hindcasting-observed decadal-scale morphologic change in San Pablo Bay, a subembayment of the San Francisco Estuary, California, USA, by means of a 3-D numerical model (Delft3D). The hindcast period, 1856-1887, is characterized by upstream hydraulic mining that resulted in a high sediment input to the estuary. The model includes wind waves, salt water and fresh water interactions, and graded sediment transport, among others. Simplified initial conditions and hydrodynamic forcing were necessary because detailed historic descriptions were lacking. Model results show significant skill. The river discharge and sediment concentration have a strong positive influence on deposition volumes. Waves decrease deposition rates and have, together with tidal movement, the greatest effect on sediment distribution within San Pablo Bay. The applied process-based (or reductionist) modeling approach is valuable once reasonable values for model parameters and hydrodynamic forcing are obtained. Sensitivity analysis reveals the dominant forcing of the system and suggests that the model planform plays a dominant role in the morphodynamic development. A detailed physical explanation of the model outcomes is difficult because of the high nonlinearity of the processes. Process formulation refinement, a more detailed description of the forcing, or further model parameter variations may lead to an enhanced model performance, albeit to a limited extent. The approach potentially provides a sound basis for prediction of future developments. Parallel use of highly schematized box models and a process-based approach as described in the present work is probably the most valuable method to assess decadal morphodynamic development. Copyright ?? 2011 by the American Geophysical Union.

  11. On the dependence of hindcast skill on ocean thermodynamics in a coupled ocean-atmosphere model

    Energy Technology Data Exchange (ETDEWEB)

    Kleeman, R. (Bureau of Meteorology Research Centre, Melbourne (Australia))

    1993-11-01

    Three different mechanisms for the generation of ENSO SST anomalies within a simplified tropical Pacific Ocean model are examined: thermocline depth changes, Ekman-induced upwelling anomalies, and zonal advection changes. The effect of varying the relative influence of these terms on the realism of tropical pacific coupled models is analyzed. The principal tool used to assess such realism is hindcast skill, with forced ocean and oscillatory behavior also being examined. Of the mechanisms considered, thermocline perturbations are shown to be crucially important for high coupled-model hindcast skills. Furthermore, it is concluded that the realism of the model (as measured by hindcast skill) deteriorates markedly when the influence on SST of Ekman upwelling becomes greater than a small fraction of the thermocline influence. This provides strong evidence for the hypothesis that Ekman upwelling anomalies (which are essentially a local response to wind stress anomalies) have only a small influence on the creation of real world SST anomalies. The implications of this latter point for coupled models involving ocean general circulation models is briefly discussed. It is also demonstrated that western boundary reflections provide a vital role by means of a negative feedback in ensuring realistic performance. The hindcast skill (as measured by NINO3 anomaly correlation) demonstrated by a model involving only the thermocline mechanism can be tuned to exceed that of the benchmark Cane and Zebiak model for hindcast lags up to 7 months (from 7 to 12 months the model skills are roughly equal). 47 refs., 32 figs.

  12. Hindcast oil spill simulations from the existing offshore wells in the Eastern Mediterranean Levantine Basin

    Science.gov (United States)

    Zodiatis, George; Alves, Tiago M.; Kokinou, Eleni; Radhakrishnan, Hari; Panagiotakis, Costas; Lardner, Robin

    2017-04-01

    Following the expansion of the exploration and exploitation of the hydrocarbons in the Eastern Mediterranean Levantine Basin during the last 5 years, oil spill simulations for 20 existing offshore platforms/wells were carried out based on new and high resolution bathymetric, meteorological, oceanographic, and geomorphological data. The oil spill simulations were carried out using the well known MEDSLIK oil spill model, with the use of high temporal and spatial resolution data for 3D sea currents, winds and waves, provided by the CYCOFOS forecasting system, downscaled from the Copernicus Marine environment monitoring service (CMEMS). The hindcast oil spill simulations from the 20 potential oil spill sources have been prepared for a period of four years, presenting the movement of the spills and the area affected, the fate parameters, the first impact on the coast and the extend of the affected coastline from each location every week. The modeled oil spills took into account the oil spill scenario following the REMPEC MEDEXPOL 2013 experiment. Moreover, a qualitative analysis of the seabed morphology has been applied to examine the direction of the oil slick expansion, shown that the direction of the major axis of the oil spills, in most of the cases examined, is oriented according to the prevailing azimuth of bathymetric features. The oil spill simulations from the existing offshore wells/platforms, show a clear trend for east and northeast movement of the oil spills in the Eastern Mediterranean Levantine Basin, with the first impact at the coast in a time interval between 1 to 20 days after the first oil spilled at sea, depending on the location of the platforms/wells and of the intensity and direction of the meteo-ocean data.

  13. An approximate method of short-term tsunami forecast and the hindcasting of some recent events

    Directory of Open Access Journals (Sweden)

    Yu. P. Korolev

    2011-11-01

    Full Text Available The paper presents a method for a short-term tsunami forecast based on sea level data from remote sites. This method is based on Green's function for the wave equation possessing the fundamental property of symmetry. This property is well known in acoustics and seismology as the reciprocity principle. Some applications of this principle on tsunami research are considered in the current study. Simple relationships and estimated transfer functions enabled us to simulate tsunami waveforms for any selected oceanic point based only on the source location and sea level data from a remote reference site. The important advantage of this method is that it is irrespective of the actual source mechanism (seismic, submarine landslide or other phenomena. The method was successfully applied to hindcast several recent tsunamis observed in the Northwest Pacific. The locations of the earthquake epicenters and the tsunami records from one of the NOAA DART sites were used as inputs for the modelling, while tsunami observations at other DART sites were used to verify the model. Tsunami waveforms for the 2006, 2007 and 2009 earthquake events near Simushir Island were simulated and found to be in good agreement with the observations. The correlation coefficients between the predicted and observed tsunami waveforms were from 0.50 to 0.85. Thus, the proposed method can be effectively used to simulate tsunami waveforms for the entire ocean and also for both regional and local tsunami warning services, assuming that they have access to the real-time sea level data from DART stations.

  14. Hindcasting of decadal‐timescale estuarine bathymetric change with a tidal‐timescale model

    Science.gov (United States)

    Ganju, Neil K.; Schoellhamer, David H.; Jaffe, Bruce E.

    2009-01-01

    Hindcasting decadal-timescale bathymetric change in estuaries is prone to error due to limited data for initial conditions, boundary forcing, and calibration; computational limitations further hinder efforts. We developed and calibrated a tidal-timescale model to bathymetric change in Suisun Bay, California, over the 1867–1887 period. A general, multiple-timescale calibration ensured robustness over all timescales; two input reduction methods, the morphological hydrograph and the morphological acceleration factor, were applied at the decadal timescale. The model was calibrated to net bathymetric change in the entire basin; average error for bathymetric change over individual depth ranges was 37%. On a model cell-by-cell basis, performance for spatial amplitude correlation was poor over the majority of the domain, though spatial phase correlation was better, with 61% of the domain correctly indicated as erosional or depositional. Poor agreement was likely caused by the specification of initial bed composition, which was unknown during the 1867–1887 period. Cross-sectional bathymetric change between channels and flats, driven primarily by wind wave resuspension, was modeled with higher skill than longitudinal change, which is driven in part by gravitational circulation. The accelerated response of depth may have prevented gravitational circulation from being represented properly. As performance criteria became more stringent in a spatial sense, the error of the model increased. While these methods are useful for estimating basin-scale sedimentation changes, they may not be suitable for predicting specific locations of erosion or deposition. They do, however, provide a foundation for realistic estuarine geomorphic modeling applications.

  15. Feasibility study of the {eta}'{yields} {pi}{sup +} {pi}{sup -} {pi}{sup 0} decay using WASA-at-COSY apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Zielinski, M.

    2008-07-15

    One of the objectives of the vast physics programme of the recently commissioned WASA-at-COSY facility is the study of fundamental symmetries via the measurements of the {eta} and {eta}' mesons decays. Especially interesting are isospin violating hadronic precesses of these mesons into 3{pi} systems driven by the term of QCD Lagrangian which depends on the mass difference of the u and d quarks. When an {eta} or an {eta}' meson is created in the hadronic reaction signals from such decays may be significantly obscured by the prompt production of {pi} mesons. In this thesis we present the estimation of the upper limit of the background due to prompt pion production for the {eta}'{yields}3{pi}{sup 0} and {eta}'{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0} decays. Using the data from proton-proton collisions measured by the COSY-11 group we have extracted differential cross sections for the multimeson production with the invariant mass corresponding to the mass of the {eta}' meson. Based on these results and on parametrizations of the total cross sections for the {eta}' meson as well as parametrization of the upper limit for the prompt pi{sup +}pi{sup -}pi{sup 0} production in the collisions of protons we discuss in details the feasibility of a measurement of the {eta}' meson decay into 3{pi} channels with the WASA-at-COSY facility. Based on the chiral unitary approach the value of the branching ratio BR({eta}'{yields}{pi}{sup +}{pi}{sup -}{pi}{sup 0}) was recently predicted to be about 1%. We show that the WASA-at-COSY has a potential to verify this result empirically. (orig.)

  16. Design Wave Height Related to Structure Lifetime

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Liu, Z.

    1999-01-01

    The determination of the design wave height (often given as the significant wave height) is usually based on statistical analysis of long-term extreme wave height measurement or hindcast. The result of such extreme wave height analysis is often given as the design wave height corresponding...... to a chosen return period. Sometimes confidence band of the design wave height is also given in order to include various sources of uncertainties. In this paper the First Order Reliability Method (FORM) is used to determine the design wave height corresponding to a certain exceedence probability within...

  17. Design Wave Height Related to Structure Lifetime

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Liu, Z.

    1996-01-01

    The determination of the design wave height (often given as the significant wave height) is usually based on statistical analysis of long-term extreme wave height measurement or hindcast. The result of such extreme wave height analysis is often given as the design wave height corresponding...... to a chosen return period. Sometimes confidence band of the design wave height is also given in order to include various sources of uncertainties. In this paper the First Order Reliability Method (FORM) is used to determine the design wave height corresponding to a certain exceedence probability within...

  18. Monte Carlo simulering och upplösningsstudier av sönderfallet η → e+e− i WASA-at-COSY detektorn

    OpenAIRE

    Ikegami Andersson, Walter Kenji

    2014-01-01

    A comparative study is done on the Mini Drift Chamber (MDC) and the Scintillating Electromagnetic Calorimeter (SEC), two main components of the WASA detector. The purpose of the study is to determine the most effective way to calculate the mass of the η−meson by determining the invariant mass of the final products in the η → e+e− decay. When calculating the invariant mass of the lepton pair the distribution from the MDC had a standard deviation of σMDC = (4.212 ± 0.080) · 10−2 GeV/c2 and from...

  19. Calculating Depth of Closure Using WIS Hindcast Data

    Science.gov (United States)

    2016-03-01

    statistical wave parameters are available in a static spreadsheet version using preselected project location and will be available in an interactive web ...of a larger effort to provide DOC estimates as a publicly available interactive web tool that will also include estimates of sediment mobility. The...placement site and retain the same volume for years while potentially attenuating high wave energy depending on depth of placement. The Hands and

  20. Correction: MurCSS: A Tool for Standardized Evaluation of Decadal Hindcast Systems

    Directory of Open Access Journals (Sweden)

    Sebastian Illing

    2016-06-01

    Full Text Available This article details a correction to the article: Illing S, Kadow C, Oliver K, Cubasch U. MurCSS: A Tool for Standardized Evaluation of Decadal Hindcast Systems. Journal of Open Research Software. 2014; 2(1: e24. DOI: http://doi.org/10.5334/jors.bf

  1. Wave

    DEFF Research Database (Denmark)

    Ibsen, Lars Bo

    2008-01-01

    Estimates for the amount of potential wave energy in the world range from 1-10 TW. The World Energy Council estimates that a potential 2TW of energy is available from the world’s oceans, which is the equivalent of twice the world’s electricity production. Whilst the recoverable resource is many...... times smaller it remains very high. For example, whilst there is enough potential wave power off the UK to supply the electricity demands several times over, the economically recoverable resource for the UK is estimated at 25% of current demand; a lot less, but a very substantial amount nonetheless....

  2. Forecasting and Hindcasting Waves With the SWAN Model in the Southern California Bight

    Science.gov (United States)

    2007-01-01

    propagating past the islands). The with a very large time interval between computations (24 h ability of MLM to correctly reproduce multiple swells...on slowly In terms of agreement with observations, there is little or no varying, unsteady and inhomogeneous depths and currents. J. Phys

  3. Long-term wave climate at DanWEC

    DEFF Research Database (Denmark)

    Tetu, Amélie; Kofoed, Jens Peter

    buoys are continuously recorded and the data is analysed on a quarterly basis. The directional wave measuring buoys were first installed in March 2015. As two years is not sufficient for long-term wave climate definition, modelled data was more appropriate for the task. Thelong-term wave climate around...... Hanstholm is defined in the present report using the hindcast data from the MIKE 21 Spectral Wave model provided by DHI, one of the partners of the project. Before the actual wave climate definition, a description of the site includinglocation and bathymetry is included. The historical wave data of the area...... andthe current network of sensors are also presented. The numerical model used toobtain the 35 years hindcast data is introduced together with its validation againstbuoy-measured data and with the description of the dataset utilised for thelong-term climate definition. The recommendations from [IEC 62600...

  4. Inner harbour wave agitation using boussinesq wave model

    Directory of Open Access Journals (Sweden)

    Panigrahi Jitendra K.

    2015-01-01

    Full Text Available Short crested waves play an important role for planning and design of harbours. In this context a numerical simulation is carried out to evaluate wave tranquility inside a real harbour located in east coast of India. The annual offshore wave climate proximity- to harbour site is established using Wave Model (WAM hindcast wave data. The deep water waves are transformed to harbour front using a Near Shore spectral Wave model (NSW. A directional analysis is carried out to determine the probable incident wave directions towards the harbour. Most critical threshold wave height and wave period is chosen for normal operating conditions using exceedence probability analysis. Irregular random waves from various directions are generated confirming to Pierson Moskowitz spectrum at 20m water depth. Wave incident into inner harbor through harbor entrance is performed using Boussinesq Wave model (BW. Wave disturbance experienced inside the harbour and at various berths are analysed. The paper discusses the progresses took place in short wave modeling and it demonstrates application of wave climate for the evaluation of harbor tranquility using various types of wave models.

  5. Inner harbour wave agitation using boussinesq wave model

    Directory of Open Access Journals (Sweden)

    Jitendra K. Panigrahi

    2015-01-01

    Full Text Available Short crested waves play an important role for planning and design of harbours. In this context a numerical simulation is carried out to evaluate wave tranquility inside a real harbour located in east coast of India. The annual offshore wave climate proximity to harbour site is established using Wave Model (WAM hindcast wave data. The deep water waves are transformed to harbour front using a Near Shore spectral Wave model (NSW. A directional analysis is carried out to determine the probable incident wave directions towards the harbour. Most critical threshold wave height and wave period is chosen for normal operating conditions using exceedence probability analysis. Irregular random waves from various directions are generated confirming to Pierson Moskowitz spectrum at 20 m water depth. Wave incident into inner harbor through harbor entrance is performed using Boussinesq Wave model (BW. Wave disturbance experienced inside the harbour and at various berths are analysed. The paper discusses the progresses took place in short wave modeling and it demonstrates application of wave climate for the evaluation of harbor tranquility using various types of wave models.

  6. EDgE multi-model hydro-meteorological seasonal hindcast experiments over Europe

    Science.gov (United States)

    Samaniego, Luis; Thober, Stephan; Kumar, Rohini; Rakovec, Oldrich; Wood, Eric; Sheffield, Justin; Pan, Ming; Wanders, Niko; Prudhomme, Christel

    2017-04-01

    Extreme hydrometeorological events (e.g., floods, droughts and heat waves) caused serious damage to society and infrastructures over Europe during the past decades. Developing a seamless and skillful operational seasonal forecasting system of these extreme events is therefore a key tool for short-term decision making at local and regional scales. The EDgE project funded by the Copernicus programme (C3S) provides an unique opportunity to investigate the skill of a newly created large multi-model hydro-meteorological ensemble for predicting extreme events over the Pan-EU domain at a higher resolution 5×5 km2. Two state-of-the-art seasonal prediction systems were chosen for this project. Two models from the North American MultiModel ensemble (NMME) with 22 realizations, and two models provided by the ECMWF with 30 realizations. All models provide daily forcings (P, Ta, Tmin, Tmax) of the the Pan-EU at 1°. Downscaling has been carried out with the MTCLIM algorithm (Bohn et al. 2013) and external drift Kriging using elevation as drift to induce orographic effects. In this project, four high-resolution seamless hydrologic simulations with the mHM (www.ufz.de/mhm), Noah-MP, VIC and PCR-GLOBWB have been completed for the common hindcast period of 1993-2012 resulting in an ensemble size of 208 realizations. Key indicators are focussing on six terrestrial Essential Climate Variables (tECVs): river runoff, soil moisture, groundwater recharge, precipitation, potential evapotranspiration, and snow water equivalent. Impact Indicators have been co-designed with stakeholders in Norway (hydro-power), UK (water supply), and Spain (river basin authority) to provide an improved information for decision making. The Indicators encompass diverse information such as the occurrence of high and low streamflow percentiles (floods, and hydrological drought) and lower percentiles of top soil moisture (agricultural drought) among others. Preliminary results evaluated at study sites in Norway

  7. The NRL Mountain Wave Forecast Model (MWFM) [Preprint

    Science.gov (United States)

    2004-06-17

    Modeling and Assimilation Office ( GMAO ). The resulting MWFM-1 “hindcasts” are shown in the remaining panels of Figure 6. At DC-8 cruise altitudes...forecast” (hindcast) at 70-100 hPa (heights ~16-18 km, the approximate ER-2 cruise altitude here) using GMAO assimilated data for May 2, 1996 at 06:00...Geophysica HALE aircraft Figure 7: MWFM-2 hindcast of mountain wave CAT at 70-100 hPa on May 2, 1996 at 12:00 UT, using GMAO assimilated data of 2.5ox2o

  8. Vertical structure and physical processes of the Madden-Julian oscillation: Linking hindcast fidelity to simulated diabatic heating and moistening: DIABATIC PROCESSES IN MJO HINDCASTS

    Energy Technology Data Exchange (ETDEWEB)

    Klingaman, Nicholas P. [National Centre for Atmospheric Science and Department of Meteorology, University of Reading, Reading UK; Woolnough, Steven J. [National Centre for Atmospheric Science and Department of Meteorology, University of Reading, Reading UK; Jiang, Xianan [Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles California USA; Jet Propulsion Laboratory, Pasadena California USA; Waliser, Duane [Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles California USA; Jet Propulsion Laboratory, Pasadena California USA; Xavier, Prince K. [UK Met Office, Exeter UK; Petch, Jon [UK Met Office, Exeter UK; Caian, Mihaela [Rossby Centre, Swedish Meteorological and Hydrological Institute, Norrköping Sweden; Hannay, Cecile [National Center for Atmospheric Research, Boulder Colorado USA; Kim, Daehyun [Department of Atmospheric Sciences, University of Washington, Seattle Washington USA; Ma, Hsi-Yen [Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore California USA; Merryfield, William J. [Canadian Centre for Climate Modelling and Analysis, Environment Canada, Victoria British Columbia Canada; Miyakawa, Tomoki [Department of Coupled Ocean-Atmosphere-Land Process Research, Japan Agency for Marine-Earth Science and Technology, Yokosuka Japan; Atmosphere and Ocean Research Institute, Tokyo University, Toyko Japan; Pritchard, Mike [Department of Earth System Sciences, University of California, Irvine California USA; Ridout, James A. [Naval Research Laboratory, Monterey California USA; Roehrig, Romain [CNRM-GAME, Météo-France and CNRS, Toulouse France; Shindo, Eiki [Meteorological Research Institute, Tsukuba Japan; Vitart, Frederic [European Centre for Medium-Range Weather Forecasts, Reading UK; Wang, Hailan [National Aeronautics and Space Administration Goddard Space Flight Center, Greenbelt Maryland USA; Cavanaugh, Nicholas R. [Scripps Institution of Oceanography, La Jolla California USA; Mapes, Brian E. [Rosenstiel School of Marine and Atmospheric Science, University of Miami, Coral Gables Florida USA; Shelly, Ann [UK Met Office, Exeter UK; Zhang, Guang J. [Scripps Institution of Oceanography, La Jolla California USA

    2015-05-26

    Many theories for the Madden-Julian oscillation (MJO) focus on diabatic processes, particularly the evolution of vertical heating and moistening. Poor MJO performance in weather and climate models is often blamed on biases in these processes and their interactions with the large-scale circulation. We introduce one of the three components of a model evaluation project, which aims to connect MJO fidelity in models to their representations of several physical processes, focusing on diabatic heating and moistening. This component consists of 20 day hindcasts, initialized daily during two MJO events in winter 2009–2010. The 13 models exhibit a range of skill: several have accurate forecasts to 20 days lead, while others perform similarly to statistical models (8–11 days). Models that maintain the observed MJO amplitude accurately predict propagation, but not vice versa. We find no link between hindcast fidelity and the precipitation-moisture relationship, in contrast to other recent studies. There is also no relationship between models' performance and the evolution of their diabatic heating profiles with rain rate. A more robust association emerges between models' fidelity and net moistening: the highest-skill models show a clear transition from low-level moistening for light rainfall to midlevel moistening at moderate rainfall and upper level moistening for heavy rainfall. The midlevel moistening, arising from both dynamics and physics, may be most important. Accurately representing many processes may be necessary but not sufficient for capturing the MJO, which suggests that models fail to predict the MJO for a broad range of reasons and limits the possibility of finding a panacea.

  9. UTLS temperature validation of MPI-ESM decadal hindcast experiments with GPS radio occultations

    Directory of Open Access Journals (Sweden)

    Torsten Schmidt

    2016-12-01

    Full Text Available Global Positioning System (GPS radio occultation (RO temperature data are used to validate MPI-ESM (Max Planck Institute – Earth System Model decadal hindcast experiments in the upper troposphere and lower stratosphere (UTLS region between 300 hPa and 10 hPa (8 km and 32 km for the time period between 2002 and 2011. The GPSRO dataset is unique since it is very precise, calibration independent and covers the globe better than the usual radiosonde dataset. In addition it is vertically finer resolved than any of the existing satellite temperature measurements available for the UTLS and provides now a unique one decade long temperature validation dataset. The initialization of the MPI-ESM decadal hindcast runs mostly increases the skill of the atmospheric temperatures when compared to uninitialized climate projections with very high skill scores for lead-year one, and gradually decreases for the later lead-years. A comparison between two different initialization sets (b0, b1 of the low-resolution (LR MPI-ESM shows increased skills in b1-LR in most parts of the UTLS in particular in the tropics. The medium resolution (MR MPI-ESM initializations are characterized by reduced temperature biases in the uninitialized runs as compared to observations and a better capturing of the high latitude northern hemisphere interannual polar vortex variability as compared to the LR model version. Negative skills are found for the b1-MR hindcasts however in the regions around the mid-latitude tropospheric jets on both hemispheres and in the vicinity of the tropical tropopause in comparison to the b1-LR variant. It is interesting to highlight that none of the model experiments can reproduce the observed positive temperature trend in the tropical tropopause region since 2001 as seen by GPSRO data.

  10. An improved hindcast approach for evaluation and diagnosis of physical processes in global climate models

    Science.gov (United States)

    Ma, H.-Y.; Chuang, C. C.; Klein, S. A.; Lo, M.-H.; Zhang, Y.; Xie, S.; Zheng, X.; Ma, P.-L.; Zhang, Y.; Phillips, T. J.

    2015-12-01

    We present an improved procedure of generating initial conditions (ICs) for climate model hindcast experiments with specified sea surface temperature and sea ice. The motivation is to minimize errors in the ICs and lead to a better evaluation of atmospheric parameterizations' performance in the hindcast mode. We apply state variables (horizontal velocities, temperature, and specific humidity) from the operational analysis/reanalysis for the atmospheric initial states. Without a data assimilation system, we apply a two-step process to obtain other necessary variables to initialize both the atmospheric (e.g., aerosols and clouds) and land models (e.g., soil moisture). First, we nudge only the model horizontal velocities toward operational analysis/reanalysis values, given a 6 h relaxation time scale, to obtain all necessary variables. Compared to the original strategy in which horizontal velocities, temperature, and specific humidity are nudged, the revised approach produces a better representation of initial aerosols and cloud fields which are more consistent and closer to observations and model's preferred climatology. Second, we obtain land ICs from an off-line land model simulation forced with observed precipitation, winds, and surface fluxes. This approach produces more realistic soil moisture in the land ICs. With this refined procedure, the simulated precipitation, clouds, radiation, and surface air temperature over land are improved in the Day 2 mean hindcasts. Following this procedure, we propose a "Core" integration suite which provides an easily repeatable test allowing model developers to rapidly assess the impacts of various parameterization changes on the fidelity of modeled cloud-associated processes relative to observations.

  11. A hindcast archive to assess forecast uncertainty of seasonal forecasts for the Columbia River Basin

    Science.gov (United States)

    Nijssen, B.

    2006-12-01

    More than half of the electricity in the northwestern United States is generated by hydropower facilities in the Columbia River Basin. Consequently, seasonal hydrologic forecasts of naturalized streamflow are of interest to system operators, energy traders and financial institutions. Much of the seasonal streamflow predictability is derived from the importance of snow melt in the Columbia River Basin. Further predictability is derived from the ENSO-state (El Niño Southern Oscillation), which affects precipitation patterns in the basin. Typically, the Pacific Northwest experiences a greater likelihood of reduced precipitation during El Niño episodes, and a greater likelihood of increased precipitation during La Niña episodes. For the 2006 water year, we created long-range operational hydrologic forecasts for selected locations in the basin using a macroscale hydrologic model and an ensemble streamflow prediction (ESP) methodology. Although our ESP approach provided a measure of the range of expected streamflow conditions, it did not account for the uncertainty in forecast initial conditions, parameter uncertainty or model uncertainty. To assess the total uncertainty associated with our hydrologic forecasts, we have created a hindcast database for the period 1950-2005, which includes 12-month forecasts made on the start of each month during the period November May. This hindcast archive enables us to assess the total uncertainty associated with our seasonal forecasts. We will present forecast verification results for selected locations in the Columbia River Basin as a function of lead time and ENSO condition.

  12. Model Development and Hindcast Simulations of NOAA’s Gulf of Maine Operational Forecast System

    Directory of Open Access Journals (Sweden)

    Zizang Yang

    2016-11-01

    Full Text Available The National Ocean Service (NOS of National Oceanic and Atmospheric Administration is developing an operational nowcast/forecast system for the Gulf of Maine (GoMOFS. The system aims to produce real-time nowcasts and short-range forecast guidance for water levels, 3-dimensional currents, water temperature, and salinity over the broad GoM region. GoMOFS will be implemented using the Regional Ocean Model System (ROMS. This paper describes the system setup and results from a one-year (2012 hindcast simulation. The hindcast performance was evaluated using the NOS standard skill assessment software. The results indicate favorable agreement between observations and model forecasts. The root-mean-squared errors are about 0.12 m for water level, less than 1.5 °C for temperature, less than 1.5 psu for salinity, and less than 0.2 m/s for currents. It is anticipated to complete the system development and the transition into operations in fiscal year 2017.

  13. Initialization shock in decadal hindcasts due to errors in wind stress over the tropical Pacific

    Science.gov (United States)

    Pohlmann, Holger; Kröger, Jürgen; Greatbatch, Richard J.; Müller, Wolfgang A.

    2017-10-01

    Low prediction skill in the tropical Pacific is a common problem in decadal prediction systems, especially for lead years 2-5 which, in many systems, is lower than in uninitialized experiments. On the other hand, the tropical Pacific is of almost worldwide climate relevance through its teleconnections with other tropical and extratropical regions and also of importance for global mean temperature. Understanding the causes of the reduced prediction skill is thus of major interest for decadal climate predictions. We look into the problem of reduced prediction skill by analyzing the Max Planck Institute Earth System Model (MPI-ESM) decadal hindcasts for the fifth phase of the Climate Model Intercomparison Project and performing a sensitivity experiment in which hindcasts are initialized from a model run forced only by surface wind stress. In both systems, sea surface temperature variability in the tropical Pacific is successfully initialized, but most skill is lost at lead years 2-5. Utilizing the sensitivity experiment enables us to pin down the reason for the reduced prediction skill in MPI-ESM to errors in wind stress used for the initialization. A spurious trend in the wind stress forcing displaces the equatorial thermocline in MPI-ESM unrealistically. When the climate model is then switched into its forecast mode, the recovery process triggers artificial El Niño and La Niña events at the surface. Our results demonstrate the importance of realistic wind stress products for the initialization of decadal predictions.

  14. On the probability of occurrence of rogue waves

    Directory of Open Access Journals (Sweden)

    E. M. Bitner-Gregersen

    2012-03-01

    Full Text Available A number of extreme and rogue wave studies have been conducted theoretically, numerically, experimentally and based on field data in the last years, which have significantly advanced our knowledge of ocean waves. So far, however, consensus on the probability of occurrence of rogue waves has not been achieved. The present investigation is addressing this topic from the perspective of design needs. Probability of occurrence of extreme and rogue wave crests in deep water is here discussed based on higher order time simulations, experiments and hindcast data. Focus is given to occurrence of rogue waves in high sea states.

  15. Hindcast skill for the Atlantic meridional overturning circulation at 26.5°N within two MPI-ESM decadal climate prediction systems

    Science.gov (United States)

    Müller, Vasco; Pohlmann, Holger; Düsterhus, André; Matei, Daniela; Marotzke, Jochem; Müller, Wolfgang A.; Zeller, Mathias; Baehr, Johanna

    2017-11-01

    We analyse the hindcast skill for the Atlantic meridional overturning circulation (AMOC) against 10 years of RAPID/MOCHA AMOC observations, which are now long enough to remove the mean seasonal cycle prior to the hindcast skill analysis. We analyse AMOC hindcast skill in two hindcast ensembles generated with two differently initialised decadal prediction systems that are both based on the earth system model MPI-ESM. We evaluate the hindcast skill for the AMOC and its components in both prediction systems against RAPID/MOCHA observations both with and without the mean seasonal cycle removed using anomaly correlation (COR) and root-mean-square error as skill measures. We find significant hindcast skill for most lead years up to 5 for monthly-mean AMOC variations only in the newer of the two prediction systems and only using COR, but with and without the mean seasonal cycle removed. In both systems and for all analysed lead years, the two geostrophic transport components (the upper-mid-ocean transport and Florida Strait combined, that is: AMOC minus Ekman) are the main source of hindcast skill. In the present model setup and with the currently available observational time series, we cannot relate AMOC hindcast skill to the upper-mid-ocean transport alone. Yet, we can show that the seasonal variability of the upper-mid-ocean transport in the free coupled model originates from eastern boundary density variability. Overall, our results indicate modest yet robust AMOC hindcast skill above the uninitialized simulation, independent of the treatment of the seasonal cycle, although we cannot directly link this hindcast skill to the initialisation of the density field with either initialisation method.

  16. Temporal downscaling of decadal sediment load estimates to a daily interval for use in hindcast simulations

    Science.gov (United States)

    Ganju, N.K.; Knowles, N.; Schoellhamer, D.H.

    2008-01-01

    In this study we used hydrologic proxies to develop a daily sediment load time-series, which agrees with decadal sediment load estimates, when integrated. Hindcast simulations of bathymetric change in estuaries require daily sediment loads from major tributary rivers, to capture the episodic delivery of sediment during multi-day freshwater flow pulses. Two independent decadal sediment load estimates are available for the Sacramento/San Joaquin River Delta, California prior to 1959, but they must be downscaled to a daily interval for use in hindcast models. Daily flow and sediment load data to the Delta are available after 1930 and 1959, respectively, but bathymetric change simulations for San Francisco Bay prior to this require a method to generate daily sediment load estimates into the Delta. We used two historical proxies, monthly rainfall and unimpaired flow magnitudes, to generate monthly unimpaired flows to the Sacramento/San Joaquin Delta for the 1851-1929 period. This step generated the shape of the monthly hydrograph. These historical monthly flows were compared to unimpaired monthly flows from the modern era (1967-1987), and a least-squares metric selected a modern water year analogue for each historical water year. The daily hydrograph for the modern analogue was then assigned to the historical year and scaled to match the flow volume estimated by dendrochronology methods, providing the correct total flow for the year. We applied a sediment rating curve to this time-series of daily flows, to generate daily sediment loads for 1851-1958. The rating curve was calibrated with the two independent decadal sediment load estimates, over two distinct periods. This novel technique retained the timing and magnitude of freshwater flows and sediment loads, without damping variability or net sediment loads to San Francisco Bay. The time-series represents the hydraulic mining period with sustained periods of increased sediment loads, and a dramatic decrease after 1910

  17. Oceanic hindcast simulations at high resolution suggest that the Atlantic MOC is bistable

    Science.gov (United States)

    Deshayes, J.; TréGuier, A.-M.; Barnier, B.; Lecointre, A.; Le Sommer, J.; Molines, J.-M.; Penduff, T.; Bourdallé-Badie, R.; Drillet, Y.; Garric, G.; Benshila, R.; Madec, G.; Biastoch, A.; Böning, C. W.; Scheinert, M.; Coward, A. C.; Hirschi, J. J.-M.

    2013-06-01

    All climate models predict a freshening of the North Atlantic at high latitude that may induce an abrupt change of the Atlantic Meridional Overturning Circulation (hereafter AMOC) if it resides in the bistable regime, where both a strong and a weak state coexist. The latter remains uncertain as there is no consensus among observations and ocean reanalyses, where the AMOC is bistable, versus most climate models that reproduce a mono-stable strong AMOC. A series of four hindcast simulations of the global ocean at 1/12° resolution, which is presently unique, are used to diagnose freshwater transport by the AMOC in the South Atlantic, an indicator of AMOC bistability. In all simulations, the AMOC resides in the bistable regime: it exports freshwater southward in the South Atlantic, implying a positive salt advection feedback that would act to amplify a decreasing trend in subarctic deep water formation as projected in climate scenarios.

  18. Continuously on-­going regional climate hindcast simulations for impact applications

    Science.gov (United States)

    Anders, Ivonne; Piringer, Martin; Kaufmann, Hildegard; Knauder, Werner; Resch, Gernot; Andre, Konrad

    2017-04-01

    Observational data for e.g. temperature, precipitation, radiation, or wind are often used as meteorological forcing for different impact models, like e.g. crop models, urban models, economic models and energy system models. To assess a climate signal, the time period covered by the observation is often too short, they have gaps in between, and are inhomogeneous over time, due to changes in the measurements itself or in the near surrounding. Thus output from global and regional climate models can close the gap and provide homogeneous and physically consistent time series of meteorological parameters. CORDEX evaluation runs performed for the IPCC-AR5 provide a good base for the regional scale. However, with respect to climate services, continuously on-going hindcast simulations are required for regularly updated applications. The Climate Research group at the national Austrian weather service, ZAMG, is focusing on high mountain regions and, especially on the Alps. The hindcast-simulation performed with the regional climate model COSMO-CLM is forced by ERAinterim and optimized for the Alpine Region. The simulation available for the period of 1979-2015 in a spatial resolution of about 10km is prolonged ongoing and fullfils the customer's needs with respect of output variables, levels, intervals and statistical measures. One of the main tasks is to capture strong precipitation events which often occur during summer when low pressure systems develop over the Golf of Genoa, moving to the Northeast. This leads to floods and landslide events in Austria, Czech Republic and Germany. Such events are not sufficiently represented in the CORDEX-evaluation runs. ZAMG use high quality gridded precipitation and temperature data for the Alpine Region (1-6km) to evaluate the model performance. Data is provided e.g. to hydrological modellers (high water, low water), but also to assess icing capability of infrastructure or the calculation the separation distances between livestock

  19. Using Combined Diagnostic Test Results to Hindcast Trends of Infection from Cross-Sectional Data.

    Directory of Open Access Journals (Sweden)

    Gustaf Rydevik

    2016-07-01

    Full Text Available Infectious disease surveillance is key to limiting the consequences from infectious pathogens and maintaining animal and public health. Following the detection of a disease outbreak, a response in proportion to the severity of the outbreak is required. It is thus critical to obtain accurate information concerning the origin of the outbreak and its forward trajectory. However, there is often a lack of situational awareness that may lead to over- or under-reaction. There is a widening range of tests available for detecting pathogens, with typically different temporal characteristics, e.g. in terms of when peak test response occurs relative to time of exposure. We have developed a statistical framework that combines response level data from multiple diagnostic tests and is able to 'hindcast' (infer the historical trend of an infectious disease epidemic. Assuming diagnostic test data from a cross-sectional sample of individuals infected with a pathogen during an outbreak, we use a Bayesian Markov Chain Monte Carlo (MCMC approach to estimate time of exposure, and the overall epidemic trend in the population prior to the time of sampling. We evaluate the performance of this statistical framework on simulated data from epidemic trend curves and show that we can recover the parameter values of those trends. We also apply the framework to epidemic trend curves taken from two historical outbreaks: a bluetongue outbreak in cattle, and a whooping cough outbreak in humans. Together, these results show that hindcasting can estimate the time since infection for individuals and provide accurate estimates of epidemic trends, and can be used to distinguish whether an outbreak is increasing or past its peak. We conclude that if temporal characteristics of diagnostics are known, it is possible to recover epidemic trends of both human and animal pathogens from cross-sectional data collected at a single point in time.

  20. Wave Climate Resource Analysis Based on a Revised Gamma Spectrum for Wave Energy Conversion Technology

    Directory of Open Access Journals (Sweden)

    Jeremiah Pastor

    2016-12-01

    Full Text Available In order to correctly predict and evaluate the response of wave energy converters (WECs, an accurate representation of wave climate resource is crucial. This paper gives an overview of wave resource modeling techniques and applies a methodology to estimate the naturally available and technically recoverable resource in a given deployment site. The methodology was initially developed by the Electric Power Research Institute (EPRI, which uses a modified gamma spectrum to interpret sea state hindcast parameter data produced by National Oceanic and Atmospheric Administration’s (NOAA’s WaveWatch III. This gamma spectrum is dependent on the calibration of two variables relating to the spectral width parameter and spectral peakedness parameter. In this study, this methodology was revised by the authors to increase its accuracy in formulating wavelength. The revised methodology shows how to assess a given geographic area’s wave resource based on its wave power density and total annual wave energy flux.

  1. Evaluation of the multi-model CORDEX-Africa hindcast using RCMES

    Science.gov (United States)

    Kim, J.; Waliser, D. E.; Lean, P.; Mattmann, C. A.; Goodale, C. E.; Hart, A.; Zimdars, P.; Hewitson, B.; Jones, C.

    2011-12-01

    Recent global climate change studies have concluded with a high confidence level that the observed increasing trend in the global-mean surface air temperatures since mid-20th century is triggered by the emission of anthropogenic greenhouse gases (GHGs). The increase in the global-mean temperature due to anthropogenic emissions is nearly monotonic and may alter the climatological norms resulting in a new climate normal. In the presence of anthropogenic climate change, assessing regional impacts of the altered climate state and developing the plans for mitigating any adverse impacts are an important concern. Assessing future climate state and its impact remains a difficult task largely because of the uncertainties in future emissions and model errors. Uncertainties in climate projections propagates into impact assessment models and result in uncertainties in the impact assessments. In order to facilitate the evaluation of model data, a fundamental step for assessing model errors, the JPL Regional Climate Model Evaluation System (RCMES: Lean et al. 2010; Hart et al. 2011) has been developed through a joint effort of the investigators from UCLA and JPL. RCMES is also a regional climate component of a larger worldwide ExArch project. We will present the evaluation of the surface temperatures and precipitation from multiple RCMs participating in the African component of the Coordinated Regional Climate Downscaling Experiment (CORDEX) that has organized a suite of regional climate projection experiments in which multiple RCMs and GCMs are incorporated. As a part of the project, CORDEX organized a 20-year regional climate hindcast study in order to quantify and understand the uncertainties originating from model errors. Investigators from JPL, UCLA, and the CORDEX-Africa team collaborate to analyze the RCM hindcast data using RCMES. The analysis is focused on measuring the closeness between individual regional climate model outputs as well as their ensembles and observed

  2. A regional tidal/subtidal circulation model of the southeastern Bering Sea: development, sensitivity analyses and hindcasting

    Science.gov (United States)

    Hermann, Albert J.; Stabeno, Phyllis J.; Haidvogel, Dale B.; Musgrave, David L.

    2002-12-01

    A regional eddy-resolving primitive equation circulation model was used to simulate circulation on the southeastern Bering Sea (SEBS) shelf and basin. This model resolves the dominant observed mean currents, eddies and meanders in the region, and simultaneously includes both tidal and subtidal dynamics. Circulation, temperature, and salinity fields for years 1995 and 1997 were hindcast, using daily wind and buoyancy flux estimates, and tidal forcing derived from a global model. This paper describes the development of the regional model, a comparison of model results with available Eulerian and Lagrangian data, a comparison of results between the two hindcast years, and a sensitivity analysis. Based on these hindcasts and sensitivity analyses, we suggest the following: (1) The Bering Slope Current is a primary source of large ( ˜100 km diameter) eddies in the SEBS basin. Smaller meanders are also formed along the 100 m isobath on the southeastern shelf, and along the 200-m isobath near the shelf break. (2) There is substantial interannual variability in the statistics of eddies within the basin, driven by variability in the strength of the ANSC. (3) The mean flow on the shelf is not strongly sensitive to changes in the imposed strength of the ANSC; rather, it is strongly sensitive to the local wind forcing. (4) Vertical mixing in the SEBS is strongly affected by both tidal and subtidal dynamics. Strongest mixing in the SEBS may in fact occur between the 100- and 400-m isobaths, near the Pribilof Islands, and in Unimak Pass.

  3. Preliminary Analysis on the Global Features of the NCEP CFSv2 Seasonal Hindcasts

    Directory of Open Access Journals (Sweden)

    Gyrlene A. M. Silva

    2014-01-01

    Full Text Available The representation of the CFSv2 ocean-atmosphere ensemble hindcasts is investigated during Dec-Jan-Feb (DJF and Jun-Jul-Aug (JJA from 1983 to 2010. The skill anomaly correlations showed that in some continents the forecasts do not have dependency with changes in the initial conditions. Also, in both seasons the model has a higher skill at the 0-month lead time with the largest spatial biases occurring over the North America, South America, and Oceania. Over the continents the largest biases in the nonlinearity of El Niño minus La Niña events are found over the eastern South Africa, part of Oceania, and central-southeastern parts of South America. During DJF the main biases are related to double-ITCZ, strengthening of SPCZ, and deepening of the Aleutian and Icelandic low pressures. The simulation of a warmer SST on the eastern of most austral oceans, the strengthening (weakening of the Subtropical (Polar Jet over the Southern Hemisphere, and the weakening of the zonal circulation near the Antarctic continent are also found in both seasons. Over the central-eastern Equatorial Pacific a cooler bias in SST is found during JJA. These biases are interpreted by analyses of the simulated global mean-state and their impact on the main patterns of variability.

  4. An Ensemble Kalman Filter with a complex marine ecosystem model: hindcasting phytoplankton in the Cretan Sea

    Directory of Open Access Journals (Sweden)

    J. I. Allen

    2003-01-01

    Full Text Available The purpose of this paper is to examine the use of a complex ecosystem model along with near real-time in situ data and a sequential data assimilation method for state estimation. The ecosystem model used is the European Regional Seas Ecosystem Model (ERSEM; Baretta et al., 1995 and the assimilation method chosen is the Ensemble Kalman Filer (EnKF. Previously, it has been shown that this method captures the nonlinear error evolution in time and is capable of both tracking the observations and providing realistic error estimates for the estimated state. This system has been used to assimilate long time series of in situ chlorophyll taken from a data buoy in the Cretan Sea. The assimilation of this data using the EnKF method results in a marked improvement in the ability of ERSEM to hindcast chlorophyll. The sensitivity of this system to the type of data used for assimilation, the frequency of assimilation, ensemble size and model errors is discussed. The predictability window of the EnKF appears to be at least 2 days. This is an indication that the methodology might be suitable for future operational data assimilation systems using more complex three-dimensional models. Key words. Oceanography: general (numerical modelling; ocean prediction – Oceanography: biological and chemical (plankton

  5. An Ensemble Kalman Filter with a complex marine ecosystem model: hindcasting phytoplankton in the Cretan Sea

    Directory of Open Access Journals (Sweden)

    J. I. Allen

    Full Text Available The purpose of this paper is to examine the use of a complex ecosystem model along with near real-time in situ data and a sequential data assimilation method for state estimation. The ecosystem model used is the European Regional Seas Ecosystem Model (ERSEM; Baretta et al., 1995 and the assimilation method chosen is the Ensemble Kalman Filer (EnKF. Previously, it has been shown that this method captures the nonlinear error evolution in time and is capable of both tracking the observations and providing realistic error estimates for the estimated state. This system has been used to assimilate long time series of in situ chlorophyll taken from a data buoy in the Cretan Sea. The assimilation of this data using the EnKF method results in a marked improvement in the ability of ERSEM to hindcast chlorophyll. The sensitivity of this system to the type of data used for assimilation, the frequency of assimilation, ensemble size and model errors is discussed. The predictability window of the EnKF appears to be at least 2 days. This is an indication that the methodology might be suitable for future operational data assimilation systems using more complex three-dimensional models.

    Key words. Oceanography: general (numerical modelling; ocean prediction – Oceanography: biological and chemical (plankton

  6. Wind waves climatology of the Southeast Pacific Ocean

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  8. Hindcasting the Continuum of Dansgaard-Oeschger variability: Mechanisms, Patterns and Timing

    Science.gov (United States)

    Timmermann, A.; Menviel, L.; Friedrich, T.; England, M. H.

    2013-12-01

    Millennial-scale variability associated with Dansgaard-Oeschger (DO) and Heinrich events (HE) is arguably one of the most puzzling climate phenomena ever discovered in paleoclimate archives of the last glacial period. With similar variability occurring during other glacial periods, it is very timely to identify the underlying mechanisms. Here, we set out to elucidate the dynamics of millennial-scale climate variability by conducting a transient global hindcast simulation with a 3-dimensional intermediate complexity Earth system model covering the period 50 ka B.P. to 30 ka B.P. The model is forced by time-varying external boundary conditions (greenhouse gases, orbital forcing, and ice-sheet orography and albedo) and anomalous North Atlantic freshwater fluxes, which capture the effects of Northern Hemisphere ice-sheet calving on millennial timescales. Together these forcings generate a realistic global climate trajectory, as demonstrated by an extensive model/paleo data comparison. Our analysis is consistent with the simple idea that variations in ice-sheet calving and related changes of the Atlantic Meridional Overturning Circulation were the main driver for the continuum of MIS3 DO and HE variability seen in paleorecords across the globe. According to this scenario, timescale and abruptness of millennial-scale variability are primarily determined by the ice-sheet/ice-shelf calving processes, rather than by the thermohaline circulation. Using a number of high-resolution paleo records from other glacial periods we demonstrate that the proposed ice-sheet calving/AMOC response mechanism can universally explain the continuum of millennial-scale glacial variability during the Late Pleistocene.

  9. Investigation of Spatial Variation of Sea States Offshore of Humboldt Bay CA Using a Hindcast Model.

    Energy Technology Data Exchange (ETDEWEB)

    Dallman, Ann Renee; Neary, Vincent Sinclair

    2014-10-01

    Spatial variability of sea states is an important consideration when performing wave resource assessments and wave resource characterization studies for wave energy converter (WEC) test sites and commercial WEC deployments. This report examines the spatial variation of sea states offshore of Humboldt Bay, CA, using the wave model SWAN . The effect of depth and shoaling on bulk wave parameters is well resolved using the model SWAN with a 200 m grid. At this site, the degree of spatial variation of these bulk wave parameters, with shoaling generally perpendicular to the depth contours, is found to depend on the season. The variation in wave height , for example, was higher in the summer due to the wind and wave sheltering from the protruding land on the coastline north of the model domain. Ho wever, the spatial variation within an area of a potential Tier 1 WEC test site at 45 m depth and 1 square nautical mile is almost negligible; at most about 0.1 m in both winter and summer. The six wave characterization parameters recommended by the IEC 6 2600 - 101 TS were compared at several points along a line perpendicular to shore from the WEC test site . As expected, these parameters varied based on depth , but showed very similar seasonal trends.

  10. An eddy-permitting, dynamically consistent adjoint-based assimilation system for the tropical Pacific: Hindcast experiments in 2000

    KAUST Repository

    Hoteit, Ibrahim

    2010-03-02

    An eddy-permitting adjoint-based assimilation system has been implemented to estimate the state of the tropical Pacific Ocean. The system uses the Massachusetts Institute of Technology\\'s general circulation model and its adjoint. The adjoint method is used to adjust the model to observations by controlling the initial temperature and salinity; temperature, salinity, and horizontal velocities at the open boundaries; and surface fluxes of momentum, heat, and freshwater. The model is constrained with most of the available data sets in the tropical Pacific, including Tropical Atmosphere and Ocean, ARGO, expendable bathythermograph, and satellite SST and sea surface height data, and climatologies. Results of hindcast experiments in 2000 suggest that the iterated adjoint-based descent is able to significantly improve the model consistency with the multivariate data sets, providing a dynamically consistent realization of the tropical Pacific circulation that generally matches the observations to within specified errors. The estimated model state is evaluated both by comparisons with observations and by checking the controls, the momentum balances, and the representation of small-scale features that were not well sampled by the observations used in the assimilation. As part of these checks, the estimated controls are smoothed and applied in independent model runs to check that small changes in the controls do not greatly change the model hindcast. This is a simple ensemble-based uncertainty analysis. In addition, the original and smoothed controls are applied to a version of the model with doubled horizontal resolution resulting in a broadly similar “downscaled” hindcast, showing that the adjustments are not tuned to a single configuration (meaning resolution, topography, and parameter settings). The time-evolving model state and the adjusted controls should be useful for analysis or to supply the forcing, initial, and boundary conditions for runs of other models.

  11. DUE AvalRS: Remote Sensing Derive Avalanche Inventory Data for Decision Support and Hind-Cast After Avalanche Events

    Science.gov (United States)

    Frauenfelder, Regula; Kronholm, Kalle; Solberg, Rune; Larsen, Siri Oyen; Salberg, Arnt-Borre; Larsen, Jan Otto; Bjordal, Heidi

    2010-12-01

    Each year, snow avalanches hit populated areas and parts of the transport network in the Norwegian mountain regions, leading to loss of lives and the damaging of buildings and infrastructure. We present the results of a feasibility study on the operation of a service providing the National Public Roads Administration (NPRA) with hind-cast avalanche inventory data on a local-to-regional scale during the course of the winter season, and as soon as possible after major avalanche events. We have explored the use of imagery from high-resolution and very-high-resolution space-borne satellites applying manual mapping and automated image segmentation.

  12. Wave simulation for the design of an innovative quay wall: the case of Vlorë Harbour

    Science.gov (United States)

    Antonini, Alessandro; Archetti, Renata; Lamberti, Alberto

    2017-01-01

    Sea states and environmental conditions are basic data for the design of marine structures. Hindcasted wave data have been applied here with the aim of identifying the proper design conditions for an innovative quay wall concept. In this paper, the results of a computational fluid dynamics model are used to optimise the new absorbing quay wall of Vlorë Harbour (Republic of Albania) and define the design loads under extreme wave conditions. The design wave states at the harbour entrance have been estimated analysing 31 years of hindcasted wave data simulated through the application of WaveWatch III. Due to the particular geography and topography of the Bay of Vlorë, wave conditions generated from the north-west are transferred to the harbour entrance with the application of a 2-D spectral wave module, whereas southern wave states, which are also the most critical for the port structures, are defined by means of a wave generation model, according to the available wind measurements. Finally, the identified extreme events have been used, through the NewWave approach, as boundary conditions for the numerical analysis of the interaction between the quay wall and the extreme events. The results show that the proposed method, based on numerical modelling at different scales from macro to meso and to micro, allows for the identification of the best site-specific solutions, also for a location devoid of any wave measurement. In this light, the objectives of the paper are two-fold. First, they show the application of sea condition estimations through the use of wave hindcasted data in order to properly define the design wave conditions for a new harbour structure. Second, they present a new approach for investigating an innovative absorbing quay wall based on CFD modelling and the NewWave theory.

  13. Bottom friction and wave-induced roughness

    Science.gov (United States)

    Lepesqueur, J.; Ardhuin, F.; Bennis, A.-C.

    2012-04-01

    The parameterization of the interaction of waves with a sandy bottom including ripple generation and relict ripple roughness (Ardhuin et al. 2003) using the sub-grid roughness algorithm by Tolman (1995) has been implemented in the WAVEWATCH III model and generalized to take into account the variability of the bottom nature, including rock and cohesive sediments. The model is applied with a triangle-based mesh to both the U.S. East-Coast and the French Atlantic to North Sea coasts. The hindcast wave heights over the North Carolina continental shelf during the SHOaling Waves EXperiment reproduce the results of Ardhuin et al. (2003). The new application in the English Channel and Southern North see shows a general better result that with the JONSWAP parameterization. In particular the use of realistic roughness is important with gravel in the central Channel and sand or sand/silt mixtures in the southern North Sea.

  14. Global validation of the wave model WAM over a one-year period using geosat wave height data

    Energy Technology Data Exchange (ETDEWEB)

    Romeiser, R. (Universitaet Hamburg (Germany))

    1993-03-15

    The high quality of wave fields simulated by the third-generation wave model WAM has already been demonstrated in various validation studies using in situ measurements as well as data from satellites as reference. However, owing to limitations of the reference data sets, the previous studies concentrated on relatively small regions or short time periods only, for which adequate measurements were available. In this paper the first global verification of the WAM model over a full 1-year period is presented. The significant wave heights hindcast for 1988 by the WAM model as implemented at the European Centre for Medium Range Weather Forecasts are compared with measurements obtained by the Geosat radar altimeter. The wave heights from WAM and Geosat show good agreement in general. However, significant regional and seasonal differences are found. The hindcast wave heights are underestimated by about 20% in large parts of the southern hemisphere and the tropical region during May-September. For the rest of the time, the agreement with Geosat data is fairly good. Together with the fact that also the rms variability of wave heights in the tropical region is clearly underestimated by WAM, this can possibly be attributed to simplifications like the neglect of atmospheric stratification effects when converting wind speeds to the wind stress fields driving WAM. Furthermore, the intercomparison indicates that low wave heights below [approx]1.5 m are generally overestimated by WAM. As it is planned to use altimeter wave heights for updating wave models in future data assimilation systems, it is quite important to have efficient quality control criteria for these data. The difference between the Geosat and WAM wave heights shows a clear dependence on the additional parameters in some cases, which must be related to quality problems of the Geosat data. Some new criteria for the rejection of incorrect Geosat data points are obtained. 16 refs., 6 figs.

  15. Trends in surface wind speed and significant wave height as revealed by ERA-Interim wind wave hindcast in the Central Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Shanas, P.R.; SanilKumar, V.

    , 2006). The main advantages of global reanalysis data are their physical consistency and relatively high 3    temporal coverage. The problem of inhomogeneity is not expected; although, the use of these data for regional climate studies presents some... the frequency of occurrences of wind-sea and swell, two probability indices were introduced by Chen et al. (2002). Ps=Ns/N and (3) Pw =Nw/N (4) Where, Ns and Nw are the numbers of swell dominated and wind-sea dominated...

  16. Assessment of wave energy resources in Hawaii

    Energy Technology Data Exchange (ETDEWEB)

    Stopa, Justin E.; Cheung, Kwok Fai [Department of Ocean and Resources Engineering, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); Chen, Yi-Leng [Department of Meteorology, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)

    2011-02-15

    Hawaii is subject to direct approach of swells from distant storms as well as seas generated by trade winds passing through the islands. The archipelago creates a localized weather system that modifies the wave energy resources from the far field. We implement a nested computational grid along the major Hawaiian Islands in the global WaveWatch3 (WW3) model and utilize the Weather Research and Forecast (WRF) model to provide high-resolution mesoscale wind forcing over the Hawaii region. Two hindcast case studies representative of the year-round conditions provide a quantitative assessment of the regional wind and wave patterns as well as the wave energy resources along the Hawaiian Island chain. These events of approximately two weeks each have a range of wind speeds, ground swells, and wind waves for validation of the model system with satellite and buoy measurements. The results demonstrate the wave energy potential in Hawaii waters. While the episodic swell events have enormous power reaching 60 kW/m, the wind waves, augmented by the local weather, provide a consistent energy resource of 15-25 kW/m throughout the year. (author)

  17. The Effect of the Leeuwin Current on Offshore Surface Gravity Waves in Southwest Western Australia

    Science.gov (United States)

    Wandres, Moritz; Wijeratne, E. M. S.; Cosoli, Simone; Pattiaratchi, Charitha

    2017-11-01

    The knowledge of regional wave regimes is critical for coastal zone planning, protection, and management. In this study, the influence of the offshore current regime on surface gravity waves on the southwest Western Australian (SWWA) continental shelf was examined. This was achieved by coupling the three dimensional, free surface, terrain-following hydrodynamic Regional Ocean Modelling System (ROMS) and the third generation wave model Simulating WAves Nearshore (SWAN) using the Coupled Ocean-Atmosphere-WaveSediment Transport (COAWST) model. Different representative states of the Leeuwin Current (LC), a strong pole-ward flowing boundary current with a persistent eddy field along the SWWA shelf edge were simulated and used to investigate their influence on different large wave events. The coupled wave-current simulations were compared to wave only simulations, which represented scenarios in the absence of a background current field. Results showed that the LC and the eddy field significantly impact SWWA waves. Significant wave heights increased (decreased) when currents were opposing (aligning with) the incoming wave directions. During a fully developed LC system significant wave heights were altered by up to ±25% and wave directions by up to ±20°. The change in wave direction indicates that the LC may modify nearshore wave dynamics and consequently alter sediment patterns. Operational regional wave forecasts and hindcasts may give flawed predictions if wave-current interaction is not properly accounted for.

  18. Changing waves and storms in the Northeast Atlantic?

    Energy Technology Data Exchange (ETDEWEB)

    Carretero, J.C.; Gomez, M.; Lozano, I. [Programa de Clima Maritimo (Puertos del Estado), Madrid (Spain)] [and others; WASA group

    1997-12-31

    The European project WASA has been set up to verifying, or to disprove hypotheses of a worsening storm and wave climate in the Northeast Atlantic and its adjacent seas in the present century. Its main conclusion is that the storm- and wave climate in most of the Northeast Atlantic and in the North Sea has undergone significant variations on time scales of decades; it has indeed roughened in recent decades, but the present intensity of the storm- and wave-climate seems to be comparable with that at the beginning of this century. Part of this variability is found to be related to the North Atlantic oscillation. An analysis of a high-resolution climate change experiment, mimicking global warming due to increased greenhouse gas concentrations, results in a weak increase of storm activity and (extreme) wave heights in the Bay of Biscay and in the North Sea, while storm action and waves slightly decrease along the Norwegian coast and in most of the remaining North Atlantic area. A weak increase in storm surges in the southern and eastern part of the North Sea is expected. These projected anthropogenic changes at the time of CO{sub 2} doubling fall well within the limits of variability observed in the past. A major methodical obstacle for the assessment of changes in the intensity of storm and wave events are inhomogeneities in the observational record, both in terms of local observations and of analyzed pro ducts (such as weather maps), which usually produce an artificial increase of extreme winds. This occurs because older analyses were based on fewer observations and with more limited conceptual and numerical models of the dynamical processes than more recent analyses. 52 refs.

  19. Validation of a homogeneous 41-year (1961-2001) winter precipitation hindcasted dataset over the Iberian Peninsula: assessment of the regional improvement of global reanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Sotillo, M.G. [Area de Medio Fisico, Puertos del Estado, Madrid (Spain); Martin, M.L. [Universidad de Valladolid, Dpto. Matematica Aplicada, Escuela Universitaria de Informatica, Campus de Segovia, Segovia (Spain); Valero, F. [Universidad Complutense de Madrid, Dpto. Astrofisica y CC. de la Atmosfera, Facultad de CC Fisicas, Madrid (Spain); Luna, M.Y. [Instituto Nacional de Meteorologia, Madrid (Spain)

    2006-11-15

    A 44-year (1958-2001) homogeneous, Mediterranean, high-resolution atmospheric database was generated through dynamical downscaling within the HIPOCAS (Hindcast of Dynamic Processes of the Ocean and Coastal Areas of Europe) Project framework. This work attempts to provide a validation of the monthly winter HIPOCAS precipitation over the Iberian Peninsula and the Balearic Islands and to evaluate the potential improvement of these new hindcasted data versus global reanalysis datasets. The validation was performed through the comparative analysis with a precipitation database derived from 4,617 in situ stations located over Iberia and the Balearics. The statistical comparative analysis between the observed and the HIPOCAS fields highlights their very good agreement not only in terms of spatial and time distribution, but also in terms of total amount of precipitation. A principal component analysis is carried out, showing that the patterns derived from the HIPOCAS data largely capture the main characteristics of the observed field. Moreover, it is worth to note that the HIPOCAS patterns reproduce accurately the observed regional characteristics linked to the main orographic features of the study domain. The existence of high correlations between the hindcasted and observed principal component time series gives a measure of the model performance ability. An additional comparative study of the HIPOCAS winter precipitation with global reanalysis data (NCEP and ERA) is performed. This study reveals the important regional improvement in the characterization of the observed precipitation introduced by the HIPOCAS hindcast relative to the above global reanalyses. Such improvement is effective not only in terms of total amount values, but also in the spatial distribution, the observed field being much more realistically reproduced by HIPOCAS than by the global reanalysis data. (orig.)

  20. Validation of a homogeneous 41-year (1961-2001) winter precipitation hindcasted dataset over the Iberian Peninsula: assessment of the regional improvement of global reanalysis

    Science.gov (United States)

    Sotillo, M. G.; Martín, M. L.; Valero, F.; Luna, M. Y.

    2006-11-01

    A 44-year (1958-2001) homogeneous, Mediterranean, high-resolution atmospheric database was generated through dynamical downscaling within the HIPOCAS (Hindcast of Dynamic Processes of the Ocean and Coastal Areas of Europe) Project framework. This work attempts to provide a validation of the monthly winter HIPOCAS precipitation over the Iberian Peninsula and the Balearic Islands and to evaluate the potential improvement of these new hindcasted data versus global reanalysis datasets. The validation was performed through the comparative analysis with a precipitation database derived from 4,617 in situ stations located over Iberia and the Balearics. The statistical comparative analysis between the observed and the HIPOCAS fields highlights their very good agreement not only in terms of spatial and time distribution, but also in terms of total amount of precipitation. A principal component analysis is carried out, showing that the patterns derived from the HIPOCAS data largely capture the main characteristics of the observed field. Moreover, it is worth to note that the HIPOCAS patterns reproduce accurately the observed regional characteristics linked to the main orographic features of the study domain. The existence of high correlations between the hindcasted and observed principal component time series gives a measure of the model performance ability. An additional comparative study of the HIPOCAS winter precipitation with global reanalysis data (NCEP and ERA) is performed. This study reveals the important regional improvement in the characterization of the observed precipitation introduced by the HIPOCAS hindcast relative to the above global reanalyses. Such improvement is effective not only in terms of total amount values, but also in the spatial distribution, the observed field being much more realistically reproduced by HIPOCAS than by the global reanalysis data.

  1. Extreme Gravity Waves In The Arabian Gulf

    Directory of Open Access Journals (Sweden)

    S. Neelamani

    2009-06-01

    Full Text Available The extreme significant wave heights and the corresponding mean wave periods were predicted for return periods of 12, 25, 50, 100 and 200 years for 38 different locations in the territorial and offshore locations of countries surrounding the Arabian Gulf. The input wave data for the study is hindcast waves obtained using a WAM model for a total period of 12 years, (1993 to 2004. The peak over threshold method (with 1.0 m as threshold value, is used for selecting the data for the extreme wave analysis. In general, a Weibull distribution is found to fit the data well compared to the Gumbel distribution for all these locations. From the joint probability of wave height and wave period, a simple polynomial relationship (Tmean = C3 (HsC4 is used to obtain the relationship between the significant wave height and mean wave period for all the 38 locations. The value of C3 is found to vary from 3.8 to 4.8 and the value of C4 is found to vary from 0.19 to 0.32. The mean wave period was found to be more sensitive to change in locations within the Gulf and it is less sensitive to change in return periods from 12 years to 200 years. The significant wave heights for 100 year return period varied from 3.0 to 4.5 for water depths of 9 to 16 m, whereas in the offshore sites (depths from 30 to 60 m it varied from 5.0 to 7.0 m. A large number of coastal projects are in progress in the Arabian Gulf and many new projects are being planned in this region for the future. The results of the present study will be highly useful for optimal design of the ocean structures for these projects.

  2. Solar and planetary oscillation control on climate change: hind-cast, forecast and a comparison with the CMIP5 GCMs

    CERN Document Server

    Scafetta, Nicola

    2013-01-01

    Global surface temperature records (e.g. HadCRUT4) since 1850 are characterized by climatic oscillations synchronous with specific solar, planetary and lunar harmonics superimposed on a background warming modulation. The latter is related to a long millennial solar oscillation and to changes in the chemical composition of the atmosphere (e.g. aerosol and greenhouse gases). However, current general circulation climate models, e.g. the CMIP5 GCMs, to be used in the AR5 IPCC Report in 2013, fail to reconstruct the observed climatic oscillations. As an alternate, an empirical model is proposed that uses: (1) a specific set of decadal, multidecadal, secular and millennial astronomic harmonics to simulate the observed climatic oscillations; (2) a 0.45 attenuation of the GCM ensemble mean simulations to model the anthropogenic and volcano forcing effects. The proposed empirical model outperforms the GCMs by better hind-casting the observed 1850-2012 climatic patterns. It is found that: (1) about 50-60% of the warmin...

  3. Composition and variability of the Denmark Strait Overflow Water in a high-resolution numerical model hindcast simulation

    Science.gov (United States)

    Behrens, Erik; Vâge, Kjetil; Harden, Benjamin; Biastoch, Arne; Böning, Claus W.

    2017-04-01

    The upstream sources and pathways of the Denmark Strait Overflow Water and their variability have been investigated using a high-resolution model hindcast. This global simulation covers the period from 1948 to 2009 and uses a fine model mesh (1/20°) to resolve mesoscale features and the complex current structure north of Iceland explicitly. The three sources of the Denmark Strait Overflow, the shelfbreak East Greenland Current (EGC), the separated EGC, and the North Icelandic Jet, have been analyzed using Eulerian and Lagrangian diagnostics. The shelfbreak EGC contributes the largest fraction in terms of volume and freshwater transport to the Denmark Strait Overflow and is the main driver of the overflow variability. The North Icelandic Jet contributes the densest water to the Denmark Strait Overflow and shows only small temporal transport variations. During summer, the net volume and freshwater transports to the south are reduced. On interannual time scales, these transports are highly correlated with the large-scale wind stress curl around Iceland and, to some extent, influenced by the North Atlantic Oscillation, with enhanced southward transports during positive phases. The Lagrangian trajectories support the existence of a hypothesized overturning loop along the shelfbreak north of Iceland, where water carried by the North Icelandic Irminger Current is transformed and feeds the North Icelandic Jet. Monitoring these two currents and the region north of the Iceland shelfbreak could provide the potential to track long-term changes in the Denmark Strait Overflow and thus also the AMOC.

  4. Southern California coastal response to CMIP5 projected 21st century wave conditions

    Science.gov (United States)

    Hegermiller, C.; Erikson, L. H.; Barnard, P.; Adams, P. N.

    2016-02-01

    Recent projections of 21st century Eastern North Pacific deep-water wave conditions under climate change scenarios predict slightly decreased significant wave heights, increased peak wave periods, and more southerly wave directions offshore of Southern California relative to historical conditions. Combined dynamical and statistical efforts were employed to project wave climate-driven changes in local erosion and accretion patterns along the Southern California coast based on these deep-water wave projections. The numerical wave model SWAN was forced with USACE WIS hindcast bulk wave parameters and reanalysis near-surface winds to generate nearshore wave conditions at the 5 m contour from 1980-2010. A nontraditional lookup table was created to establish the functional relationship between deep-water wave conditions defined by the ERA-Interim wave reanalysis and nearshore wave conditions simulated with SWAN. Historical and future deep-water wave time series were translated to the nearshore via the lookup table. Refraction across the continental shelf reduces the difference between projected and historical nearshore wave angles. Never the less, changes in gradients in longshore transport, resulting from long-term changes in wave angle, create new hot spots for erosion and accretion. This work identifies potentially vulnerable areas on which to focus protection and mitigation efforts and provides an approach for assessing how the future evolution of the wave climate due to climate change may affect coastal processes and hazards.

  5. The climatology of the Red Sea - part 2: the waves

    KAUST Repository

    Langodan, Sabique

    2017-05-09

    The wave climatology of the Red Sea is described based on a 30-year hindcast generated using WAVEWATCH III configured on a 5-km resolution grid and forced by Red Sea reanalysis surface winds from the advanced Weather Research and Forecasting model. The wave simulations have been validated using buoy and altimeter data. The four main wind systems in the Red Sea characterize the corresponding wave climatology. The dominant ones are the two opposite wave systems with different genesis, propagating along the axis of the basin. The highest waves are generated at the centre of the Red Sea as a consequence of the strong seasonal winds blowing from the Tokar Gap on the African side. There is a general long-term trend toward lowering the values of the significant wave height over the whole basin, with a decreasing rate depending on the genesis of the individual systems.

  6. Storm-wave trends in Mexican waters of the Gulf of Mexico and Caribbean Sea

    Directory of Open Access Journals (Sweden)

    E. Ojeda

    2017-08-01

    Full Text Available Thirty-year time series of hindcast wave data were analysed for 10 coastal locations along the eastern Mexican coast to obtain information about storm events occurring in the region, with the goal of examining the possible presence of interannual trends in the number of storm-wave events and their main features (wave height, duration and energy content. The storms were defined according to their significant wave height and duration, and the events were classified as related to either tropical cyclones or Norte events. The occurrence and characteristics of both types of events were analysed independently. There is no statistically significant change in the number of storm-wave events related to Nortes or their characteristics during the study period. However, there is a subtle increase in the number of events related to tropical cyclones in the western Caribbean region and a more evident increase in wave height and energy content of these events.

  7. A test-bed modeling study for wave resource assessment

    Science.gov (United States)

    Yang, Z.; Neary, V. S.; Wang, T.; Gunawan, B.; Dallman, A.

    2016-02-01

    Hindcasts from phase-averaged wave models are commonly used to estimate standard statistics used in wave energy resource assessments. However, the research community and wave energy converter industry is lacking a well-documented and consistent modeling approach for conducting these resource assessments at different phases of WEC project development, and at different spatial scales, e.g., from small-scale pilot study to large-scale commercial deployment. Therefore, it is necessary to evaluate current wave model codes, as well as limitations and knowledge gaps for predicting sea states, in order to establish best wave modeling practices, and to identify future research needs to improve wave prediction for resource assessment. This paper presents the first phase of an on-going modeling study to address these concerns. The modeling study is being conducted at a test-bed site off the Central Oregon Coast using two of the most widely-used third-generation wave models - WaveWatchIII and SWAN. A nested-grid modeling approach, with domain dimension ranging from global to regional scales, was used to provide wave spectral boundary condition to a local scale model domain, which has a spatial dimension around 60km by 60km and a grid resolution of 250m - 300m. Model results simulated by WaveWatchIII and SWAN in a structured-grid framework are compared to NOAA wave buoy data for the six wave parameters, including omnidirectional wave power, significant wave height, energy period, spectral width, direction of maximum directionally resolved wave power, and directionality coefficient. Model performance and computational efficiency are evaluated, and the best practices for wave resource assessments are discussed, based on a set of standard error statistics and model run times.

  8. Investigation of short-term effective radiative forcing of fire aerosols over North America using nudged hindcast ensembles

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yawen; Zhang, Kai; Qian, Yun; Wang, Yuhang; Zou, Yufei; Song, Yongjia; Wan, Hui; Liu, Xiaohong; Yang, Xiuqun

    2018-01-03

    Aerosols from fire emissions can potentially have large impact on clouds and radiation. However, fire aerosol sources are often intermittent, and their effect on weather and climate is difficult to quantify. Here we investigated the short-term effective radiative forcing of fire aerosols using the global aerosol–climate model Community Atmosphere Model version 5 (CAM5). Different from previous studies, we used nudged hindcast ensembles to quantify the forcing uncertainty due to the chaotic response to small perturbations in the atmosphere state. Daily mean emissions from three fire inventories were used to consider the uncertainty in emission strength and injection heights. The simulated aerosol optical depth (AOD) and mass concentrations were evaluated against in situ measurements and reanalysis data. Overall, the results show the model has reasonably good predicting skills. Short (10-day) nudged ensemble simulations were then performed with and without fire emissions to estimate the effective radiative forcing. Results show fire aerosols have large effects on both liquid and ice clouds over the two selected regions in April 2009. Ensemble mean results show strong negative shortwave cloud radiative effect (SCRE) over almost the entirety of southern Mexico, with a 10-day regional mean value of -3.0Wm-2. Over the central US, the SCRE is positive in the north but negative in the south, and the regional mean SCRE is small (-0.56Wm-2). For the 10-day average, we found a large ensemble spread of regional mean shortwave cloud radiative effect over southern Mexico (15.6% of the corresponding ensemble mean) and the central US (64.3 %), despite the regional mean AOD time series being almost indistinguishable during the 10-day period. Moreover, the ensemble spread is much larger when using daily averages instead of 10-day averages. This demonstrates the importance of using a large ensemble of simulations to estimate the short-term aerosol effective radiative forcing.

  9. Evaluation of cool season precipitation event characteristics over the Northeast US in a suite of downscaled climate model hindcasts

    Science.gov (United States)

    Loikith, Paul C.; Waliser, Duane E.; Kim, Jinwon; Ferraro, Robert

    2017-08-01

    Cool season precipitation event characteristics are evaluated across a suite of downscaled climate models over the northeastern US. Downscaled hindcast simulations are produced by dynamically downscaling the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA2) using the National Aeronautics and Space Administration (NASA)-Unified Weather Research and Forecasting (WRF) regional climate model (RCM) and the Goddard Earth Observing System Model, Version 5 (GEOS-5) global climate model. NU-WRF RCM simulations are produced at 24, 12, and 4-km horizontal resolutions using a range of spectral nudging schemes while the MERRA2 global downscaled run is provided at 12.5-km. All model runs are evaluated using four metrics designed to capture key features of precipitation events: event frequency, event intensity, even total, and event duration. Overall, the downscaling approaches result in a reasonable representation of many of the key features of precipitation events over the region, however considerable biases exist in the magnitude of each metric. Based on this evaluation there is no clear indication that higher resolution simulations result in more realistic results in general, however many small-scale features such as orographic enhancement of precipitation are only captured at higher resolutions suggesting some added value over coarser resolution. While the differences between simulations produced using nudging and no nudging are small, there is some improvement in model fidelity when nudging is introduced, especially at a cutoff wavelength of 600 km compared to 2000 km. Based on the results of this evaluation, dynamical regional downscaling using NU-WRF results in a more realistic representation of precipitation event climatology than the global downscaling of MERRA2 using GEOS-5.

  10. Assessment of offshore wind power potential in the Aegean and Ionian Seas based on high-resolution hindcast model results

    Directory of Open Access Journals (Sweden)

    Takvor Soukissian

    2017-03-01

    Full Text Available In this study long-term wind data obtained from high-resolution hindcast simulations is used to analytically assess offshore wind power potential in the Aegean and Ionian Seas and provide wind climate and wind power potential characteristics at selected locations, where offshore wind farms are at the concept/planning phase. After ensuring the good model performance through detailed validation against buoy measurements, offshore wind speed and wind direction at 10 m above sea level are statistically analyzed on the annual and seasonal time scale. The spatial distribution of the mean wind speed and wind direction are provided in the appropriate time scales, along with the mean annual and the inter-annual variability; these statistical quantities are useful in the offshore wind energy sector as regards the preliminary identification of favorable sites for exploitation of offshore wind energy. Moreover, the offshore wind power potential and its variability are also estimated at 80 m height above sea level. The obtained results reveal that there are specific areas in the central and the eastern Aegean Sea that combine intense annual winds with low variability; the annual offshore wind power potential in these areas reach values close to 900 W/m2, suggesting that a detailed assessment of offshore wind energy would be worth noticing and could lead in attractive investments. Furthermore, as a rough estimate of the availability factor, the equiprobable contours of the event [4 m/s ≤ wind speed ≤ 25 m/s] are also estimated and presented. The selected lower and upper bounds of wind speed correspond to typical cut-in and cut-out wind speed thresholds, respectively, for commercial offshore wind turbines. Finally, for seven offshore wind farms that are at the concept/planning phase the main wind climate and wind power density characteristics are also provided.

  11. Building a Pre-Competitive Knowledge Base to Support Australia's Wave Energy Industry

    Science.gov (United States)

    Hoeke, R. K.; Hemer, M. A.; Symonds, G.; Rosebrock, U.; Kenyon, R.; Zieger, S.; Durrant, T.; Contardo, S.; O'Grady, J.; Mcinnes, K. L.

    2016-02-01

    A pre-competitive, query-able and openly available spatio-temporal atlas of Australia's wind-wave energy resource and marine management uses is being delivered. To provide the best representation of wave energy resource information, accounting for both spatial and temporal characteristics of the resource, a 34+yr numerical hindcast of wave conditions in the Australian region has been developed. Considerable in situ and remotely sensed data have been collected to support calibration and validation of the hindcast, resulting in a high-quality characterisation of the available wave resource in the Australian domain. Planning for wave energy projects is also subject to other spatial constraints. Spatial information on alternative uses of the marine domain including, for example, fisheries and aquaculture, oil and gas, shipping, navigation and ports, marine parks and reserves, sub-sea cables and infrastructure, shipwrecks and sites of cultural significance, have been compiled to complement the spatial characterisation of resource and support spatial planning of future wave energy projects. Both resource and spatial constraint information are being disseminated via a state-of-the-art portal, designed to meet the needs of all industry stakeholders. Another aspect currently impeding the industry in Australia is the limited evidence-base of impacts of wave energy extraction on adjacent marine and coastal environments. To build this evidence base, a network of in situ wave measurement devices have been deployed surrounding the 3 wave energy converters of Carnegie Wave Energy Limited's Perth Wave Energy Project. This data is being used to calibrate and validate numerical simulations of the project site. Early stage results will be presented.

  12. A global wave parameter database for geophysical applications. Part 2: Model validation with improved source term parameterization

    Science.gov (United States)

    Rascle, Nicolas; Ardhuin, Fabrice

    2013-10-01

    A multi-scale global hindcast of ocean waves is presented that covers the years 1994-2012, based on recently published parameterizations for wind sea and swell dissipation [Ardhuin, F., Rogers, E., Babanin, A., Filipot, J.-F., Magne, R., Roland, A., van der Westhuysen, A., Queffeulou, P., Lefevre, J.-M., Aouf, L., Collard, F., 2010. Semi-empirical dissipation source functions for wind-wave models: Part I. Definition, calibration and validation. J. Phys. Oceanogr. 40 (9), 1917-1941]. Results from this hindcast include traditional wave parameters, like the significant wave height and mean periods, and we particularly consider the accuracy of the results for phenomenal sea states, with significant heights above 14 m. Using unbiased winds, there is no evidence of a bias in wave heights even for this very high range. Various spectral moments were also validated, including the surface Stokes drift and mean square slopes that are relevant for wave-current interactions modelling and remote sensing, and also spectra of seismic noise sources. The estimation of these parameters is made more accurate by the new wave growth and dissipation parameterizations. Associated air-sea fluxes of momentum and energy are significantly different from what is obtained with the WAM-Cycle 4 parameterization, with a roughness that is practically a function of wind speed only. That particular output of the model does not appear very realistic and will require future adjustments of the generation and dissipation parameterizations.

  13. Wave-Related Reynolds Number Parameterizations of CO2 and DMS Transfer Velocities

    Science.gov (United States)

    Brumer, Sophia E.; Zappa, Christopher J.; Blomquist, Byron W.; Fairall, Christopher W.; Cifuentes-Lorenzen, Alejandro; Edson, James B.; Brooks, Ian M.; Huebert, Barry J.

    2017-10-01

    Predicting future climate hinges on our understanding of and ability to quantify air-sea gas transfer. The latter relies on parameterizations of the gas transfer velocity k, which represents physical mass transfer mechanisms and is usually parameterized as a nonlinear function of wind forcing. In an attempt to reduce uncertainties in k, this study explores empirical parameterizations that incorporate both wind speed and sea state dependence via wave-wind and breaking Reynolds numbers, RH and RB. Analysis of concurrent eddy covariance gas transfer and measured wavefield statistics supplemented by wave model hindcasts shows for the first time that wave-related Reynolds numbers collapse four open ocean data sets that have a wind speed dependence of CO2 transfer velocity ranging from lower than quadratic to cubic. Wave-related Reynolds number and wind speed show comparable performance for parametrizing dimethyl sulfide (DMS) which, because of its higher solubility, is less affected by bubble-mediated exchange associated with wave breaking.

  14. Nearshore Wave Predictions along the Oregon and Southwest Washington Coasts

    Science.gov (United States)

    García-Medina, G.; Özkan-Haller, H. T.; Ruggiero, P.

    2012-12-01

    The Pacific Northwest region of the United States of America is characterized as having one of the most severe wave climates in the northern hemisphere. In addition, an observed multi-decadal increase in wave heights and the potential of harvesting wave energy in the region is attracting local governments, the private sector and scientific communities to understand wave transformation across the shelf and expand the predictive capabilities. To satisfy these and other needs, a high-resolution wave forecasting model was recently implemented for the Oregon and Southwest Washington coasts. The modeling domain extends from Klamath, California (41.50o) to the south to Taholah, Washington (47.35o) to the north and to the shelf break at the offshore boundary. This implementation has been proven accurate with linear correlation coefficients in the excess of 0.83 and percent errors of ˜ 20% when comparing results from multiple hindcasts to ground truth data even at water depths as shallow as 13 m. This implementation is able to capture the alongshore variations in the wave field caused by the major bathymetric features in the region. The forecasting model is run daily producing 84 hour forecasts. The results are disseminated via the Northwest Association of Networked Ocean Observing System webpage (http://www.nanoos.org). Spectral and bulk parameter forecasts are being made available at 233 locations along the 25 meter contour. In addition spatial plots of swell wave height, peak wave period and direction are made available for each forecast hour.

  15. Regional improvement of global reanalyses by means of a new long-term Mediterranean hindcasted precipitation dataset: a first study over the Iberian Peninsula

    Directory of Open Access Journals (Sweden)

    M. G. Sotillo

    2006-01-01

    Full Text Available Generation of a Mediterranean long-term (1958-2001 homogeneous high resolution environmental database constituted the main objective whitin the HIPOCAS Project. The high number of parameters included in this database allows a complete characterization of Mediterranean storms. In this paper, the HIPOCAS precipitation reliability over the Iberian Peninsula and the Balearic Islands is evaluated against long-term in-situ observations from Iberia. In order to provide a more complete study, comparisons of the HIPOCAS field with NCEP/NCAR and ERA global reanalysis show the important improvement in the characterisation of the observed precipitation introduced by the HIPOCAS hindcast.

  16. The CAUSES Model Intercomparison Project: Using hindcast approach to study the U.S. summertime surface warm temperature bias

    Science.gov (United States)

    Ma, H. Y.; Klein, S. A.; Xie, S.; Zhang, C.; Morcrette, C. J.; Van Weverberg, K.; Petch, J.

    2016-12-01

    The CAUSES (Clouds Above the United States and Errors at the Surface) is a joint GASS/RGCM/ASR model intercomparison project with an observational focus (data from the U.S. DOE ARM SGP site and other observations). The goal of this project is to evaluate the role of clouds, radiation and precipitation processes in contributing to the surface air temperature bias in the region of the central U.S., which is seen in several weather and climate models. In this project, we use a short-term hindcast approach and examine the error growth due to cloud-associated processes while the large-scale state remains close to observations. The study period is from April 1 to August 31, 2011, which also covers the entire Midlatitude Continental Convective Clouds Experiment (MC3E) campaign that provides very frequent radiosondes (8 per day) and many extensive cloud and precipitation radar observations. Our preliminary analysis indicates that the warm surface air temperature bias in the mean diurnal cycle of the whole study period is very robust across all the participating models over the ARM SGP site. During the spring season (April-May), the daytime warm bias in most models is mostly due to excessive net surface shortwave flux resulting from insufficient deep convective cloud fraction or too optically thin clouds. The nighttime warm bias is likely due to the excessive downwelling longwave flux warming resulting from the persisting deep clouds. During the summer season (June-August), bias contribution from precipitation bias becomes important. The insufficient seasonal accumulated precipitation from the propagating convective systems originated from the Rockies contributes to lower soil moisture. Such condition drives the land surface to a dry state whereby radiative input can only be balanced by sensible heat loss through an increased surface air temperature. More information about the CAUSES project can be found through the following project webpage (http

  17. Multi-decadal changes in southern hemisphere subduction rates in a 1/12° ocean model hindcast

    Science.gov (United States)

    Nowatzki, Eva; Patara, Lavinia; Böning, Claus; Karstensen, Johannes

    2017-04-01

    Mode and Intermediate Waters formed in the mid-latitudes of the Southern Ocean represent a major agent for the ventilation of the southern hemisphere lower thermocline, playing a key role in the uptake and intermittent storage of anthropogenic CO2. Long-term hydrographic records as well as modelling studies have provided indications that characteristics of these water masses have been changing over the last decades. Changes in heat, freshwater and momentum fluxes may all contribute to the water mass variability. In this study, we investigate the temporal and spatial variability of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) formation and its linkages to changing atmospheric conditions with a global ocean - sea-ice model for the time period 1979-2007. The model employs a horizontal resolution of 1/12° for the Southern Ocean and is forced with the CORE-II interannually-varying atmospheric forcing data set. The hindcast simulation is complemented by a second experiment with a repeated 'normal-year' atmospheric forcing in order to separate atmospherically-related changes from stochastic variability and spurious model trends. We find that subduction rates in the density range of SAMW and AAIW are dominated by the lateral induction term and as such are tightly linked to the maximum mixed layer depth (MLD) at the end of winter. The model simulation shows multi-decadal trends in subduction rates, however the trends are not uniform across the density range of SAMW/ AAIW and differ between the Pacific and Indian Ocean sectors. Largest changes in AAIW formation are found in the southeast Pacific, whereas changes in SAMW formation are most pronounced in the Indian Ocean. In the Pacific, the decrease of subduction rates in the AAIW range is contrasted by a positive trend in the SAMW range. The changes in subduction rates are linked to salinity and thus density trends of the winter mixed layer that can be traced to multi-decadal trends in heat and

  18. Investigation of short-term effective radiative forcing of fire aerosols over North America using nudged hindcast ensembles

    Directory of Open Access Journals (Sweden)

    Y. Liu

    2018-01-01

    Full Text Available Aerosols from fire emissions can potentially have large impact on clouds and radiation. However, fire aerosol sources are often intermittent, and their effect on weather and climate is difficult to quantify. Here we investigated the short-term effective radiative forcing of fire aerosols using the global aerosol–climate model Community Atmosphere Model version 5 (CAM5. Different from previous studies, we used nudged hindcast ensembles to quantify the forcing uncertainty due to the chaotic response to small perturbations in the atmosphere state. Daily mean emissions from three fire inventories were used to consider the uncertainty in emission strength and injection heights. The simulated aerosol optical depth (AOD and mass concentrations were evaluated against in situ measurements and reanalysis data. Overall, the results show the model has reasonably good predicting skills. Short (10-day nudged ensemble simulations were then performed with and without fire emissions to estimate the effective radiative forcing. Results show fire aerosols have large effects on both liquid and ice clouds over the two selected regions in April 2009. Ensemble mean results show strong negative shortwave cloud radiative effect (SCRE over almost the entirety of southern Mexico, with a 10-day regional mean value of −3.0 W m−2. Over the central US, the SCRE is positive in the north but negative in the south, and the regional mean SCRE is small (−0.56 W m−2. For the 10-day average, we found a large ensemble spread of regional mean shortwave cloud radiative effect over southern Mexico (15.6 % of the corresponding ensemble mean and the central US (64.3 %, despite the regional mean AOD time series being almost indistinguishable during the 10-day period. Moreover, the ensemble spread is much larger when using daily averages instead of 10-day averages. This demonstrates the importance of using a large ensemble of simulations to estimate the short

  19. Trends in marine plankton composition and export production in a CCSM-BEC hindcast (1960-2006)

    Science.gov (United States)

    Laufkoetter, Charlotte; Vogt, Meike; Gruber, Nicolas

    2013-04-01

    Climate-driven changes in marine plankton distribution are assumed to influence primary production, export production and export efficiency. We analyse trends in marine primary and particle export production and their relation to marine phytoplankton community composition using a hindcast simulation of the Biogeochemical Elemental Cycling Model (BEC) coupled to the Community Climate System Model over the period 1960-2006. The BEC models one generic zooplankton type and three phytoplankton types, diatoms, diazotrophs and small phytoplankton. In our simulation, small phytoplankton biomass, diatom biomass and zooplankton biomass decrease by 8%, 3% and 5%, respectively over the last 50 years. This decrease in plankton biomass is followed by a decrease in global primary and export production by 6% and 7%. Primary and export production decrease strongest in the Western Pacific (-18% and -23% respectively), where increased stratification leads to a decrease in total phytoplankton (-10%) and a decrease in diatom fraction (-12x%). The effect is a decrease in zooplankton biomass (-14%) and a lower export efficiency (-5%). Strong phytoplankton composition changes occur in the Southern Ocean and North Atlantic, where increased wind stress leads to stronger mixing, which reduces the biomass of small phytoplankton (-5% in the North Atlantic, -28% in the Southern Ocean), while diatoms profit from higher nutrient inputs and lower grazing pressure (+40% in the North Atlantic, + 22% in the Southern Ocean). The export efficiency and the relative fraction of diatoms are positively correlated (r=0.8) in most areas except the Northern Pacific and Antarctic Circumpolar Current, where the correlation is negative (r=-0.5). In areas where the correlation between diatom fraction and export efficiency is negative, small phytoplankton are simulated to consist of a high fraction of calcifiers, which are parameterized to produce faster sinking particles than diatoms in our model

  20. Trend analysis of the wave storminess: the wave direction

    Science.gov (United States)

    Casas Prat, M.; Sierra, J. P.; Mösso, C.; Sánchez-Arcilla, A.

    2009-09-01

    directionality. It is based on 44 year hindcast model data (1958-2001) of the HIPOCAS project, enabling to work with a longer time series compared to the existing measured ones. 41 nodes of this database are used, containing 3 hourly simulated data of significant wave height and wave direction, among other parameters. For storm definition, the Peak Over Threshold (POT) method is used with some additional duration requirements in order to analyse statistically independent events (Mendoza & Jiménez, 2006). Including both wave height and storm duration, the wave storminess is characterised by the energy content (Mendoza & Jiménez, 2004), being in turn log-transformed because of its positive scale. Separately, the wave directionality itself is analysed in terms of different sectors and approaching their probability of occurrence by counting events and using Bayesian inference (Agresti, 2002). Therefore, the original data is transformed into compositional data and, before performing the trend analysis, the isometric logratio (ilr) transformation (Egozcue et al., 2003) is done. In general, the trend analysis methodology consists in two steps: 1) trend detection and 2) trend quantification. For 1) the Mann Kendall test is used in order to identify the nodes with significant trend. For these selected nodes, the trend quantification is done, comparing two methods: 1) a simple linear regression analysis complemented with the bootstrap technique and 2) a Bayesian analysis, assuming normally distributed data with linearly increasing mean. Preliminary results show no significant trend for both annual mean and maximum energy content except for some nodes located to the Northern Catalan coast. Regarding the wave direction (but not only considering stormy conditions) there is a tendency of North direction to decrease whereas South and Southeast direction seems to increase.

  1. A global wave parameter database for geophysical applications. Part 2: Model validation with improved source term parameterization

    OpenAIRE

    Rascle, Nicolas; Ardhuin, Fabrice

    2013-01-01

    A multi-scale global hindcast of ocean waves is presented that covers the years 1994-2012, based on recently published parameterizations for wind sea and swell dissipation [Ardhuin, F., Rogers, E., Babanin, A., Filipot, J.-F., Magne, R., Roland, A., van der Westhuysen, A., Queffeulou, P., Lefevre, J.-M., Aouf, L., Collard, F., 2010. Semi-empirical dissipation source functions for wind-wave models: Part I. Definition, calibration and validation. J. Phys. Oceanogr. 40 (9), 1917-1941]. Results f...

  2. Multiscale climate emulator of multimodal wave spectra: MUSCLE-spectra

    Science.gov (United States)

    Rueda, Ana; Hegermiller, Christie A.; Antolinez, Jose A. A.; Camus, Paula; Vitousek, Sean; Ruggiero, Peter; Barnard, Patrick L.; Erikson, Li H.; Tomás, Antonio; Mendez, Fernando J.

    2017-02-01

    Characterization of multimodal directional wave spectra is important for many offshore and coastal applications, such as marine forecasting, coastal hazard assessment, and design of offshore wave energy farms and coastal structures. However, the multivariate and multiscale nature of wave climate variability makes this complex problem tractable using computationally expensive numerical models. So far, the skill of statistical-downscaling model-based parametric (unimodal) wave conditions is limited in large ocean basins such as the Pacific. The recent availability of long-term directional spectral data from buoys and wave hindcast models allows for development of stochastic models that include multimodal sea-state parameters. This work introduces a statistical downscaling framework based on weather types to predict multimodal wave spectra (e.g., significant wave height, mean wave period, and mean wave direction from different storm systems, including sea and swells) from large-scale atmospheric pressure fields. For each weather type, variables of interest are modeled using the categorical distribution for the sea-state type, the Generalized Extreme Value (GEV) distribution for wave height and wave period, a multivariate Gaussian copula for the interdependence between variables, and a Markov chain model for the chronology of daily weather types. We apply the model to the southern California coast, where local seas and swells from both the Northern and Southern Hemispheres contribute to the multimodal wave spectrum. This work allows attribution of particular extreme multimodal wave events to specific atmospheric conditions, expanding knowledge of time-dependent, climate-driven offshore and coastal sea-state conditions that have a significant influence on local nearshore processes, coastal morphology, and flood hazards.

  3. A Process-Based Assessment of Decadal-Scale Surface Temperature Evolutions in the NCAR CCSM4's 25-Year Hindcast Experiments

    Science.gov (United States)

    Deng, Yi; Chen, Junwen

    2017-04-01

    This study represents an initial effort in the context of the coupled atmosphere-surface climate feedback-response analysis method (CFRAM) to partition the temporal evolution of the global surface temperature from 1981 to 2005 into components associated with individual radiative and non-radiative (dynamical) processes in the NCAR CCSM4's decadal hindcasts. When compared with the observation (ERA-Interim), the CCSM4 is able to predict an overall warming trend as well as the transient cooling occurring during the period 1989-1994. However, while the model captures fairly well the positive contributions of the CO2 and surface albedo change to the temperature evolution, it has an overly strong water vapor effect that dictates the temperature evolution in the hindcast. This is in contrast with the observation where changes in surface dynamics (mainly ocean circulation and heat content change) dominates the actual temperature evolution. Atmospheric dynamics in both the observation and model works against the surface temperature tendency through turbulent and convective heat transport, leading to an overall negative contribution to the evolution of the surface temperature. Impacts of solar forcing and ozone change on the surface temperature change are relatively weak during this period. The magnitude of cloud effect is considerably smaller compared to that in the observation and the spatial distribution of the cloud effect is also significantly different between the two especially over the equatorial Pacific. The value and limitations of this process-based temperature decomposition are discussed.

  4. Wave Energy Resource along the Coast of Santa Catarina (Brazil

    Directory of Open Access Journals (Sweden)

    Pasquale Contestabile

    2015-12-01

    Full Text Available Brazil has one of the largest electricity markets in South America, which needs to add 6000 MW of capacity every year in order to satisfy growing the demand from an increasing and more prosperous population. Apart from biomass, no other renewable energy sources, besides hydroelectricity, play a relevant role in the energy mix. The potential for wind and wave energy is very large. Brazil's Santa Catarina state government is starting a clean energy program in the state, which is expected to bring more than 1 GW of capacity. Assessment of wave energy resources is needed along the coastline. This work studied the potential wave energy along the north-central coasts of Santa Catarina, in Southern Brazil, by analysis of the hindcast data from the European Centre for Medium-Range Weather Forecasts (ECMWF. The annual offshore wave power was found to be equal to 15.25 kW/m, the bulk of which is provided by southeastern waves. The nearshore energetic patterns were studied by means of a numerical coastal propagation model (Mike21 SW. The mean wave power of 20 m isobaths is 11.43 kW/m. Supplementary considerations are drawn on realistic perspectives for wave energy converters installations.

  5. Electromagnetic Waves

    DEFF Research Database (Denmark)

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis...

  6. Dual Waves

    OpenAIRE

    Kallosh, Renata

    1994-01-01

    We study the gravitational waves in the 10-dimensional target space of the superstring theory. Some of these waves have unbroken supersymmetries. They consist of Brinkmann metric and of a 2-form field. Sigma-model duality is applied to such waves. The corresponding solutions we call dual partners of gravitational waves, or dual waves. Some of these dual waves upon Kaluza-Klein dimensional reduction to 4 dimensions become equivalent to the conformo-stationary solutions of axion-dilaton gravity...

  7. Characterization of the Deep Water Surface Wave Variability in the California Current Region

    Science.gov (United States)

    Villas Bôas, Ana B.; Gille, Sarah T.; Mazloff, Matthew R.; Cornuelle, Bruce D.

    2017-11-01

    Surface waves are crucial for the dynamics of the upper ocean not only because they mediate exchanges of momentum, heat, energy, and gases between the ocean and the atmosphere, but also because they determine the sea state. The surface wave field in a given region is set by the combination of local and remote forcing. The present work characterizes the seasonal variability of the deep water surface wave field in the California Current region, as retrieved from over two decades of satellite altimetry data combined with wave buoys and wave model hindcast (WaveWatch III). In particular, the extent to which the local wind modulates the variability of the significant wave height, peak period, and peak direction is assessed. During spring/summer, regional-scale wind events of up to 10 m/s are the dominant forcing for waves off the California coast, leading to relatively short-period waves (8-10 s) that come predominantly from the north-northwest. The wave climatology throughout the California Current region shows average significant wave heights exceeding 2 m during most of the year, which may have implications for the planning and retrieval methods of the Surface Water and Ocean Topography (SWOT) satellite mission.

  8. The CELSIUS\\WASA Detector Facility

    Science.gov (United States)

    Zabierowski, Janusz; CELSIUS\\WASA Collaboration; Bargholtz, C.; Bogoslawsky, D.; Bondar, A.; Calén, H.; Clement, H.; Demirörs, L.; Ekström, C.; Fransson, K.; Fridén, C.-J.; Gornov, M.; Grebenev, V.; Greiff, J.; Gurov, Y.; Gustafsson, L.; Höistad, B.; Ivanov, G.; Jacewicz, M.; Jiganov, E.; Johansson, A.; Johansson, T.; Keleta, S.; Kilian, K.; Kimura, N.; Koch, I.; Kullander, S.; Kupść, A.; Kurdadze, L.; Kuzmin, A.; Kuznetsov, A.; Marciniewsk, P.; Morosov, B.; Nawrot, A.; Nefkens, B. M. K.; Oelert, W.; Oreshkin, S.; Pauly, C.; Petukhov, Y.; Povtorejko, A.; Pätzold, J.; Reistad, D.; Ruber, R. J. M. Y.; Sandukovsky, V.; Scobel, W.; Sefzick, T.; Shafigullin, R.; Sidorov, V.; Shwartz, B.; Sopov, V.; Stepaniak, J.; Sukhanov, A.; Tchernychev, V.; Tegnér, P.-E.; Engblom, P. Thörngren Tikhomirov, V.; Turowiecki, A.; Wagner, G.; Wiedner, U.; Wilhelmsen, K.; Wilhelmi, Z.; Yamamoto, A.; Yamaoka, H.; Zabierowski, J.; Zlomańczuk, J.

    The 4π multidetector system for investigation of η-meson rare decays at the Uppsala CELSIUS storage ring is presented. A detailed description of the design, and achieved performance parameters is given.

  9. National-scale wave energy resource assessment for Australia

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Michael G.; Heap, Andrew D. [Geoscience Australia, Marine and Coastal Environment Group, GPO Box 378, Canberra, ACT 2601 (Australia)

    2010-08-15

    A nationally consistent wave resource assessment is presented for Australian shelf (<300 m) waters. Wave energy and power were derived from significant wave height and period, and wave direction hindcast using the AusWAM model for the period 1 March 1997 to 29 February 2008 inclusive. The spatial distribution of wave energy and power is available on a 0.1 grid covering 110-156 longitude and 7-46 latitude. Total instantaneous wave energy on the entire Australian shelf is on average 3.47 PJ. Wave power is greatest on the 3000 km-long southern Australian shelf (Tasmania/Victoria, southern Western Australia and South Australia), where it widely attains a time-average value of 25-35 kW m{sup -1} (90th percentile of 60-78 kW m{sup -1}), delivering 800-1100 GJ m{sup -1} of energy in an average year. New South Wales and southern Queensland shelves, with moderate levels of wave power (time-average: 10-20 kW m{sup -1}; 90th percentile: 20-30 kW m{sup -1}), are also potential sites for electricity generation due to them having a similar reliability in resource delivery to the southern margin. Time-average wave power for most of the northern Australian shelf is <10 kW m{sup -1}. Seasonal variations in wave power are consistent with regional weather patterns, which are characterised by winter SE trade winds/summer monsoon in the north and winter temperate storms/summer sea breezes in the south. The nationally consistent wave resource assessment for Australian shelf waters can be used to inform policy development and site-selection decisions by industry. (author)

  10. A high-resolution assessment of wind and wave energy potentials in the Red Sea

    KAUST Repository

    Langodan, Sabique

    2016-08-24

    This study presents an assessment of the potential for harvesting wind and wave energy from the Red Sea based on an 18-year high-resolution regional atmospheric reanalysis recently generated using the Advanced Weather Research Forecasting model. This model was initialized with ERA-Interim global data and the Red Sea reanalysis was generated using a cyclic three-dimensional variational approach assimilating available data in the region. The wave hindcast was generated using WAVEWATCH III on a 5 km resolution grid, forced by the Red Sea reanalysis surface winds. The wind and wave products were validated against data from buoys, scatterometers and altimeters. Our analysis suggests that the distribution of wind and wave energy in the Red Sea is inhomogeneous and is concentrated in specific areas, characterized by various meteorological conditions including weather fronts, mesoscale vortices, land and sea breezes and mountain jets. A detailed analysis of wind and wave energy variation was performed at three hotspots representing the northern, central and southern parts of the Red Sea. Although there are potential sites for harvesting wind energy from the Red Sea, there are no potential sites for harvesting wave energy because wave energy in the Red Sea is not strong enough for currently available wave energy converters. Wave energy should not be completely ignored, however, at least from the perspective of hybrid wind-wave projects. (C) 2016 Elsevier Ltd. All rights reserved.

  11. Improved estimates of nearshore wave conditions in the Gulf of Finland

    Science.gov (United States)

    Björkqvist, Jan-Victor; Tuomi, Laura; Fortelius, Carl; Pettersson, Heidi; Tikka, Kimmo; Kahma, Kimmo K.

    2017-07-01

    The heterogeneous coastline of the Gulf of Finland can result in widely varying wave conditions in a small geographical area. It is therefore challenging to obtain comprehensive information about the wave spectrum, which is needed to accurately quantify, e.g. the wave-bottom interactions. In this study, we implemented the wave model WAM to the coastal waters off Helsinki using a high-resolution 0.1 nmi grid and found that the model mostly predicts the wave field well. However, WAM overestimated the wave energy for south-westerly winds blowing over the peninsula sheltering the study area. This spurious behaviour was not caused by inaccuracies in the wind forcing, the boundary wave field or the available bathymetric grids. We present two methods for improving the prediction of the near-shore wave field. The first approach, which is also used to describe the structure of the wave field, is based on e.g. wave growth relations and models the fetch-limited and the longer waves separately. The second method determines a so-called effective wind forcing for the wave model by comparing the observed and modelled non-dimensional wave spectra. Both methods were validated using wave buoy observations and were found to clearly improve the predictions for the significant wave height and wave spectrum at the study site for south-westerly winds. Because some prior information on the wave conditions is required to implement the methods, they are best suited for expanding the usability of any limited measurement dataset available for a study. The method based on the effective wind forcing can also be implemented for operational forecasting or be used to gather statistics from hindcasts.

  12. An Open-Access, Multi-Decadal, Three-Dimensional, Hydrodynamic Hindcast Dataset for the Long Island Sound and New York/New Jersey Harbor Estuaries

    Directory of Open Access Journals (Sweden)

    Nickitas Georgas

    2016-08-01

    Full Text Available This article presents the results and validation of a comprehensive, multi-decadal, hindcast simulation performed using the New York Harbor Observing and Prediction System´s (NYHOPS three-dimensional hydrodynamic model. Meteorological forcing was based on three-hourly gridded data from the North American Regional Reanalysis of the US National Centers for Environmental Prediction. Distributed hydrologic forcing was based on daily United States Geologic Survey records. Offshore boundary conditions for NYHOPS at the Mid-Atlantic Bight shelf break included hourly subtidal water levels from a larger-scale model ran for the same period, tides, and temperature and salinity profiles based on the Simple Ocean Data Assimilation datasets. The NYHOPS model’s application to hindcast total water level and 3D water temperature and salinity conditions in its region over three decades was validated against observations from multiple agencies. Average indices of agreement were: 0.93 for storm surge (9 cm RMSE, 90% of errors less than 15 cm, 0.99 for water temperature (1.1 °C RMSE, 99% of errors less than 3 °C, and 0.86 for salinity (1.8 psu RMSE, 96% of errors less than 3.5 psu. The model’s skill in simulating bottom water temperature, validated against historic data from the Long Island Sound bottom trawl survey, did not drift over the years, a significant and encouraging finding for multi-decadal model applications used to identify climatic trends, such as the warming presented here. However, the validation reveals residual biases in some areas such as small tributaries that receive urban discharges from the NYC drainage network. With regard to the validation of storm surge at coastal stations, both the considerable strengths and remaining limitations of the use of North American Regional Reanalysis (NARR to force such a model application are discussed.

  13. Plasma waves

    CERN Document Server

    Swanson, DG

    1989-01-01

    Plasma Waves discusses the basic development and equations for the many aspects of plasma waves. The book is organized into two major parts, examining both linear and nonlinear plasma waves in the eight chapters it encompasses. After briefly discussing the properties and applications of plasma wave, the book goes on examining the wave types in a cold, magnetized plasma and the general forms of the dispersion relation that characterize the waves and label the various types of solutions. Chapters 3 and 4 analyze the acoustic phenomena through the fluid model of plasma and the kinetic effects. Th

  14. Operational wave now- and forecast in the German Bight as a basis for the assessment of wave-induced hydrodynamic loads on coastal dikes

    Science.gov (United States)

    Dreier, Norman; Fröhle, Peter

    2017-12-01

    The knowledge of the wave-induced hydrodynamic loads on coastal dikes including their temporal and spatial resolution on the dike in combination with actual water levels is of crucial importance of any risk-based early warning system. As a basis for the assessment of the wave-induced hydrodynamic loads, an operational wave now- and forecast system is set up that consists of i) available field measurements from the federal and local authorities and ii) data from numerical simulation of waves in the German Bight using the SWAN wave model. In this study, results of the hindcast of deep water wave conditions during the winter storm on 5-6 December, 2013 (German name `Xaver') are shown and compared with available measurements. Moreover field measurements of wave run-up from the local authorities at a sea dike on the German North Sea Island of Pellworm are presented and compared against calculated wave run-up using the EurOtop (2016) approach.

  15. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star.......Denne rapport beskriver numeriske beregninger af forskellige flydergeometrier for bølgeenergianlæget Wave Star....

  16. Heat Waves

    Science.gov (United States)

    Heat Waves Dangers we face during periods of very high temperatures include: Heat cramps: These are muscular pains and ... having trouble with the heat. If a heat wave is predicted or happening… - Slow down. Avoid strenuous ...

  17. Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Sørensen, H. C.

    1998-01-01

    This paper concerns with the development of the wave energy converter (WEC) Wave Dragon. This WEC is based on the overtopping principle. An overview of the performed research done concerning the Wave Dragon over the past years is given, and the results of one of the more comprehensive studies......, concerning a hydraulic evaluation and optimisation of the geometry of the Wave Dragon, is presented. Furthermore, the plans for the future development projects are sketched....

  18. Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Jonah Maxwell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-10-18

    This report has slides on Gravitational Waves; Pound and Rebka: A Shocking Fact; Light is a Ruler; Gravity is the Curvature of Spacetime; Gravitational Waves Made Simple; How a Gravitational Wave Affects Stuff Here; LIGO; This Detection: Neutron Stars; What the Gravitational Wave Looks Like; The Sound of Merging Neutron Stars; Neutron Star Mergers: More than GWs; The Radioactive Cloud; The Kilonova; and finally Summary, Multimessenger Astronomy.

  19. Electromagnetic Waves

    OpenAIRE

    Blok, H.; van den Berg, P.M.

    2011-01-01

    This book is dedicated to various aspects of electromagnetic wave theory and its applications in science and technology. The covered topics include the fundamental physics of electromagnetic waves, theory of electromagnetic wave propagation and scattering, methods of computational analysis, material characterization, electromagnetic properties of plasma, analysis and applications of periodic structures and waveguide components, etc.

  20. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Knapp, W.

    2006-01-01

    Wave Dragon is a floating wave energy converter working by extracting energy principally by means of overtopping of waves into a reservoir. A 1:4.5 scale prototype has been sea tested for 20 months. This paper presents results from testing, experiences gained and developments made during...

  1. Wave phenomena

    CERN Document Server

    Towne, Dudley H

    1988-01-01

    This excellent undergraduate-level text emphasizes optics and acoustics, covering inductive derivation of the equation for transverse waves on a string, acoustic plane waves, boundary-value problems, polarization, three-dimensional waves and more. With numerous problems (solutions for about half). ""The material is superbly chosen and brilliantly written"" - Physics Today. Problems. Appendices.

  2. Hydrodynamics of a bathymetrically complex fringing coral reef embayment: Wave climate, in situ observations, and wave prediction

    Science.gov (United States)

    Hoeke, R.; Storlazzi, C.; Ridd, P.

    2011-01-01

    This paper examines the relationship between offshore wave climate and nearshore waves and currents at Hanalei Bay, Hawaii, an exposed bay fringed with coral reefs. Analysis of both offshore in situ data and numerical hindcasts identify the predominance of two wave conditions: a mode associated with local trade winds and an episodic pattern associated with distant source long-period swells. Analysis of 10 months of in situ data within the bay show that current velocities are up to an order of magnitude greater during long-period swell episodes than during trade wind conditions; overall circulation patterns are also fundamentally different. The current velocities are highly correlated with incident wave heights during the swell episodes, while they are not during the modal trade wind conditions. A phase-averaged wave model was implemented with the dual purpose of evaluating application to bathymetrically complex fringing reefs and to examine the propagation of waves into the nearshore in an effort to better explain the large difference in observed circulation during the two offshore wave conditions. The prediction quality of this model was poorer for the episodic condition than for the lower-energy mode, however, it illustrated how longer-period swells are preferentially refracted into the bay and make available far more nearshore wave energy to drive currents compared to waves during modal conditions. The highly episodic circulation, the nature of which is dependent on complex refraction patterns of episodic, long-period swell has implications for flushing and sediment dynamics for incised fringing reef-lined bays that characterize many high islands at low latitudes around the world.

  3. Maximum Wave Run-up Measured on a Natural Beach Owing to Extreme Waves

    Science.gov (United States)

    Thornton, E. B.; MacMahan, J. H.

    2014-12-01

    Unique field data indicative of maximum run-up owing to extreme wave conditions with a 50 year return period are obtained from the distribution of sea-glass on 10-18 m high dunes. The hypothesis that sea-glass is an indicator of maximum run-up is verified by the observations that new sea-glass on a beach is found at the rackline, the highest point of run-up. The source of the sea-glass is a garbage dump on the dune in southern Monterey Bay from 1937-1951. It is estimated that the dump, located on an erosive shoreline, was falling into the ocean by at least 1960, so that the maximum run-up values have a return period of at least 50 years. Various empirical run-up models based both on extensive laboratory and field measurements are assessed to include contributions from sea-swell and infragravity waves, setup and tidal elevation, which are parameterized on wave height and surf parameter, P, which is a function of wave height, period and beach slope. Deep water hindcast waves (1958-2011) refracted to 4m water depth are used as input to the models. Beach and dune slopes averaged over the run-up region from mean water level to the maximum run-up ranged 0.1 - 0.63 (angle of repose). Reasonable comparison with model predicted run-up with distribution of sea-glass on the dune were obtained for P model equations were derived, suggesting a possible deficiency in the models.

  4. Combination of different types of ensembles for the adaptive simulation of probabilistic flood forecasts: hindcasts for the Mulde 2002 extreme event

    Directory of Open Access Journals (Sweden)

    J. Dietrich

    2008-03-01

    Full Text Available Flood forecasts are essential to issue reliable flood warnings and to initiate flood control measures on time. The accuracy and the lead time of the predictions for head waters primarily depend on the meteorological forecasts. Ensemble forecasts are a means of framing the uncertainty of the potential future development of the hydro-meteorological situation.

    This contribution presents a flood management strategy based on probabilistic hydrological forecasts driven by operational meteorological ensemble prediction systems. The meteorological ensemble forecasts are transformed into discharge ensemble forecasts by a rainfall-runoff model. Exceedance probabilities for critical discharge values and probabilistic maps of inundation areas can be computed and presented to decision makers. These results can support decision makers in issuing flood alerts. The flood management system integrates ensemble forecasts with different spatial resolution and different lead times. The hydrological models are controlled in an adaptive way, mainly depending on the lead time of the forecast, the expected magnitude of the flood event and the availability of measured data.

    The aforementioned flood forecast techniques have been applied to a case study. The Mulde River Basin (South-Eastern Germany, Czech Republic has often been affected by severe flood events including local flash floods. Hindcasts for the large scale extreme flood in August 2002 have been computed using meteorological predictions from both the COSMO-LEPS ensemble prediction system and the deterministic COSMO-DE local model. The temporal evolution of a the meteorological forecast uncertainty and b the probability of exceeding flood alert levels is discussed. Results from the hindcast simulations demonstrate, that the systems would have predicted a high probability of an extreme flood event, if they would already have been operational in 2002. COSMO-LEPS showed a reasonably good

  5. Dynamical influence of gravity waves generated by the Vestfjella Mountains in Antarctica: radar observations, fine-scale modelling and kinetic energy budget analysis

    Directory of Open Access Journals (Sweden)

    Joel Arnault

    2012-02-01

    Full Text Available Gravity waves generated by the Vestfjella Mountains (in western Droning Maud Land, Antarctica, southwest of the Finnish/Swedish Aboa/Wasa station have been observed with the Moveable atmospheric radar for Antarctica (MARA during the SWEDish Antarctic Research Programme (SWEDARP in December 2007/January 2008. These radar observations are compared with a 2-month Weather Research Forecast (WRF model experiment operated at 2 km horizontal resolution. A control simulation without orography is also operated in order to separate unambiguously the contribution of the mountain waves on the simulated atmospheric flow. This contribution is then quantified with a kinetic energy budget analysis computed in the two simulations. The results of this study confirm that mountain waves reaching lower-stratospheric heights break through convective overturning and generate inertia gravity waves with a smaller vertical wavelength, in association with a brief depletion of kinetic energy through frictional dissipation and negative vertical advection. The kinetic energy budget also shows that gravity waves have a strong influence on the other terms of the budget, i.e. horizontal advection and horizontal work of pressure forces, so evaluating the influence of gravity waves on the mean-flow with the vertical advection term alone is not sufficient, at least in this case. We finally obtain that gravity waves generated by the Vestfjella Mountains reaching lower stratospheric heights generally deplete (create kinetic energy in the lower troposphere (upper troposphere–lower stratosphere, in contradiction with the usual decelerating effect attributed to gravity waves on the zonal circulation in the upper troposphere–lower stratosphere.

  6. Gravitation Waves

    CERN Multimedia

    CERN. Geneva

    2005-01-01

    We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort, with special emphasis on the LIGO detectors and search results.

  7. Janus Waves

    OpenAIRE

    Papazoglou, Dimitris G.; Fedorov, Vladimir Yu.; Tzortzakis, Stelios

    2016-01-01

    We show the existence of a family of waves that share a common interesting property affecting the way they propagate and focus. These waves are a superposition of twin waves, which are conjugate to each other under inversion of the propagation direction. In analogy to holography, these twin "real" and "virtual" waves are related respectively to the converging and the diverging part of the beam and can be clearly visualized in real space at two distinct foci under the action of a focusing lens...

  8. Sensitivity analysis of a data assimilation technique for hindcasting and forecasting hydrodynamics of a complex coastal water body

    Science.gov (United States)

    Ren, Lei; Hartnett, Michael

    2017-02-01

    Accurate forecasting of coastal surface currents is of great economic importance due to marine activities such as marine renewable energy and fish farms in coastal regions in recent twenty years. Advanced oceanographic observation systems such as satellites and radars can provide many parameters of interest, such as surface currents and waves, with fine spatial resolution in near real time. To enhance modelling capability, data assimilation (DA) techniques which combine the available measurements with the hydrodynamic models have been used since the 1990s in oceanography. Assimilating measurements into hydrodynamic models makes the original model background states follow the observation trajectory, then uses it to provide more accurate forecasting information. Galway Bay is an open, wind dominated water body on which two coastal radars are deployed. An efficient and easy to implement sequential DA algorithm named Optimal Interpolation (OI) was used to blend radar surface current data into a three-dimensional Environmental Fluid Dynamics Code (EFDC) model. Two empirical parameters, horizontal correlation length and DA cycle length (CL), are inherent within OI. No guidance has previously been published regarding selection of appropriate values of these parameters or how sensitive OI DA is to variations in their values. Detailed sensitivity analysis has been performed on both of these parameters and results presented. Appropriate value of DA CL was examined and determined on producing the minimum Root-Mean-Square-Error (RMSE) between radar data and model background states. Analysis was performed to evaluate assimilation index (AI) of using an OI DA algorithm in the model. AI of the half-day forecasting mean vectors' directions was over 50% in the best assimilation model. The ability of using OI to improve model forecasts was also assessed and is reported upon.

  9. Rossby Waves

    OpenAIRE

    2005-01-01

    tut quiz Tutorial Quiz Interactive Media Element This interactive tutorial reviews the mechanisms of Rossby waves. Rossby waves in both the northern and southern hemispheres are considered. The interactions involve answering simple fill-in-the-blank questions. Diagrams are used to illustrate some of the concepts reviewed. MR4322 Dynamic Meteorology

  10. Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter; Friis-Madsen, Erik

    2008-01-01

    Since March 2003 a prototype of Wave Dragon has been tested in an inland sea in Denmark. This has been a great success with all subsystems tested and improved through working in an offshore environment. The project has proved the Wave Dragon device and has enabled the next stage, a production sized...

  11. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Brorsen, Michael; Frigaard, Peter

    Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star.......Nærværende rapport beskriver numeriske beregninger af den hydrodynamiske interaktion mellem 5 flydere i bølgeenergianlægget Wave Star....

  12. Wave Solutions

    CERN Document Server

    Christov, Ivan C

    2012-01-01

    In classical continuum physics, a wave is a mechanical disturbance. Whether the disturbance is stationary or traveling and whether it is caused by the motion of atoms and molecules or the vibration of a lattice structure, a wave can be understood as a specific type of solution of an appropriate mathematical equation modeling the underlying physics. Typical models consist of partial differential equations that exhibit certain general properties, e.g., hyperbolicity. This, in turn, leads to the possibility of wave solutions. Various analytical techniques (integral transforms, complex variables, reduction to ordinary differential equations, etc.) are available to find wave solutions of linear partial differential equations. Furthermore, linear hyperbolic equations with higher-order derivatives provide the mathematical underpinning of the phenomenon of dispersion, i.e., the dependence of a wave's phase speed on its wavenumber. For systems of nonlinear first-order hyperbolic equations, there also exists a general ...

  13. Hindcast of the 2009 South Pacific tsunami - validation of GIS methodologies for local vulnerability and risk assessment in American Samoa

    Science.gov (United States)

    Harbitz, C. B.; Sverdrup-Thygeson, K.; Kaiser, G.; Swarny, R.; Gruenburg, L.; Glimsdal, S.; Løvholt, F.; McAdoo, B. G.; Frauenfelder, R.

    2010-12-01

    On September 29th, 2009 at 6:48 AM local time, a series of earthquakes generated near the Tonga trench (15.509°S, 172.034°W) triggered a tsunami that reached the shores of Tonga, the Independent State of Samoa, and American Samoa. Effects of the tsunami were seen on several other Pacific islands. Devastation was widespread, resulting in 9 fatalities in Tonga, 149 in the independent State of Samoa and 34 in this study’s region of focus, American Samoa, which was selected mainly because of better data availability. Pago Pago, the capital on the main island of Tutuila, was especially affected by the tsunami because of its natural deep water harbor. Leone, located on the southwest coast of the island, was hit directly by waves propagating northeast from the earthquake’s epicenter. The villages of Poloa, Amanave, Alao, and Tula were also heavily damaged, but Leone and Pago Pago sustained some of the most wide-spread damage on Tutuila due to the combination of large populations with environmental and geographic factors. Following the disaster, teams from several nations evaluated damages and evidence of inundation levels. This study seeks to use information (including population, building types, infrastructure, inundation, flow depth, damages, and death tolls) gathered after the tsunami by researchers in American Samoa in order to validate a pre-existing GIS tsunami vulnerability and risk assessment model. The tsunami inundation, damage and mortality information found from journal papers, reports, newspaper articles, internet, personal communication with local agencies, photos, aerial views, and satellite images, was applied to deduce population density, building vulnerability, and the cause and location of tsunami deaths. The GIS model was adapted for optimal use of the available data. In the GIS model the mortality risk is a “product” of hazard, exposure, and mortality. The hazard is represented by the maximum tsunami flow depth, the exposure is described by

  14. The impact of surface currents and sea level on the wave field evolution during St. Jude storm in the eastern Baltic Sea

    Directory of Open Access Journals (Sweden)

    Marili Viitak

    2016-07-01

    Full Text Available A third generation numerical wave model SWAN (Simulating WAves Nearshore was applied to study the spatio-temporal effect of surface currents and sea level height on significant wave height; and to describe the mechanisms responsible for wave–current interaction in the eastern Baltic Sea. Simulation results were validated by comparison with in situ wave measurements in deep and shallow water, carried out using the directional wave buoy and RDCP respectively, and with TerraSAR-X imagery. A hindcast period from 23 to 31 October 2013 included both a period of calm to moderate weather conditions and a severe North-European windstorm called St. Jude. The prevailing wind directions were southerly to westerly. Four simulations with SWAN were made: a control run with dynamical forcing by wind only; and simulations with additional inputs of surface currents and sea level, both separately and combined. A clear effect of surface currents and sea level on the wave field evolution was found. It manifested itself as an increase or decrease of significant wave height of up to 20%. The strength of the interaction was influenced by the propagation directions of waves and surface currents and the severity of weather conditions. An increase in the wave height was mostly seen in shallower waters and in areas where waves and surface currents were propagating in opposite directions. In deeper parts of the eastern Baltic Sea and in case of waves and surface currents propagating in the same direction a decrease occurred.

  15. The sinking of the El Faro: predicting real world rogue waves during Hurricane Joaquin.

    Science.gov (United States)

    Fedele, Francesco; Lugni, Claudio; Chawla, Arun

    2017-09-11

    We present a study on the prediction of rogue waves during the 1-hour sea state of Hurricane Joaquin when the Merchant Vessel El Faro sank east of the Bahamas on October 1, 2015. High-resolution hindcast of hurricane-generated sea states and wave simulations are combined with novel probabilistic models to quantify the likelihood of rogue wave conditions. The data suggests that the El Faro vessel was drifting at an average speed of approximately 2.5 m/s prior to its sinking. As a result, we estimated that the probability that El Faro encounters a rogue wave whose crest height exceeds 14 meters while drifting over a time interval of 10 (50) minutes is ~1/400 (1/130). The largest simulated wave is generated by the constructive interference of elementary spectral components (linear dispersive focusing) enhanced by bound nonlinearities. Not surprisingly then, its characteristics are quite similar to those displayed by the Andrea, Draupner and Killard rogue waves.

  16. Consolidation Waves

    OpenAIRE

    Berg, Ward; Smit, Han

    2007-01-01

    textabstractThis paper explains why consolidation acquisitions occur in waves and it predicts the differing role each firm is likely to play in the consolidation game. We propose that whether a firm assumes the role of rival consolidator, target, or passive observer depends on the position of the firm relative to the entity that merges first. Our model predicts that an initial acquisition triggers a wave of follow-on acquisitions, where the process of asset accumulation by the consolidator is...

  17. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Andersen, Thomas Lykke

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star....

  18. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star.......Nærværende rapport beskriver modelforsøg udført på Aalborg Universitet, Institut for Byggeri og Anlæg med bølgeenergianlæget Wave Star....

  19. Blast Waves

    CERN Document Server

    Needham, Charles E

    2010-01-01

    The primary purpose of this text is to document many of the lessons that have been learned during the author’s more than forty years in the field of blast and shock. The writing therefore takes on an historical perspective, in some sense, because it follows the author’s experience. The book deals with blast waves propagating in fluids or materials that can be treated as fluids. It begins by distinguishing between blast waves and the more general category of shock waves. It then examines several ways of generating blast waves, considering the propagation of blast waves in one, two and three dimensions as well as through the real atmosphere. One section treats the propagation of shocks in layered gases in a more detailed manner. The book also details the interaction of shock waves with structures in particular reflections, progressing from simple to complex geometries, including planar structures, two-dimensional structures such as ramps or wedges, reflections from heights of burst, and three-dimensional st...

  20. Wave Generation Theory

    DEFF Research Database (Denmark)

    Frigaard, Peter; Høgedal, Michael; Christensen, Morten

    The intention of this manual is to provide some formulas and techniques which can be used for generating waves in hydraulic laboratories. Both long crested waves (2-D waves) and short crested waves (3-D waves) are considered....

  1. Mapping and Assessment of the United States Ocean Wave Energy Resource

    Energy Technology Data Exchange (ETDEWEB)

    Jacobson, Paul T; Hagerman, George; Scott, George

    2011-12-01

    This project estimates the naturally available and technically recoverable U.S. wave 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, wave power 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 wave energy along wave crests, which enables wave diffraction to substantially reestablish wave power densities within a few kilometers of a linear array, even for fixed terminator devices. The total available wave energy resource along the U.S. continental shelf edge, based on accumulating unit circle wave power 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 wave 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 wave power 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.

  2. Efficient Wave Energy Amplification with Wave Reflectors

    OpenAIRE

    Kramer, Morten Mejlhede; Frigaard, Peter Bak

    2002-01-01

    Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified ...

  3. Finite Amplitude Ocean Waves

    Indian Academy of Sciences (India)

    IAS Admin

    (2). Hence, small amplitude waves are also called linear waves. Most of the aspects of the ocean waves can be explained by the small amplitude wave theory. Let us now see the water particle motion due to waves. While wave energy is carried by the wave as it progresses forward, the water particles oscillate up and down.

  4. Investigation of hurricane Ivan using the coupled ocean-atmosphere-wave-sediment transport (COAWST) model

    Science.gov (United States)

    Zambon, Joseph B.; He, Ruoying; Warner, John C.

    2014-01-01

    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–wave coupled exchange processes are performed to assess the impacts of coupling on the predictions of the atmosphere, ocean, and wave environments during the occurrence of a TC. Modest improvement in track but significant improvement in intensity are found when using the fully atmosphere–ocean-wave coupled configuration versus uncoupled (e.g., standalone atmosphere, ocean, or wave) model simulations. Surface wave 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 ocean (on the shelf) is caused primarily by advection (equally by advection and diffusion).

  5. Shallow Water Waves and Solitary Waves

    OpenAIRE

    Hereman, Willy

    2013-01-01

    Encyclopedic article covering shallow water wave models used in oceanography and atmospheric science. Sections: Definition of the Subject; Introduction and Historical Perspective; Completely Integrable Shallow Water Wave Equations; Shallow Water Wave Equations of Geophysical Fluid Dynamics; Computation of Solitary Wave Solutions; Numerical Methods; Water Wave Experiments and Observations; Future Directions, and Bibliography.

  6. Wave groups in unidirectional surface wave models

    NARCIS (Netherlands)

    van Groesen, Embrecht W.C.

    1998-01-01

    Uni-directional wave models are used to study wave groups that appear in wave tanks of hydrodynamic laboratories; characteristic for waves in such tanks is that the wave length is rather small, comparable to the depth of the layer. In second-order theory, the resulting Nonlinear Schrödinger (NLS)

  7. Wave Dragon

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter

    På foranledning af Löwenmark F.R.I, er der udført numeriske beregninger af Wave Dragons (herefter WD) armes effektivitet for forskellige geometriske udformninger. 5 geometriske modeller, hvor WD's arme er forkortet/forlænget er undersøgt for 3 forskellige drejninger af armene. I alt er 15...

  8. Gravitational waves

    CERN Document Server

    Ciufolini, I; Moschella, U; Fre, P

    2001-01-01

    Gravitational waves (GWs) are a hot topic and promise to play a central role in astrophysics, cosmology, and theoretical physics. Technological developments have led us to the brink of their direct observation, which could become a reality in the coming years. The direct observation of GWs will open an entirely new field: GW astronomy. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of previously unseen phenomena, such as the coalescence of compact objects (neutron stars and black holes), the fall of stars into supermassive black holes, stellar core collapses, big-bang relics, and the new and unexpected.With a wide range of contributions by leading scientists in the field, Gravitational Waves covers topics such as the basics of GWs, various advanced topics, GW detectors, astrophysics of GW sources, numerical applications, and several recent theoretical developments. The material is written at a level suitable for postgraduate students entering the field.

  9. Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten; Frigaard, Peter; Brorsen, Michael

    Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004.......Nærværende rapport beskriver foreløbige hovedkonklusioner på modelforsøg udført på Aalborg Universitet, Institut for Vand, Jord og Miljøteknik med bølgeenergianlægget Wave Star i perioden 13/9 2004 til 12/11 2004....

  10. Wave Propagation

    CERN Document Server

    Ferrarese, Giorgio

    2011-01-01

    Lectures: A. Jeffrey: Lectures on nonlinear wave propagation.- Y. Choquet-Bruhat: Ondes asymptotiques.- G. Boillat: Urti.- Seminars: D. Graffi: Sulla teoria dell'ottica non-lineare.- G. Grioli: Sulla propagazione del calore nei mezzi continui.- T. Manacorda: Onde nei solidi con vincoli interni.- T. Ruggeri: "Entropy principle" and main field for a non linear covariant system.- B. Straughan: Singular surfaces in dipolar materials and possible consequences for continuum mechanics

  11. Shock Waves

    CERN Document Server

    Jiang, Z

    2005-01-01

    The International Symposium on Shock Waves (ISSW) is a well established series of conferences held every two years in a different location. A unique feature of the ISSW is the emphasis on bridging the gap between physicists and engineers working in fields as different as gas dynamics, fluid mechanics and materials sciences. The main results presented at these meetings constitute valuable proceedings that offer anyone working in this field an authoritative and comprehensive source of reference.

  12. Operationalization of Prediction, Hindcast, and Evaluation Systems using the Freie Univ Evaluation System Framework (Freva) incl. a Showcase in Decadal Climate Prediction

    Science.gov (United States)

    Kadow, Christopher; Illing, Sebastian; Schartner, Thomas; Ulbrich, Uwe; Cubasch, Ulrich

    2017-04-01

    Operationalization processes are important for Weather and Climate Services. Complex data and work flows need to be combined fast to fulfill the needs of service centers. Standards in data and software formats help in automatic solutions. In this study we show a software solution in between hindcasts, forecasts, and validation to be operationalized. Freva (see below) structures data and evaluation procedures and can easily be monitored. Especially in the development process of operationalized services, Freva supports scientists and project partners. The showcase of the decadal climate prediction project MiKlip (fona-miklip.de) shows such a complex development process. Different predictions, scientists input, tasks, and time evolving adjustments need to be combined to host precise climate informations in a web environment without losing track of its evolution. The Freie Univ Evaluation System Framework (Freva - freva.met.fu-berlin.de) is a software infrastructure for standardized data and tool solutions in Earth system science. Freva runs on high performance computers to handle customizable evaluation systems of research projects, institutes or universities. It combines different software technologies into one common hybrid infrastructure, including all features present in the shell and web environment. The database interface satisfies the international standards provided by the Earth System Grid Federation (ESGF). Freva indexes different data projects into one common search environment by storing the meta data information of the self-describing model, reanalysis and observational data sets in a database. This implemented meta data system with its advanced but easy-to-handle search tool supports users, developers and their plugins to retrieve the required information. A generic application programming interface (API) allows scientific developers to connect their analysis tools with the evaluation system independently of the programming language used. Users of the

  13. REFLECTION OF ELECTROMAGNETIC WAVES FROM SOUND WAVES

    Science.gov (United States)

    The reflection of electromagnetic waves normally incident on the wavefronts of a semi-infinite standing sound wave is discussed. By analogy with the...with the sound frequency. An experiment is described in which the Bragg reflection of 3 cm electromagnetic waves from a standing sound wave beneath a water surface is observed.

  14. Impact of Wave Dragon on Wave Climate

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Tedd, James; Kramer, Morten

    This report is an advisory paper for use in determining the wave dragon effects on hydrography, by considering the effect on the wave climate in the region of a wave dragon. This is to be used in the impact assessment for the Wave Dragon pre-commercial demonstrator....

  15. A comparison of dynamical and statistical downscaling methods for regional wave climate projections along French coastlines.

    Science.gov (United States)

    Laugel, Amélie; Menendez, Melisa; Benoit, Michel; Mattarolo, Giovanni; Mendez, Fernando

    2013-04-01

    Wave climate forecasting is a major issue for numerous marine and coastal related activities, such as offshore industries, flooding risks assessment and wave energy resource evaluation, among others. Generally, there are two main ways to predict the impacts of the climate change on the wave climate at regional scale: the dynamical and the statistical downscaling of GCM (Global Climate Model). In this study, both methods have been applied on the French coast (Atlantic , English Channel and North Sea shoreline) under three climate change scenarios (A1B, A2, B1) simulated with the GCM ARPEGE-CLIMAT, from Météo-France (AR4, IPCC). The aim of the work is to characterise the wave climatology of the 21st century and compare the statistical and dynamical methods pointing out advantages and disadvantages of each approach. The statistical downscaling method proposed by the Environmental Hydraulics Institute of Cantabria (Spain) has been applied (Menendez et al., 2011). At a particular location, the sea-state climate (Predictand Y) is defined as a function, Y=f(X), of several atmospheric circulation patterns (Predictor X). Assuming these climate associations between predictor and predictand are stationary, the statistical approach has been used to project the future wave conditions with reference to the GCM. The statistical relations between predictor and predictand have been established over 31 years, from 1979 to 2009. The predictor is built as the 3-days-averaged squared sea level pressure gradient from the hourly CFSR database (Climate Forecast System Reanalysis, http://cfs.ncep.noaa.gov/cfsr/). The predictand has been extracted from the 31-years hindcast sea-state database ANEMOC-2 performed with the 3G spectral wave model TOMAWAC (Benoit et al., 1996), developed at EDF R&D LNHE and Saint-Venant Laboratory for Hydraulics and forced by the CFSR 10m wind field. Significant wave height, peak period and mean wave direction have been extracted with an hourly-resolution at

  16. Efficient Wave Energy Amplification with Wave Reflectors

    DEFF Research Database (Denmark)

    Kramer, Morten Mejlhede; Frigaard, Peter Bak

    2002-01-01

    Wave Energy Converters (WEC's) extract wave energy from a limited area, often a single point or line even though the wave energy is generally spread out along the wave crest. By the use of wave reflectors (reflecting walls) the wave energy is effectively focused and increased to approximately 130......-140%. In the paper a procedure for calculating the efficiency and optimizing the geometry of wave reflectors are described, this by use of a 3D boundary element method. The calculations are verified by laboratory experiments and a very good agreement is found. The paper gives estimates of possible power benifit...... for different geometries of the wave reflectors and optimal geometrical design parameters are specified. On this basis inventors of WEC's can evaluate whether a specific WEC possible could benefit from wave reflectors....

  17. Time clustering of wave storms in the Mediterranean Sea

    Science.gov (United States)

    Besio, Giovanni; Briganti, Riccardo; Romano, Alessandro; Mentaschi, Lorenzo; De Girolamo, Paolo

    2017-03-01

    In this contribution we identify storm time clustering in the Mediterranean Sea through a comprehensive analysis of the Allan factor. This parameter is evaluated from a long time series of wave height provided by oceanographic buoy measurements and hindcast reanalysis of the whole basin, spanning the period 1979-2014 and characterized by a horizontal resolution of about 0.1° in longitude and latitude and a temporal sampling of 1 h Mentaschi et al. (2015). The nature of the processes highlighted by the AF and the spatial distribution of the parameter are both investigated. Results reveal that the Allan factor follows different curves at two distinct timescales. The range of timescales between 12 h to 50 days is characterized by a departure from the Poisson distribution. For timescales above 50 days, a cyclic Poisson process is identified. The spatial distribution of the Allan factor reveals that the clustering at smaller timescales is present to the north-west of the Mediterranean, while seasonality is observed across the whole basin. This analysis is believed to be important for assessing the local increased flood and coastal erosion risks due to storm clustering.

  18. The physics of waves

    CERN Document Server

    Georgi, Howard

    1993-01-01

    The first complete introduction to waves and wave phenomena by a renowned theorist. Covers damping, forced oscillations and resonance; normal modes; symmetries; traveling waves; signals and Fourier analysis; polarization; diffraction.

  19. Predicting freakish sea state with an operational third-generation wave model

    Science.gov (United States)

    Waseda, T.; In, K.; Kiyomatsu, K.; Tamura, H.; Miyazawa, Y.; Iyama, K.

    2014-04-01

    The understanding of freak wave generation mechanisms has advanced and the community has reached a consensus that spectral geometry plays an important role. Numerous marine accident cases were studied and revealed that the narrowing of the directional spectrum is a good indicator of dangerous sea. However, the estimation of the directional spectrum depends on the performance of the third-generation wave model. In this work, a well-studied marine accident case in Japan in 1980 (Onomichi-Maru incident) is revisited and the sea states are hindcasted using both the DIA (discrete interaction approximation) and SRIAM (Simplified Research Institute of Applied Mechanics) nonlinear source terms. The result indicates that the temporal evolution of the basic parameters (directional spreading and frequency bandwidth) agree reasonably well between the two schemes and therefore the most commonly used DIA method is qualitatively sufficient to predict freakish sea state. The analyses revealed that in the case of Onomichi-Maru, a moving gale system caused the spectrum to grow in energy with limited downshifting at the accident's site. This conclusion contradicts the marine inquiry report speculating that the two swell systems crossed at the accident's site. The unimodal wave system grew under strong influence of local wind with a peculiar energy transfer.

  20. Super-ensemble techniques applied to wave forecast: performance and limitations

    Directory of Open Access Journals (Sweden)

    F. Lenartz

    2010-06-01

    Full Text Available Nowadays, several operational ocean wave forecasts are available for a same region. These predictions may considerably differ, and to choose the best one is generally a difficult task. The super-ensemble approach, which consists in merging different forecasts and past observations into a single multi-model prediction system, is evaluated in this study. During the DART06 campaigns organized by the NATO Undersea Research Centre, four wave forecasting systems were simultaneously run in the Adriatic Sea, and significant wave height was measured at six stations as well as along the tracks of two remote sensors. This effort provided the necessary data set to compare the skills of various multi-model combination techniques. Our results indicate that a super-ensemble based on the Kalman Filter improves the forecast skills: The bias during both the hindcast and forecast periods is reduced, and the correlation coefficient is similar to that of the best individual model. The spatial extrapolation of local results is not straightforward and requires further investigation to be properly implemented.

  1. Monthly and seasonal predictability of heat waves in West Africa with CNRM-CM

    Science.gov (United States)

    Batté, Lauriane; Ardilouze, Constantin; Déqué, Michel

    2017-04-01

    West Africa, and in particular Sahel, are vulnerable to spring heat waves during which maximum daily temperatures reach over 40°C for several consecutive days. These heat waves have severe consequences on the health and activities of local populations. Moreover, several studies suggest that their frequency and intensity may increase in future decades. The French National Research Agency (ANR) project ACASIS brings together researchers from different backgrounds (geography, climate, meteorology, epidemiology, demography) to improve the understanding of the causes and consequences of these heat waves, as well as their variability and predictability at different time and spatial scales. In this presentation we wish to assess the predictability of Sahelian heat waves in the sub-seasonal and seasonal forecasts with Météo-France system 5, based on the CNRM-CM coupled model updated from its CMIP5 version. The seasonal forecasts are issued each month as part of the Copernicus C3S initiative ; sub-seasonal runs are released for research purposes in the framework of the WWRP/WCRP S2S project. Both forecasts are calibrated with corresponding hindcasts over the 1993-2014 period. Despite surface temperature biases, and trouble in properly representing the persistence of heat spells over the region, some evidence of predictive skill is found for duration and frequency of heat waves defined as a threshold of consecutive days of daily minimum or maximum temperatures reaching over the 90th percentile. A more detailed assessment of the spring 2016 real-time forecasts will also be presented, using a weather regime approach to illustrate how the seasonal prediction system managed to capture the large-scale signal for above-normal occurrences and duration of heat waves last year, but failed to correctly pinpoint the geographical location of these anomalies.

  2. Extreme Wave Simulation due to Typhoon Bolaven based on locally Enhanced Fine-Mesh Unstructured Grid Model

    Science.gov (United States)

    Kim, Kyeong Ok; Choi, Byung Ho; Jung, Kyung Tae

    2016-04-01

    The performance of an integrally coupled wave-tide-surge model using the unstructured mesh system has been tested for the typhoon Bolaven which is regarded as the most powerful storm to strike the Korean Peninsula in nearly a decade with wind gusts measured up to 50 m/s, causing serious damages with 19 victims. Use of the unstructured mesh in coastal sea regions of marginal scale allows all energy from deep to shallow waters to be seamlessly followed; the physics of wave-circulation interactions can be then correctly resolved. The model covers the whole Yellow and East China Seas with locally refined meshes near the regions of Gageo Island (offshore southwestern corner of the Korean Peninsula) and south of Jeju Island (Gangjeong and Seogwipo ports). The wind and pressure fields during the passage of typhoon Bolaven are generated by the blending method. Generally the numerical atmospheric model cannot satisfactorily reproduce the strength of typhoons due to dynamic and resolution restrictions. In this study we could achieve an improved conservation of the typhoon strength by blending the Holland typhoon model result by the empirical formula onto the ambient meteorological fields of NCEP dataset. The model results are compared with the observations and the model performance is then evaluated. The computed wave spectrums for one and two dimensions are compared with the observation in Ieodo station. Results show that the wind wave significantly enhances the current intensity and surge elevation, addressing that to incorporate the wave-current interaction effect in the wave-tide-surge coupled model is important for the accurate prediction of current and sea surface elevation as well as extreme waves in shallow coastal sea regions. The resulting modeling system can be used for hindcasting and forecasting the wave-tide-surges in marine environments with complex coastlines, shallow water depth and fine sediment.

  3. customary land tenure and land documentation in the wasa amenfi ...

    African Journals Online (AJOL)

    J\\s a follo\\\\-UP to the NLP. a I.and J\\dministration Programme. (LJ\\P) is currently undernay to improve access to land and ensure certainty of land rights. The pilot phase of the programme has been on since 2004 and has among other objectives sought lo establish pilot projects in the dcman.:ation and registrat ion of allodial ...

  4. ELECTRON CYCLOTRON WAVES

    NARCIS (Netherlands)

    Westerhof, E.

    2010-01-01

    This lecture gives an overview of heating and current drive with electron cyclotron waves. We present the main theoretical aspects of wave propagation, wave absorption, and non-inductive current drive, as well as important technical aspects for the application of high power electron cyclotron waves,

  5. Electron cyclotron waves

    NARCIS (Netherlands)

    Westerhof, E.

    2012-01-01

    This lecture gives an overview of heating and current drive with electron cyclotron waves. We present the main theoretical aspects of wave propagation, wave absorption, and non-inductive current drive, as well as important technical aspects for the application of high power electron cyclotron waves,

  6. Electron cyclotron waves

    NARCIS (Netherlands)

    Westerhof, E.

    2008-01-01

    This lecture gives an overview of heating and current drive with electron cyclotron waves. We present the main theoretical aspects of wave propagation, wave absorption, and non-inductive current drive, as well as important technical aspects for the application of high power electron cyclotron waves,

  7. Waves in inhomogeneous media

    NARCIS (Netherlands)

    Gerritsen, S.

    2007-01-01

    In this thesis we study wave propagation in inhomogeneous media. Examples of the classical (massless) waves we consider are acoustic waves (sound) and electromagnetic waves (light, for example). Interaction with inhomogeneities embedded in a reference medium alter the propagation direction, velocity

  8. Wave Data Analysis

    DEFF Research Database (Denmark)

    Alikhani, Amir; Frigaard, Peter; Burcharth, Hans F.

    1998-01-01

    The data collected over the course of the experiment must be analysed and converted into a form suitable for its intended use. Type of analyses range from simple to sophisticated. Depending on the particular experiment and the needs of the researcher. In this study three main part of irregular wave...... data analyses are presented e.g. Time Domain (Statistical) Analyses, Frequency Domain (Spectral) Analyses and Wave Reflection Analyses. Random wave profile and definitions of representative waves, distributions of individual wave height and wave periods and spectra of sea waves are presented....

  9. Hindcast and forecast of grand solar minina and maxima using a three-frequency dynamo model based on Jupiter-Saturn tidal frequencies modulating the 11-year sunspot cycle

    Science.gov (United States)

    Scafetta, Nicola

    2016-04-01

    The Schwabe frequency band of the Zurich sunspot record since 1749 is found to be made of three major cycles with periods of about 9.98, 10.9 and 11.86 years. The two side frequencies appear to be closely related to the spring tidal period of Jupiter and Saturn (range between 9.5 and 10.5 years, and median 9.93 years) and to the tidal sidereal period of Jupiter (about 11.86 years). The central cycle can be associated to a quasi-11-year sunspot solar dynamo cycle that appears to be approximately synchronized to the average of the two planetary frequencies. A simplified harmonic constituent model based on the above two planetary tidal frequencies and on the exact dates of Jupiter and Saturn planetary tidal phases, plus a theoretically deduced 10.87-year central cycle reveals complex quasi-periodic interference/beat patterns. The major beat periods occur at about 115, 61 and 130 years, plus a quasi-millennial large beat cycle around 983 years. These frequencies and other oscillations appear once the model is non-linearly processed. We show that equivalent synchronized cycles are found in cosmogenic records used to reconstruct solar activity and in proxy climate records throughout the Holocene (last 12,000 years) up to now. The quasi-secular beat oscillations hindcast reasonably well the known prolonged periods of low solar activity during the last millennium such as the Oort, Wolf, Sporer, Maunder and Dalton minima, as well as the 17 115-year long oscillations found in a detailed temperature reconstruction of the Northern Hemisphere covering the last 2000 years. The millennial cycle hindcasts equivalent solar and climate cycles for 12,000 years. Finally, the harmonic model herein proposed reconstructs the prolonged solar minima that occurred during 1900- 1920 and 1960-1980 and the secular solar maxima around 1870-1890, 1940-1950 and 1995-2005 and a secular upward trending during the 20th century: this modulated trending agrees well with some solar proxy model, with

  10. Wave disc engine apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Muller, Norbert; Piechna, Janusz; Sun, Guangwei; Parraga, Pablo-Francisco

    2018-01-02

    A wave disc engine apparatus is provided. A further aspect employs a constricted nozzle in a wave rotor channel. A further aspect provides a sharp bend between an inlet and an outlet in a fluid pathway of a wave rotor, with the bend being spaced away from a peripheral edge of the wave rotor. A radial wave rotor for generating electricity in an automotive vehicle is disclosed in yet another aspect.

  11. Directional Validation of Wave Predictions

    Science.gov (United States)

    2007-03-01

    likelihood estimator [referred to as MLE or sented to others’? How far can one go in condensing MLM : Capon et al. (1967) and Oltman-Shav and Guza these...of energy above the peak, or those of Rogers et al. (2003). both. Even with excellent agreement in the three nondi- "* Season hindcast covers 0000 UTC...C. Ris, A. J. van der Westhuysen, and M. Zijlema, cast at all frequency bands, model-data agreement is 2t05: SWAN Cycle Ill, version 40.41. User

  12. Robust Wave Resource Estimation

    DEFF Research Database (Denmark)

    Lavelle, John; Kofoed, Jens Peter

    2013-01-01

    An assessment of the wave energy resource at the location of the Danish Wave Energy test Centre (DanWEC) is presented in this paper. The Wave Energy Converter (WEC) test centre is located at Hanstholm in the of North West Denmark. Information about the long term wave statistics of the resource...... is necessary for WEC developers, both to optimise the WEC for the site, and to estimate its average yearly power production using a power matrix. The wave height and wave period sea states parameters are commonly characterized with a bivariate histogram. This paper presents bivariate histograms and kernel...... density estimates of the PDF as a function both of Hm0 and Tp, and Hm0 and T0;2, together with the mean wave power per unit crest length, Pw, as a function of Hm0 and T0;2. The wave elevation parameters, from which the wave parameters are calculated, are filtered to correct or remove spurious data...

  13. Observational Evidence Against Mountain-Wave Generation of Ice Nuclei as a Prerequisite for the Formation of Three Solid Nitric Acid Polar Stratospheric Clouds Observed in the Arctic in Early December 1999

    Science.gov (United States)

    Pagan, Kathy L.; Tabazadeh, Azadeh; Drdla, Katja; Hervig, Mark E.; Eckermann, Stephen D.; Browell, Edward V.; Legg, Marion J.; Foschi, Patricia G.

    2004-01-01

    A number of recently published papers suggest that mountain-wave activity in the stratosphere, producing ice particles when temperatures drop below the ice frost point, may be the primary source of large NAT particles. In this paper we use measurements from the Advanced Very High Resolution Radiometer (AVHRR) instruments on board the National Oceanic and Atmospheric Administration (NOAA) polar-orbiting satellites to map out regions of ice clouds produced by stratospheric mountain-wave activity inside the Arctic vortex. Lidar observations from three DC-8 flights in early December 1999 show the presence of solid nitric acid (Type Ia or NAT) polar stratospheric clouds (PSCs). By using back trajectories and superimposing the position maps on the AVHRR cloud imagery products, we show that these observed NAT clouds could not have originated at locations of high-amplitude mountain-wave activity. We also show that mountain-wave PSC climatology data and Mountain Wave Forecast Model 2.0 (MWFM-2) raw hemispheric ray and grid box averaged hemispheric wave temperature amplitude hindcast data from the same time period are in agreement with the AVHRR data. Our results show that ice cloud formation in mountain waves cannot explain how at least three large scale NAT clouds were formed in the stratosphere in early December 1999.

  14. Hindcast, GIS and susceptibility modelling to assist oil spill clean-up and mitigation on the southern coast of Cyprus (Eastern Mediterranean)

    Science.gov (United States)

    Alves, Tiago M.; Kokinou, Eleni; Zodiatis, George; Lardner, Robin

    2016-11-01

    This study uses new oil-spill models, bathymetric, meteorological, oceanographic, geomorphological and geological data to assess the impact of distinct oil spill scenarios on the southern coast of Cyprus, Eastern Mediterranean. This approach results from the urgent need to predict oil spill dispersion after new oil terminals and depots were built at Vasilikos, southern coast of Cyprus. The terminals have been able to receive tankers with 500,000 deadweight tonnes from November 2014. The new geomorphological and geological data in this work show the shoreline of Cyprus to be of high susceptibility due to: (a) the presence of a narrow continental shelf capable of trapping large quantities of hydrocarbons; (b) the existence of uplifted wave-cut platforms, coastal lagoons and pools forming natural traps for oil, and (c) the presence of important tourist and Natura 2000 sites. Under particular weather and oceanographic conditions, oil spills offshore Larnaca Bay will quickly spread and reach the shoreline 46 h after the initial accident. Significantly, the models in this paper show a reduction from 84% to 19% in the volume of oil trapped on the coast if dispersants are applied, with the latter 19% being potentially kept at bay using booms and mechanical removal techniques. Based on these results, we suggest the early use of dispersants, booms and mechanical removal procedures to prevent the spreading of oil spilt in the broad area of Larnaca Bay.

  15. Wave Meteorology and Soaring

    Science.gov (United States)

    Wiley, Scott

    2008-01-01

    This viewgraph document reviews some mountain wave turbulence and operational hazards while soaring. Maps, photographs, and satellite images of the meteorological phenomena are included. Additionally, photographs of aircraft that sustained mountain wave damage are provided.

  16. Viscothermal wave propagation

    NARCIS (Netherlands)

    Nijhof, M.J.J.

    2010-01-01

    In this work, the accuracy, efficiency and range of applicability of various (approximate) models for viscothermal wave propagation are investigated. Models for viscothermal wave propagation describe thewave behavior of fluids including viscous and thermal effects. Cases where viscothermal effects

  17. Cold wave lotion poisoning

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002693.htm Cold wave lotion poisoning To use the sharing features on this page, please enable JavaScript. Cold wave lotion is a hair care product used ...

  18. Electromagnetic ultrasonic guided waves

    CERN Document Server

    Huang, Songling; Li, Weibin; Wang, Qing

    2016-01-01

    This book introduces the fundamental theory of electromagnetic ultrasonic guided waves, together with its applications. It includes the dispersion characteristics and matching theory of guided waves; the mechanism of production and theoretical model of electromagnetic ultrasonic guided waves; the effect mechanism between guided waves and defects; the simulation method for the entire process of electromagnetic ultrasonic guided wave propagation; electromagnetic ultrasonic thickness measurement; pipeline axial guided wave defect detection; and electromagnetic ultrasonic guided wave detection of gas pipeline cracks. This theory and findings on applications draw on the author’s intensive research over the past eight years. The book can be used for nondestructive testing technology and as an engineering reference work. The specific implementation of the electromagnetic ultrasonic guided wave system presented here will also be of value for other nondestructive test developers.

  19. Coronal Waves and Oscillations

    Directory of Open Access Journals (Sweden)

    Nakariakov Valery M.

    2005-07-01

    Full Text Available Wave and oscillatory activity of the solar corona is confidently observed with modern imaging and spectral instruments in the visible light, EUV, X-ray and radio bands, and interpreted in terms of magnetohydrodynamic (MHD wave theory. The review reflects the current trends in the observational study of coronal waves and oscillations (standing kink, sausage and longitudinal modes, propagating slow waves and fast wave trains, the search for torsional waves, theoretical modelling of interaction of MHD waves with plasma structures, and implementation of the theoretical results for the mode identification. Also the use of MHD waves for remote diagnostics of coronal plasma - MHD coronal seismology - is discussed and the applicability of this method for the estimation of coronal magnetic field, transport coefficients, fine structuring and heating function is demonstrated.

  20. Detonation Wave Profile

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Laboratory

    2015-12-14

    The Zel’dovich-von Neumann-Doering (ZND) profile of a detonation wave is derived. Two basic assumptions are required: i. An equation of state (EOS) for a partly burned explosive; P(V, e, λ). ii. A burn rate for the reaction progress variable; d/dt λ = R(V, e, λ). For a steady planar detonation wave the reactive flow PDEs can be reduced to ODEs. The detonation wave profile can be determined from an ODE plus algebraic equations for points on the partly burned detonation loci with a specified wave speed. Furthermore, for the CJ detonation speed the end of the reaction zone is sonic. A solution to the reactive flow equations can be constructed with a rarefaction wave following the detonation wave profile. This corresponds to an underdriven detonation wave, and the rarefaction is know as a Taylor wave.

  1. Imaging gravity waves in lower stratospheric AMSU-A radiances, Part 2: Validation case study

    Directory of Open Access Journals (Sweden)

    S. D. Eckermann

    2006-01-01

    Full Text Available Two-dimensional radiance maps from Channel 9 (~60–90 hPa of the Advanced Microwave Sounding Unit (AMSU-A, acquired over southern Scandinavia on 14 January 2003, show plane-wave-like oscillations with a wavelength λh of ~400–500 km and peak brightness temperature amplitudes of up to 0.9 K. The wave-like pattern is observed in AMSU-A radiances from 8 overpasses of this region by 4 different satellites, revealing a growth in the disturbance amplitude from 00:00 UTC to 12:00 UTC and a change in its horizontal structure between 12:00 UTC and 20:00 UTC. Forecast and hindcast runs for 14 January 2003 using high-resolution global and regional numerical weather prediction (NWP models generate a lower stratospheric mountain wave over southern Scandinavia with peak 90 hPa temperature amplitudes of ~5–7 K at 12:00 UTC and a similar horizontal wavelength, packet width, phase structure and time evolution to the disturbance observed in AMSU-A radiances. The wave's vertical wavelength is ~12 km. These NWP fields are validated against radiosonde wind and temperature profiles and airborne lidar profiles of temperature and aerosol backscatter ratios acquired from the NASA DC-8 during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II. Both the amplitude and phase of the stratospheric mountain wave in the various NWP fields agree well with localized perturbation features in these suborbital measurements. In particular, we show that this wave formed the type II polar stratospheric clouds measured by the DC-8 lidar. To compare directly with the AMSU-A data, we convert these validated NWP temperature fields into swath-scanned brightness temperatures using three-dimensional Channel 9 weighting functions and the actual AMSU-A scan patterns from each of the 8 overpasses of this region. These NWP-based brightness temperatures contain two-dimensional oscillations due to this resolved stratospheric mountain wave that have an amplitude, wavelength

  2. Modelling sand wave variation

    NARCIS (Netherlands)

    Sterlini-Van der Meer, Fenneke

    2009-01-01

    The sea floor of shallow seas is rarely flat and often dynamic. A widely occurring bedform type is the sand wave. Sand waves form more or less regular wavelike patterns on the seabed with crests up to one third of the water depth, wave lengths of hundreds of metres and a migration rate of metres up

  3. Wave Dragon MW

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter

    Wave Dragon is a wave energy converter of the overtopping type. The device has been thoroughly tested on a 1:51.8 scale model in wave laboratories and a 1:4.5 scale model deployed in Nissum Bredning, a large inland waterway in Denmark. Based on the experience gained a full scale, multi MW prototype...

  4. Wave Reflection Model Tests

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Larsen, Brian Juul

    The investigation concerns the design of a new internal breakwater in the main port of Ibiza. The objective of the model tests was in the first hand to optimize the cross section to make the wave reflection low enough to ensure that unacceptable wave agitation will not occur in the port. Secondly...... wave overtopping was studied as well....

  5. Modeling Regional Seismic Waves

    Science.gov (United States)

    1991-03-25

    Shear waves are almost always observed from underground explosions. One can visualize many ways to convert explosion P waves into SV waves. An ob- vious...of the observed moment to the input source moment, Moba /Mo, as a function of the compressional velocities a, of the embedded sphere for different whole

  6. Fundamentals of wave phenomena

    CERN Document Server

    Hirose, Akira

    2010-01-01

    This textbook provides a unified treatment of waves that either occur naturally or can be excited and propagated in various media. This includes both longitudinal and transverse waves. The book covers both mechanical and electrical waves, which are normally covered separately due to their differences in physical phenomena.

  7. B-waves revisited

    Directory of Open Access Journals (Sweden)

    Andreas Spiegelberg

    2016-12-01

    With the still unmet need for a clinically acceptable method for acquiring intracranial compliance, and the revival of ICP waveform analysis, B-waves are moving back into the research focus. Herein we provide a concise review of the literature on B-waves, including a critical assessment of non-invasive methods for obtaining B-wave surrogates.

  8. Gravitational-Wave Astronomy

    Indian Academy of Sciences (India)

    We present a broad overview of the emerging field of gravitational-wave astronomy. Although gravitational waves have not been directly de- tected yet, the worldwide scientific community is engaged in an exciting search for these elusive waves. Once detected, they will open up a new observational window to the Universe.

  9. Spin wave generation by surface acoustic waves

    Science.gov (United States)

    Li, Xu; Labanowski, Dominic; Salahuddin, Sayeef; Lynch, Christopher S.

    2017-07-01

    Surface acoustic waves (SAW) on piezoelectric substrates can excite spin wave resonance (SWR) in magnetostrictive films through magnetoelastic coupling. This acoustically driven SWR enables the excitation of a single spin wave mode with an in-plane wave vector k matched to the magnetoelastic wave vector. A 2D frequency domain finite element model is presented that fully couples elastodynamics, micromagnetics, and piezoelectricity with interface spin pumping effects taken into account. It is used to simulate SAW driven SWR on a ferromagnetic and piezoelectric heterostructure device with an interdigital transducer configuration. These results, for the first time, present the spatial distribution of magnetization components that, together with elastic wave, exponentially decays along the propagation direction due to magnetic damping. The results also show that the system transmission rate S21(dB) can be tuned by both an external bias field and the SAW wavevector. Acoustic spin pumping at magnetic film/normal metal interface leads to damping enhancement in magnetic films that decreases the energy absorption rate from elastic energy. This weakened interaction between the magnetic energy and elastic energy leads to a lower evanescence rate of the SAW that results in a longer distance propagation. With strong magnetoelastic coupling, the SAW driven spin wave is able to propagate up to 1200 μm. The results give a quantitative indication of the acoustic spin pumping contribution to linewidth broadening.

  10. Trends in significant wave height and surface wind speed in the China Seas between 1988 and 2011

    Science.gov (United States)

    Zheng, Chongwei; Zhang, Ren; Shi, Weilai; Li, Xin; Chen, Xuan

    2017-10-01

    Wind and waves are key components of the climate system as they drive air-sea interactions and influence weather systems and atmospheric circulation. In marine environments, understanding surface wind and wave fields and their evolution over time is important for conducting safe and efficient human activities, such as navigation and engineering. This study considers long-term trends in the sea surface wind speed (WS) and significant wave height (SWH) in the China Seas over the period 1988-2011 using the Cross-Calibrated Multi-Platform (CCMP) ocean surface wind product and a 24-year hindcast wave dataset obtained from the WAVEWATCH-III (WW3) wave model forced with CCMP winds. The long-term trends in WS and SWH in the China Seas are analyzed over the past 24 years to provide a reference point from which to assess future climate change and offshore wind and wave energy resource development in the region. Results demonstrate that over the period 1988-2011 in the China Seas: 1) WS and SWH showed a significant increasing trend of 3.38 cm s-1 yr-1 and 1.52 cm yr-1, respectively; 2) there were notable regional differences in the long-term trends of WS and SWH; 3) areas with strong increasing trends were located mainly in the middle of the Tsushima Strait, the northern and southern areas of the Taiwan Strait, and in nearshore regions of the northern South China Sea; and 4) the long-term trend in WS was closely associated with El Niño and a significant increase in the occurrence of gale force winds in the region.

  11. Wave turbulence in annular wave tank

    Science.gov (United States)

    Onorato, Miguel; Stramignoni, Ettore

    2014-05-01

    We perform experiments in an annular wind wave tank at the Dipartimento di Fisica, Universita' di Torino. The external diameter of the tank is 5 meters while the internal one is 1 meter. The tank is equipped by two air fans which can lead to a wind of maximum 5 m/s. The present set up is capable of studying the generation of waves and the development of wind wave spectra for large duration. We have performed different tests including different wind speeds. For large wind speed we observe the formation of spectra consistent with Kolmogorv-Zakharov predictions.

  12. Exothermic waves in continua

    Science.gov (United States)

    Chernyi, G. G.

    Theoretical and experimental research related to the generation and propagation of exothermic waves in combustible gas mixtures as well as solid and liquid combustible media is reviewed. In particular, attention is given to detonation phenomena, the stationary structure of chemical detonation waves for various gas and condensed explosive models, discontinuous solutions for motions with exothermic discontinuities, and heat release in thermonuclear reactions. The discussion also covers frontal polymerization and crystallization waves, stationary combustion waves in systems with high-temperature self-propagating synthesis, and initiation of exothermic waves in continua with allowance for transfer processes.

  13. The Wave Dragon

    DEFF Research Database (Denmark)

    Sørensen, H. C.; Hansen, R.; Friis-Madsen, E.

    2000-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type, utilizing a patented wave reflector design to focus the waves towards a ramp, and the overtopping is used for electricity production through a set of Kaplan/propeller hydro turbines. During the last 2 years, excessive...... design an testing has been performed on a scale 1:50 model of the Wave Dragon, and on a scale 1:3:5 model turbine. Thus survivability, overtopping, hydraulic response, turbine performance and feasibility have been verified....

  14. The Wave Energy Device

    DEFF Research Database (Denmark)

    Frigaard, Peter; Kofoed, Jens Peter; Tedd, James William

    2006-01-01

    The Wave Dragon is a 4 to 11 MW offshore wave energy converter of the overtopping type. It basically consists of two wave reflectors focusing the waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power......'s first offshore wave energy converter. During this period an extensive measuring program has established the background for optimal design of the structure and regulation of the power take off system. Planning for full scale deployment of a 7 MW unit within the next 2 years is in progress. The prototype...

  15. Pulsars and Gravitational Waves

    Science.gov (United States)

    Lee, K. J.; Xu, R. X.; Qiao, G. J.

    2010-04-01

    The relationship between pulsar-like compact stars and gravitational waves is briefly reviewed. Due to regular spins, pulsars could be useful tools for us to detect ~nano-Hz low-frequency gravitational waves by pulsar-timing array technique; besides, they would also be ~kilo-Hz high-frequency gravitational wave radiators because of their compactness. The wave strain of an isolated pulsar depends on the equation state of cold matter at supra-nuclear densities. Therefore, a real detection of gravitational wave should be very meaningful in gravity physics, micro-theory of elementary strong interaction, and astronomy.

  16. Physics of waves

    CERN Document Server

    Elmore, William C

    1985-01-01

    Because of the increasing demands and complexity of undergraduate physics courses (atomic, quantum, solid state, nuclear, etc.), it is often impossible to devote separate courses to the classic wave phenomena of optics, acoustics, and electromagnetic radiation. This brief comprehensive text helps alleviate the problem with a unique overview of classical wave theory in one volume.By examining a sequence of concrete and specific examples (emphasizing the physics of wave motion), the authors unify the study of waves, developing abstract and general features common to all wave motion. The fundam

  17. Questions about elastic waves

    CERN Document Server

    Engelbrecht, Jüri

    2015-01-01

    This book addresses the modelling of mechanical waves by asking the right questions about them and trying to find suitable answers. The questions follow the analytical sequence from elementary understandings to complicated cases, following a step-by-step path towards increased knowledge. The focus is on waves in elastic solids, although some examples also concern non-conservative cases for the sake of completeness. Special attention is paid to the understanding of the influence of microstructure, nonlinearity and internal variables in continua. With the help of many mathematical models for describing waves, physical phenomena concerning wave dispersion, nonlinear effects, emergence of solitary waves, scales and hierarchies of waves as well as the governing physical parameters are analysed. Also, the energy balance in waves and non-conservative models with energy influx are discussed. Finally, all answers are interwoven into the canvas of complexity.

  18. 4-wave dynamics in kinetic wave turbulence

    CERN Document Server

    Chibbaro, Sergio; Rondoni, Lamberto

    2016-01-01

    A general Hamiltonian wave system with quartic resonances is considered, in the standard kinetic limit of a continuum of weakly interacting dispersive waves with random phases. The evolution equation for the multimode characteristic function $Z$ is obtained within an "interaction representation" and a perturbation expansion in the small nonlinearity parameter. A frequency renormalization is performed to remove linear terms that do not appear in the 3-wave case. Feynman-Wyld diagrams are used to average over phases, leading to a first order differential evolution equation for $Z$. A hierarchy of equations, analogous to the Boltzmann hierarchy for low density gases is derived, which preserves in time the property of random phases and amplitudes. This amounts to a general formalism for both the $N$-mode and the 1-mode PDF equations for 4-wave turbulent systems, suitable for numerical simulations and for investigating intermittency.

  19. Wave Overtopping Characteristics of the Wave Dragon

    DEFF Research Database (Denmark)

    Tedd, James; Kofoed, Jens Peter

    Simulation work has been used extensively with the Wave dragon and other overtopping devices to analyse the power production performance of them and to optimise the structural design and the control strategy. A time domain approach to this is well documented in Jakobsen & Frigaard 1999. Using...... measurements taken from the Wave Dragon Nissum Bredning prototype, some of the previous assumptions have been slightly modified and improved upon, so that the simulation method better represents the reality of what is occurring....

  20. Short-wave contributions in the storm surge associated with Xynthia, February 2010, western France

    Science.gov (United States)

    Bertin, X.; Li, K.; Roland, A.; Breilf, J. F.; Chaumillon, E.

    2012-04-01

    This study aims to hindcast and analyze the storm surge caused by Xynthia, a mid-latitude storm that severely hit the central part of the Bay of Biscay on the 27-28th of February 2010. This storm surge locally exceeded 1.5 m and peaked at the same time as a high spring tide (Bertin et al., 2012). A new storm surge modeling system was applied, based on the unstructured-grid circulation model SELFE (Zhang and Batista, 2008) and the spectral wave model WWM II (Roland et al., 2008). These two models are fully coupled and parallelized and share the same grid and domain decomposition. The modelling system was implemented over the North-East Atlantic Ocean and the space was discretized using an unstructured grid with a resolution ranging from 30 km in Deep Ocean to 25 m in near shore zones. Such a fine resolution was required to properly represent the surf zone. The modelling system resulted in tidal and wave predictions with errors of the order of 2 and 15%, respectively. The storm surge associated with Xynthia was also well predicted along the Bay of Biscay, with root mean square errors of the order of 0.10 m. Numerical experiments were then performed to analyze the physical processes controlling the development of the storm surge and revealed firstly that the wind caused most of the water level anomaly through an Ekman setup process. The comparison between a wave-dependant and a quadratic parameterization to compute wind stress showed that the storm surge was strongly amplified by the presence of steep and young wind-waves, related to their rapid development in the restricted fetch of the Bay of Biscay. The gradient of wave radiation stress contributed to the whole storm surge by about 0.05 to 0.10 m at the available tide gages. Nevertheless, these gages were located in sheltered harbors and modeling results showed that wave-induced setup locally exceeded 0.5 m in areas more exposed to ocean waves. The unstructured grid is currently being extended inland to simulate

  1. Cycloidal Wave Energy Converter

    Energy Technology Data Exchange (ETDEWEB)

    Stefan G. Siegel, Ph.D.

    2012-11-30

    This program allowed further advancing the development of a novel type of wave energy converter, a Cycloidal Wave Energy Converter or CycWEC. A CycWEC consists of one or more hydrofoils rotating around a central shaft, and operates fully submerged beneath the water surface. It operates under feedback control sensing the incoming waves, and converts wave power to shaft power directly without any intermediate power take off system. Previous research consisting of numerical simulations and two dimensional small 1:300 scale wave flume experiments had indicated wave cancellation efficiencies beyond 95%. The present work was centered on construction and testing of a 1:10 scale model and conducting two testing campaigns in a three dimensional wave basin. These experiments allowed for the first time for direct measurement of electrical power generated as well as the interaction of the CycWEC in a three dimensional environment. The Atargis team successfully conducted two testing campaigns at the Texas A&M Offshore Technology Research Center and was able to demonstrate electricity generation. In addition, three dimensional wave diffraction results show the ability to achieve wave focusing, thus increasing the amount of wave power that can be extracted beyond what was expected from earlier two dimensional investigations. Numerical results showed wave cancellation efficiencies for irregular waves to be on par with results for regular waves over a wide range of wave lengths. Using the results from previous simulations and experiments a full scale prototype was designed and its performance in a North Atlantic wave climate of average 30kW/m of wave crest was estimated. A full scale WEC with a blade span of 150m will deliver a design power of 5MW at an estimated levelized cost of energy (LCOE) in the range of 10-17 US cents per kWh. Based on the new results achieved in the 1:10 scale experiments these estimates appear conservative and the likely performance at full scale will

  2. Gravitational wave astronomy

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    In the past year, the LIGO-Virgo Collaboration announced the first secure detection of gravitational waves. This discovery heralds the beginning of gravitational wave astronomy: the use of gravitational waves as a tool for studying the dense and dynamical universe. In this talk, I will describe the full spectrum of gravitational waves, from Hubble-scale modes, through waves with periods of years, hours and milliseconds. I will describe the different techniques one uses to measure the waves in these bands, current and planned facilities for implementing these techniques, and the broad range of sources which produce the radiation. I will discuss what we might expect to learn as more events and sources are measured, and as this field matures into a standard part of the astronomical milieu.

  3. Analysis of Waves

    DEFF Research Database (Denmark)

    Frigaard, Peter; Andersen, Thomas Lykke

    The present book describes the most important aspects of wave analysis techniques applied to physical model tests. Moreover, the book serves as technical documentation for the wave analysis software WaveLab 3, cf. Aalborg University (2012). In that respect it should be mentioned that supplementary...... to the present technical documentation exists also the online help document describing the WaveLab software in detail including all the inputs and output fields. In addition to the two main authors also Tue Hald, Jacob Helm-Petersen and Morten Møller Jakobsen have contributed to the note. Their input is highly...... acknowledged. The outline of the book is as follows: • Chapter 2 and 3 describes analysis of waves in time and frequency domain. • Chapter 4 and 5 describes the separation of incident and reflected waves for the two-dimensional case. • Chapter 6 describes the estimation of the directional spectra which also...

  4. Waves and compressible flow

    CERN Document Server

    Ockendon, Hilary

    2016-01-01

    Now in its second edition, this book continues to give readers a broad mathematical basis for modelling and understanding the wide range of wave phenomena encountered in modern applications.  New and expanded material includes topics such as elastoplastic waves and waves in plasmas, as well as new exercises.  Comprehensive collections of models are used to illustrate the underpinning mathematical methodologies, which include the basic ideas of the relevant partial differential equations, characteristics, ray theory, asymptotic analysis, dispersion, shock waves, and weak solutions. Although the main focus is on compressible fluid flow, the authors show how intimately gasdynamic waves are related to wave phenomena in many other areas of physical science.   Special emphasis is placed on the development of physical intuition to supplement and reinforce analytical thinking. Each chapter includes a complete set of carefully prepared exercises, making this a suitable textbook for students in applied mathematics, ...

  5. Waves in the seas

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.

    of component waves of various periods and heights. This is the most commonly used theory for practical applications like design of ships, oil rigs and coastal structures such as jetties, ports, and sea walls. This theory also provides sufficient intellectual... of wind waves in the sea is a wide and interesting field with ap- plications in marine exploration ac- tivities, underwater pipe laying, pol- lution control, ports and shipping in- volving billions of dollars worth of transactions. Not all sea waves look...

  6. Spheroidal wave functions

    CERN Document Server

    Flammer, Carson

    2005-01-01

    Intended to facilitate the use and calculation of spheroidal wave functions, this applications-oriented text features a detailed and unified account of the properties of these functions. Addressed to applied mathematicians, mathematical physicists, and mathematical engineers, it presents tables that provide a convenient means for handling wave problems in spheroidal coordinates.Topics include separation of the scalar wave equation in spheroidal coordinates, angle and radial functions, integral representations and relations, and expansions in spherical Bessel function products. Additional subje

  7. Dyakonov surface waves

    DEFF Research Database (Denmark)

    Takayama, Osamu; Crasovan, Lucian Cornel; Johansen, Steffen Kjær

    2008-01-01

    The interface of two semi-infinite media, where at least one of them is a birefringent crystal, supports a special type of surface wave that was predicted theoretically by D'yakonov in 1988. Since then, the properties of such waves, which exist in transparent media only under very special......, the existence of these surface waves in specific material examples is analyzed, discussing the challenge posed by their experimental observation....

  8. WaveNet

    Science.gov (United States)

    2015-10-30

    Coastal Inlets Research Program WaveNet WaveNet is a web-based, Graphical-User-Interface ( GUI ) data management tool developed for Corps coastal...generates tabular and graphical information for project planning and design documents. The WaveNet is a web-based GUI designed to provide users with a...data from different sources, and employs a combination of Fortran, Python and Matlab codes to process and analyze data for USACE applications

  9. Gravitation Waves seminar

    CERN Multimedia

    CERN. Geneva HR-RFA

    2006-01-01

    We will present a brief introduction to the physics of gravitational waves and their properties. We will review potential astrophysical sources of gravitational waves, and the physics and astrophysics that can be learned from their study. We will survey the techniques and technologies for detecting gravitational waves for the first time, including bar detectors and broadband interferometers, and give a brief status report on the international search effort.

  10. Gravitational Wave Astronomy

    CERN Multimedia

    CERN. Geneva

    2006-01-01

    Gravitational wave astronomy is expected to become an observational field within the next decade. First direct detection of gravitational waves is possible with existing terrestrial-based detectors, and highly probable with proposed upgrades. In this three-part lecture series, we give an overview of the field, including material on gravitional wave sources, detection methods, some details of interferometric detectors, data analysis methods, and current results from observational data-taking runs of the LIGO and GEO projects.

  11. WAVES VHDL interface

    Science.gov (United States)

    Hanna, James P.

    1994-06-01

    The Waveform and Vector Exchange Specification (WAVES) is the Industry standard representation for digital stimulus and response for both the design and test communities. The VHSIC Hardware Description Language (VHDL) is the Industry standard language for the design, modeling, and simulation of digital electronics. Together VHDL and WAVES provide powerful support for top-down design and test methodologies and concurrent engineering practices. Although the syntax of WAVES is a subset of VHDL, no special support for using WAVES in a VHDL environment is defined within the language. This report will introduce and describe a VHDL package that was developed at Rome Laboratory to provide a software interface to support the use of WAVES in a VHDL environment. This VHDL package is referred to as the WAVES VHDL interface and has been proposed as a standard practice for a top-down design and test methodology using WAVES and VHDL. This report is not intended to provide a tutorial on VHDL or WAVES. It is assumed that the reader has an adequate understanding of the VHDL language and some modeling techniques. Further, it is assumed that the reader has an understanding of the WAVES language and can follow a simple Level 1 dataset description.

  12. Non-diffractive waves

    CERN Document Server

    Hernandez-Figueroa, Hugo E; Recami, Erasmo

    2013-01-01

    This continuation and extension of the successful book ""Localized Waves"" by the same editors brings together leading researchers in non-diffractive waves to cover the most important results in their field and as such is the first to present the current state.The well-balanced presentation of theory and experiments guides readers through the background of different types of non-diffractive waves, their generation, propagation, and possible applications. The authors include a historical account of the development of the field, and cover different types of non-diffractive waves, including Airy

  13. Wave Loads on Cylinders

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Frigaard, Peter

    1989-01-01

    Wave loads may be defined as time varying forces on a body resulting from the wave induced flow fields which surrounds the body in whole or in part. Such unsteady fluid forces are the net result of pressure and shear forces integrated over the instantaneous wetted area.......Wave loads may be defined as time varying forces on a body resulting from the wave induced flow fields which surrounds the body in whole or in part. Such unsteady fluid forces are the net result of pressure and shear forces integrated over the instantaneous wetted area....

  14. Propagation of waves

    CERN Document Server

    David, P

    2013-01-01

    Propagation of Waves focuses on the wave propagation around the earth, which is influenced by its curvature, surface irregularities, and by passage through atmospheric layers that may be refracting, absorbing, or ionized. This book begins by outlining the behavior of waves in the various media and at their interfaces, which simplifies the basic phenomena, such as absorption, refraction, reflection, and interference. Applications to the case of the terrestrial sphere are also discussed as a natural generalization. Following the deliberation on the diffraction of the "ground? wave around the ear

  15. Caustics of atmospheric waves

    Science.gov (United States)

    Godin, Oleg A.

    2015-04-01

    Much like light and sound, acoustic-gravity waves in inhomogeneous atmosphere often have a caustic or caustics, where the ray theory predicts unphysical, divergent values of the wave amplitude and needs to be modified. Increase of the wave magnitude in the vicinity of a caustic makes such vicinities of primary interest in a number of problems, where a signal needs to be separated from a background noise. The value of wave focusing near caustics should be carefully quantified in order to evaluate possible nonlinearities promoted by the focusing. Physical understanding of the wave field in the vicinity of a caustic is also important for understanding of the wave reflection from and transmission (tunneling) through the caustic. To our knowledge, in contrast to caustics of acoustic, electromagnetic, and seismic waves as well as gravity waves in incompressible fluids, asymptotics of acoustic-gravity waves in the vicinity of a caustic have never been studied systematically. In this paper, we fill this gap. Atmospheric waves are considered as linear acoustic-gravity waves in a neutral, horizontally stratified, moving ideal gas of variable composition. Air temperature and wind velocity are assumed to be gradually varying functions of height, and slowness of these variations determines the large parameter of the problem. The scale height of the atmosphere can be large or small compared to the vertical wavelength. It is found that the uniform asymptotics of the wave field in the presence of a simple caustic can be expressed in terms of the Airy function and its derivative. As for the acoustic waves, the argument of the Airy function is expressed in terms of the eikonal calculated in the ray, or WKB, approximation. The geometrical, or Berry, phase, which arises in the consistent WKB approximation for acoustic-gravity waves, plays an important role in the caustic asymptotics. In the uniform asymptotics, the terms with the Airy function and its derivative are weighted by cosine

  16. The Wave Energy Sector

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter

    2017-01-01

    shaped by the development, research, and teaching that we have carried out at the Wave Energy Research Group at Aalborg University over the past decades. It is our belief and experience that it would be useful writing and compiling such a handbook in order to enhance the understanding of the sector......This Handbook for Ocean Wave Energy aims at providing a guide into the field of ocean wave energy utilization. The handbook offers a concise yet comprehensive overview of the main aspects and disciplines involved in the development of wave energy converters (WECs). The idea for the book has been...

  17. Exitation of Whistler Waves by a Helical Wave Structure

    DEFF Research Database (Denmark)

    Balmashnov, A. A.; Lynov, Jens-Peter; Michelsen, Poul

    1981-01-01

    The excitation of whistler waves in a radial inhomogeneous plasma is investigated experimentally, using a slow-wave structure consisting of a helix of variable length surrounding the plasma column. The excited waves were observed to have a wave-vector parallel to the external magnetic field....... The possibility of exciting the waves in different radial regions is demonstrated....

  18. Heat wave over India during summer 2015: an assessment of real time extended range forecast

    Science.gov (United States)

    Pattanaik, D. R.; Mohapatra, M.; Srivastava, A. K.; Kumar, Arun

    2017-08-01

    Hot winds are the marked feature of summer season in India during late spring preceding the climatological onset of the monsoon season in June. Some years the conditions becomes very vulnerable with the maximum temperature ( T max) exceeding 45 °C for many days over parts of north-western, eastern coastal states of India and Indo-Gangetic plain. During summer of 2015 (late May to early June) eastern coastal states, central and northwestern parts of India experienced severe heat wave conditions leading to loss of thousands of human life in extreme high temperature conditions. It is not only the loss of human life but also the animals and birds were very vulnerable to this extreme heat wave conditions. In this study, an attempt is made to assess the performance of real time extended range forecast (forecast up to 3 weeks) of this scorching T max based on the NCEP's Climate Forecast System (CFS) latest version coupled model (CFSv2). The heat wave condition was very severe during the week from 22 to 28 May with subsequent week from 29 May to 4 June also witnessed high T max over many parts of central India including eastern coastal states of India. The 8 ensemble members of operational CFSv2 model are used once in a week to prepare the weekly bias corrected deterministic (ensemble mean) T max forecast for 3 weeks valid from Friday to Thursday coinciding with the heat wave periods of 2015. Using the 8 ensemble members separately and the CFSv2 corresponding hindcast climatology the probability of above and below normal T max is also prepared for the same 3 weeks. The real time deterministic and probabilistic forecasts did indicate impending heat wave over many parts of India during late May and early June of 2015 associated with strong northwesterly wind over main land mass of India, delaying the sea breeze, leading to heat waves over eastern coastal regions of India. Thus, the capability of coupled model in providing early warning of such killer heat wave can be very

  19. Extreme bottom velocities induced by wind wave and currents in the Gulf of Gdańsk

    Science.gov (United States)

    Cieślikiewicz, Witold; Dudkowska, Aleksandra; Gic-Grusza, Gabriela; Jędrasik, Jan

    2017-11-01

    The principal goal of this study is to get some preliminary insights about the intensity of water movement generated by wind waves, and due to the currents in the bottom waters of Gulf of Gdańsk, during severe storms. The Gulf of Gdańsk is located in the southern Baltic Sea. This paper presents the results of analysis of wave and current-induced velocities during extreme wind conditions, which are determined based on long-term historical records. The bottom velocity fields originated from wind wave and wind currents, during analysed extreme wind events, are computed independently of each other. The long-term wind wave parameters for the Baltic Sea region are derived from the 44-year hindcast wave database generated in the framework of the project HIPOCAS funded by the European Union. The output from the numerical wave model WAM provides the boundary conditions for the model SWAN operating in high-resolution grid covering the area of the Gulf of Gdańsk. Wind current velocities are calculated with the M3D hydrodynamic model developed in the Institute of Oceanography of the University of Gdańsk based on the POM model. The three dimensional current fields together with trajectories of particle tracers spreading out of bottom boundary layer are modelled, and the calculated fields of bottom velocities are presented in the form of 2D maps. During northerly winds, causing in the Gulf of Gdańsk extreme waves and most significant wind-driven circulation, the wave-induced bottom velocities are greater than velocities due to currents. The current velocities in the bottom layer appeared to be smaller by an order of magnitude than the wave-induced bottom orbital velocities. Namely, during most severe northerly storms analysed, current bottom velocities ranged about 0.1-0.15 m/s, while the root mean square of wave-induced near-seabed velocities reached maximum values of up to 1.4 m/s in the southern part of Gulf of Gdańsk.

  20. Parametric analysis of change in wave number of surface waves

    Directory of Open Access Journals (Sweden)

    Tadić Ljiljana

    2015-01-01

    Full Text Available The paper analyzes the dependence of the change wave number of materials soil constants, ie the frequency of the waves. The starting point in this analysis cosists of wave equation and dynamic stiffness matrix of soil.

  1. Design wave estimation considering directional distribution of waves

    Digital Repository Service at National Institute of Oceanography (India)

    SanilKumar, V.; Deo, M.C.

    The design of coastal and offshore structures requires design significant wave height having a certain return period. The commonly followed procedure to estimate the design wave height, does not give any consideration to the directions of waves...

  2. On conformally related -waves

    Indian Academy of Sciences (India)

    Conformal transformations; conformal Killing vectors; -waves. Abstract. Brinkmann [1] has shown that conformally related distinct Ricci flat solutions are -waves. Brinkmann's result has been generalized to include the conformally invariant source terms. It has been shown that [4] if g i k and g ¯ i k ( = − 2 g i k , : a ...

  3. Developing de Broglie Wave

    Directory of Open Access Journals (Sweden)

    Zheng-Johansson J. X.

    2006-10-01

    Full Text Available The electromagnetic component waves, comprising together with their generating oscillatory massless charge a material particle, will be Doppler shifted when the charge hence particle is in motion, with a velocity v, as a mere mechanical consequence of the source motion. We illustrate here that two such component waves generated in opposite directions and propagating at speed c between walls in a one-dimensional box, superpose into a traveling beat wave of wavelength Λd=vcΛ and phase velocity c2/v+v which resembles directly L. de Broglie’s hypothetic phase wave. This phase wave in terms of transmitting the particle mass at the speed v and angular frequency Ωd= 2πv/Λd, with Λd and Ωd obeying the de Broglie relations, represents a de Broglie wave. The standing-wave function of the de Broglie (phase wave and its variables for particle dynamics in small geometries are equivalent to the eigen-state solutions to Schrödinger equation of an identical system.

  4. Gravitational waves from inflation

    Science.gov (United States)

    Guzzetti, M. C.; Bartolo, N.; Liguori, M.; Matarrese, S.

    2016-09-01

    The production of a stochastic background of gravitational waves is a fundamental prediction of any cosmological inflationary model. The features of such a signal encode unique information about the physics of the Early Universe and beyond, thus representing an exciting, powerful window on the origin and evolution of the Universe. We review the main mechanisms of gravitational-wave production, ranging from quantum fluctuations of the gravitational field to other mechanisms that can take place during or after inflation. These include e.g. gravitational waves generated as a consequence of extra particle production during inflation, or during the (p)reheating phase. Gravitational waves produced in inflation scenarios based on modified gravity theories and second-order gravitational waves are also considered. For each analyzed case, the expected power spectrum is given. We discuss the discriminating power among different models, associated with the validity/violation of the standard consistency relation between tensor-to-scalar ratio r and tensor spectral index nT. In light of the prospects for (directly/indirectly) detecting primordial gravitational waves, we give the expected present-day gravitational radiation spectral energy-density, highlighting the main characteristics imprinted by the cosmic thermal history, and we outline the signatures left by gravitational waves on the Cosmic Microwave Background and some imprints in the Large-Scale Structure of the Universe. Finally, current bounds and prospects of detection for inflationary gravitational waves are summarized.

  5. Slow frictional waves

    Science.gov (United States)

    Viswanathan, Koushik; Sundaram, Narayan; Chandrasekar, Srinivasan

    Stick-slip, manifest as intermittent tangential motion between two dry solid surfaces, is a friction instability that governs diverse phenomena from automobile brake squeals to earthquakes. We show, using high-speed in situ imaging of an adhesive polymer interface, that low velocity stick-slip is fundamentally of three kinds, corresponding to passage of three different surface waves -- separation pulses, slip pulses and the well-known Schallamach waves. These waves, traveling much slower than elastic waves, have clear distinguishing properties. Separation pulses and Schallamach waves involve local interface separation, and propagate in opposite directions while slip pulses are characterized by a sharp stress front and do not display any interface detachment. A change in the stick-slip mode from separation to slip pulse is effected simply by increasing the normal force. Together, these three waves constitute all possible stick-slip modes in adhesive friction and are shown to have direct analogues in muscular locomotory waves in soft bodied invertebrates. A theory for slow wave propagation is also presented which is capable of explaining the attendant interface displacements, velocities and stresses.

  6. The Relativistic Wave Vector

    Science.gov (United States)

    Houlrik, Jens Madsen

    2009-01-01

    The Lorentz transformation applies directly to the kinematics of moving particles viewed as geometric points. Wave propagation, on the other hand, involves moving planes which are extended objects defined by simultaneity. By treating a plane wave as a geometric object moving at the phase velocity, novel results are obtained that illustrate the…

  7. Those Elusive Gravitational Waves

    Science.gov (United States)

    MOSAIC, 1976

    1976-01-01

    The presence of gravitational waves was predicted by Einstein in his theory of General Relativity. Since then, scientists have been attempting to develop a detector sensitive enough to measure these cosmic signals. Once the presence of gravitational waves is confirmed, scientists can directly study star interiors, galaxy cores, or quasars. (MA)

  8. Parsimonious Surface Wave Interferometry

    KAUST Repository

    Li, Jing

    2017-10-24

    To decrease the recording time of a 2D seismic survey from a few days to one hour or less, we present a parsimonious surface-wave interferometry method. Interferometry allows for the creation of a large number of virtual shot gathers from just two reciprocal shot gathers by crosscoherence of trace pairs, where the virtual surface waves can be inverted for the S-wave velocity model by wave-equation dispersion inversion (WD). Synthetic and field data tests suggest that parsimonious wave-equation dispersion inversion (PWD) gives S-velocity tomograms that are comparable to those obtained from a full survey with a shot at each receiver. The limitation of PWD is that the virtual data lose some information so that the resolution of the S-velocity tomogram can be modestly lower than that of the S-velocity tomogram inverted from a conventional survey.

  9. Electromagnetic wave energy converter

    Science.gov (United States)

    Bailey, R. L. (Inventor)

    1973-01-01

    Electromagnetic wave energy is converted into electric power with an array of mutually insulated electromagnetic wave absorber elements each responsive to an electric field component of the wave as it impinges thereon. Each element includes a portion tapered in the direction of wave propagation to provide a relatively wideband response spectrum. Each element includes an output for deriving a voltage replica of the electric field variations intercepted by it. Adjacent elements are positioned relative to each other so that an electric field subsists between adjacent elements in response to the impinging wave. The electric field results in a voltage difference between adjacent elements that is fed to a rectifier to derive dc output power.

  10. Ion Acoustic Waves in the Presence of Electron Plasma Waves

    DEFF Research Database (Denmark)

    Michelsen, Poul; Pécseli, Hans; Juul Rasmussen, Jens

    1977-01-01

    Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave.......Long-wavelength ion acoustic waves in the presence of propagating short-wavelength electron plasma waves are examined. The influence of the high frequency oscillations is to decrease the phase velocity and the damping distance of the ion wave....

  11. 4-wave dynamics in kinetic wave turbulence

    Science.gov (United States)

    Chibbaro, Sergio; Dematteis, Giovanni; Rondoni, Lamberto

    2018-01-01

    A general Hamiltonian wave system with quartic resonances is considered, in the standard kinetic limit of a continuum of weakly interacting dispersive waves with random phases. The evolution equation for the multimode characteristic function Z is obtained within an ;interaction representation; and a perturbation expansion in the small nonlinearity parameter. A frequency renormalization is performed to remove linear terms that do not appear in the 3-wave case. Feynman-Wyld diagrams are used to average over phases, leading to a first order differential evolution equation for Z. A hierarchy of equations, analogous to the Boltzmann hierarchy for low density gases is derived, which preserves in time the property of random phases and amplitudes. This amounts to a general formalism for both the N-mode and the 1-mode PDF equations for 4-wave turbulent systems, suitable for numerical simulations and for investigating intermittency. Some of the main results which are developed here in detail have been tested numerically in a recent work.

  12. Summer heat waves over western Europe 1880-2003, their relationship to large-scale forcings and predictability

    Energy Technology Data Exchange (ETDEWEB)

    Della-Marta, P.M. [University of Bern, Institute of Geography, Climatology and Meteorology Research Group, Bern (Switzerland); Federal Office for Meteorology and Climatology MeteoSwiss, Zurich (Switzerland); National Climate Center, Bureau of Meteorology, Melbourne (Australia); Luterbacher, J.; Xoplaki, E.; Wanner, H. [University of Bern, Institute of Geography, Climatology and Meteorology Research Group, Bern (Switzerland); NCCR Climate, Bern (Switzerland); Weissenfluh, H. von [University of Bern, Institute of Geography, Climatology and Meteorology Research Group, Bern (Switzerland); Brunet, M. [University Rovira i Virgili, Climate Change Research Group, Tarragona (Spain)

    2007-08-15

    We investigate the large-scale forcing and teleconnections between atmospheric circulation (sea level pressure, SLP), sea surface temperatures (SSTs), precipitation and heat wave events over western Europe using a new dataset of 54 daily maximum temperature time series. Forty four of these time series have been homogenised at the daily timescale to ensure that the presence of inhomogeneities has been minimised. The daily data have been used to create a seasonal index of the number of heat waves. Using canonical correlation analysis (CCA), heat waves over western Europe are shown to be related to anomalous high pressure over Scandinavia and central western Europe. Other forcing factors such as Atlantic SSTs and European precipitation, the later as a proxy for soil moisture, a known factor in strengthening land-atmosphere feedback processes, are also important. The strength of the relationship between summer SLP anomalies and heat waves is improved (from 35%) to account for around 46% of its variability when summer Atlantic and Mediterranean SSTs and summer European precipitation anomalies are included as predictors. This indicates that these predictors are not completely collinear rather that they each have some contribution to accounting for summer heat wave variability. However, the simplicity and scale of the statistical analysis masks this complex interaction between variables. There is some useful predictive skill of summer heat waves using multiple lagged predictors. A CCA using preceding winter North Atlantic SSTs and preceding January to May Mediterranean total precipitation results in significant hindcast (1972-2003) Spearman rank correlation skill scores up to 0.55 with an average skill score over the domain equal to 0.28 {+-} 0.28. In agreement with previous studies focused on mean summer temperature, there appears to be some predictability of heat wave events on the decadal scale from the Atlantic Multidecadal Oscillation (AMO), although the long

  13. Summer heat waves over western Europe 1880 2003, their relationship to large-scale forcings and predictability

    Science.gov (United States)

    Della-Marta, P. M.; Luterbacher, J.; von Weissenfluh, H.; Xoplaki, E.; Brunet, M.; Wanner, H.

    2007-08-01

    We investigate the large-scale forcing and teleconnections between atmospheric circulation (sea level pressure, SLP), sea surface temperatures (SSTs), precipitation and heat wave events over western Europe using a new dataset of 54 daily maximum temperature time series. Forty four of these time series have been homogenised at the daily timescale to ensure that the presence of inhomogeneities has been minimised. The daily data have been used to create a seasonal index of the number of heat waves. Using canonical correlation analysis (CCA), heat waves over western Europe are shown to be related to anomalous high pressure over Scandinavia and central western Europe. Other forcing factors such as Atlantic SSTs and European precipitation, the later as a proxy for soil moisture, a known factor in strengthening land atmosphere feedback processes, are also important. The strength of the relationship between summer SLP anomalies and heat waves is improved (from 35%) to account for around 46% of its variability when summer Atlantic and Mediterranean SSTs and summer European precipitation anomalies are included as predictors. This indicates that these predictors are not completely collinear rather that they each have some contribution to accounting for summer heat wave variability. However, the simplicity and scale of the statistical analysis masks this complex interaction between variables. There is some useful predictive skill of summer heat waves using multiple lagged predictors. A CCA using preceding winter North Atlantic SSTs and preceding January to May Mediterranean total precipitation results in significant hindcast (1972 2003) Spearman rank correlation skill scores up to 0.55 with an average skill score over the domain equal to 0.28 ± 0.28. In agreement with previous studies focused on mean summer temperature, there appears to be some predictability of heat wave events on the decadal scale from the Atlantic Multidecadal Oscillation (AMO), although the long

  14. Abnormal Waves Modelled as Second-order Conditional Waves

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher

    2005-01-01

    The paper presents results for the expected second order short-crested wave conditional of a given wave crest at a specific point in time and space. The analysis is based on the second order Sharma and Dean shallow water wave theory. Numerical results showing the importance of the spectral density......, the water depth and the directional spreading on the conditional mean wave profile are presented. Application of conditional waves to model and explain abnormal waves, e.g. the well-known New Year Wave measured at the Draupner platform January 1st 1995, is discussed. Whereas the wave profile can be modelled...... quite well by the second order conditional wave including directional spreading and finite water depth the probability to encounter such a wave is still, however, extremely rare. The use of the second order conditional wave as initial condition to a fully non-linear three-dimensional analysis...

  15. Stress wave focusing transducers

    Energy Technology Data Exchange (ETDEWEB)

    Visuri, S.R., LLNL

    1998-05-15

    Conversion of laser radiation to mechanical energy is the fundamental process behind many medical laser procedures, particularly those involving tissue destruction and removal. Stress waves can be generated with laser radiation in several ways: creation of a plasma and subsequent launch of a shock wave, thermoelastic expansion of the target tissue, vapor bubble collapse, and ablation recoil. Thermoelastic generation of stress waves generally requires short laser pulse durations and high energy density. Thermoelastic stress waves can be formed when the laser pulse duration is shorter than the acoustic transit time of the material: {tau}{sub c} = d/c{sub s} where d = absorption depth or spot diameter, whichever is smaller, and c{sub s} = sound speed in the material. The stress wave due to thermoelastic expansion travels at the sound speed (approximately 1500 m/s in tissue) and leaves the site of irradiation well before subsequent thermal events can be initiated. These stress waves, often evolving into shock waves, can be used to disrupt tissue. Shock waves are used in ophthalmology to perform intraocular microsurgery and photodisruptive procedures as well as in lithotripsy to fragment stones. We have explored a variety of transducers that can efficiently convert optical to mechanical energy. One such class of transducers allows a shock wave to be focused within a material such that the stress magnitude can be greatly increased compared to conventional geometries. Some transducer tips could be made to operate regardless of the absorption properties of the ambient media. The size and nature of the devices enable easy delivery, potentially minimally-invasive procedures, and precise tissue- targeting while limiting thermal loading. The transducer tips may have applications in lithotripsy, ophthalmology, drug delivery, and cardiology.

  16. Symmetric waves are traveling waves for a shallow water equation for surface waves of moderate amplitude

    OpenAIRE

    Geyer, Anna

    2016-01-01

    Following a general principle introduced by Ehrnstr\\"{o}m et.al. we prove that for an equation modeling the free surface evolution of moderate amplitude waves in shallow water, all symmetric waves are traveling waves.

  17. Water wave scattering

    CERN Document Server

    Mandal, Birendra Nath

    2015-01-01

    The theory of water waves is most varied and is a fascinating topic. It includes a wide range of natural phenomena in oceans, rivers, and lakes. It is mostly concerned with elucidation of some general aspects of wave motion including the prediction of behaviour of waves in the presence of obstacles of some special configurations that are of interest to ocean engineers. Unfortunately, even the apparently simple problems appear to be difficult to tackle mathematically unless some simplified assumptions are made. Fortunately, one can assume water to be an incompressible, in viscid and homogeneous

  18. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden; Bjerrum Møller, Hans

    1975-01-01

    The energies of spin waves propagating in the c direction of Tb have been studied by inelastic neutron scattering, as a function of a magnetic field applied along the easy and hard directions in the basal plane, and as a function of temperature. From a general spin Hamiltonian, consistent...... with the symmetry, we deduce the dispersion relation for the spin waves in a basal-plane ferromagnet. This phenomenological spin-wave theory accounts for the observed behavior of the magnon energies in Tb. The two q⃗-dependent Bogoliubov components of the magnon energies are derived from the experimental results...

  19. Vibrations and waves

    CERN Document Server

    Kaliski, S

    2013-01-01

    This book gives a comprehensive overview of wave phenomena in different media with interacting mechanical, electromagnetic and other fields. Equations describing wave propagation in linear and non-linear elastic media are followed by equations of rheological models, models with internal rotational degrees of freedom and non-local interactions. Equations for coupled fields: thermal, elastic, electromagnetic, piezoelectric, and magneto-spin with adequate boundary conditions are also included. Together with its companion volume Vibrations and Waves. Part A: Vibrations this work provides a wealth

  20. Relativistic wave mechanics

    CERN Document Server

    Corinaldesi, Ernesto

    1963-01-01

    Geared toward advanced undergraduate and graduate students of physics, this text provides readers with a background in relativistic wave mechanics and prepares them for the study of field theory. The treatment originated as a series of lectures from a course on advanced quantum mechanics that has been further amplified by student contributions.An introductory section related to particles and wave functions precedes the three-part treatment. An examination of particles of spin zero follows, addressing wave equation, Lagrangian formalism, physical quantities as mean values, translation and rotat

  1. Wave Height Distribution for Nonlinear Swell Waves in Deep an Depth Limited Wave Conditions

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke; Knudsen, Jannie Elkær

    2017-01-01

    This paper presents initial results from an on-going study on the influence from wave nonlinearity on the wave height distribution in deep- and depth-limited nonlinear wave conditions. A fully nonlinear VOF model, IH-2VOF, is applied to model the propagation of irregular waves on a sloping sea bed...... from deep to shallow water, including the effects of wave breaking. Different wave nonlinearities are evaluated in the model and the effects of the wave nonlinearity, described by the so-called Ursell-number, on the wave height distributions along the sloping sea bed are evaluated. The widely used...

  2. Theory of Gravitational Waves

    CERN Document Server

    Tiec, Alexandre Le

    2016-01-01

    The existence of gravitational radiation is a natural prediction of any relativistic description of the gravitational interaction. In this chapter, we focus on gravitational waves, as predicted by Einstein's general theory of relativity. First, we introduce those mathematical concepts that are necessary to properly formulate the physical theory, such as the notions of manifold, vector, tensor, metric, connection and curvature. Second, we motivate, formulate and then discuss Einstein's equation, which relates the geometry of spacetime to its matter content. Gravitational waves are later introduced as solutions of the linearized Einstein equation around flat spacetime. These waves are shown to propagate at the speed of light and to possess two polarization states. Gravitational waves can interact with matter, allowing for their direct detection by means of laser interferometers. Finally, Einstein's quadrupole formulas are derived and used to show that nonspherical compact objects moving at relativistic speeds a...

  3. Violent breaking wave impacts

    DEFF Research Database (Denmark)

    Bredmose, Henrik; Peregrine, D.H.; Bullock, G.N.

    2009-01-01

    a better understanding of the processes involved. The wave's approach towards a structure is modelled with classical irrotational flow to obtain the different types of impact profiles that may or may not lead to air entrapment. The subsequent impact is modelled with a novel compressible-flow model...... local error. The high pressures measured during wave impacts on a breakwater are reproduced and it is shown that trapped air can be compressed to a pressure of several atmospheres. Pressure shock waves, reflected off nearby surfaces such as the seabed, can lead to pressures comparable with those...... for a homogeneous mixture of incompressible liquid and ideal gas. This enables a numerical description of both trapped air pockets and the propagation of pressure shock waves through the aerated water. An exact Riemann solver is developed to permit a finite-volume solution to the flow model with smallest possible...

  4. Traveling-wave photodetector

    Science.gov (United States)

    Hietala, Vincent M.; Vawter, Gregory A.

    1993-01-01

    The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size.

  5. Turbulence generation by waves

    Energy Technology Data Exchange (ETDEWEB)

    Kaftori, D.; Nan, X.S.; Banerjee, S. [Univ. of California, Santa Barbara, CA (United States)

    1995-12-31

    The interaction between two-dimensional mechanically generated waves, and a turbulent stream was investigated experimentally in a horizontal channel, using a 3-D LDA synchronized with a surface position measuring device and a micro-bubble tracers flow visualization with high speed video. Results show that although the wave induced orbital motion reached all the way to the wall, the characteristics of the turbulence wall structures and the turbulence intensity close to the wall were not altered. Nor was the streaky nature of the wall layer. On the other hand, the mean velocity profile became more uniform and the mean friction velocity was increased. Close to the free surface, the turbulence intensity was substantially increased as well. Even in predominantly laminar flows, the introduction of 2-D waves causes three dimensional turbulence. The turbulence enhancement is found to be proportional to the wave strength.

  6. Sound wave transmission (image)

    Science.gov (United States)

    When sounds waves reach the ear, they are translated into nerve impulses. These impulses then travel to the brain where they are interpreted by the brain as sound. The hearing mechanisms within the inner ear, can ...

  7. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

    Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...

  8. NOAA NDBC SOS - waves

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA NDBC SOS server is part of the IOOS DIF SOS Project. The stations in this dataset have waves data. Because of the nature of SOS requests, requests for data...

  9. SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Vicinanza, Diego; Frigaard, Peter

    2008-01-01

    The SSG (Sea Slot-cone Generator) is a wave energy converter of the overtopping type. The structure consists of a number of reservoirs one on the top of each others above the mean water level, in which the water of incoming waves is stored temporary. In each reservoir, expressively designed low...... head hydroturbines are converting the potential energy of the stored water into power. A key to success for the SSG will be the low cost of the structure and its robustness. The construction of the pilot plant is scheduled and this paper aims to describe the concept of the SSG wave energy converter...... and the studies behind the process that leads to its construction. The pilot plant is an on-shore full scale module in 3 levels with an expected power production of 320 MWh/y in the North Sea. Location, wave climate and laboratory tests results will be used here to describe the pilot plant and its characteristics....

  10. Wave Equation Inversion of Skeletonized SurfaceWaves

    KAUST Repository

    Zhang, Zhendong

    2015-08-19

    We present a surface-wave inversion method that inverts for the S-wave velocity from the Rayleigh dispersion curve for the fundamental-mode. We call this wave equation inversion of skeletonized surface waves because the dispersion curve for the fundamental-mode Rayleigh wave is inverted using finite-difference solutions to the wave equation. The best match between the predicted and observed dispersion curves provides the optimal S-wave velocity model. Results with synthetic and field data illustrate the benefits and limitations of this method.

  11. Electromagnetic van Kampen waves

    Energy Technology Data Exchange (ETDEWEB)

    Ignatov, A. M., E-mail: aign@fpl.gpi.ru [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2017-01-15

    The theory of van Kampen waves in plasma with an arbitrary anisotropic distribution function is developed. The obtained solutions are explicitly expressed in terms of the permittivity tensor. There are three types of perturbations, one of which is characterized by the frequency dependence on the wave vector, while for the other two, the dispersion relation is lacking. Solutions to the conjugate equations allowing one to solve the initial value problem are analyzed.

  12. Geometric wave equations

    CERN Document Server

    Shatah, Jalal

    2000-01-01

    This volume contains notes of the lectures given at the Courant Institute and a DMV-Seminar at Oberwolfach. The focus is on the recent work of the authors on semilinear wave equations with critical Sobolev exponents and on wave maps in two space dimensions. Background material and references have been added to make the notes self-contained. The book is suitable for use in a graduate-level course on the topic.

  13. Wave Atom Based Watermarking

    OpenAIRE

    Bukhari, Ijaz; Nuhman-ul-Haq; Hyat, Khizar

    2013-01-01

    Watermarking helps in ensuring originality, ownership and copyrights of a digital image. This paper aims at embedding a Watermark in an image using Wave Atom Transform. Preference of Wave Atoms on other transformations has been due to its sparser expansion, adaptability to the direction of local pattern, and sharp frequency localization. In this scheme, we had tried to spread the watermark in an image so that the information at one place is very small and undetectable. In order to extract the...

  14. The gravitational wave rocket

    OpenAIRE

    Bonnor, W. B.; Piper, M. S.

    1997-01-01

    Einstein's equations admit solutions corresponding to photon rockets. In these a massive particle recoils because of the anisotropic emission of photons. In this paper we ask whether rocket motion can be powered only by the emission of gravitational waves. We use the double series approximation method and show that this is possible. A loss of mass and gain in momentum arise in the second approximation because of the emission of quadrupole and octupole waves.

  15. Sound Waves Levitate Substrates

    Science.gov (United States)

    Lee, M. C.; Wang, T. G.

    1982-01-01

    System recently tested uses acoustic waves to levitate liquid drops, millimeter-sized glass microballoons, and other objects for coating by vapor deposition or capillary attraction. Cylindrical contactless coating/handling facility employs a cylindrical acoustic focusing radiator and a tapered reflector to generate a specially-shaped standing wave pattern. Article to be processed is captured by the acoustic force field under the reflector and moves as reflector is moved to different work stations.

  16. Wave Star C5

    DEFF Research Database (Denmark)

    Kramer, Morten; Kristensen, Tom Sten

    Design pile loads in this document are based on the Morison equation. In Chapter 3 and 4 the background for the design loads provided in Chapter 5 are given. In the remaining chapters from Chapter 6 and onward discussions and explanations of the results are given. A historical list of activities ...... to the present revision is given in Appendix A. Calculations of extreme events with wave slamming and plunging wave breaking is included in Appendix B and C....

  17. Wind Generated Rogue Waves in an Annular Wave Flume.

    Science.gov (United States)

    Toffoli, A; Proment, D; Salman, H; Monbaliu, J; Frascoli, F; Dafilis, M; Stramignoni, E; Forza, R; Manfrin, M; Onorato, M

    2017-04-07

    We investigate experimentally the statistical properties of a wind-generated wave field and the spontaneous formation of rogue waves in an annular flume. Unlike many experiments on rogue waves where waves are mechanically generated, here the wave field is forced naturally by wind as it is in the ocean. What is unique about the present experiment is that the annular geometry of the tank makes waves propagating circularly in an unlimited-fetch condition. Within this peculiar framework, we discuss the temporal evolution of the statistical properties of the surface elevation. We show that rogue waves and heavy-tail statistics may develop naturally during the growth of the waves just before the wave height reaches a stationary condition. Our results shed new light on the formation of rogue waves in a natural environment.

  18. Chorus Wave Modulation of Langmuir Waves in the Radiation Belts

    Science.gov (United States)

    Li, Jinxing; Bortnik, Jacob; An, Xin; Li, Wen; Thorne, Richard M.; Zhou, Meng; Kurth, William S.; Hospodarsky, George B.; Funsten, Herbert O.; Spence, Harlan E.

    2017-12-01

    Using high-resolution waveforms measured by the Van Allen Probes, we report a novel observation in the radiation belts. Namely, we show that multiband, discrete, rising-tone whistler mode chorus emissions exhibit a one-to-one correlation with Langmuir wave bursts. Moreover, the periodic Langmuir wave bursts are generally observed at the phase location where the chorus wave E|| component is oriented opposite to its propagation direction. The electron measurements show a beam in phase space density at the particle velocity that matches the parallel phase velocity of the chorus waves. Based on this evidence, we conclude that the chorus waves accelerate the suprathermal electrons via Landau resonance and generate a localized electron beam in phase space density. Consequently, the Langmuir waves are excited locally and are modulated by the chorus wave phase. This microscale interaction between chorus waves and high-frequency electrostatic waves provides a new insight into the nonlinear wave-particle interaction process.

  19. The gravitational wave decade

    Science.gov (United States)

    Conklin, John

    2016-03-01

    With the expected direct detection of gravitational waves by Advanced LIGO and pulsar timing arrays in the near future, and with the recent launch of LISA Pathfinder this can arguably be called the decade of gravitational waves. Low frequency gravitational waves in the mHz range, which can only be observed from space, provide the richest science and complement high frequency observatories on the ground. A space-based observatory will improve our understanding of the formation and growth of massive black holes, create a census of compact binary systems in the Milky Way, test general relativity in extreme conditions, and enable searches for new physics. LISA, by far the most mature concept for detecting gravitational waves from space, has consistently ranked among the nation's top priority large science missions. In 2013, ESA selected the science theme ``The Gravitational Universe'' for its third large mission, L3, under the Cosmic Visions Program, with a planned launch date of 2034. NASA has decided to join with ESA on the L3 mission as a junior partner and has recently assembled a study team to provide advice on how NASA might contribute to the European-led mission. This talk will describe these efforts and the activities of the Gravitational Wave Science Interest Group and the L3 Study Team, which will lead to the first space-based gravitational wave observatory.

  20. Solitary waves in fluids

    CERN Document Server

    Grimshaw, RHJ

    2007-01-01

    After the initial observation by John Scott Russell of a solitary wave in a canal, his insightful laboratory experiments and the subsequent theoretical work of Boussinesq, Rayleigh and Korteweg and de Vries, interest in solitary waves in fluids lapsed until the mid 1960's with the seminal paper of Zabusky and Kruskal describing the discovery of the soliton. This was followed by the rapid development of the theory of solitons and integrable systems. At the same time came the realization that solitary waves occur naturally in many physical systems, and play a fundamental role in many circumstances. The aim of this text is to describe the role that soliton theory plays in fluids in several contexts. After an historical introduction, the book is divided five chapters covering the basic theory of the Korteweg-de Vries equation, and the subsequent application to free-surface solitary waves in water to internal solitary waves in the coastal ocean and the atmospheric boundary layer, solitary waves in rotating flows, ...

  1. Shock wave treatment in medicine

    Indian Academy of Sciences (India)

    Extracorporeal shock wave therapy in orthopedics and traumatology is still a young therapy method. Since the last few years the development of shock wave therapy has progressed rapidly. Shock waves have changed the treatment of urolithiasis substantially. Today shock waves are the first choice to treat kidney and ...

  2. Nonlinear surface waves over topography

    NARCIS (Netherlands)

    Janssen, T.T.

    2006-01-01

    As ocean surface waves radiate into shallow coastal areas and onto beaches, their lengths shorten, wave heights increase, and the wave shape transforms from nearsinusoidal to the characteristic saw-tooth shapes at the onset of breaking; in the ensuing breaking process the wave energy is cascaded to

  3. Wave Separation, Wave Intensity, the Reservoir-Wave Concept, and the Instantaneous Wave-Free Ratio: Presumptions and Principles

    NARCIS (Netherlands)

    Westerhof, Nico; Segers, Patrick; Westerhof, Berend E.

    2015-01-01

    Wave separation analysis and wave intensity analysis (WIA) use (aortic) pressure and flow to separate them in their forward and backward (reflected) waves. While wave separation analysis uses measured pressure and flow, WIA uses their derivatives. Because differentiation emphasizes rapid changes,

  4. Partnership for Wave Power - Roadmaps

    DEFF Research Database (Denmark)

    Nielsen, Kim; Krogh, Jan; Brodersen, Hans Jørgen

    This Wave Energy Technology Roadmap is developed by the Partnership for Wave Power including nine Danish wave energy developers. It builds on to the strategy [1] published by the Partnership in 2012, a document that describes the long term vision of the Danish Wave Energy sector: “By 2030...

  5. The Shape of Things to Come: Estimating Northern-Hemisphere (NH) Transient Climate Response Through Hindcasting and Forecasting the Frequency Distribution of Earth's NH Land Temperature Anomalies for the Period 1951-2071

    Science.gov (United States)

    Leclerc, D. F.

    2016-12-01

    Northern-hemisphere (NH) heatwaves, during which temperatures rise 5 standard deviations (SD), sigma, above the historical mean temperature, mu, are becoming frequent; these events skew temperature anomaly (delta T) profiles towards extreme values. Although general extreme value (GEV) distributions have modeled precipitation data, their application to temperatures have met with limited success. This work presents a modified three-parameter (mu, sigma and tau (skew)) Exponential-Gaussian (eGd) model that hindcasts decadal NH land winter (DJF) and summer (JJA) delta Ts from 1951 to 2011, and forecasts profiles for a business-as-usual (BAU) scenario for 2061-2071. We accessed 12 numerical binned (0.05 °C/bin) z-scored NH decadal datasets (posted online until August 2015) from the publicly available website http://www.columbia.edu/ mhs119/PerceptionsAndDice/ mentioned in Hansen et al, PNAS 109 E2415-E2423 (2012) and stated to be in the public domain. No pre-processing was done. Parameters were calculated for the 12 NH datasets pasted into Microsoft Excel™ through the method of moments for 1-tail distributions and through the BEST deconvolution program described by Pommé and Marroyo, Applied Radiation and Isotopes 96 148-153 (2015) for 2-tail distributions. We used maximum likelihood estimation (MLE), residual sum of squares (RSS) and F-test to find optimal parameter values. Calculated 1st (= sigma + tau) and 2nd (= sigma2 + tau2) moments were found to be within 0.5% of observed values. Land delta Ts were recovered from the z-score values by multiplying the winter data by its SD (1.2 °C) and likewise the summer data by 0.6 °C. Results were all within 0.05 °C of 10-year averages from the GHCNv3 NH land dataset. Assuming BAU (increases from 2.1 to 2.6 ppm/y CO2) and using temperature rises of 0.27 °C and 0.35 °C per decade, for summer and winter, respectively, and forecasting to 2071, we obtain for the transient climate response for doubled CO2 (560 ppm CO2) mean

  6. Nonlinear wave interactions of kinetic sound waves

    Directory of Open Access Journals (Sweden)

    G. Brodin

    2015-08-01

    Full Text Available We reconsider the nonlinear resonant interaction between three electrostatic waves in a magnetized plasma. The general coupling coefficients derived from kinetic theory are reduced here to the low-frequency limit. The main contribution to the coupling coefficient we find in this way agrees with the coefficient recently presented in Annales Geophysicae. But we also deduce another contribution which sometimes can be important, and which qualitatively agrees with that of an even more recent paper. We have thus demonstrated how results derived from fluid theory can be improved and generalized by means of kinetic theory. Possible extensions of our results are outlined.

  7. Metamaterials, from electromagnetic waves to water waves, bending waves and beyond

    KAUST Repository

    Dupont, G.

    2015-08-04

    We will review our recent work on metamaterials for different types of waves. Transposition of transform optics to water waves and bending waves on plates will be considered with potential applications of cloaking to water waves protection and anti-vibrating systems.

  8. Partial-wave expansions of angular spectra of plane waves.

    Science.gov (United States)

    Lock, James A

    2006-11-01

    Focused electromagnetic beams are frequently modeled by either an angular spectrum of plane waves or a partial-wave sum of spherical multipole waves. The connection between these two beam models is explored here. The partial-wave expansion of an angular spectrum containing evanescent components is found to possess only odd partial waves. On the other hand, the partial-wave expansion of an alternate angular spectrum constructed so as to be free of evanescent components contains all partial waves but describes a propagating beam with a small amount of standing-wave component mixed in. A procedure is described for minimizing the standing-wave component so as to more accurately model a purely forward propagating experimental beam.

  9. Wave Dragon Wave Energy Converters Used as Coastal Protection

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke; Kofoed, Jens Peter

    2011-01-01

    This paper deals with wave energy converters used to reduce the wave height along shorelines. For this study the Wave Dragon wave energy converter is chosen. The wave height reduction from a single device has been evaluated from physical model tests in scale 1:51.8 of the 260 x 150 m, 24 kW/m model....... Different stiffness of the mooring system and reflector joints has been tested for different wave steepness and relative floating ratios. The influence of each of these parameters on the wave transmission is presented. Additionally, a numerical case study is performed for the Santander Bay in the northern...... Spain, to evaluate the potential for reducing wave heights close the shore by means of Wave Dragons....

  10. Nonstationary distributions of wave intensities in wave turbulence

    Science.gov (United States)

    Choi, Yeontaek; Jo, Sanggyu; Kwon, Young-Sam; Nazarenko, Sergey

    2017-09-01

    We obtain a general solution for the probability density function (PDF) of wave intensities in non-stationary wave turbulence. The solution is expressed in terms of the initial PDF and the wave action spectrum satisfying the wave-kinetic equation. We establish that, in the absence of wave breaking, the wave statistics converge to a Gaussian distribution in forced-dissipated wave systems while approaching a steady state. Also, we find that in non-stationary systems, if the statistic is Gaussian initially, it will remain Gaussian for all time. Generally, if the statistic is not initially Gaussian, it will remain non-Gaussian over the characteristic nonlinear evolution time of the wave spectrum. In freely decaying wave turbulence, substantial deviations from Gaussianity may persist infinitely long.

  11. Prototype Testing of the Wave Energy Converter Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter Bak; Friis-Madsen, Erik

    2004-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period...... from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57 x 27 m wide and 237 tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world's first offshore wave energy...... converter. The prototype is fully equipped with hydro turbines and automatic control systems, and is instrumented in order to monitor power production, wave climate, forces in mooring lines, stresses in the structure and movements of the Wave Dragon. During the last months, extensive testing has started...

  12. Prototype Testing of the Wave Energy Converter Wave Dragon

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter; Friis-Madsen, Erik

    2006-01-01

    The Wave Dragon is an offshore wave energy converter of the overtopping type. It consists of two wave reflectors focusing the incoming waves towards a ramp, a reservoir for collecting the overtopping water and a number of hydro turbines for converting the pressure head into power. In the period...... from 1998 to 2001 extensive wave tank testing on a scale model was carried at Aalborg University. Then, a 57!27 m wide and 237 tonnes heavy (incl. ballast) prototype of the Wave Dragon, placed in Nissum Bredning, Denmark, was grid connected in May 2003 as the world’s first offshore wave energy...... converter. The prototype is fully equipped with hydro turbines and automatic control systems, and is instrumented in order to monitor power production, wave climate, forces in mooring lines, stresses in the structure and movements of the Wave Dragon. In the period May 2003 to January 2005 an extensive...

  13. THz wave emission microscope

    Science.gov (United States)

    Yuan, Tao

    Sensing and imaging using Terahertz (THz) radiation has attracted more and more interest in the last two decades thanks to the abundant material 'finger prints' in the THz frequency range. The low photon energy also makes THz radiation an attractive tool for nondestructive evaluation of materials and devices, biomedical applications, security checks and explosive screening. Due to the long wavelength, the far-field THz wave optical systems have relatively low spatial resolution. This physical limitation confines THz wave sensing and imaging to mostly macro-size samples. To investigate local material properties or micro-size structures and devices, near-field technology has to be employed. In this dissertation, the Electro-Optical THz wave emission microscope is investigated. The basic principle is to focus the femtosecond laser to a tight spot on a thin THz emitter layer to produce a THz wave source with a similar size as the focus spot. The apparatus provides a method for placing a THz source with sub-wavelength dimension in the near-field range of the investigated sample. Spatial resolution to the order of one tenth of the THz wavelength is demonstrated by this method. The properties of some widely used THz wave emission materials under tight focused pump light are studied. As an important branch of THz time domain spectroscopy (THz-TDS), THz wave emission spectroscopy has been widely used as a tool to investigate the material physics, such as energy band structure, carrier dynamics, material nonlinear properties and dynamics. As the main work of this dissertation, we propose to combine the THz wave emission spectroscopy with scanning probe microscopy (SPM) to build a tip-assisted THz wave emission microscope (TATEM), which is a valuable extension to current SPM science and technology. Illuminated by a femtosecond laser, the biased SPM tip forms a THz wave source inside the sample beneath the tip. The source size is proportional to the apex size of the tip so

  14. Potential changes of wave steepness and occurrence of rogue waves

    Science.gov (United States)

    Bitner-Gregersen, Elzbieta M.; Toffoli, Alessandro

    2015-04-01

    Wave steepness is an important characteristic of a sea state. It is also well established that wave steepness is one of the parameter responsible for generation of abnormal waves called also freak or rogue waves. The study investigates changes of wave steepness in the past and future wave climate in the North Atlantic. The fifth assessment report IPCC (2013) uses four scenarios for future greenhouse gas concentrations in the atmosphere called Representative Concentration Pathways (RCP). Two of these scenarios RCP 4.5 and RCP 8.5 have been selected to project future wave conditions in the North Atlantic. RCP 4.5 is believed to achieve the political target of a maximum global mean temperature increase of 2° C while RPC 8.5 is close to 'business as usual' and expected to give a temperature increase of 4° C or more. The analysis includes total sea, wind sea and swell. Potential changes of wave steepness for these wave systems are shown and compared with wave steepness derived from historical data. Three historical data sets with different wave model resolutions are used. The investigations show also changes in the mean wind direction as well as in the relative direction between wind sea and swell. Consequences of wave steepness changes for statistics of surface elevation and generation of rogue waves are demonstrated. Uncertainties associated with wave steepness projections are discussed.

  15. Waves in Motion

    Science.gov (United States)

    McGourty, L.; Rideout, K.

    2005-12-01

    "Waves in Motion" This teaching unit was created by Leslie McGourty and Ken Rideout under the Research Experience for Teachers (RET) program at MIT Haystack Observatory during the summer of 2005. The RET program is funded by a grant from the National Science Foundation. The goals of this teaching unit are to deepen students' understanding about waves, wave motion, and the electromagnetic spectrum as a whole. Specifically students will comprehend the role radio waves play in our daily lives and in the investigation of the universe. The lessons can be used in a high school physics, earth science or astronomy curriculum. The unit consists of a series of interlocking lectures, activities, and investigations that can be used as stand alone units to supplement a teacher's existing curriculum, as an independent investigation for a student, or as a long exploration into radio astronomy with a theme of waves in space: how and where they carry their information. Special emphasis is given to the Relativity theories in honor of the "World Year of Physics" to celebrate Einstein's 1905 contributions. The lessons are currently being implemented at the high school level, the preliminary results of which will be presented. At the end of the academic year, the units will be evaluated and updated, reflecting student input and peer review after which they will be posted on the internet for teachers to use in their classrooms.

  16. Rupture, waves and earthquakes

    Science.gov (United States)

    UENISHI, Koji

    2017-01-01

    Normally, an earthquake is considered as a phenomenon of wave energy radiation by rupture (fracture) of solid Earth. However, the physics of dynamic process around seismic sources, which may play a crucial role in the occurrence of earthquakes and generation of strong waves, has not been fully understood yet. Instead, much of former investigation in seismology evaluated earthquake characteristics in terms of kinematics that does not directly treat such dynamic aspects and usually excludes the influence of high-frequency wave components over 1 Hz. There are countless valuable research outcomes obtained through this kinematics-based approach, but “extraordinary” phenomena that are difficult to be explained by this conventional description have been found, for instance, on the occasion of the 1995 Hyogo-ken Nanbu, Japan, earthquake, and more detailed study on rupture and wave dynamics, namely, possible mechanical characteristics of (1) rupture development around seismic sources, (2) earthquake-induced structural failures and (3) wave interaction that connects rupture (1) and failures (2), would be indispensable. PMID:28077808

  17. Rupture, waves and earthquakes.

    Science.gov (United States)

    Uenishi, Koji

    2017-01-01

    Normally, an earthquake is considered as a phenomenon of wave energy radiation by rupture (fracture) of solid Earth. However, the physics of dynamic process around seismic sources, which may play a crucial role in the occurrence of earthquakes and generation of strong waves, has not been fully understood yet. Instead, much of former investigation in seismology evaluated earthquake characteristics in terms of kinematics that does not directly treat such dynamic aspects and usually excludes the influence of high-frequency wave components over 1 Hz. There are countless valuable research outcomes obtained through this kinematics-based approach, but "extraordinary" phenomena that are difficult to be explained by this conventional description have been found, for instance, on the occasion of the 1995 Hyogo-ken Nanbu, Japan, earthquake, and more detailed study on rupture and wave dynamics, namely, possible mechanical characteristics of (1) rupture development around seismic sources, (2) earthquake-induced structural failures and (3) wave interaction that connects rupture (1) and failures (2), would be indispensable.

  18. Tango waves in a bidomain model of fertilization calcium waves

    Science.gov (United States)

    Li, Yue-Xian

    2003-12-01

    Fertilization of an egg cell is marked by one or several Ca 2+ waves that travel across the intra-cellular space, called fertilization Ca 2+ waves. Patterns of Ca 2+ waves observed in mature or immature oocytes include traveling fronts and pulses as well as concentric and spiral waves. These patterns have been studied in other excitable media in physical, chemical, and biological systems. Here, we report the discovery of a new wave phenomenon in the numerical study of a bidomain model of fertilization Ca 2+ waves. This wave is a front that propagates in a back-and-forth manner that resembles the movement of tango dancers, thus is called a tango wave. When the medium is excitable, a forward-moving tango wave can generate traveling pulses that propagate down the space without reversal. The study shows that the occurrence of tango waves is related to spatial inhomogeneity in the local dynamics. This is tested and confirmed by simulating similar waves in a medium with stationary spatial inhomogeneity. Similar waves are also obtained in a FitzHugh-Nagumo system with a linear spatial ramp. In both the bidomain model of Ca 2+ waves and the FitzHugh-Nagumo system, the front is stable when the slope of a linear ramp is large. As the slope decreases beyond a critical value, front oscillations occur. The study shows that tango waves facilitate the dispersion of localized Ca 2+. Key features of the bidomain model underlying the occurrence of tango waves are revealed. These features are commonly found in egg cells of a variety of species. Thus, we predict that tango waves can occur in real egg cells provided that a slowly varying inhomogeneity does occur following the sperm entry. The observation of tango wave-like waves in nemertean worm and ascidian eggs seems to support such a prediction.

  19. Conversion from surface wave to surface wave on reflection

    DEFF Research Database (Denmark)

    Novitsky, Andrey

    2010-01-01

    We discuss the reflection and transmission of an incident surface wave to a pure surface wave state at another interface. This is allowed only for special media parameters: at least one of the media must be magnetic. We found such material characteristics that the obliquely incident surface wave...... can be transmitted without changing its direction (nevertheless the amplitude varies). For other media parameters, only normally incident surface waves can be converted to surface waves. We propose applications of the predicted conversion as a beam splitter and polarization filter for surface waves....

  20. Experimental Study on the WavePiston Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter; Angelelli, E.

    This report presents the results of an experimental study of the power performance of the WavePiston wave energy converter. It focuses mainly on evaluating the power generating capabilities of the device and the effect of the following issues: Scaling ratios PTO loading Wave height and wave period...... dependency Oblique incoming waves Distance between plates During the study, the model supplied by the client, WavePiston, has been rigorously tested as all the anticipated tests have been done thoroughly and during all tests, good quality data has been obtained from all the sensors....

  1. Waves in continuous media

    CERN Document Server

    Gavrilyuk, S L; Sukhinin, S V

    2017-01-01

    Starting with the basic notions and facts of the mathematical theory of waves illustrated by numerous examples, exercises, and methods of solving typical problems Chapters 1 & 2 show e.g. how to recognize the hyperbolicity property, find characteristics, Riemann invariants and conservation laws for quasilinear systems of equations, construct and analyze solutions with weak or strong discontinuities, and how to investigate equations with dispersion and to construct travelling wave solutions for models reducible to nonlinear evolution equations. Chapter 3 deals with surface and internal waves in an incompressible fluid. The efficiency of mathematical methods is demonstrated on a hierarchy of approximate submodels generated from the Euler equations of homogeneous and non-homogeneous fluids. The self-contained presentations of the material is complemented by 200+ problems of different level of difficulty, numerous illustrations, and bibliographical recommendations.

  2. Piezoelectric wave motor

    Science.gov (United States)

    Yerganian, Simon Scott

    2001-07-17

    A piezoelectric motor having a stator in which piezoelectric elements are contained in slots formed in the stator transverse to the desired wave motion. When an electric field is imposed on the elements, deformation of the elements imposes a force perpendicular to the sides of the slot, deforming the stator. Appropriate frequency and phase shifting of the electric field will produce a wave in the stator and motion in a rotor. In a preferred aspect, the piezoelectric elements are configured so that deformation of the elements in direction of an imposed electric field, generally referred to as the d.sub.33 direction, is utilized to produce wave motion in the stator. In a further aspect, the elements are compressed into the slots so as to minimize tensile stresses on the elements in use.

  3. IR Hot Wave

    Energy Technology Data Exchange (ETDEWEB)

    Graham, T. B.

    2010-04-01

    The IR Hot Wave{trademark} furnace is a breakthrough heat treatment system for manufacturing metal components. Near-infrared (IR) radiant energy combines with IR convective heating for heat treating. Heat treatment is an essential process in the manufacture of most components. The controlled heating and cooling of a metal or metal alloy alters its physical, mechanical, and sometimes chemical properties without changing the object's shape. The IR Hot Wave{trademark} furnace offers the simplest, quickest, most efficient, and cost-effective heat treatment option for metals and metal alloys. Compared with other heat treatment alternatives, the IR Hot Wave{trademark} system: (1) is 3 to 15 times faster; (2) is 2 to 3 times more energy efficient; (3) is 20% to 50% more cost-effective; (4) has a {+-}1 C thermal profile compared to a {+-}10 C thermal profile for conventional gas furnaces; and (5) has a 25% to 50% smaller footprint.

  4. Nonlinear Water Waves

    CERN Document Server

    2016-01-01

    This volume brings together four lecture courses on modern aspects of water waves. The intention, through the lectures, is to present quite a range of mathematical ideas, primarily to show what is possible and what, currently, is of particular interest. Water waves of large amplitude can only be fully understood in terms of nonlinear effects, linear theory being not adequate for their description. Taking advantage of insights from physical observation, experimental evidence and numerical simulations, classical and modern mathematical approaches can be used to gain insight into their dynamics. The book presents several avenues and offers a wide range of material of current interest. Due to the interdisciplinary nature of the subject, the book should be of interest to mathematicians (pure and applied), physicists and engineers. The lectures provide a useful source for those who want to begin to investigate how mathematics can be used to improve our understanding of water wave phenomena. In addition, some of the...

  5. Fast Plane Wave Imaging

    DEFF Research Database (Denmark)

    Jensen, Jonas

    This PhD project investigates and further develops methods for ultrasound plane wave imaging and blood flow estimation with the objective of overcoming some of the major limitations in conventional ultrasound systems, which are related to low frame rates and only estimation of velocities along...... the ultrasound beam. The first part of the contribution investigates the compromise between frame rate and plane wave image quality including the influence of grating lobes from a λ-pitch transducer. A method for optimizing the image quality is suggested, and it is shown that the frame rate can be increased...... healthy volunteers. Complex flow patterns were measured in an anthropomorphic flow phantom and showed good agreement with the velocity field simulated using computational fluid dynamics. The last part of the contribution investigates two clinical applications. Plane wave imaging was used for slow velocity...

  6. The Juno Waves Investigation

    Science.gov (United States)

    Kurth, W. S.; Hospodarsky, G. B.; Kirchner, D. L.; Mokrzycki, B. T.; Averkamp, T. F.; Robison, W. T.; Piker, C. W.; Sampl, M.; Zarka, P.

    2017-11-01

    Jupiter is the source of the strongest planetary radio emissions in the solar system. Variations in these emissions are symptomatic of the dynamics of Jupiter's magnetosphere and some have been directly associated with Jupiter's auroras. The strongest radio emissions are associated with Io's interaction with Jupiter's magnetic field. In addition, plasma waves are thought to play important roles in the acceleration of energetic particles in the magnetosphere, some of which impact Jupiter's upper atmosphere generating the auroras. Since the exploration of Jupiter's polar magnetosphere is a major objective of the Juno mission, it is appropriate that a radio and plasma wave investigation is included in Juno's payload. This paper describes the Waves instrument and the science it is to pursue as part of the Juno mission.

  7. Nonlinear elastic waves in materials

    CERN Document Server

    Rushchitsky, Jeremiah J

    2014-01-01

    The main goal of the book is a coherent treatment of the theory of propagation in materials of nonlinearly elastic waves of displacements, which corresponds to one modern line of development of the nonlinear theory of elastic waves. The book is divided on five basic parts: the necessary information on waves and materials; the necessary information on nonlinear theory of elasticity and elastic materials; analysis of one-dimensional nonlinear elastic waves of displacement – longitudinal, vertically and horizontally polarized transverse plane nonlinear elastic waves of displacement; analysis of one-dimensional nonlinear elastic waves of displacement – cylindrical and torsional nonlinear elastic waves of displacement; analysis of two-dimensional nonlinear elastic waves of displacement – Rayleigh and Love nonlinear elastic surface waves. The book is addressed first of all to people working in solid mechanics – from the students at an advanced undergraduate and graduate level to the scientists, professional...

  8. GEODYNAMIC WAVES AND GRAVITY

    Directory of Open Access Journals (Sweden)

    A. V. Vikulin

    2015-09-01

    Full Text Available  Gravity phenomena related to the Earth movements in the Solar System and through the Galaxy are reviewed. Such movements are manifested by geological processes on the Earth and correlate with geophysical fields of the Earth. It is concluded that geodynamic processes and the gravity phenomena (including those of cosmic nature are related.  The state of the geomedium composed of blocks is determined by stresses with force moment and by slow rotational waves that are considered as a new type of movements [Vikulin, 2008, 2010]. It is shown that the geomedium has typical rheid properties [Carey, 1954], specifically an ability to flow while being in the solid state [Leonov, 2008]. Within the framework of the rotational model with a symmetric stress tensor, which is developed by the authors [Vikulin, Ivanchin, 1998; Vikulin et al., 2012a, 2013], such movement of the geomedium may explain the energy-saturated state of the geomedium and a possibility of its movements in the form of vortex geological structures [Lee, 1928]. The article discusses the gravity wave detection method based on the concept of interactions between gravity waves and crustal blocks [Braginsky et al., 1985]. It is concluded that gravity waves can be recorded by the proposed technique that detects slow rotational waves. It is shown that geo-gravitational movements can be described by both the concept of potential with account of gravitational energy of bodies [Kondratyev, 2003] and the nonlinear physical acoustics [Gurbatov et al., 2008]. Based on the combined description of geophysical and gravitational wave movements, the authors suggest a hypothesis about the nature of spin, i.e. own moment as a demonstration of the space-time ‘vortex’ properties.  

  9. GEODYNAMIC WAVES AND GRAVITY

    Directory of Open Access Journals (Sweden)

    A. V. Vikulin

    2014-01-01

    Full Text Available  Gravity phenomena related to the Earth movements in the Solar System and through the Galaxy are reviewed. Such movements are manifested by geological processes on the Earth and correlate with geophysical fields of the Earth. It is concluded that geodynamic processes and the gravity phenomena (including those of cosmic nature are related.  The state of the geomedium composed of blocks is determined by stresses with force moment and by slow rotational waves that are considered as a new type of movements [Vikulin, 2008, 2010]. It is shown that the geomedium has typical rheid properties [Carey, 1954], specifically an ability to flow while being in the solid state [Leonov, 2008]. Within the framework of the rotational model with a symmetric stress tensor, which is developed by the authors [Vikulin, Ivanchin, 1998; Vikulin et al., 2012a, 2013], such movement of the geomedium may explain the energy-saturated state of the geomedium and a possibility of its movements in the form of vortex geological structures [Lee, 1928]. The article discusses the gravity wave detection method based on the concept of interactions between gravity waves and crustal blocks [Braginsky et al., 1985]. It is concluded that gravity waves can be recorded by the proposed technique that detects slow rotational waves. It is shown that geo-gravitational movements can be described by both the concept of potential with account of gravitational energy of bodies [Kondratyev, 2003] and the nonlinear physical acoustics [Gurbatov et al., 2008]. Based on the combined description of geophysical and gravitational wave movements, the authors suggest a hypothesis about the nature of spin, i.e. own moment as a demonstration of the space-time ‘vortex’ properties.  

  10. Metamaterials and wave control

    CERN Document Server

    Lheurette, Eric

    2013-01-01

    Since the concept was first proposed at the end of the 20th Century, metamaterials have been the subject of much research and discussion throughout the wave community. More than 10 years later, the number of related published articles is increasing significantly. Onthe one hand, this success can be attributed to dreams of new physical objects which are the consequences of the singular properties of metamaterials. Among them, we can consider the examples of perfect lensing and invisibility cloaking. On other hand,metamaterials also provide new tools for the design of well-known wave functions s

  11. Mechanics, Waves and Thermodynamics

    Science.gov (United States)

    Ranjan Jain, Sudhir

    2016-05-01

    Figures; Preface; Acknowledgement; 1. Energy, mass, momentum; 2. Kinematics, Newton's laws of motion; 3. Circular motion; 4. The principle of least action; 5. Work and energy; 6. Mechanics of a system of particles; 7. Friction; 8. Impulse and collisions; 9. Central forces; 10. Dimensional analysis; 11. Oscillations; 12. Waves; 13. Sound of music; 14. Fluid mechanics; 15. Water waves; 16. The kinetic theory of gases; 17. Concepts and laws of thermodynamics; 18. Some applications of thermodynamics; 19. Basic ideas of statistical mechanics; Bibliography; Index.

  12. Cyclotron waves in plasma

    CERN Document Server

    Lominadze, D G

    2013-01-01

    Cyclotron Waves in Plasma is a four-chapter text that covers the basic physical concepts of the theory of cyclotron waves and cyclotron instabilities, brought about by the existence of steady or alternating plasma currents flowing perpendicular to the magnetic field.This book considers first a wide range of questions associated with the linear theory of cyclotron oscillations in equilibrium plasmas and in electron plasmas in metals and semiconductors. The next chapter deals with the parametric excitation of electron cyclotron oscillations in plasma in an alternating electric field. A chapter f

  13. Nonlinear wave equations

    CERN Document Server

    Li, Tatsien

    2017-01-01

    This book focuses on nonlinear wave equations, which are of considerable significance from both physical and theoretical perspectives. It also presents complete results on the lower bound estimates of lifespan (including the global existence), which are established for classical solutions to the Cauchy problem of nonlinear wave equations with small initial data in all possible space dimensions and with all possible integer powers of nonlinear terms. Further, the book proposes the global iteration method, which offers a unified and straightforward approach for treating these kinds of problems. Purely based on the properties of solut ions to the corresponding linear problems, the method simply applies the contraction mapping principle.

  14. Hysteretic Faraday Waves

    CERN Document Server

    Périnet, Nicolas; Chergui, Jalel; Juric, Damir; Shin, Seungwon

    2016-01-01

    We report on the numerical and theoretical study of the subcritical bifurcation of parametrically amplified waves appearing at the interface between two immiscible incompressible fluids when the layer of the lower fluid is very shallow. As a critical control parameter is surpassed, small amplitude surface waves bifurcate towards highly nonlinear ones, with twice their amplitude. We propose a simple phenomenological model which can describe the observed bifurcation. We relate this hysteresis with the change of shear stress using a simple stress balance, in agreement with numerical results.

  15. Nonlinear waves and weak turbulence

    CERN Document Server

    Zakharov, V E

    1997-01-01

    This book is a collection of papers on dynamical and statistical theory of nonlinear wave propagation in dispersive conservative media. Emphasis is on waves on the surface of an ideal fluid and on Rossby waves in the atmosphere. Although the book deals mainly with weakly nonlinear waves, it is more than simply a description of standard perturbation techniques. The goal is to show that the theory of weakly interacting waves is naturally related to such areas of mathematics as Diophantine equations, differential geometry of waves, Poincaré normal forms, and the inverse scattering method.

  16. SUPERSYMMETRIC STRING WAVES

    NARCIS (Netherlands)

    BERGSHOEFF, E

    We present plane-wave-type solutions to the superstring effective action which have unbroken space-time supersymmetries. They describe dilaton, axion and gauge fields in a generalization of the Brinkmann metric. A crucial property of the solutions is a conspiracy between the metric and the axion

  17. SUPERSYMMETRIC STRING WAVES

    NARCIS (Netherlands)

    BERGSHOEFF, EA; KALLOSH, R; ORTIN, T

    1993-01-01

    We present plane-wave-type solutions of the lowest-order superstring effective action which have unbroken space-time supersymmetries. They are given by a stringy generalization of the Brinkmann metric, dilaton, axion, and gauge fields. Some conspiracy between the metric and the axion field is

  18. Flood Wave Propagation

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 6; Issue 5. Flood Wave Propagation-The Saint Venant Equations. P P Mujumdar. General Article Volume 6 Issue 5 May 2001 pp 66-73. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/006/05/0066-0073 ...

  19. Waves and Water Beetles

    Science.gov (United States)

    Tucker, Vance A.

    1971-01-01

    Capillary and gravity water waves are related to the position, wavelength, and velocity of an object in flowing water. Water patterns are presented for ships and the whirling beetle with an explanation of how the design affects the objects velocity and the observed water wavelengths. (DS)

  20. Surface Acoustic Wave Devices

    DEFF Research Database (Denmark)

    Dühring, Maria Bayard

    application is modulation of optical waves in waveguides. This presentation elaborates on how a SAW is generated by interdigital transducers using a 2D model of a piezoelectric, inhomogeneous material implemented in the high-level programming language Comsol Multiphysics. The SAW is send through a model...

  1. Springing of ships waves

    NARCIS (Netherlands)

    Van Gunsteren, F.F.

    1978-01-01

    This thesis is the result of an investigation of the assumptions underlying the general applied method for the calculation of springing of ships in waves, which has been proposed by the author some decade ago. It has been found that, contrary to the general practice in seakeeping research, the

  2. "Hearing" Electromagnetic Waves

    Science.gov (United States)

    Rojo, Marta; Munoz, Juan

    2014-01-01

    In this work, an educational experience is described in which a microwave communication link is used to make students aware that all electromagnetic waves have the same physical nature and properties. Experimental demonstrations are linked to theoretical concepts to increase comprehension of the physical principles underlying electromagnetic…

  3. Semiclassical multicomponent wave function

    NARCIS (Netherlands)

    Mostovoy, M.V.

    1994-01-01

    A consistent method for obtaining the semiclassical multicomponent wave function for any value of adiabatic parameter is discussed and illustrated by examining the motion of a neutral particle in a nonuniform magnetic field. The method generalizes the Bohr-Sommerfeld quantization rule to

  4. Deflagration Wave Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Menikoff, Ralph [Los Alamos National Laboratory

    2012-04-03

    Shock initiation in a plastic-bonded explosives (PBX) is due to hot spots. Current reactive burn models are based, at least heuristically, on the ignition and growth concept. The ignition phase occurs when a small localized region of high temperature (or hot spot) burns on a fast time scale. This is followed by a growth phase in which a reactive front spreads out from the hot spot. Propagating reactive fronts are deflagration waves. A key question is the deflagration speed in a PBX compressed and heated by a shock wave that generated the hot spot. Here, the ODEs for a steady deflagration wave profile in a compressible fluid are derived, along with the needed thermodynamic quantities of realistic equations of state corresponding to the reactants and products of a PBX. The properties of the wave profile equations are analyzed and an algorithm is derived for computing the deflagration speed. As an illustrative example, the algorithm is applied to compute the deflagration speed in shock compressed PBX 9501 as a function of shock pressure. The calculated deflagration speed, even at the CJ pressure, is low compared to the detonation speed. The implication of this are briefly discussed.

  5. Making Waves (Postprint)

    Science.gov (United States)

    2013-10-06

    Shock waves are a primary mechanism for the acceleration of particles at the Sun and in other astrophysical settings, such as supernovae . Shocks at the...Publishers Limited. All rights reserved Approved for public release; distribution is unlimited. DISTRIBUTION LIST DTIC/OCP 8725 John J. Kingman Rd

  6. Surface gravity-wave lensing

    Science.gov (United States)

    Elandt, Ryan B.; Shakeri, Mostafa; Alam, Mohammad-Reza

    2014-02-01

    Here we show that a nonlinear resonance between oceanic surface waves caused by small seabed features (the so-called Bragg resonance) can be utilized to create the equivalent of lenses and curved mirrors for surface gravity waves. Such gravity wave lenses, which are merely small changes to the seafloor topography and therefore are surface noninvasive, can focus or defocus the energy of incident waves toward or away from any desired focal point. We further show that for a broadband incident wave spectrum (i.e., a wave group composed of a multitude of different-frequency waves), a polychromatic topography (occupying no more than the area required for a monochromatic lens) can achieve a broadband lensing effect. Gravity wave lenses can be utilized to create localized high-energy wave zones (e.g., for wave energy harvesting or creating artificial surf zones) as well as to disperse waves in order to create protected areas (e.g., harbors or areas near important offshore facilities). In reverse, lensing of oceanic waves may be caused by natural seabed features and may explain the frequent appearance of very high amplitude waves in certain bodies of water.

  7. Electromagnetic waves, gravitational waves and the prophets who predicted them

    OpenAIRE

    Papachristou, Costas J.

    2016-01-01

    Using non-excessively-technical language and written in informal style, this article introduces the reader to the concepts of electromagnetic and gravitational waves and recounts the prediction of existence of these waves by Maxwell and Einstein, respectively. The issue of gravitational radiation is timely in view of the recent announcement of the detection of gravitational waves by the LIGO scientific team.

  8. Investigation of Wave Transmission from a Floating Wave Dragon Wave Energy Converter

    DEFF Research Database (Denmark)

    Nørgaard, Jørgen Harck; Andersen, Thomas Lykke

    2012-01-01

    This paper focuses on the calibration of the MIKE21BW model against the measured wave height reduction behind a 24 kW/m Wave Dragon (WD) wave energy converter. A numerical model is used to determine the wave transmission through the floating WD in varying wave conditions. The transmission obtained...... from the MIKE21BW model is compared to results from a simpler model, based on the integration of wave energy flux. The conclusion is that the simplified approach provides results similar to the transmission obtained from the numerical model, both for a single WD and a farm of multiple WDs....

  9. Transformation method and wave control

    Science.gov (United States)

    Chang, Zheng; Hu, Jin; Hu, Geng-Kai

    2010-12-01

    Transformation method provides an efficient way to control wave propagation by materials. The transformed relations for field and material during a transformation are essential to fulfill this method. We propose a systematic method to derive the transformed relations for a general physic process, the constraint conditions are obtained by considering geometrical and physical constraint during a mapping. The proposed method is applied to Navier's equation for elastodynamics, Helmholtz's equation for acoustic wave and Maxwell's equation for electromagnetic wave, the corresponding transformed relations are derived, which can be used in the framework of transformation method for wave control. We show that contrary to electromagnetic wave, the transformed relations are not uniquely determined for elastic wave and acoustic wave, so we have a freedom to choose them differently. Using the obtained transformed relations, we also provide some examples for device design, a concentrator for elastic wave, devices for illusion acoustic and illusion optics are conceived and validated by numerical simulations.

  10. Superluminal waves in amplifying media

    Energy Technology Data Exchange (ETDEWEB)

    Oraevsky, Anatolii N [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

    1998-12-31

    In amplifying media steady-state waves can travel faster than the speed of light in vacuum without violating the principles of special relativity. The possibility of generating superluminal waves in induced elementary particle production processes is discussed. (methodological notes)

  11. Gravitational Waves: The Evidence Mounts

    Science.gov (United States)

    Wick, Gerald L.

    1970-01-01

    Reviews the work of Weber and his colleagues in their attempts at detecting extraterrestial gravitational waves. Coincidence events recorded by special detectors provide the evidence for the existence of gravitational waves. Bibliography. (LC)

  12. Interpretation of wave energy spectra

    National Research Council Canada - National Science Library

    Thompson, E.F

    1980-01-01

    Guidelines for interpreting nondirectional wave energy spectra and presented. A simple method is given for using the spectrum to estimate a significant height and period for each major wave train in most sea states...

  13. Wave propagation in electromagnetic media

    CERN Document Server

    Davis, Julian L

    1990-01-01

    This is the second work of a set of two volumes on the phenomena of wave propagation in nonreacting and reacting media. The first, entitled Wave Propagation in Solids and Fluids (published by Springer-Verlag in 1988), deals with wave phenomena in nonreacting media (solids and fluids). This book is concerned with wave propagation in reacting media-specifically, in electro­ magnetic materials. Since these volumes were designed to be relatively self­ contained, we have taken the liberty of adapting some of the pertinent material, especially in the theory of hyperbolic partial differential equations (concerned with electromagnetic wave propagation), variational methods, and Hamilton-Jacobi theory, to the phenomena of electromagnetic waves. The purpose of this volume is similar to that of the first, except that here we are dealing with electromagnetic waves. We attempt to present a clear and systematic account of the mathematical methods of wave phenomena in electromagnetic materials that will be readily accessi...

  14. Diurnal variation of mountain waves

    Directory of Open Access Journals (Sweden)

    R. M. Worthington

    2006-11-01

    Full Text Available Mountain waves could be modified as the boundary layer varies between stable and convective. However case studies show mountain waves day and night, and above e.g. convective rolls with precipitation lines over mountains. VHF radar measurements of vertical wind (1990–2006 confirm a seasonal variation of mountain-wave amplitude, yet there is little diurnal variation of amplitude. Mountain-wave azimuth shows possible diurnal variation compared to wind rotation across the boundary layer.

  15. Regulatory effects of terahertz waves

    OpenAIRE

    Vyacheslav F. Kirichuk; Alexey N. Ivanov

    2013-01-01

    There are modern data about biological effects of terahertz (THz) waves in this article. Items of interaction of THz waves with bio objects of different organization level. A complex of the data indicates that the realization of a THz wave effect in biosystems is possible at molecular, cellular, tissular, organ and system levels of regulation. There are data about changes in nervous and humoral regulation of an organism and metabolic effects of THz waves.

  16. Extreme events in Faraday waves

    Science.gov (United States)

    Punzmann, Horst; Shats, Michael; Xia, Hua

    2014-05-01

    Observations of extreme wave events in the ocean are rare due to their low statistical probability. In the laboratory however, the evolution of extreme wave events can be studied in great detail with high spatial and temporal resolution. The reported surface wave experiments in the short wavelength gravity-capillary range aim to contribute to the understanding of some of the underlying mechanisms for rogue wave generation. In this talk, we report on extreme wave events in parametrically excited Faraday waves. Faraday waves appear if a fluid is accelerated (normal to the fluid surface) above a critical threshold. A variety of novel tools have been deployed to characterize the 2D surface elevation. The results presented show spatio-temporal and statistical data on the surface wave conditions leading up to extreme wave events. The peak in wave amplitude during such an event is shown to exceed six times the standard deviation of the average wave field with significantly increased statistical probability compared to the background wave field [1]. The experiments also show that parametrically excited waves can be viewed as assembles of oscillons [2] (or oscillating solitons) where modulation instability seems to play a crucial role in their formation. More detailed studies on the oscillon dynamics reveal that the onset of an increased probability of extreme wave events correlates with the increase in the oscillons mobility and merger [3]. Reference: 1. Xia H., Maimbourg T., Punzmann H., and Shats M., Oscillon dynamics and rogue wave generation in Faraday surface ripples, Physical Review Letters 109, 114502 (2012) 2. Shats M., Xia H., and Punzmann H., Parametrically excited water surface ripples as ensembles of oscillons, Physical Review Letters 108, 034502 (2012) 3. Shats M., Punzmann H., Xia H., Capillary rogue waves, Physical Review Letters, 104, 104503 (2010)

  17. Gravitational Waves from Orphan Memory

    OpenAIRE

    McNeill, Lucy O.; Thrane, Eric; Lasky, Paul D.

    2017-01-01

    Gravitational-wave memory manifests as a permanent distortion of an idealized gravitational-wave detector and arises generically from energetic astrophysical events. For example, binary black hole mergers are expected to emit memory bursts a little more than an order of magnitude smaller in strain than the oscillatory parent waves. We introduce the concept of "orphan memory": gravitational-wave memory for which there is no detectable parent signal. In particular, high-frequency gravitational-...

  18. Electromagnetic wave dynamics in matter-wave superradiant scattering.

    Science.gov (United States)

    Deng, L; Payne, M G; Hagley, E W

    2010-02-05

    We present a small-signal wave propagation theory on matter-wave superradiant scattering. We show, in a longitudinally excited condensate, that the backward-propagating, superradiantly generated optical field propagates with ultraslow group velocity and that the small-signal gain profile has a Bragg resonance. We further show a unidirectional suppression of optical superradiant scattering, and explain why matter-wave superradiance can occur only when the pump laser is red detuned. This is the first analytical theory on field propagation in matter-wave superradiance that can explain all matter-wave superradiance experiments to date that used a single-frequency, long-pulse, red-detuned laser.

  19. Shock Waves in Gas Dynamics

    Directory of Open Access Journals (Sweden)

    Abdolrahman Razani

    2007-11-01

    Full Text Available Shock wave theory was studied in literature by many authors. This article presents a survey with references about various topics related to shock waves: Hyperbolic conservation laws, Well-posedness theory, Compactness theory, Shock and reaction-diffusion wave, The CJ and ZND theory, Existence of detonation in Majda's model, Premixed laminar flame, Multidimensional gas flows, Multidimensional Riemann problem.

  20. Waves In Space Plasmas (WISP)

    Science.gov (United States)

    Fredericks, R. W.

    1980-01-01

    Topics included in the WISP science objectives are: (1) VLF wave injection experiments; (2) traveling ionospheric disturbances and atmospheric gravity waves; (3) ionospheric bubbles; and (4) plasma wave physics. Flow charts of the WISP investigation organization, the project life cycle and the instrumentation are given.

  1. The wave buoy analogy - estimating high-frequency wave excitations

    DEFF Research Database (Denmark)

    Nielsen, Ulrik Dam

    2008-01-01

    The paper deals with the wave buoy analogy where a ship is considered as a wave buoy, so that measured ship responses are used as a basis to estimate wave spectra and associated sea state parameters. The study presented follows up on a previous paper, Nielsen [Nielsen UD. Response-based estimation...... of sea state parameters — influence of filtering. Ocean Engineering 2007;34:1797–810.], where time series of ship responses were generated from a known wave spectrum for the purpose of the inverse process — the estimation of the underlying wave excitations. Similar response generations and vice versa...... be estimated reasonably well, even considering high-frequency wave components of a wind sea wave spectrum....

  2. Experiments on the WavePiston, Wave Energy Converter

    DEFF Research Database (Denmark)

    Angelelli, E.; Zanuttigh, B.; Kofoed, Jens Peter

    2011-01-01

    This paper analyses the performance of a new Wave Energy Converter (WEC) of the Oscillating Water Column type (OWC), named WavePiston. This near-shore floating device is composed of plates (i.e. energy collectors) sliding around a cylinder, that is placed perpendicular to the shore. Tests...... in the wave basin at Aalborg University allowed to investigate power production in the North Sea typical wave climate, with varying design parameters such as plate dimensions and their mutual distance. The power produced per meter by each collector is about the 5% of the available wave power. Experimental...... results and survivability considerations suggest that the WavePiston would be particularly suited for installations in milder seas. An example application is therefore presented in the Mediterranean Sea, off-shore the island of Sicily. In this case, each collector harvests the 10% of the available wave...

  3. Testing, Analysis and Control of Wave Dragon, Wave Energy Converter

    DEFF Research Database (Denmark)

    Tedd, James

    One of the prongs in the attack on climate change is the development of alternative, non-polluting sources of energy. Wave Dragon is a device at the forefront of this field of development, converting the energy of ocean waves into electricity. This thesis presents the author's work on the technical...... the expected performance. Other sources of generation are presented, including development and tank testing of a novel power absorbing joint. Wave Dragon belongs in the family of overtopping wave energy converters. The energy is captured by waves running up a ramp and overtopping the crest into a reservoir...... of the process Wave Dragon has undergone to develop from an inventor's concept to a serious contender in the wave energy industry is very valuable. This shows the gradual steps of development testing, increasing in scale and complexity, in parallel with the growth in the organisational structure behind...

  4. INTERFERENCE OF UNIDIRECTIONAL SHOCK WAVES

    Directory of Open Access Journals (Sweden)

    P. V. Bulat

    2015-05-01

    Full Text Available Subject of study.We consider interference of unidirectional shock waves or, as they are called, catching up shock waves. The scope of work is to give a classification of the shock-wave structures that arise in this type of interaction of shock waves, and the area of their existence. Intersection of unidirectional shock waves results in arising of a shock-wave structure at the intersection point, which contains the main shock wave, tangential discontinuity and one more reflected gas-dynamic discontinuity of unknown beforehand type. The problem of determining the type of reflected discontinuity is the main problem that one has to solve in the study of catching shock waves interference. Main results.The paper presents the pictures of shock-wave structures arising at the interaction of catching up shock waves. The areas with a regular and irregular unidirectional interaction of shocks are described. Characteristic shock-wave structures are of greatest interest, where reflected gas-dynamic discontinuity degenerates into discontinuous characteristics. Such structures have a number of extreme properties. We have found the areas of existence for such shock-wave structures. There are also areas in which the steady-state solution is not available. The latter has determined revival of interest for the theoretical study of the problem, because the facts of sudden shock-wave structure destruction inside the air intake of supersonic aircrafts at high Mach numbers have been discovered. Practical significance.The theory of interference for unidirectional shock waves and design procedure are usable in the design of supersonic air intakes. It is also relevant for application possibility investigation of catching up oblique shock waves to create overcompressed detonation in perspective detonation air-jet and rocket engines.

  5. Wave theory of information

    CERN Document Server

    Franceschetti, Massimo

    2017-01-01

    Understand the relationship between information theory and the physics of wave propagation with this expert guide. Balancing fundamental theory with engineering applications, it describes the mechanism and limits for the representation and communication of information using electromagnetic waves. Information-theoretic laws relating functional approximation and quantum uncertainty principles to entropy, capacity, mutual information, rate distortion, and degrees of freedom of band-limited radiation are derived and explained. Both stochastic and deterministic approaches are explored, and applications for sensing and signal reconstruction, wireless communication, and networks of multiple transmitters and receivers are reviewed. With end-of-chapter exercises and suggestions for further reading enabling in-depth understanding of key concepts, it is the ideal resource for researchers and graduate students in electrical engineering, physics and applied mathematics looking for a fresh perspective on classical informat...

  6. Nonlinear Hysteretic Torsional Waves.

    Science.gov (United States)

    Cabaret, J; Béquin, P; Theocharis, G; Andreev, V; Gusev, V E; Tournat, V

    2015-07-31

    We theoretically study and experimentally report the propagation of nonlinear hysteretic torsional pulses in a vertical granular chain made of cm-scale, self-hanged magnetic beads. As predicted by contact mechanics, the torsional coupling between two beads is found to be nonlinear hysteretic. This results in a nonlinear pulse distortion essentially different from the distortion predicted by classical nonlinearities and in a complex dynamic response depending on the history of the wave particle angular velocity. Both are consistent with the predictions of purely hysteretic nonlinear elasticity and the Preisach-Mayergoyz hysteresis model, providing the opportunity to study the phenomenon of nonlinear dynamic hysteresis in the absence of other types of material nonlinearities. The proposed configuration reveals a plethora of interesting phenomena including giant amplitude-dependent attenuation, short-term memory, as well as dispersive properties. Thus, it could find interesting applications in nonlinear wave control devices such as strong amplitude-dependent filters.

  7. Shock waves & explosions

    CERN Document Server

    Sachdev, PL

    2004-01-01

    Understanding the causes and effects of explosions is important to experts in a broad range of disciplines, including the military, industrial and environmental research, aeronautic engineering, and applied mathematics. Offering an introductory review of historic research, Shock Waves and Explosions brings analytic and computational methods to a wide audience in a clear and thorough way. Beginning with an overview of the research on combustion and gas dynamics in the 1970s and 1980s, the author brings you up to date by covering modeling techniques and asymptotic and perturbative methods and ending with a chapter on computational methods.Most of the book deals with the mathematical analysis of explosions, but computational results are also included wherever they are available. Historical perspectives are provided on the advent of nonlinear science, as well as on the mathematical study of the blast wave phenomenon, both when visualized as a point explosion and when simulated as the expansion of a high-pressure ...

  8. Magnetostatic wave oscillator frequencies

    Science.gov (United States)

    Sethares, J. C.; Stiglitz, M. R.; Weinberg, I. J.

    1981-03-01

    The frequencies of magnetostatic wave (MSW) oscillators employing three principal modes of propagation, surface (MSSW), forward (MSFVW), and backward (MSBVW) volume waves, have been investigated. Previous (MSW) oscillator papers dealt with MSSW. Oscillators were fabricated using LPE-YIG MSW delay lines in a feedback loop of a 2-4 GHz amplifier. Wide and narrow band transducers were employed. Oscillator frequency as a function of biasing field is in agreement with a theoretical analysis. The analysis predicts frequency in terms of material parameters, biasing field, and transducer geometry. With wide band transducers a comb of frequencies is generated. Narrow band transducers for MSSW and MSFVW select a single mode; and MSBVW selects two modes. Spurious modes, attributed to instrumentation, are more than 20 dB below the main response, and bandwidths are less than 0.005 percent. No other spurious modes are observed. MSW oscillators produce clean electronically tunable signals and appear attractive in frequency agile systems.

  9. Electromagnetic fields and waves

    CERN Document Server

    Iskander, Magdy F

    2013-01-01

    The latest edition of Electromagnetic Fields and Waves retains an authoritative, balanced approach, in-depth coverage, extensive analysis, and use of computational techniques to provide a complete understanding of electromagnetic—important to all electrical engineering students. An essential feature of this innovative text is the early introduction of Maxwell's equations, together with the quantifying experimental observations made by the pioneers who discovered electromagnetics. This approach directly links the mathematical relations in Maxwell's equations to real experiments and facilitates a fundamental understanding of wave propagation and use in modern practical applications, especially in today's wireless world. New and expanded topics include the conceptual relationship between Coulomb's law and Gauss's law for calculating electric fields, the relationship between Biot-Savart's and Ampere's laws and their use in calculating magnetic fields from current sources, the development of Faraday's law from e...

  10. Catching the Telecom Wave

    Science.gov (United States)

    Tian, Jing

    2001-03-01

    The telecom wave is sweeping the globe; however, many of us feel caught in backwater disciplines. How does one leverage her skills to become a player in a fast-growing field? This talk will suggest some strategies and share some personal experiences: in transitioning from established companies (electronics and biotech) to a very early stage telecom start-up; in choosing an appropriate industry segment and the right startup; and in preparing for immersing oneself in the start up environment.

  11. Frozen waves: experimental generation

    OpenAIRE

    Vieira, TA; Gesualdi, MRR; Zamboni-Rached, M

    2012-01-01

    Frozen waves (FWs) are very interesting particular cases of nondiffracting beams whose envelopes are static and whose longitudinal intensity patterns can be chosen a priori. We present here for the first time (that we know of) the experimental generation of FWs. The experimental realization of these FWs was obtained using a holographic setup for the optical reconstruction of computer generated holograms (CGH), based on a 4-f Fourier filtering system and a nematic liquid crystal spatial light ...

  12. Bunge on gravitational waves

    OpenAIRE

    Romero, Gustavo E.

    2017-01-01

    I discuss the recent claims made by Mario Bunge on the philosophical implications of the discovery of gravitational waves. I think that Bunge is right when he points out that the detection implies the materiality of spacetime, but I reject his identification of spacetime with the gravitational field. I show that Bunge's analysis of the spacetime inside a hollow sphere is defective, but this in no way affects his main claim.

  13. Internal Ocean Waves

    Science.gov (United States)

    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 Original Data Resolution: 90

  14. On wave turbulence in MHD

    Directory of Open Access Journals (Sweden)

    S. Galtier

    2001-01-01

    Full Text Available We describe the fundamental differences between weak (wave turbulence in incompressible and weakly compressible MHD at the level of three-wave interactions. The main difference is in the structure of the resonant manifolds and the mechanisms of redistribution of spectral densities along the applied magnetic field B0. Similar to pure acoustic waves, a three-wave resonance between collinear wave vectors is observed but, in addition, we also have a resonance through tilted planes and spheres. The properties of resonances and their consequences for the asymptotics are also discussed.

  15. Handbook of Ocean Wave Energy

    DEFF Research Database (Denmark)

    This book offers a concise, practice-oriented reference-guide to the field of ocean wave energy. The ten chapters highlight the key rules of thumb, address all the main technical engineering aspects and describe in detail all the key aspects to be considered in the techno-economic assessment...... in the wave energy sector. •Offers a practice-oriented reference guide to the field of ocean wave energy •Presents an overview as well as a deeper insight into wave energy converters •Covers both the economic and engineering aspects related to ocean wave energy conversion...

  16. Carpet cloak for water waves

    Science.gov (United States)

    Wang, Zhenyu; Li, Chunyang; Zatianina, Razafizana; Zhang, Pei; Zhang, Yongqiang

    2017-11-01

    Cloaking is a challenging topic in the field of wave motion, and is of significant theoretical value. In this article, a type of carpet cloak has been theoretically designed for water waves by using the effective medium and transformation theory. This carpet cloak device, created by a three-dimensional printer, is composed of a periodic structure which realizes the equivalent anisotropic water depth. We demonstrate its excellent cloaking performance numerically and experimentally in a wide range of frequencies and angles of incidence, with low wave attenuation characteristics and simple device realization of this carpet cloak illustrating that water wave transformation is a powerful method with which to manipulate water waves.

  17. Focusing of Shear Shock Waves

    Science.gov (United States)

    Giammarinaro, Bruno; Espíndola, David; Coulouvrat, François; Pinton, Gianmarco

    2018-01-01

    Focusing is a ubiquitous way to transform waves. Recently, a new type of shock wave has been observed experimentally with high-frame-rate ultrasound: shear shock waves in soft solids. These strongly nonlinear waves are characterized by a high Mach number, because the shear wave velocity is much slower, by 3 orders of magnitude, than the longitudinal wave velocity. Furthermore, these waves have a unique cubic nonlinearity which generates only odd harmonics. Unlike longitudinal waves for which only compressional shocks are possible, shear waves exhibit cubic nonlinearities which can generate positive and negative shocks. Here we present the experimental observation of shear shock wave focusing, generated by the vertical motion of a solid cylinder section embedded in a soft gelatin-graphite phantom to induce linearly vertically polarized motion. Raw ultrasound data from high-frame-rate (7692 images per second) acquisitions in combination with algorithms that are tuned to detect small displacements (approximately 1 μ m ) are used to generate quantitative movies of gel motion. The features of shear shock wave focusing are analyzed by comparing experimental observations with numerical simulations of a retarded-time elastodynamic equation with cubic nonlinearities and empirical attenuation laws for soft solids.

  18. Review of water wave kinematics

    Energy Technology Data Exchange (ETDEWEB)

    Sterndorff, M.J.

    1995-03-01

    The present report covers a comprehensive review of water wave kinematics carried out by Danish Hydraulic Institute (DHI) in connection with the EFP`93 project: Dynamics of Mono Tower Platforms (ref. EFP`93, 1313/93-0009). This project is carried out in cooperation with Ramboell, Hannemann and Hoejlund A/S. The main objectives of the project are to develop and verify a method for the determination of the non-linear wave load and the dynamic response of mono tower platforms. One of the characteristics of mono tower platforms is that due to the small water plane area the hydrodynamic loading will be very concentrated. Such platforms may therefore respond strongly and in a highly dynamic manner to short waves and high order components of extreme waves having periods corresponding to the first natural period of the platform. A key element in the hydrodynamic load process is the wave kinematics. The present report is a comprehensive review of recent literature concerning wave theories, wave-current interaction, laboratory experiments, and field measurements of water wave kinematics. The review has been concentrated on non-breaking waves on deep to intermediate water depths. Papers concerning shallow water waves have only been reviewed if they present methods which may be applied for deep to intermediate water waves. (au) EFP-93; 30 refs.

  19. Brief communication: Multiscaled solitary waves

    Science.gov (United States)

    Derzho, Oleg G.

    2017-11-01

    It is analytically shown how competing nonlinearities yield multiscaled structures for internal solitary waves in stratified shallow fluids. These solitary waves only exist for large amplitudes beyond the limit of applicability of the Korteweg-de Vries (KdV) equation or its usual extensions. The multiscaling phenomenon exists or does not exist for almost identical density profiles. The trapped core inside the wave prevents the appearance of such multiple scales within the core area. The structural stability of waves of large amplitudes is briefly discussed. Waves of large amplitudes displaying quadratic, cubic and higher-order nonlinear terms have stable and unstable branches. Multiscaled waves without a vortex core are shown to be structurally unstable. It is anticipated that multiscaling phenomena will exist for solitary waves in various physical contexts.

  20. Residual Liquefaction under Standing Waves

    DEFF Research Database (Denmark)

    Kirca, V.S. Ozgur; Sumer, B. Mutlu; Fredsøe, Jørgen

    2012-01-01

    This paper summarizes the results of an experimental study which deals with the residual liquefaction of seabed under standing waves. It is shown that the seabed liquefaction under standing waves, although qualitatively similar, exhibits features different from that caused by progressive waves....... The experimental results show that the buildup of pore-water pressure and the resulting liquefaction first starts at the nodal section and spreads towards the antinodal section. The number of waves to cause liquefaction at the nodal section appears to be equal to that experienced in progressive waves for the same...... wave height. Recommendations are made as to how to assess liquefaction potential in standing waves. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE)....

  1. Waves in geophysical fluids tsunamis, rogue waves, internal waves and internal tides

    CERN Document Server

    Schneider, Wilhelm; Trulsen, Karsten

    2006-01-01

    Waves in Geophysical Fluids describes: the forecasting and risk evaluation of tsunamis by tectonic motion, land slides, explosions, run-up, and maps the tsunami sources in the world's oceans; stochastic Monte-Carlo simulations and focusing mechanisms for rogue waves, nonlinear wave models, breather formulas, and the kinematics of the Draupner wave; the full story about the discovery of the very large oceanic internal waves, how the waves are visible from above through the signatures on the sea surface, and how to compute them; observations of energetic internal tides and hot spots from several field campaigns in all parts of the world's oceans, with interpretation of spectra. An essential work for students, scientists and engineers working with the fundamental and applied aspects of ocean waves.

  2. Skeletonized wave equation of surface wave dispersion inversion

    KAUST Repository

    Li, Jing

    2016-09-06

    We present the theory for wave equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. Similar to wave-equation travel-time inversion, the complicated surface-wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the (kx,ω) domain. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2D or 3D velocity models. This procedure, denoted as wave equation dispersion inversion (WD), does not require the assumption of a layered model and is less prone to the cycle skipping problems of full waveform inversion (FWI). The synthetic and field data examples demonstrate that WD can accurately reconstruct the S-wave velocity distribution in laterally heterogeneous media.

  3. Forecasting the impact of storm waves and sea-level rise on Midway Atoll and Laysan Island within the Papahānaumokuākea Marine National Monument—a comparison of passive versus dynamic inundation models

    Science.gov (United States)

    Storlazzi, Curt D.; Berkowitz, Paul; Reynolds, Michelle H.; Logan, Joshua B.

    2013-01-01

    Two inundation events in 2011 underscored the potential for elevated water levels to damage infrastructure and affect terrestrial ecosystems on the low-lying Northwestern Hawaiian Islands in the Papahānaumokuākea Marine National Monument. The goal of this study was to compare passive "bathtub" inundation models based on geographic information systems (GIS) to those that include dynamic water levels caused by wave-induced set-up and run-up for two end-member island morphologies: Midway, a classic atoll with islands on the shallow (2-8 m) atoll rim and a deep, central lagoon; and Laysan, which is characterized by a deep (20-30 m) atoll rim and an island at the center of the atoll. Vulnerability to elevated water levels was assessed using hindcast wind and wave data to drive coupled physics-based numerical wave, current, and water-level models for the atolls. The resulting model data were then used to compute run-up elevations using a parametric run-up equation under both present conditions and future sea-level-rise scenarios. In both geomorphologies, wave heights and wavelengths adjacent to the island shorelines increased more than three times and four times, respectively, with increasing values of sea-level rise, as more deep-water wave energy could propagate over the atoll rim and larger wind-driven waves could develop on the atoll. Although these increases in water depth resulted in decreased set-up along the islands’ shorelines, the larger wave heights and longer wavelengths due to sea-level rise increased the resulting wave-induced run-up. Run-up values were spatially heterogeneous and dependent on the direction of incident wave direction, bathymetry, and island configuration. Island inundation was modeled to increase substantially when wave-driven effects were included, suggesting that inundation and impacts to infrastructure and terrestrial habitats will occur at lower values of predicted sea-level rise, and thus sooner in the 21st century, than suggested

  4. Numerical Modeling of Medium Term Morphological Changes at Manavgat River Mouth Due to Combined Action of Waves and River Discharges

    Science.gov (United States)

    Demirci, E.; Baykal, C.; Guler, I.

    2016-12-01

    In this study, hydrodynamic conditions due to river discharge, wave action and sea level fluctuations within a seven month period and the morphological response of the Manavgat river mouth are modeled with XBeach, a two-dimensional depth-averaged (2DH) numerical model developed to compute the natural coastal response during time-varying storm and hurricane conditions (Roelvink et al., 2010). The study area shows an active behavior on its nearshore morphology, thus, two jetties were constructed at the river mouth between years 1996-2000. Recently, Demirci et al. (2016) has studied the impacts of an excess river discharge and concurrent wave action and tidal fluctuations on the Manavgat river mouth morphology for the duration of 12 days (December 4th and 15th, 1998) while the construction of jetties were carried on. It is concluded that XBeach has presumed the final morphology fairly well with the calibrated set of input parameters. Here, the river mouth modeled at a further past date before the construction of jetties with the similar set of input parameters (between August 1st, 1995-March 8th, 1996) to reveal the drastic morphologic change near the mouth due to high river discharge and severe storms happened in a longer period of time. Wave climate effect is determined with the wave hindcasting model, W61, developed by Middle East Technical University-OERC with the NCEP-CFSR wind data as well as the sea level data. River discharge, wave and sea level data are introduced as input parameters in the XBeach numerical model and the final output morphological change is compared with the final bed level measurements. References:Demirci, E., Baykal, C., Guler, I., Ergin, A., & Sogut, E. (postponed). Numerical Modelling on Hydrodynamic Flow Conditions and Morphological Changes Using XBeach Near Manavgat River Mouth. Accepted as Oral presentation at the 35thInt. Conf. on Coastal Eng., Istanbul, Turkey. Guler, I., Ergin, A., Yalçıner, A. C., (2003). Monitoring Sediment

  5. Wave Induced Loads on the LEANCON Wave Energy Converter

    DEFF Research Database (Denmark)

    Frigaard, Peter; Kofoed, Jens Peter; Beserra, Eliab Ricarte

    This report is a product of the co-operation agreement between Aalborg University and LEANCON (by Kurt Due Rasmussen) on the evaluation and development of the LEANCON wave energy converter (WEC). The work reported here has focused on evaluation of the wave induced loads on the device, based...... in the laboratory, all under the supervision of the personnel of the Wave Energy Research Group at Department of Civil Engineering, Aalborg University....

  6. Hydrodynamic Performance of a Wave Energy Converter

    Science.gov (United States)

    Yang, Yingchen

    2010-11-01

    To harvest energy from ocean waves, a new wave energy converter (WEC) was proposed and tested in a wave tank. The WEC freely floats on the water surface and rides waves. It utilizes its wave-driven angular oscillation to convert the mechanical energy of waves into electricity. To gain the maximum possible angular oscillation of the WEC under specified wave conditions, both floatation of the WEC and wave interaction with the WEC play critical roles in a joint fashion. During the experiments, the submersion condition of the WEC and wave condition were varied. The results were analyzed in terms of the oscillation amplitude, stability, auto-orientation capability, and wave frequency dependency.

  7. Wave-equation Qs Inversion of Skeletonized Surface Waves

    KAUST Repository

    Li, Jing

    2017-02-08

    We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is the one that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs inversion (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to full waveform inversion (FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsurface Qs distribution as long as the Vs model is known with sufficient accuracy.

  8. Skeletonized wave-equation Qs tomography using surface waves

    KAUST Repository

    Li, Jing

    2017-08-17

    We present a skeletonized inversion method that inverts surface-wave data for the Qs quality factor. Similar to the inversion of dispersion curves for the S-wave velocity model, the complicated surface-wave arrivals are skeletonized as simpler data, namely the amplitude spectra of the windowed Rayleigh-wave arrivals. The optimal Qs model is then found that minimizes the difference in the peak frequencies of the predicted and observed Rayleigh wave arrivals using a gradient-based wave-equation optimization method. Solutions to the viscoelastic wave-equation are used to compute the predicted Rayleigh-wave arrivals and the misfit gradient at every iteration. This procedure, denoted as wave-equation Qs tomography (WQs), does not require the assumption of a layered model and tends to have fast and robust convergence compared to Q full waveform inversion (Q-FWI). Numerical examples with synthetic and field data demonstrate that the WQs method can accurately invert for a smoothed approximation to the subsur-face Qs distribution as long as the Vs model is known with sufficient accuracy.

  9. Gabor Wave Packet Method to Solve Plasma Wave Equations

    Energy Technology Data Exchange (ETDEWEB)

    A. Pletzer; C.K. Phillips; D.N. Smithe

    2003-06-18

    A numerical method for solving plasma wave equations arising in the context of mode conversion between the fast magnetosonic and the slow (e.g ion Bernstein) wave is presented. The numerical algorithm relies on the expansion of the solution in Gaussian wave packets known as Gabor functions, which have good resolution properties in both real and Fourier space. The wave packets are ideally suited to capture both the large and small wavelength features that characterize mode conversion problems. The accuracy of the scheme is compared with a standard finite element approach.

  10. Theory of Detonation Waves

    Science.gov (United States)

    1942-05-04

    following hYJ?oth- .. esis: The detonation wave ini tiatos the detonation in the neie ;hboring layer of the intact explosive by the discontinuity of...3-2) may be stated as ( 4-4) / ( -’« dJ:J. ~ = ~- {1.;. n)’A (n,’P, V) as a conversion formula U1 the abo’lre s~nso. i.e., / li This is the... formula ( 4-4) which expresses x in terms of n. If we have oontinui ty, i.e,., if n _,. 0 implies P ~p , V --+V , then ( 3-3) yields A (n 1 Pl. V

  11. Directional Ocean Wave Spectra

    Science.gov (United States)

    1991-01-01

    Press or the Set ies Editors. Published in the Series Handbook of Paleozoology, Emil Kurt-Schnyder and Hans Reiber, Irans- lated by Emil Kucera ... Jan 19S𔄁) possible, but wave-current interactions must be taken I’ hrý1 B" %nv~ N . and w’ ’A I’ lw"iR Kcis’. oi . 1" into account. I-0& 111( Oplen...ice pack that was deformned h\\ ain underlying sase Npecrum. givntedreto of eeg ,. propagation: train.’ Phe deformed ice \\ieklded a simple, wecll

  12. Wave propagation scattering theory

    CERN Document Server

    Birman, M Sh

    1993-01-01

    The papers in this collection were written primarily by members of the St. Petersburg seminar in mathematical physics. The seminar, now run by O. A. Ladyzhenskaya, was initiated in 1947 by V. I. Smirnov, to whose memory this volume is dedicated. The papers in the collection are devoted mainly to wave propagation processes, scattering theory, integrability of nonlinear equations, and related problems of spectral theory of differential and integral operators. The book is of interest to mathematicians working in mathematical physics and differential equations, as well as to physicists studying va

  13. Millimeter Wave Communications

    Science.gov (United States)

    1984-06-01

    64 64:7 34OF9 043 64 ?~ 4’ ’ J "IN0󈨀 ŗ 34 69044137 Saw a.? 64 3 3 6 N @6’ 4’ ) IF6 1.41 W i V ature will give values to be expected (Reference 9: 322...Octooer 1978, the Atmospheric Sciences Laboratories c’nducted a malor test called DIRT-I, to obtain direct sensor information about the properties of dust...wave frequencies (2.15) D where G v Antenna gain a Wavelength in meters c = Speed of light - 3.0 x 10meterslsecond f a Frequency in Hertz A

  14. Gravitational-Wave Astronomy

    Science.gov (United States)

    Kelly, Bernard J.

    2010-01-01

    Einstein's General Theory of Relativity is our best classical description of gravity, and informs modern astronomy and astrophysics at all scales: stellar, galactic, and cosmological. Among its surprising predictions is the existence of gravitational waves -- ripples in space-time that carry energy and momentum away from strongly interacting gravitating sources. In my talk, I will give an overview of the properties of this radiation, recent breakthroughs in computational physics allowing us to calculate the waveforms from galactic mergers, and the prospect of direct observation with interferometric detectors such as LIGO and LISA.

  15. Elementary wave optics

    CERN Document Server

    Webb, Robert H

    2005-01-01

    This undergraduate textbook presents thorough coverage of the standard topics of classical optics and optical instrument design; it also offers significant details regarding the concepts of modern optics. Its survey of the mathematical tools of optics grants students insights into the physical principles of quantum mechanics.Two principal concepts occur throughout: a treatment of scattering from real scatterers (leading to Huygens' principles, diffraction theory, the index of refraction, and related topics); and the difference between coherent and noncoherent wave phenomena. Examinations of su

  16. Models of wave memory

    CERN Document Server

    Kashchenko, Serguey

    2015-01-01

    This monograph examines in detail models of neural systems described by delay-differential equations. Each element of the medium (neuron) is an oscillator that generates, in standalone mode, short impulses also known as spikes. The book discusses models of synaptic interaction between neurons, which lead to complex oscillatory modes in the system. In addition, it presents a solution to the problem of choosing the parameters of interaction in order to obtain attractors with predetermined structure. These attractors are represented as images encoded in the form of autowaves (wave memory). The target audience primarily comprises researchers and experts in the field, but it will also be beneficial for graduate students.

  17. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden

    1975-01-01

    The selection rules for the linear couplings between magnons and phonons propagating in the c direction of a simple basal-plane hcp ferromagnet are determined by general symmetry considerations. The acoustic-optical magnon-phonon interactions observed in the heavy-rare-earth metals have been expl...... by Liu. The coupled magnon—transverse-phonon system for the c direction of Tb is analyzed in detail, and the strengths of the couplings are deduced as a function of wave vector by combining the experimental studies with the theory....

  18. Holographic magnetisation density waves

    Energy Technology Data Exchange (ETDEWEB)

    Donos, Aristomenis [Centre for Particle Theory and Department of Mathematical Sciences, Durham University,Stockton Road, Durham, DH1 3LE (United Kingdom); Pantelidou, Christiana [Departament de Fisica Quantica i Astrofisica & Institut de Ciencies del Cosmos (ICC),Universitat de Barcelona,Marti i Franques 1, 08028 Barcelona (Spain)

    2016-10-10

    We numerically construct asymptotically AdS black brane solutions of D=4 Einstein theory coupled to a scalar and two U(1) gauge fields. The solutions are holographically dual to d=3 CFTs in a constant external magnetic field along one of the U(1)’s. Below a critical temperature the system’s magnetisation density becomes inhomogeneous, leading to spontaneous formation of current density waves. We find that the transition can be of second order and that the solutions which minimise the free energy locally in the parameter space of solutions have averaged stressed tensor of a perfect fluid.

  19. The detection of gravitational waves

    CERN Document Server

    Barish, Barry C

    1996-01-01

    General Relativity predicts the emission of gravitanional waves whenever compact concentrations of energy change shape. This could occur in a variety of astrophysical phenomena. For example, the coalescence of binary systems such as a pair of neutron stars or black holes emit gravitanional waves that propagate through space at the speed of light, and in principle, can be directly detected on the earth's surface. This lecture series will review the possible sources of gravitanional waves and the various approaches toward detection, with special emphasis on long baseline interferometer detectors. The Laser Interferometer Gravitanional Wave Observatory (LIGO) is being constructed with a goal to detect these waves and then to use them as a new tool to explore and study the Universe. The sources of gravitanional waves and techniques for detection will be presented, as well as the status and prospects for the LIGO project.

  20. The SSG Wave Energy Converter

    DEFF Research Database (Denmark)

    Vicinanza, Diego; Margheritini, Lucia; Kofoed, Jens Peter

    2012-01-01

    The Sea-wave Slot-cone Generator concept (SSG) is a Wave Energy Converter based on the wave overtopping principle utilizing several reservoirs placed on top of each other, in which the energy of the incoming wave will be stored as potential energy. The water captured in the reservoirs will then run...... through turbines for electricity production. The system utilizes a wide spectrum of different wave conditions by means of multiple reservoirs, located at different levels above the still water level. Thereby, it obtains a high overall efficiency and it can be suitable for shoreline and breakwater...... at the Svaaheia site (Norway), Port of Hanstholm (Denmark) and Port of Garibaldi (Oregon, USA). In the last-mentioned two projects, the Sea-wave Slot-cone Generator technology is integrated into outer harbor breakwater and jetty reconstruction projects. Comprehensive studies have been performed in the last years...

  1. Oscillating nonlinear acoustic shock waves

    DEFF Research Database (Denmark)

    Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth

    2016-01-01

    We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... that at resonance a stationary state arise consisting of multiple oscillating shock waves. Off resonance driving leads to a nearly linear oscillating ground state but superimposed by bursts of a fast oscillating shock wave. Based on a travelling wave ansatz for the fluid velocity potential with an added 2'nd order...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....

  2. Handbook of Ocean Wave Energy

    DEFF Research Database (Denmark)

    This book offers a concise, practice-oriented reference-guide to the field of ocean wave energy. The ten chapters highlight the key rules of thumb, address all the main technical engineering aspects and describe in detail all the key aspects to be considered in the techno-economic assessment...... of wave energy converters. Written in an easy-to-understand style, the book answers questions relevant to readers of different backgrounds, from developers, private and public investors, to students and researchers. It is thereby a valuable resource for both newcomers and experienced practitioners...... in the wave energy sector. •Offers a practice-oriented reference guide to the field of ocean wave energy •Presents an overview as well as a deeper insight into wave energy converters •Covers both the economic and engineering aspects related to ocean wave energy conversion...

  3. Quantum Emulation of Gravitational Waves.

    Science.gov (United States)

    Fernandez-Corbaton, Ivan; Cirio, Mauro; Büse, Alexander; Lamata, Lucas; Solano, Enrique; Molina-Terriza, Gabriel

    2015-07-14

    Gravitational waves, as predicted by Einstein's general relativity theory, appear as ripples in the fabric of spacetime traveling at the speed of light. We prove that the propagation of small amplitude gravitational waves in a curved spacetime is equivalent to the propagation of a subspace of electromagnetic states. We use this result to propose the use of entangled photons to emulate the evolution of gravitational waves in curved spacetimes by means of experimental electromagnetic setups featuring metamaterials.

  4. Snell's Law for Spin Waves

    OpenAIRE

    Stigloher, Johannes; Decker, Martin; Körner, Helmut S.; TANABE, Kenji; Moriyama, Takahiro; Taniguchi, Takuya; Hata, Hiroshi; Madami, Marco; Gubbiotti, Gianluca; Kobayashi, Kensuke; Ono, Teruo; Back, Christian H.

    2016-01-01

    We report the experimental observation of Snell's law for magneto-static spin waves in thin ferromagnetic Permalloy films by imaging incident, refracted and reflected waves. We use a thickness step as the interface between two media with different dispersion relation. Since the dispersion relation for magneto-static waves in thin ferromagnetic films is anisotropic, deviations from the isotropic Snell's law known in optics are observed for incidence angles larger than 25\\textdegree{} with resp...

  5. A simple electron plasma wave

    Energy Technology Data Exchange (ETDEWEB)

    Brodin, G., E-mail: gert.brodin@physics.umu.se [Department of Physics, Umeå University, SE-901 87 Umeå (Sweden); Stenflo, L. [Department of Physics, Linköping University, SE-581 83 Linköping (Sweden)

    2017-03-18

    Considering a class of solutions where the density perturbations are functions of time, but not of space, we derive a new exact large amplitude wave solution for a cold uniform electron plasma. This result illustrates that most simple analytical solutions can appear even if the density perturbations are large. - Highlights: • The influence of large amplitude electromagnetic waves on electrostatic oscillations is found. • A generalized Mathieu equation is derived. • Anharmonic wave profiles are computed numerically.

  6. Surface Waves on Metamaterials Interfaces

    DEFF Research Database (Denmark)

    Takayama, Osamu; Shkondin, Evgeniy; Panah, Mohammad Esmail Aryaee

    2016-01-01

    We analyze surface electromagnetic waves supported at the interface between isotropic medium and effective anisotropic material that can be realized by alternating conductive and dielectrics layers. This configuration can host various types of surface waves and therefore can serve as a rich...... platform for applications of surface photonics. Most of these surface waves are directional and as such their propagation can be effectively controlled by changing wavelength or material parameters tuning....

  7. Vector wave propagation method.

    Science.gov (United States)

    Fertig, M; Brenner, K-H

    2010-04-01

    In this paper, we extend the scalar wave propagation method (WPM) to vector fields. The WPM [Appl. Opt.32, 4984 (1993)] was introduced in order to overcome the major limitations of the beam propagation method (BPM). With the WPM, the range of application can be extended from the simulation of waveguides to simulation of other optical elements like lenses, prisms and gratings. In that reference it was demonstrated that the wave propagation scheme provides valid results for propagation angles up to 85 degrees and that it is not limited to small index variations in the axis of propagation. Here, we extend the WPM to three-dimensional vectorial fields (VWPMs) by considering the polarization dependent Fresnel coefficients for transmission in each propagation step. The continuity of the electric field is maintained in all three dimensions by an enhanced propagation vector and the transfer matrix. We verify the validity of the method by transmission through a prism and by comparison with the focal distribution from vectorial Debye theory. Furthermore, a two-dimensional grating is simulated and compared with the results from three-dimensional RCWA. Especially for 3D problems, the runtime of the VWPM exhibits special advantage over the RCWA.

  8. Rotational waves in geodynamics

    Science.gov (United States)

    Gerus, Artyom; Vikulin, Alexander

    2015-04-01

    The rotation model of a geoblock with intrinsic momentum was constructed by A.V. Vikulin and A.G. Ivanchin [9, 10] to describe seismicity within the Pacific Ocean margin. It is based on the idea of a rotational motion of geoblocks as the parts of the rotating body of the Earth that generates rotary deformation waves. The law of the block motion was derived in the form of the sine-Gordon equation (SG) [5, 9]; the dimensionless form of the equation is: δ2θ δ2θ δξ2 - δη2 = sinθ, (1) where θ = β/2, ξ = k0z and η = v0k0t are dimensionless coordinates, z - length of the chain of masses (blocks), t - time, β - turn angle, ν0 - representative velocity of the process, k0 - wave number. Another case analyzed was a chain of nonuniformly rotating blocks, with deviation of force moments from equilibrium positions μ, considering friction forces α along boundaries, which better matched a real-life seismic process. As a result, the authors obtained the law of motion for a block in a chain in the form of the modified SG equation [8]: δ2θ δ2θ δθ- δξ2 - δ η2 = sin θ+ α δη + μδ(ξ)sin θ (2)

  9. Google Wave Up and Running

    CERN Document Server

    Ferrate, Andres

    2010-01-01

    Catch Google Wave, the revolutionary Internet protocol and web service that lets you communicate and collaborate in realtime. With this book, you'll understand how Google Wave integrates email, instant messaging (IM), wiki, and social networking functionality into a powerful and extensible platform. You'll also learn how to use its features, customize its functions, and build sophisticated extensions with Google Wave's open APIs and network protocol. Written for everyone -- from non-techies to ninja coders -- Google Wave: Up and Running provides a complete tour of this complex platform. You'

  10. Wave-equation dispersion inversion

    KAUST Repository

    Li, Jing

    2016-12-08

    We present the theory for wave-equation inversion of dispersion curves, where the misfit function is the sum of the squared differences between the wavenumbers along the predicted and observed dispersion curves. The dispersion curves are obtained from Rayleigh waves recorded by vertical-component geophones. Similar to wave-equation traveltime tomography, the complicated surface wave arrivals in traces are skeletonized as simpler data, namely the picked dispersion curves in the phase-velocity and frequency domains. Solutions to the elastic wave equation and an iterative optimization method are then used to invert these curves for 2-D or 3-D S-wave velocity models. This procedure, denoted as wave-equation dispersion inversion (WD), does not require the assumption of a layered model and is significantly less prone to the cycle-skipping problems of full waveform inversion. The synthetic and field data examples demonstrate that WD can approximately reconstruct the S-wave velocity distributions in laterally heterogeneous media if the dispersion curves can be identified and picked. The WD method is easily extended to anisotropic data and the inversion of dispersion curves associated with Love waves.

  11. Electromagnetic waves in stratified media

    CERN Document Server

    Wait, James R; Fock, V A; Wait, J R

    2013-01-01

    International Series of Monographs in Electromagnetic Waves, Volume 3: Electromagnetic Waves in Stratified Media provides information pertinent to the electromagnetic waves in media whose properties differ in one particular direction. This book discusses the important feature of the waves that enables communications at global distances. Organized into 13 chapters, this volume begins with an overview of the general analysis for the electromagnetic response of a plane stratified medium comprising of any number of parallel homogeneous layers. This text then explains the reflection of electromagne

  12. Wave motion in elastic solids

    CERN Document Server

    Graff, Karl F

    1991-01-01

    This highly useful textbook presents comprehensive intermediate-level coverage of nearly all major topics of elastic wave propagation in solids. The subjects range from the elementary theory of waves and vibrations in strings to the three-dimensional theory of waves in thick plates. The book is designed not only for a wide audience of engineering students, but also as a general reference for workers in vibrations and acoustics. Chapters 1-4 cover wave motion in the simple structural shapes, namely strings, longitudinal rod motion, beams and membranes, plates and (cylindrical) shells. Chapter

  13. Wigner functions of s waves

    DEFF Research Database (Denmark)

    Dahl, Jens Peder; Varro, S.; Wolf, A.

    2007-01-01

    We derive explicit expressions for the Wigner function of wave functions in D dimensions which depend on the hyperradius-that is, of s waves. They are based either on the position or the momentum representation of the s wave. The corresponding Wigner function depends on three variables......: the absolute value of the D-dimensional position and momentum vectors and the angle between them. We illustrate these expressions by calculating and discussing the Wigner functions of an elementary s wave and the energy eigenfunction of a free particle....

  14. Newnes short wave listening handbook

    CERN Document Server

    Pritchard, Joe

    2013-01-01

    Newnes Short Wave Listening Handbook is a guide for starting up in short wave listening (SWL). The book is comprised of 15 chapters that discuss the basics and fundamental concepts of short wave radio listening. The coverage of the text includes electrical principles; types of signals that can be heard in the radio spectrum; and using computers in SWL. The book also covers SWL equipment, such as receivers, converters, and circuits. The text will be of great use to individuals who want to get into short wave listening.

  15. Stabilized wave segments in an excitable medium with a phase wave at the wave back

    Science.gov (United States)

    Zykov, V. S.; Bodenschatz, E.

    2014-04-01

    The propagation velocity and the shape of a stationary propagating wave segment are determined analytically for excitable media supporting excitation waves with trigger fronts and phase backs. The general relationships between the medium's excitability and the wave segment parameters are obtained in the framework of the free boundary approach under quite usual assumptions. Two universal limits restricting the region of existence of stabilized wave segments are found. The comparison of the analytical results with numerical simulations of the well-known Kessler-Levine model demonstrates their good quantitative agreement. The findings should be applicable to a wide class of systems, such as the propagation of electrical waves in the cardiac muscle or wave propagation in autocatalytic chemical reactions, due to the generality of the free-boundary approach used.

  16. Excitation of surface plasma waves over corrugated slow-wave ...

    Indian Academy of Sciences (India)

    A microwave propagating along vacuum–dielectric–plasma interface excites surface plasma wave (SPW). A periodic slow-wave structure placed over dielectric slows down the SPW. The phase velocity of slow SPW is sensitive to height, periodicity, number of periods, thickness and the separation between dielectric and ...

  17. Wave Forces on a Vertical Smooth Cylinder in Directional Waves

    DEFF Research Database (Denmark)

    Høgedal, M.; Skourup, J.; Burcharth, H. F.

    1994-01-01

    In this paper the results from physical experiments with an instrumented cylinder conducted in laboratory environments are presented. The primary aim of the study has been to investigate the effect from wave directionality on the local and depth integrated maximum wave forces on a smooth vertical...

  18. Solitary wave and periodic wave solutions for Burgers, Fisher ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 85; Issue 1. Solitary wave and periodic wave solutions for Burgers, Fisher, Huxley and combined forms of these equations by the (′/)-expansion method. Jalil Manafian Mehrdad Lakestani. Volume 85 Issue 1 July 2015 pp 31-52 ...

  19. New exact travelling wave solutions of bidirectional wave equations

    Indian Academy of Sciences (India)

    where , , and d are real constants. In general, the exact travelling wave solutions will be helpful in the theoretical and numerical study of the nonlinear evolution systems. In this paper, we obtain exact travelling wave solutions of system (1) using the modified tanh–coth function method with computerized symbolic ...

  20. Excitation of surface plasma waves over corrugated slow-wave ...

    Indian Academy of Sciences (India)

    Abstract. A microwave propagating along vacuum–dielectric–plasma interface excites surface plasma wave (SPW). A periodic slow-wave structure placed over dielectric slows down the SPW. The phase velocity of slow SPW is sensitive to height, periodicity, number of periods, thickness and the separation between ...

  1. From the Somigliana waves to the evanescent waves

    Directory of Open Access Journals (Sweden)

    Pietro Caloi

    2010-02-01

    Full Text Available The Rayleigh equation has real coefficients; therefore, also the case of complex conjugated roots may be explained physically. The Author proves that the Somigliana waves may be formed for Poisson ratio values until 0.30543; for gradually less rigid media, they are missing altogether and degenerate into evanescent waves.

  2. Short wave breaking effects on low frequency waves

    NARCIS (Netherlands)

    Daly, C.; Roelvink, J.A.; Van Dongeren, A.; Van Thiel de Vries, J.S.M.; McCall, R.T.

    2010-01-01

    The effect of short wave breaking on low frequency waves is investigated using two breaker formulations implemented in a time-dependent numerical model (XBeach): (1) an advective-deterministic approach (ADA) and (2) the probabilistic breaker formulation of Roelvink (1993). Previous research has

  3. Ulysses Observations of Nonlinear Wave-wave Interactions in the ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Astrophysics and Astronomy; Volume 21; Issue 3-4. Ulysses Observations of Nonlinear Wave-wave Interactions in the Source Regions of Type III Solar Radio Bursts. G. Thejappa R. J. MacDowall. Session XI – Solar Wind & Interplanetary Magnetic Fields Volume 21 Issue 3-4 ...

  4. Depth averaged wave-current interaction in the multi bank morphology of the southern North Sea

    Science.gov (United States)

    Komijani, Homayoon; Osuna, Pedro; Ocampo Torres, Francisco; Monbaliu, Jaak

    2017-04-01

    The effects of wind induced waves on the barotropic mean flow during a storm event in the southern North Sea are investigated. The well known radiation stress gradient theory of Longuet-Higgins and Stewart (1962, 1964) together with the influence of waves through the Stokes drift (Hasselmann, 1971 and Garret, 1976) are incorporated in the RANS equation system of the COHERENS circulation model (Luyten et al., 2005) following the methodology worked out by Bennis et al. (2011) . The SWAN spectral wave model (version 40.91, http://www.swan.tudelft.nl/) is used to provide the wave information. This allows us to take into account the dissipative terms of wave momentum flux to the mean flow such as depth induced wave breaking and bottom friction as well as the conservative terms of wave effects such as the vortex-force and wave induced pressure gradient. The resulting coupled COHERENS-SWAN model has been validated using the well known planar beach test case proposed by Haas and Warner (2009) in depth averaged mode. For the application in the southern North Sea, a series of nested grids using COHERENS (circulation model) and WAM cycle 4.5.3 (spectral wave model applied to the North Sea shelf area, Monbaliu et al. 2000; Günther, H. and A. Behrens, personal communications, May 2012) is set up to provide the hydrodynamic and wave boundary conditions for the COHERENS-SWAN two way coupled wave-current model for the Belgian coastal zone model. The improvements obtained in hindcasting the circulation processes in the Belgian coastal area during a storm event will be highlighted. But also difficulties faced in the coupling of the models and in the simulation of a real case storm will be discussed. In particular, some of the approaches for dealing with the numerical instabilities due to multi bank morphology of the southern North Sea will be addressed. References : Bennis, A.-C., F. Ardhuin, and F. Dumas (2011). "On the coupling of wave and three-dimensional circulation models

  5. Vector plane wave spectrum of an arbitrary polarized electromagnetic wave.

    Science.gov (United States)

    Guo, Hanming; Chen, Jiabi; Zhuang, Songlin

    2006-03-20

    By using the method of modal expansions of the independent transverse fields, a formula of vector plane wave spectrum (VPWS) of an arbitrary polarized electromagnetic wave in a homogenous medium is derived. In this formula VPWS is composed of TM- and TE-mode plane wave spectrum, where the amplitude and unit polarized direction of every plane wave are separable, which has more obviously physical meaning and is more convenient to apply in some cases compared to previous formula of VPWS. As an example, the formula of VPWS is applied to the well-known radially and azimuthally polarized beam. In addition, vector Fourier-Bessel transform pairs of an arbitrary polarized electromagnetic wave with circular symmetry are also derived.

  6. Pulse wave analysis with diffusing-wave spectroscopy.

    Science.gov (United States)

    Belau, Markus; Scheffer, Wolfgang; Maret, Georg

    2017-07-01

    Hypertension is a major risk factor for cardiovascular disease and thus at the origin of many deaths by e.g. heart attack or stroke. Hypertension is caused by many factors including an increase in arterial stiffness which leads to changes in pulse wave velocity and wave reflections. Those often result in an increased left ventricular load which may result in heart failure as well as an increased pulsatile pressure in the microcirculation l to damage to blood vessels. In order to specifically treat the different causes of hypertension it is desirable to perform a pulse wave analysis as a complement to measurements of systolic and diastolic pressure by brachial cuff sphygmomanometry. Here we show that Diffusing Wave Spectroscopy, a novel non-invasive portable tool, is able to monitor blood flow changes with a high temporal resolution. The measured pulse travel times give detailed information of the pulse wave blood flow profile.

  7. Wave-to-wire Modelling of Wave Energy Converters

    DEFF Research Database (Denmark)

    Ferri, Francesco

    and non-technical issues. These can be efficiently summarised in the cost of the energy produced by the various wave energy converters: If compared with other renewable energy technologies the cost of energy from the ocean waves is still significantly higher. Holding the comparison it also important...... to noticed that there is not a clear front runner in the wave energy sector, which fades effort and funding over a too broad frame. In order to assist efficient development and analysis of wave energy converters and therefore to accelerate the sector progression towards commercialisation, a generally......, but talking about renewable energy partially ravels the problem out. Wave energy is a large, mostly untapped, renewable energy resource. It has the potential to contribute significantly to the future energy mix, but the sector has not yet rolled off into the market in consequence of a number of technical...

  8. Turbulent wind waves on a water current

    Directory of Open Access Journals (Sweden)

    M. V. Zavolgensky

    2008-05-01

    Full Text Available An analytical model of water waves generated by the wind over the water surface is presented. A simple modeling method of wind waves is described based on waves lengths diagram, azimuthal hodograph of waves velocities and others. Properties of the generated waves are described. The wave length and wave velocity are obtained as functions on azimuth of wave propagation and growth rate. Motionless waves dynamically trapped into the general picture of three dimensional waves are described. The gravitation force does not enter the three dimensional of turbulent wind waves. That is why these waves have turbulent and not gravitational nature. The Langmuir stripes are naturally modeled and existence of the rogue waves is theoretically proved.

  9. Standing wave tube electro active polymer wave energy converter

    Science.gov (United States)

    Jean, Philippe; Wattez, Ambroise; Ardoise, Guillaume; Melis, C.; Van Kessel, R.; Fourmon, A.; Barrabino, E.; Heemskerk, J.; Queau, J. P.

    2012-04-01

    Over the past 4 years SBM has developed a revolutionary Wave Energy Converter (WEC): the S3. Floating under the ocean surface, the S3 amplifies pressure waves similarly to a Ruben's tube. Only made of elastomers, the system is entirely flexible, environmentally friendly and silent. Thanks to a multimodal resonant behavior, the S3 is capable of efficiently harvesting wave energy from a wide range of wave periods, naturally smoothing the irregularities of ocean wave amplitudes and periods. In the S3 system, Electro Active Polymer (EAP) generators are distributed along an elastomeric tube over several wave lengths, they convert wave induced deformations directly into electricity. The output is high voltage multiphase Direct Current with low ripple. Unlike other conventional WECs, the S3 requires no maintenance of moving parts. The conception and operating principle will eventually lead to a reduction of both CAPEX and OPEX. By integrating EAP generators into a small scale S3, SBM achieved a world first: direct conversion of wave energy in electricity with a moored flexible submerged EAP WEC in a wave tank test. Through an extensive testing program on large scale EAP generators, SBM identified challenges in scaling up to a utility grid device. French Government supports the consortium consisting of SBM, IFREMER and ECN in their efforts to deploy a full scale prototype at the SEMREV test center in France at the horizon 2014-2015. SBM will be seeking strategic as well as financial partners to unleash the true potentials of the S3 Standing Wave Tube Electro Active Polymer WEC.

  10. Surf Wave Hydrodynamics in the Coastal Environment

    NARCIS (Netherlands)

    Salmon, J.E.

    2016-01-01

    Stochastic wave models play a central role in our present-day wave modelling capabilities. They are frequently used to compute wave statistics, to generate boundary conditions and to include wave effects in coupled model systems. Historically, such models were developed to predict the wave field

  11. Gravitational wave experiments

    CERN Document Server

    Hamilton, W O

    1993-01-01

    There were three oral sessions and one poster session for Workshop C1 on Gravitational Wave Experiments. There was also an informal experimental roundtable held one after- noon. The first two oral sessions were devoted mainly to progress reports from various interferometric and bar detector groups. A total of 15 papers were presented in these two sessions. The third session of Workshop C1 was devoted primarily to theoretical and experimental investigations associated with the proposed interferometric detectors. Ten papers were presented in this session. In addition, there were a total of 13 papers presented in the poster session. There was some overlap between the presentations in the third oral session and the posters since only two of the serious posters were devoted to technology not pertinent to interferometers. In general, the papers showed the increasing maturity of the experimental aspects of the field since most presented the results of completed investigations rather than making promises of wonderf...

  12. Metamaterial electromagnetic wave absorbers.

    Science.gov (United States)

    Watts, Claire M; Liu, Xianliang; Padilla, Willie J

    2012-06-19

    The advent of negative index materials has spawned extensive research into metamaterials over the past decade. Metamaterials are attractive not only for their exotic electromagnetic properties, but also their promise for applications. A particular branch-the metamaterial perfect absorber (MPA)-has garnered interest due to the fact that it can achieve unity absorptivity of electromagnetic waves. Since its first experimental demonstration in 2008, the MPA has progressed significantly with designs shown across the electromagnetic spectrum, from microwave to optical. In this Progress Report we give an overview of the field and discuss a selection of examples and related applications. The ability of the MPA to exhibit extreme performance flexibility will be discussed and the theory underlying their operation and limitations will be established. Insight is given into what we can expect from this rapidly expanding field and future challenges will be addressed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Focusing of electromagnetic waves

    Energy Technology Data Exchange (ETDEWEB)

    Dhayalan, V.

    1996-12-31

    The focusing of electromagnetic waves inside a slab has been examined together with two special cases in which the slab is reduced to a single interface or a single medium. To that end the exact solutions for the fields inside a layered medium have been used, given in terms of the outside current source in order to obtain the solutions for the focused electric field inside a slab. Both exact and asymptotic solutions of the problem have been considered, and the validity of the latter has been discussed. The author has developed a numerical algorithm for evaluation of the diffraction integral with special emphasis on reducing the computing time. The numerical techniques in the paper can be readily applied to evaluate similar diffraction integrals occurring e.g. in microstrip antennas. 46 refs.

  14. Waves in metamaterials

    CERN Document Server

    Solymar, Laszlo

    2014-01-01

    Metamaterials is a young subject born in the 21st century. It is concerned with artificial materials which can have electrical and magnetic properties difficult or impossible to find in nature. The building blocks in most cases are resonant elements much smaller than the wavelength of the electromagnetic wave. The book offers a comprehensive treatment of all aspects of research in this field at a level that should appeal to final year undergraduates in physics or in electrical and electronic engineering. The mathematics is kept at a minimum; the aim is to explain the physics in simple terms and enumerate the major advances. It can be profitably read by graduate and post-graduate students in order to find out what has been done in the field outside their speciality, and by experts who may gain new insight about the inter-relationship of the physical phenomena involved.

  15. Gravitational waves and antennas

    CERN Multimedia

    CERN. Geneva

    2003-01-01

    Gravitational waves and their detection represent today a hot topic, which promises to play a central role in astrophysics, cosmology and theoretical physics. Technological developments have enabled the construction of such sensitive detectors that the detection of gravitational radiation and the start of a new astronomy could become a reality during the next few years. This is expected to bring a revolution in our knowledge of the universe by allowing the observation of hiterto unseen phenomena such as coalescence of compact objects (neutron stars and black holes) fall of stars into supermassive black holes, stellar core collapses, big bang relics and the new and unexpected. In these lectures I give a brief overview of this challenging field of modern physics. Topics : Basic properties of gravitational radiation. Astrophysical sources. Principle of operation of detectors. Interferometers (both ground based and space-based), bars and spheres. Present status of the experiments, their recent results and their f...

  16. Hydraulic Response of the Wave Energy Converter Wave Dragon in Nissum Bredning

    DEFF Research Database (Denmark)

    Kofoed, Jens Peter; Frigaard, Peter

    This report deals with the hydraulic performance of the wave energy converter Wave Dragon, Nissum Bredning prototype.......This report deals with the hydraulic performance of the wave energy converter Wave Dragon, Nissum Bredning prototype....

  17. Fascinating World of Shock Waves

    Indian Academy of Sciences (India)

    Srimath

    The dissipation of mechanical, nuclear, chemi- cal, and electrical energy in a limited space will usually result in ... the vehicle and the shock wave usually referred to as the shock layer will be a region of high .... successfully visualized a shock wave during an electric spark discharge process using stroboscopic method.

  18. Exact piecewise flat gravitational waves

    NARCIS (Netherlands)

    van de Meent, M.|info:eu-repo/dai/nl/314007067

    2011-01-01

    We generalize our previous linear result (van de Meent 2011 Class. Quantum Grav 28 075005) in obtaining gravitational waves from our piecewise flat model for gravity in 3+1 dimensions to exact piecewise flat configurations describing exact planar gravitational waves. We show explicitly how to

  19. Wave Manipulation by Topology Optimization

    DEFF Research Database (Denmark)

    Andkjær, Jacob Anders

    topology optimization can be used to design structures for manipulation of the electromagnetic and acoustic waves. The wave problems considered here fall within three classes. The first class concerns the design of cloaks, which when wrapped around an object will render the object undetectable...

  20. Opdriftsbaserede modeller for Wave Star

    DEFF Research Database (Denmark)

    Kramer, Morten

    Formålet med dette skrift er at få en forhåndsvurdering af mulige effektforøgelser for Wave Star ved anvendelse af aktiv akkumulatordrift. Disse vurderinger baseres på simuleringsmodeller for driften af Wave Star i uregelmæssige bølger. Modellen er udarbejdet i programmeringssproget Delphi og er en...

  1. Just How Does Sound Wave?

    Science.gov (United States)

    Shipman, Bob

    2006-01-01

    When children first hear the term "sound wave" perhaps they might associate it with the way a hand waves or perhaps the squiggly line image on a television monitor when sound recordings are being made. Research suggests that children tend to think sound somehow travels as a discrete package, a fast-moving invisible thing, and not something that…

  2. Solitons in a wave tank

    DEFF Research Database (Denmark)

    Olsen, M.; Smith, H.; Scott, Alwyn C.

    1984-01-01

    A wave tank experiment (first described by the nineteenth-century engineer and naval architect John Scott Russell) relates a linear eigenvalue problem from elementary quantum mechanics to a striking feature of modern nonlinear wave theory: multiple generation of solitons. The tank experiment...

  3. Wave Generation in Physical Models

    DEFF Research Database (Denmark)

    Andersen, Thomas Lykke; Frigaard, Peter

    The present book describes the most important aspects of wave generation techniques in physical models. Moreover, the book serves as technical documentation for the wave generation software AwaSys 6, cf. Aalborg University (2012). In addition to the two main authors also Tue Hald and Michael...

  4. Book review: Extreme ocean waves

    Science.gov (United States)

    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.

  5. Spin waves theory and applications

    CERN Document Server

    Stancil, Daniel D

    2009-01-01

    Magnetic materials can support propagating waves of magnetization; since these are oscillations in the magneto static properties of the material, they are called magneto static waves (sometimes 'magnons' or 'magnetic polarons'). This book discusses magnetic properties of materials, and magnetic moments of atoms and ions

  6. Directional wave measurements and modelling

    Digital Repository Service at National Institute of Oceanography (India)

    Anand, N.M.; Nayak, B.U.; Bhat, S.S.; SanilKumar, V.

    -dimensional spectra and sech@u2@@ (beta theta) spreading function seem to provide a better estimate of the directional energy distribution for the monsoon conditions. While non-linear wave-wave interaction seems to be the major governing factor in the directional...

  7. Wave energy absorption by ducks

    DEFF Research Database (Denmark)

    Kurniawan, Adi

    2017-01-01

    We study the absorption of wave energy by a single and multiple cam-shaped bodies referred to as ducks. Numerical models are developed under the assumptions of linear theory. We consider wave absorption by a single duck as well as by two lines of ducks meeting at an angle....

  8. Compressive passive millimeter wave imager

    Science.gov (United States)

    Gopalsami, Nachappa; Liao, Shaolin; Elmer, Thomas W; Koehl, Eugene R; Heifetz, Alexander; Raptis, Apostolos C

    2015-01-27

    A compressive scanning approach for millimeter wave imaging and sensing. A Hadamard mask is positioned to receive millimeter waves from an object to be imaged. A subset of the full set of Hadamard acquisitions is sampled. The subset is used to reconstruct an image representing the object.

  9. Probabilistic aspects of ocean waves

    NARCIS (Netherlands)

    Battjes, J.A.

    1977-01-01

    Background material for a special lecture on probabilistic aspects of ocean waves for a seminar in Trondheim. It describes long term statistics and short term statistics. Statistical distributions of waves, directional spectra and frequency spectra. Sea state parameters, response peaks, encounter

  10. Sediment transport under breaking waves

    DEFF Research Database (Denmark)

    Christensen, Erik Damgaard; Hjelmager Jensen, Jacob; Mayer, Stefan

    2000-01-01

    generated at the surface where the wave breaks as well as the turbulence generated near the bed due to the wave-motion and the undertow. In general, the levels of turbulent kinetic energy are found to be higher than experiments show. This results in an over prediction of the sediment transport. Nevertheless...

  11. Collected papers on wave mechanics

    CERN Document Server

    Schrödinger, Erwin

    1929-01-01

    Quantisation as a problem of proper values ; the continuous transition from micro- to macro-mechanics ; on the relation between the quantum mechanics of Heisenberg, Born, and Jordan, and that of Schrödinger ; the Compton effect ; the energy-momentum theorem for material waves ; the exchange of energy according to wave mechanics

  12. Assimilation of Wave Imaging Radar Observations for Real-time Wave-by-Wave Forecasting

    Energy Technology Data Exchange (ETDEWEB)

    Simpson, Alexandra [Oregon State Univ., Corvallis, OR (United States); Haller, Merrick [Oregon State Univ., Corvallis, OR (United States). School of Civil & Construction Engineering; Walker, David [SRI International, Menlo Park, CA (United States); Lynett, Pat [Univ. of Southern California, Los Angeles, CA (United States)

    2017-08-29

    This project addressed Topic 3: “Wave Measurement Instrumentation for Feed Forward Controls” under the FOA number DE-FOA-0000971. The overall goal of the program was to develop a phase-resolving wave forecasting technique for application to the active control of Wave Energy Conversion (WEC) devices. We have developed an approach that couples a wave imaging marine radar with a phase-resolving linear wave model for real-time wave field reconstruction and forward propagation of the wave field in space and time. The scope of the project was to develop and assess the performance of this novel forecasting system. Specific project goals were as follows: Develop and verify a fast, GPU-based (Graphical Processing Unit) wave propagation model suitable for phase-resolved computation of nearshore wave transformation over variable bathymetry; Compare the accuracy and speed of performance of the wave model against a deep water model in their ability to predict wave field transformation in the intermediate water depths (50 to 70 m) typical of planned WEC sites; Develop and implement a variational assimilation algorithm that can ingest wave imaging radar observations and estimate the time-varying wave conditions offshore of the domain of interest such that the observed wave field is best reconstructed throughout the domain and then use this to produce model forecasts for a given WEC location; Collect wave-resolving marine radar data, along with relevant in situ wave data, at a suitable wave energy test site, apply the algorithm to the field data, assess performance, and identify any necessary improvements; and Develop a production cost estimate that addresses the affordability of the wave forecasting technology and include in the Final Report. The developed forecasting algorithm (“Wavecast”) was evaluated for both speed and accuracy against a substantial synthetic dataset. Early in the project, performance tests definitively demonstrated that the system was capable of

  13. Application of a wind-wave-current coupled model in the Catalan coast (NW Mediterranean sea), for wind energy purposes

    Science.gov (United States)

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

    2016-04-01

    This work shows the main results of the HAREAMAR project (including HAREMAR, ENE2012-38772-C02-01 and DARDO, ENE2012-38772-C02-02 projects), concerning the local Wind, Wave and Current simulation at St. Jordi Bay (NW Mediterranean Sea). Offshore Wind Energy has become one of the main topics within the research in Wind Energy research. Although there are quite a few models with a high level of reliability for wind simulation and prediction in onshore places, the wind prediction needs further investigations for adaptation to the Offshore emplacements, taking into account the interaction atmosphere-ocean. The main problem in these ocean areas is the lack of wind data, which neither allows for characterizing the energy potential and wind behaviour in a particular place, nor validating the forecasting models. The main objective of this work is to reduce the local prediction errors, in order to make the meteo-oceanographic hindcast and forecast more reliable. The COAWST model (Coupled-Ocean-Atmosphere-Wave Sediment Transport Model; Warner et al., 2010) system has been implemented in the region considering a set of downscaling nested meshes to obtain high-resolution outputs in the region. The adaptation to this particular area, combining the different wind, wave and ocean model domains has been far from simple, because the grid domains for the three models differ significantly. This work shows the main results of the COAWST model implementation to this particular area, including both monthly and other set of tests in different atmospheric situations, especially chosen for their particular interest. The time period considered for the validation is the whole year 2012. A comparative study between the WRF, SWAN and ROMS model outputs (without coupling), the COWAST model outputs, and a buoy measurements moored in the region was performed for this year. References Warner, J.C., Armstrong, B., He, R., and Zambon, J.B., 2010, Development of a Coupled Ocean-Atmosphere-Wave

  14. Bubble Dynamics and Shock Waves

    CERN Document Server

    2013-01-01

    This volume of the Shock Wave Science and Technology Reference Library is concerned with the interplay between bubble dynamics and shock waves. It is divided into four parts containing twelve chapters written by eminent scientists. Topics discussed include shock wave emission by laser generated bubbles (W Lauterborn, A Vogel), pulsating bubbles near boundaries (DM Leppinen, QX Wang, JR Blake), interaction of shock waves with bubble clouds (CD Ohl, SW Ohl), shock propagation in polydispersed bubbly liquids by model equations (K Ando, T Colonius, CE Brennen. T Yano, T Kanagawa,  M Watanabe, S Fujikawa) and by DNS (G Tryggvason, S Dabiri), shocks in cavitating flows (NA Adams, SJ Schmidt, CF Delale, GH Schnerr, S Pasinlioglu) together with applications involving encapsulated bubble dynamics in imaging (AA Doinikov, A Novell, JM Escoffre, A Bouakaz),  shock wave lithotripsy (P Zhong), sterilization of ships’ ballast water (A Abe, H Mimura) and bubbly flow model of volcano eruptions ((VK Kedrinskii, K Takayama...

  15. Juno Waves observations at Jupiter

    Science.gov (United States)

    Kurth, W. S.; Hospodarsky, G. B.; Imai, M.; Tetrick, S. S.; Gurnett, D. A.; Ye, S.-Y.; Louarn, P.; Valek, P.; Allegrini, F.; Connerney, J. E. P.; Mauk, B. H.; Bolton, S. J.; Levin, S. M.; Adriani, A.; Gladstone, G. R.; McComas, D. J.; Zarka, P.

    2017-09-01

    The Juno spacecraft successfully entered Jupiter orbit on 5 July 2016. One of Juno's primary objectives is to explore Jupiter's polar magnetosphere. An obvious major aspect of this exploration includes remote and in situ observations of Jupiter's auroras and the processes responsible for them. To this end, Juno carries a suite of particle, field, and remote sensing instruments. One of these instruments is a radio and plasma wave instrument called Waves, designed to detect one electric field component of waves in the frequency range of 50 Hz to 41 MHz and one magnetic field component of waves in the range of 50 Hz to 20 kHz. Juno has now made scientific observations on several perijove passes beginning with Perijove 1 on 27 August 2016. This paper presents some of the early observations of the Juno Waves instrument.

  16. Shallow water cnoidal wave interactions

    Directory of Open Access Journals (Sweden)

    A. R. Osborne

    1994-01-01

    Full Text Available The nonlinear dynamics of cnoidal waves, within the context of the general N-cnoidal wave solutions of the periodic Korteweg-de Vries (KdV and Kadomtsev-Petvishvilli (KP equations, are considered. These equations are important for describing the propagation of small-but-finite amplitude waves in shallow water; the solutions to KdV are unidirectional while those of KP are directionally spread. Herein solutions are constructed from the 0-function representation of their appropriate inverse scattering transform formulations. To this end a general theorem is employed in the construction process: All solutions to the KdV and KP equations can be written as the linear superposition of cnoidal waves plus their nonlinear interactions. The approach presented here is viewed as significant because it allows the exact construction of N degree-of-freedom cnoidal wave trains under rather general conditions.

  17. Waves In Space Plasmas (WISP)

    Science.gov (United States)

    Taylor, W. W. L.

    1986-01-01

    Waves in space plasmas (WISP) utilizes powerful radio transmitters and sensitive receivers to probe the secrets of the magnetosphere, ionosphere and atmosphere. The scientific objective is to achieve a better understanding of the physical processes occurring in these regions. For example, audio frequency radio waves will be radiated from the long WISP antenna, will travel to the outer reaches of the magnetosphere, and will interact with Van Allen belt particles, releasing some of their energy which amplifies the waves. Study of this interaction will give a better understanding of a major magnetospheric process, wave-particle interactions. Radio waves from WISP at higher frequencies (AM radio and beyond) will be reflected by the ionosphere and will, for example, advance our understanding of bubbles in the equatorial ionosphere which affect satellite communications.

  18. Strong winds and waves offshore

    DEFF Research Database (Denmark)

    Larsén, Xiaoli Guo

    2016-01-01

    This report is prepared for Statoil, with the intention to introdu e DTU Wind Energy's ongoing resear h a tivities on o shore extreme wind and wave onditions. The purpose is to share our re ent ndings and to establish possible further ollaboration with Statoil. The fo us of this report is on the ......This report is prepared for Statoil, with the intention to introdu e DTU Wind Energy's ongoing resear h a tivities on o shore extreme wind and wave onditions. The purpose is to share our re ent ndings and to establish possible further ollaboration with Statoil. The fo us of this report...... is on the meteorologi al and o eani onditions related to storm winds and waves over the North Sea. With regard to the o shore wind energy appli ation, the parameters addressed here in lude: extreme wind and extreme waves, storm wind and waves and turbulen e issues for o shore onditions....

  19. Three-wave and four-wave interactions in gravity wave turbulence

    Science.gov (United States)

    Aubourg, Quentin; Campagne, Antoine; Peureux, Charles; Ardhuin, Fabrice; Sommeria, Joel; Viboud, Samuel; Mordant, Nicolas

    2017-11-01

    Weak-turbulence theory is a statistical framework to describe a large ensemble of nonlinearly interacting waves. The archetypal example of such system is the ocean surface that is made of interacting surface gravity waves. Here we describe a laboratory experiment dedicated to probe the statistical properties of turbulent gravity waves. We set up an isotropic state of interacting gravity waves in the Coriolis facility (13-m-diam circular wave tank) by exciting waves at 1 Hz by wedge wave makers. We implement a stereoscopic technique to obtain a measurement of the surface elevation that is resolved in both space and time. Fourier analysis shows that the laboratory spectra are systematically steeper than the theoretical predictions and the field observations in the Black Sea by Leckler et al. [F. Leckler et al., J. Phys. Oceanogr. 45, 2484 (2015), 10.1175/JPO-D-14-0237.1]. We identify a strong impact of surface dissipation on the scaling of the Fourier spectrum at the scales that are accessible in the experiments. We use bicoherence and tricoherence statistical tools in frequency and/or wave-vector space to identify the active nonlinear coupling. These analyses are also performed on the field data by Leckler et al. for comparison with the laboratory data. Three-wave coupling is characterized by and shown to involve mostly quasiresonances of waves with second- or higher-order harmonics. Four-wave coupling is not observed in the laboratory but is evidenced in the field data. We discuss temporal scale separation to explain our observations.

  20. Tropical cyclogenesis in a tropical wave critical layer: easterly waves

    Directory of Open Access Journals (Sweden)

    T. J. Dunkerton

    2009-08-01

    Full Text Available The development of tropical depressions within tropical waves over the Atlantic and eastern Pacific is usually preceded by a "surface low along the wave" as if to suggest a hybrid wave-vortex structure in which flow streamlines not only undulate with the waves, but form a closed circulation in the lower troposphere surrounding the low. This structure, equatorward of the easterly jet axis, is identified herein as the familiar critical layer of waves in shear flow, a flow configuration which arguably provides the simplest conceptual framework for tropical cyclogenesis resulting from tropical waves, their interaction with the mean flow, and with diabatic processes associated with deep moist convection. The recirculating Kelvin cat's eye within the critical layer represents a sweet spot for tropical cyclogenesis in which a proto-vortex may form and grow within its parent wave. A common location for storm development is given by the intersection of the wave's critical latitude and trough axis at the center of the cat's eye, with analyzed vorticity centroid nearby. The wave and vortex live together for a time, and initially propagate at approximately the same speed. In most cases this coupled propagation continues for a few days after a tropical depression is identified. For easterly waves, as the name suggests, the propagation is westward. It is shown that in order to visualize optimally the associated Lagrangian motions, one should view the flow streamlines, or stream function, in a frame of reference translating horizontally with the phase propagation of the parent wave. In this co-moving frame, streamlines are approximately equivalent to particle trajectories. The closed circulation is quasi-stationary, and a dividing streamline separates air within the cat's eye from air outside. The critical layer equatorward of the easterly jet axis is important to tropical cyclogenesis because its cat's eye provides (i a region of