Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
An Algorithm To Derive Wind Speed And Direction As Well As Ocean Wave Directional Spectra From Hf Radar Backscatter Measurements Based On Neural Network
Download An Algorithm To Derive Wind Speed And Direction As Well As Ocean Wave Directional Spectra From Hf Radar Backscatter Measurements Based On Neural Network full books in PDF, epub, and Kindle. Read online An Algorithm To Derive Wind Speed And Direction As Well As Ocean Wave Directional Spectra From Hf Radar Backscatter Measurements Based On Neural Network ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis An Algorithm to Derive Wind Speed and Direction as Well as Ocean Wave Directional Spectra from HF Radar Backscatter Measurements Based on Neural Network by : Wei Shen
Download or read book An Algorithm to Derive Wind Speed and Direction as Well as Ocean Wave Directional Spectra from HF Radar Backscatter Measurements Based on Neural Network written by Wei Shen and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Algorithm to Derive Wind Speed and Direction as Well as Ocean Wave Directional Spectra from HF Radar Backscatter Measurements Based on Neural Networks by : Wei Shen
Download or read book An Algorithm to Derive Wind Speed and Direction as Well as Ocean Wave Directional Spectra from HF Radar Backscatter Measurements Based on Neural Networks written by Wei Shen and published by . This book was released on 2011 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Oceanobs'19: An Ocean of Opportunity. Volume I by : Tong Lee
Download or read book Oceanobs'19: An Ocean of Opportunity. Volume I written by Tong Lee and published by Frontiers Media SA. This book was released on 2020-12-31 with total page 783 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Book Synopsis An Algorithm for the Extraction of Ocean Wave Parameters from Wide Beam HF Radar (CODAR) Backscatter by : Eric William Gill
Download or read book An Algorithm for the Extraction of Ocean Wave Parameters from Wide Beam HF Radar (CODAR) Backscatter written by Eric William Gill and published by . This book was released on 1990 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development and Evaluation of New Algorithms for the Retrieval of Wind and Internal Wave Parameters from Shipborne Marine Radar Data by : Björn Lund
Download or read book Development and Evaluation of New Algorithms for the Retrieval of Wind and Internal Wave Parameters from Shipborne Marine Radar Data written by Björn Lund and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this work is to develop and evaluate techniques for the retrieval of wind and internal wave (IW) information from marine X-band radar data. While ocean wind measurements are crucial for the transfer of energy and momentum across the air-sea interface, IWs play an important role in tidal energy transport. Marine radars work by transmitting microwave energy from a rotating antenna that also measures the backscatter. The radar backscatter from the sea surface is controlled by the wind-generated small ripple waves through the Bragg-scattering mechanism. Surface winds are thus the dominant factor for generating the radar backscatter. The varying surface current fields associated with IWs interact with the ripples, generating rough convergent and smooth divergent zones. Radars are capable of imaging such IW-induced surface signatures as bands of enhanced and weakened backscatter. The advantage of radar-based wind information is that it is obtained from a large area around the instrument. Marine radar wind data are therefore much less likely to be affected by platform-induced air flow distortions than in-situ measurements. Previous investigators have already demonstrated marine radar's suitability as a wind sensor [31, 30], however, these works have been limited to fixed-platform data. Here, the focus lies on shipborne marine radar data. Such data present the challenge that the existing wind streak-based approach for retrieving wind directions cannot be directly applied. This is because the wind streak signal may become obscured by the horizontal ship motion, since wind streaks become visible only after averaging over a sequence of radar images. In addition, moving platforms face a greater variability of conditions, which may further complicate a radar-based wind retrieval. Grazing incidence HH-polarized (horizontal transmit and receive) X-band radar data exhibit a single intensity peak in upwind direction. To retrieve the wind direction, this work proposes a least-squares fit technique that identifies the upwind peak in the range-averaged backscatter dependency on the antenna look direction. This technique requires no motion correction and is therefore well-suited for shipborne data. In addition, it functions well even if sections of the radar field of view are masked. An empirical model function is derived to retrieve the wind speed from the mean radar backscatter intensity. Data from the U.S. Office of Naval Research (ONR) Impact of Typhoons on the Ocean in the Pacific (ITOP) experiment are used for a comparison between radar-based wind estimates and anemometer measurements. The two data sets show good agreement. In addition, this work proposes a technique that uses geolocated marine radar data to extract wind streak information through a localized Radon transform. To compare streak- and upwind peak-based wind direction retrieval techniques, fixed and moving platform marine radar data from the ONR-sponsored High Resolution Air-Sea Interaction (Hi-Res) experiment are used. Wind directions obtained using the upwind peak method show a better agreement with the reference data than those obtained from the wind streaks. The difference between fixed and moving platform for the wind streak approach indicates that the image geolocation affects the wind retrieval negatively. Standard deviations as low as 6.0° and 0.42 m/s for the comparison between radar-based and reference wind data show that marine radars can yield highly reliable wind estimates. Regarding IWs, a new fully automated tool to retrieve IW signatures from marine radar image sequences is developed and applied to data collected during ONR's Non-Linear Internal Wave Initiative / Shallow Water '06 experiment (NLIWI/SW06). Marine radars have the advantage over satellite systems that their high temporal resolution enables the study of the IW evolution. The proposed technique employs our knowledge about the wind dependency of the radar backscatter to correct for the image ramp, i.e. the return signal's dependency on range and antenna look direction. The ramp-corrected radar images are then geolocated and averaged, which greatly enhances the IW signal. By determining the IW group velocity and correcting for it before the radar images are averaged, the IW signal is further enhanced. Such pre-processing enables a reliable retrieval of IW surface signatures by clustering local peaks and troughs, and tracking those clusters through time. This work also includes a detailed analysis of data collected during the tracking of a particularly energetic IW. The radar-derived time series of IW speed, direction, and soliton maps yield unique information about the IW's spatio-temporal evolution, including evidence of wave-wave interactions. In addition, it is demonstrated that marine radar data can be used to retrieve information about the interior ocean dynamics associated with the IW. The IW-induced backscatter modulation is correlated with the measured surface current gradients and IW amplitudes. Alternatively, results are shown where IW amplitudes were derived from the distances between positive and negative radar backscatter peaks. This approach was first introduced by Xue et al. [132] and is based on an extended Korteweg-de-Vries (eKdV) equation. This approach has the advantage that it is much less dependent on the prevailing wind conditions. To summarize, the marine radar backscatter dependency on wind is analyzed, and new wind retrieval techniques from shipborne radar data are proposed. The gained knowledge on the backscatter's wind dependency is then applied to marine radar data containing IW surface signatures. This work proposes a new methodology for retrieving these signatures and uses the resulting IW soliton maps to derive information about the IW-associated interior ocean dynamics.
Book Synopsis The Interaction of Ocean Waves and Wind by : Peter Janssen
Download or read book The Interaction of Ocean Waves and Wind written by Peter Janssen and published by Cambridge University Press. This book was released on 2004-10-28 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book was published in 2004. The Interaction of Ocean Waves and Wind describes in detail the two-way interaction between wind and ocean waves and shows how ocean waves affect weather forecasting on timescales of 5 to 90 days. Winds generate ocean waves, but at the same time airflow is modified due to the loss of energy and momentum to the waves; thus, momentum loss from the atmosphere to the ocean depends on the state of the waves. This volume discusses ocean wave evolution according to the energy balance equation. An extensive overview of nonlinear transfer is given, and as a by-product the role of four-wave interactions in the generation of extreme events, such as freak waves, is discussed. Effects on ocean circulation are described. Coupled ocean-wave, atmosphere modelling gives improved weather and wave forecasts. This volume will interest ocean wave modellers, physicists and applied mathematicians, and engineers interested in shipping and coastal protection.
Book Synopsis An Algorithm for the Extraction of Ocean Wave Spectra from Narrow Beam HF Radar Backscatteer by : Randy Keith Howell
Download or read book An Algorithm for the Extraction of Ocean Wave Spectra from Narrow Beam HF Radar Backscatteer written by Randy Keith Howell and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An algorithm is developed and tested to interpret ocean wave spectra from the backscatter return of one or more narrow beam HF radars. The basis of this measurement is the inversion of the integral equation representing the second order radar cross section of the ocean surface (Barrick and Lipa, 1986; Srivastava, 1984; Walsh and Howell, 1990). This equation is numerically inverted by approximating it as a matrix equation and factorizing the resultant kernel matrix using a singular value decomposition to obtain its pseudo-inverse. -- Due to the limitations of the assumption used to linearize the integral equation, the proposed inversion algorithm is best suited for general use at high HF frequencies (≈ 20 to 30 MHz). However, this algorithm may still be applied for the crucial task of monitoring large sea state conditions at even very low HF frequencies (
Book Synopsis Remote Sensing of Atmospheric Conditions for Wind Energy Applications by : Charlotte Bay Hasager
Download or read book Remote Sensing of Atmospheric Conditions for Wind Energy Applications written by Charlotte Bay Hasager and published by MDPI. This book was released on 2019-05-24 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Special Issue “Atmospheric Conditions for Wind Energy Applications” hosts papers on aspects of remote sensing for atmospheric conditions for wind energy applications. Wind lidar technology is presented from a theoretical view on the coherent focused Doppler lidar principles. Furthermore, wind lidar for applied use for wind turbine control, wind farm wake, and gust characterizations is presented, as well as methods to reduce uncertainty when using lidar in complex terrain. Wind lidar observations are used to validate numerical model results. Wind Doppler lidar mounted on aircraft used for observing winds in hurricane conditions and Doppler radar on the ground used for very short-term wind forecasting are presented. For the offshore environment, floating lidar data processing is presented as well as an experiment with wind-profiling lidar on a ferry for model validation. Assessments of wind resources in the coastal zone using wind-profiling lidar and global wind maps using satellite data are presented.
Book Synopsis Ocean Wind and Wave Parameter Estimation from Ship-borne X-band Marine Radar Data by : Xinlong Liu
Download or read book Ocean Wind and Wave Parameter Estimation from Ship-borne X-band Marine Radar Data written by Xinlong Liu and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ocean wind and wave parameters are important for the study of oceanography, on- and off-shore activities, and the safety of ship navigation. Conventionally, such parameters have been measured by in-situ sensors such as anemometers and buoys. During the last three decades, sea surface observation using X-band marine radar has drawn wide attention since marine radars can image both temporal and spatial variations of the sea surface. In this thesis, novel algorithms for wind and wave parameter retrieval from X-band marine radar data are developed and tested using radar, anemometer, and buoy data collected in a sea trial off the east coast of Canada in the North Atlantic Ocean. Rain affects radar backscatter and leads to less reliable wind parameters measurements. In this thesis, algorithms are developed to enable reliable wind parameters measurements under rain conditions. Firstly, wind directions are extracted from raincontaminated radar data using either a 1D or 2D ensemble empirical mode decomposition (EEMD) technique and are seen to compare favourably with an anemometer reference. Secondly, an algorithm based on EEMD and amplitude modulation (AM) analysis to retrieve wind direction and speed from both rain-free and rain-contaminated X-band marine radar images is developed and is shown to be an improvement over an earlier 1D spectral analysis-based method. For wave parameter measurements, an empirical modulation transfer function (MTF) is required for traditional spectral analysis-based techniques. Moreover, the widely used signal-to-noise ratio (SNR)-based method for significant wave height (HS) estimation may not always work well for a ship-borne X-band radar, and it requires external sensors for calibration. In this thesis, two methods are first presented for HS estimation from X-band marine radar data. One is an EEMD-based method, which enables satisfactory HS measurements obtained from a ship-borne radar. The other is a modified shadowingbased method, which enables HS measurements without the inclusion of external sensors. Furthermore, neither method requires the MTF. Finally, an algorithm based on the Radon transform is proposed to estimate wave direction and periods from X-band marine radar images with satisfactory results.
Download or read book The Norwegian Coastal Current written by and published by Fagbokforlaget. This book was released on 2007 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Norwegian coastal current originates primarily from the freshwater outflow from the Baltic and the freshwater runoff from Norway. It flows northwards along the coast of Norway as a low-salinity current. This coastal region is the spawning ground for a number of important oceanic fish stocks, and the physical environment has an impact on the recruitment, growth, and geographical distribution of these stocks. In the late 1920s and early 1930s, the Institute of Marine Research in Norway established a coastal oceanographic observation system. This continued to evolve, and its core elements are still in operation. Drawing on the results generated by this observation system, as well as by other coastal studies, this book reviews the current understanding of the physical/chemical conditions in the Norwegian coastal current in such a way as to make the material more easily accessible to non-specialists. A series of chapters introduces readers to the geography, currents, water masses, and the temporal and spatial variability of the Norwegian coastal current. Interannual fluctuations in physical conditions are most likely to be the prime cause of ecosystem variability. The editor hopes that this book will act as a point of departure for a future summary of the ecology of Norwegian coastal waters.
Book Synopsis Algorithms for Wind Parameter Retrieval from Rain-contaminated X-band Marine Radar Images by : Yali Wang
Download or read book Algorithms for Wind Parameter Retrieval from Rain-contaminated X-band Marine Radar Images written by Yali Wang and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Real-time Coastal Observing Systems for Marine Ecosystem Dynamics and Harmful Algal Blooms by : Babin, Marcel
Download or read book Real-time Coastal Observing Systems for Marine Ecosystem Dynamics and Harmful Algal Blooms written by Babin, Marcel and published by UNESCO. This book was released on 2008-06-05 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proliferation of harmful phytoplankton in marine ecosystems can cause massive fish kills, contaminate seafood with toxins, impact local and regional economies and dramatically affect ecological balance. Real-time observations are essential for effective short-term operational forecasting, but observation and modelling systems are still being developed. This volume provides guidance for developing real-time and near real-time sensing systems for observing and predicting plankton dynamics, including harmful algal blooms, in coastal waters. The underlying theory is explained and current trends in research and monitoring are discussed.Topics covered include: coastal ecosystems and dynamics of harmful algal blooms; theory and practical applications of in situ and remotely sensed optical detection of microalgal distributions and composition; theory and practical applications of in situ biological and chemical sensors for targeted species and toxin detection; integrated observing systems and platforms for detection; diagnostic and predictive modelling of ecosystems and harmful algal blooms, including data assimilation techniques; observational needs for the public and government; and future directions for research and operations.
Book Synopsis Wind Measurement by Conventional Radar with a Dual Beam Pattern by : David Atlas
Download or read book Wind Measurement by Conventional Radar with a Dual Beam Pattern written by David Atlas and published by . This book was released on 1966 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Ocean Remote Sensing Technologies by : Weimin Huang
Download or read book Ocean Remote Sensing Technologies written by Weimin Huang and published by IET. This book was released on 2021-12-17 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a systematic introduction to the principles, state-of-the-art methods and applications of high frequency surface/sky wave radar and microwave marine radar, as well as an exploration of ongoing challenges in the field. It is a valuable resource for the radar and remote sensing communities.
Book Synopsis An Algorithm for the Extraction of Ocean Surface Current Velocity from Bistatic HF Groundwave Radar Data by : Qiu Jin
Download or read book An Algorithm for the Extraction of Ocean Surface Current Velocity from Bistatic HF Groundwave Radar Data written by Qiu Jin and published by . This book was released on 2007 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis International Aerospace Abstracts by :
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 934 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Nonlinear Approach to Ocean Wave Spectrum Extraction from Bistatic HF-radar Data by : Murilo Teixeira Silva
Download or read book A Nonlinear Approach to Ocean Wave Spectrum Extraction from Bistatic HF-radar Data written by Murilo Teixeira Silva and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, a new approach to the extraction of the directional ocean wave spectrum from bistatic high frequency (HF) radar data is proposed. The proposed method relies on the simplification of the second-order bistatic radar cross-section, analogous to the one presented by Shahidi and Gill [1] for the monostatic case, to facilitate the use of nonlinear optimization methods, such as regularized nonlinear least-squares. Initially, the historic development of the techniques related to the extraction of the ocean wave spectrum from HF radar data is provided in order to contextualize the work of this thesis. Then, an overview of the theory related to ocean waves and the bistatic radar cross-section is shown. Later, the nonlinear optimization method used in this thesis, Tikhonov regularization in Hilbert spaces, is explained, as well as the theoretical background necessary to understand the method. Once the theory is laid out, the simplification of the second-order bistatic HF radar cross section is presented. The simplification consists of a change of variables that allow the use of the "sifting" property of the Dirac delta function. This reduces the dependence of the second-order bistatic cross-section to a single variable. After the simplification process is shown, the methodology for extracting the directional ocean wave spectrum from bistatic HF radar data is discussed. As a proof-of-concept, the method is initially applied to the second-order bistatic cross section, without the presence of noise. The method successfully extracted the directional ocean wave spectrum without assuming any function model for the nondirectional ocean wave spectrum, and assuming a cosine-power model for the directional spreading function. Next, the first-order bistatic HF radar cross section is added to the second-order cross section, and the proposed method is applied, still without noise present. The proposed method was also able to extract the directional ocean wave spectrum and very low error is added by the inclusion of the first-order cross section. Finally, different levels of noise are added to the cross section including the first and second- orders, and the presented method is applied for the extraction. Again, the method yields good results, with acceptable levels of error for the different noise levels. This new approach to the extraction of the directional ocean wave spectrum from bistatic HF radar data presents, to the author's knowledge, the first nonlinear extraction method for bistatic HF radar data. Further developments of the technique, such as the use of different nonlinear extraction methods, or a general directional spreading function, are suggested.
