Download or read book Lagrangian Drifter Observations in Rip Currents written by Ronald Alan George and published by . This book was released on 1999 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Langrangian Drifter Observations in Rip Currents written by Ronald Alan George and published by . This book was released on 1999 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lagrangian Observations of Rip Currents written by and published by . This book was released on 2007 with total page 43 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive field rip-current experiment (RCEX) was conducted from 14 April to 18 May 2007 in Sand City, California, on Monterey Bay. Lagrangian observations were made with inexpensive (1 50), handheld, Differential Global Positioning Systems (DGPS) mounted on surf zone drifters. The inexpensive DGPS requires post-processing to achieve accuracy O(0.4m) and O(0.01m/s). Thirty drifters were constructed and deployed in well-developed, rip-currents to map the circulation patterns for the first time in the field at a high spatial resolution. Drifter observations obtained during three-hour periods on seven different days under varying wave and tidal conditions describe eddies with a rotational period of 4.7min, confined to the surf-zone and coupled to the rip morphology. On average, three drifters per hour exited the surfzone. Dependent upon wave conditions, one or two eddies existed between 90m-spaced rip-channels, creating a seaward flow in the channels and shoreward flow over the shoals. Cross-shore volumetric flow rates for an alongshore transect through the eddy centers balance to a difference of less than 10% of the gross flow discharge. Velocity measurements obtained from drifter data are evaluated with velocities obtained from stationary, in-situ instruments.

Download or read book Lagrangian Field Observations of Rip Currents written by Jeffrey W. Brown and published by ProQuest. This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lagrangian Observations of Surfzone Currents written by Wilford Edward Schmidt and published by . This book was released on 2003 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Pharmacist at Work written by William Charles Alpers and published by . This book was released on 2010-09 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Observations of Laboratory Rip Currents written by Brian Keith Sapp and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Laboratory experiments of rip current systems are performed in a wave basin with a bar and rip channel geometry at the Ocean Engineering Laboratory at the University of Delaware. The experiments include both in situ water level and velocity measurements and optical visualization of the flow field under a variety of normal-incident wave conditions. Digital video is used to record surface drifters moving through a rip current system. A method is presented that tracks these digitally-recorded drifters into long Lagrangian sequences. The laboratory measurements capture both an Eulerian and Lagrangian description of the rip current system. Time-averaged rip current properties are calculated and analyzed using both in situ and video measurements. From the video, Lagrangian velocities are computed with forward differencing of the low-pass filtered drifter tracks. Wave properties are also estimated using the orbital drifter motions and linear (Airy) wave theory. The effects of various wave conditions on the time-averaged rip current systems are investigated to show that wave height is a critical parameter. Measurements of circulation cells are obtained by spatially averaging the drifter track velocity measurements into a polar grid ranging from 0.25 m to 3.25 m from the center of the cell. Circulation cell features, such as the center of circulation and cell width, are calculated to characterize their response to various wave conditions. Spectral analyses are used to characterize the rip current pulsations in the experimental measurements. Three frequencies are found to be energetic in several of the experiments in the low frequency band: the wave group frequency, a lower frequency, and the interaction of the wave group and lower frequencies. Some experiments have significant energy at each of the three peaks, where others have only one or none. The lower frequency motions have also been found in the video measurements and attributed to rip meandering. Possible causes for the low-frequency pulsations, including wave basin seiching, circulation cell instabilities, and wave-current interaction, are discussed. This thesis adds to previous rip current studies by providing a spatially-large and time-varying perspective of rip current systems as a whole.

Download or read book Measuring Ocean Currents written by Antony Joseph and published by Newnes. This book was released on 2013-08-12 with total page 447 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measuring Ocean Currents: Tools, Technologies, and Data covers all major aspects of ocean current measurements in view of the implications of ocean currents on changing climate, increasing pollution levels, and offshore engineering activities. Although more than 70% of the Earth is covered by ocean, there is limited information on the countless fine- to large-scale water motions taking place within them. This book fills that information gap as the first work that summarizes the state-of-the-art methods and instruments used for surface, subsurface, and abyssal ocean current measurements. Readers of this book will find a wealth of information on Lagrangian measurements, horizontal mapping, imaging, Eulerian measurements, and vertical profiling techniques. In addition, the book describes modern technologies for remote measurement of ocean currents and their signatures, including HF Doppler radar systems, satellite-borne sensors, ocean acoustic tomography, and more. Crucial aspects of ocean currents are described in detail as well, including dispersion of effluents discharged into the sea and transport of beneficial materials—as well as environmentally hazardous materials—from one region to another. The book highlights several important practical applications, showing how measurements relate to climate change and pollution levels, how they affect coastal and offshore engineering activities, and how they can aid in tsunami detection. Coverage of measurement, mapping and profiling techniques Descriptions of technologies for remote measurement of ocean currents and their signatures Reviews crucial aspects of ocean currents, including special emphasis on the planet-spanning thermohaline circulation, known as the ocean's "conveyor belt," and its crucial role in climate change

Download or read book Lagrangian Drifter Observations in San Diego Bay written by Ron George and published by . This book was released on 1997 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lagrangian Measurements of Eddy Characteristics in the California Current System written by James Gary Sires and published by . This book was released on 1997 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the Eastern Boundary Current program in 1993, 96 Argos-tracked surface drifters, drogued to 15 m depth, and satellite thermal imagery were used to provide a description of the mesoscale features in the California Current System off the northern California coast. The drifter movements and satellite images revealed a highly energetic series of filaments and eddies that dominated the summer flow field off the coast, similar to those noted in the earlier CODE, OPTOMA, and CTZ studies. Winter mesoscale activity in the region was less energetic, with the principle feature being the poleward-flowing Davidson Current. Translation rates for mesoscale eddies were deduced from drifter trajectories in the summer period. Translation rates, vorticity, divergence and eddy center positions were also estimated for a cyclone and anticylone sampled in July and September, respectively, by constraining observed drifter velocities to a linear Taylor expansion in the least square sense. Translation rates from this technique were similar to those observed from previous shipboard surveys and drifter motions. Using observations over 7 (12) days, the cyclonic (anticyclonic) eddy was determined to have a translation rate of 3.7 (4.2) cm/s to the southwest. The least square technique, applied to shorter time periods, however, provided unreliable estimates of eddy properties when drifters were not evenly distributed around the eddy.

Download or read book Field Observations of Rip Currents written by James H. MacMahan and published by . This book was released on 2003 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Rip Currents written by Stephen Leatherman and published by CRC Press. This book was released on 2011-05-09 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rip Currents: Beach Safety, Physical Oceanography, and Wave Modeling is the culmination of research from over 100 coastal scientists, engineers, forecast meteorologists, lifeguard chiefs, and other practitioners from around the world who participated in the 1st International Rip Current Symposium. These experts identify advancements in research tha

Download or read book Data Compilation from Southern Ocean Lagrangian Drifter Observation SOLO During December 1977 May 1978 written by S. J. Worley and published by . This book was released on 1979 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Field Measurements and Modeling of Surfzone Currents on Inhomogeneous Beaches written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Field observations of surfzone current patterns on open coast, alongshore inhomogeneous (rip-channeled) beaches during varying wave and tidal conditions are described for three different sites (Monterey, CA; Truc Vert, France; Perranporth, United Kingdom). Bathymetry, offshore waves, tidal elevation, in-situ co-located pressure and current observations, and Lagrangian drifter measurements were obtained, and data analysis procedures are explained. Two distinct surfzone current patterns were observed: (1) an alongshore sinuous current pattern coupled to the underlying bathymetry, and (2) a rip current circulation pattern. To date, alongshore currents have primarily been observed and described on alongshore homogeneous beaches. Surprisingly, new observations on alongshore inhomogeneous beaches found that sinuous alongshore currents occurred for 40% of the time, rather than the expected rip current circulation. Alongshore sinuous currents typically occurred during low waves and mid-tides, associated with small differences in wave angle from shore-normal. Numerical results from XBeach show that the surfzone alongshore momentum balance is between the alongshore pressure gradient and the combination of alongshore wave forcing and non-linear advective acceleration. The alongshore (a)symmetrical balance of terms was the distinguishing factor between alongshore sinuous currents and rip currents. Rip currents typically developed during large waves and/or low tides, which consisted of coherent surfzone eddies, bound in the cross-shore by the surf zone width, and in the alongshore by the quasi-periodic rip channel spacing. These rip currents episodically exited the surf zone (~ 15% per hour), indicating a greater amount of surf zone retention than previously thought. A "human drifter" was observed to mimic the response of the surfzone drifters, having a 10% chance of exiting the surf zone. Most observed rip current systems were asymmetric, circulating in one dominant direction. Therefore, following the traditional advice to "swim parallel" to the shoreline when trapped in a rip current, a swimmer has a 50% chance of choosing the correct alongshore direction to reach safety. These findings suggest that a beach-goer should remain calm and afloat, and they will have a 90% chance of being returned onshore to wading depths.

Download or read book Lagrangian Surface Drifter Analyses from Observations and Numerical Modeling in the Subpolar North Atlantic written by Thilo Klenz and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lagrangian surface drifters are powerful tools to study the dynamics of the ocean across a variety of spatial and temporal scales, ranging from regional to global and monthly to climatological, respectively. This dissertation investigates the utility of Lagrangian surface drifters for estimating the mechanical input of energy into the ocean by the atmosphere, and for gathering information about the underlying dynamics driving oceanic variability. The basis for the analysis was a large dataset of 88 surface drifters deployed in the subpolar North Atlantic between 2018 and 2019. In addition, numerical drifters from both idealized and realistic ocean models were used to supplement the observations. The study region is characterized by pronounced mesoscale eddy activity and, due to its proximity to the North Atlantic storm track, strong atmospheric storms causing energetic near-inertial oscillations. It is hence well-suited for the analyses presented here. We introduced a novel surface drifter instrument, the Minimet, that measures sea surface wind in situ along the drifter track. Estimates of in situ Minimet wind power input were found to be over 40% higher than those using a reanalysis wind product. This discrepancy was likely due to Minimets accurately capturing strong high-frequency wind events that were misrepresented in the reanalysis product, highlighting the utility of the Minimets for both wind power input calculations and the important validation of gridded wind products. We currently lack a basic understanding of the Lagrangian velocity frequency spectrum and how it relates to the underlying dynamics. We therefore investigated the Lagrangian spectral shape and found significant variability linked to eddy kinetic energy. Lastly, we established a direct link between the Lagrangian velocity frequency spectrum and Eulerian kinetic energy wavenumber spectrum. This link had not previously been made from single particles and together with a better understanding of the Lagrangian frequency spectrum furthers our ability to efficiently utilize Lagrangian data.

Download or read book Encyclopedia of Coastal Science written by Charles W. Finkl and published by Springer. This book was released on 2019-06-25 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thoroughly revised and expanded edition of the much acclaimed Encyclopedia of Coastal Science edited by M. Schwarz (Springer 2005), presents an interdisciplinary approach that includes biology, ecology, engineering, geology, geomorphology, oceanography, remote sensing, technological advances, and anthropogenic impacts on coasts. Within its covers the Encyclopedia of Coastal Science, 2nd ed. brings together and coordinates many aspects of coastal and related sciences that are widely dispersed in the scientific literature. The broadly interdisciplinary subject matter of this volume features contributions by over 280 well-known international specialists in their respective fields and provides an abundance of figures in full-color with line drawings and photographs, and other illustrations such as satellite images. Not only does this volume offer a large number of new and revised entries, it also includes an illustrated glossary of coastal geomorphology, extensive bibliographic citations, and cross-references. It provides a comprehensive reference work for students, scientific and technical professionals as well as administrators, managers, and informed lay readers. Reviews from the first edition: Awarded for Excellence in Scholarly and Professional Publishing: “Honorable Mention”, in the category Single Volume/Science from the Association of American Publishers (AAP) 2005. "The contents and approach are interdisciplinary and, under a single cover, one finds subjects normally scattered throughout scientific literature." "The topics cover a broad spectrum, so does the geographic range of the contributors. ... besides geomorphologists, biologists, ecologists, engineers, geographers, geologists, oceanographers and technologists will find information related to their respective fields ... . Inclusion of appendices ... is very useful. The illustrated glossary of geomorphology will prove very useful for many of us ... ." Roger H. Charlier, Journal of Coastal Research, Volume 21, Issue 4, Page 866, July 2005. "It is an excellent work that should be included in any carefully selected list of best science reference books of the year "Summing Up: Highly recommended. " M.L. Larsgaard, Choice, Volume 43, Issue 6, Page 989, February 2006. "This volume is a comprehensive collection of articles covering all aspects of the subject: social and economic, engineering, coastal processes, habitats, erosion, geological features, research and observation." ... "As with similar works reviewed, I chose to read articles on familiar topics to see if they covered the expected, and some on unfamiliar topics to see if they could be readily understood. The book passed both tests, but the style is denser and more fact-filled than most of the encyclopedias I have reviewed." John Goodier, Reference Reviews, Volume 20, Issue 2, pages 35-36, 2006

Download or read book Field Observations on the Morphodynamics of Rip Currents written by Robert William Brander and published by . This book was released on 1996 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: