Waves in the Ocean in This Document We Will Discuss Three Types of Waves: Wind-Driven Waves, Tides and Tsunamis
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
Glossary Physics (I-Introduction)
1 Glossary Physics (I-introduction) - Efficiency: The percent of the work put into a machine that is converted into useful work output; = work done / energy used [-]. = eta In machines: The work output of any machine cannot exceed the work input (<=100%); in an ideal machine, where no energy is transformed into heat: work(input) = work(output), =100%. Energy: The property of a system that enables it to do work. Conservation o. E.: Energy cannot be created or destroyed; it may be transformed from one form into another, but the total amount of energy never changes. Equilibrium: The state of an object when not acted upon by a net force or net torque; an object in equilibrium may be at rest or moving at uniform velocity - not accelerating. Mechanical E.: The state of an object or system of objects for which any impressed forces cancels to zero and no acceleration occurs. Dynamic E.: Object is moving without experiencing acceleration. Static E.: Object is at rest.F Force: The influence that can cause an object to be accelerated or retarded; is always in the direction of the net force, hence a vector quantity; the four elementary forces are: Electromagnetic F.: Is an attraction or repulsion G, gravit. const.6.672E-11[Nm2/kg2] between electric charges: d, distance [m] 2 2 2 2 F = 1/(40) (q1q2/d ) [(CC/m )(Nm /C )] = [N] m,M, mass [kg] Gravitational F.: Is a mutual attraction between all masses: q, charge [As] [C] 2 2 2 2 F = GmM/d [Nm /kg kg 1/m ] = [N] 0, dielectric constant Strong F.: (nuclear force) Acts within the nuclei of atoms: 8.854E-12 [C2/Nm2] [F/m] 2 2 2 2 2 F = 1/(40) (e /d ) [(CC/m )(Nm /C )] = [N] , 3.14 [-] Weak F.: Manifests itself in special reactions among elementary e, 1.60210 E-19 [As] [C] particles, such as the reaction that occur in radioactive decay. -
Coastal Flood Defences - Groynes
Coastal Flood Defences - Groynes Coastal flood defences are key to protecting our coasts against flooding, which is when normally dry, low lying flat land is inundated by sea water. Hard engineering methods are forms of coastal flood defences which mitigate the risk of flooding and coastal erosion and the consequential effects. Hard Engineering Hard engineering methods are often used as a temporary measure to protect against coastal flooding as they are costly and only last for a relatively short amount of time before they require maintenance. However, they are very effective at protecting the coastline in the short-term as they are immediately effective as opposed to some longer term soft engineering methods. But they are often intrusive and can cause issues elsewhere at other areas along the coastline. Groynes are low lying wood or concrete structures which are situated out to sea from the shore. They are designed to trap sediment, dissipate wave energy and restrict the transfer of sediment away from the beach through long shore drift. Longshore drift is caused when prevailing winds blow waves across the shore at an angle which carries sediment along the beach.Groynes prevent this process and therefore, slow the process of erosion at the shore. They can also be permeable or impermeable, permeable groynes allow some sediment to pass through and some longshore drift to take place. However, impermeable groynes are solid and prevent the transfer of any sediment. Advantages and Disadvantages +Groynes are easy to construct. +They have long term durability and are low maintenance. +They reduce the need for the beach to be maintained through beach nourishment and the recycling of sand. -
Transport Due to Transient Progressive Waves of Small As Well As of Large Amplitude
This draft was prepared using the LaTeX style file belonging to the Journal of Fluid Mechanics 1 Transport due to Transient Progressive Waves Juan M. Restrepo1,2 , Jorge M. Ram´ırez 3 † 1Department of Mathematics, Oregon State University, Corvallis OR 97330 USA 2Kavli Institute of Theoretical Physics, University of California at Santa Barbara, Santa Barbara CA 93106 USA. 3Departamento de Matem´aticas, Universidad Nacional de Colombia Sede Medell´ın, Medell´ın Colombia (Received xx; revised xx; accepted xx) We describe and analyze the mean transport due to numerically-generated transient progressive waves, including breaking waves. The waves are packets and are generated with a boundary-forced air-water two-phase Navier Stokes solver. The analysis is done in the Lagrangian frame. The primary aim of this study is to explain how, and in what sense, the transport generated by transient waves is larger than the transport generated by steady waves. Focusing on a Lagrangian framework kinematic description of the parcel paths it is clear that the mean transport is well approximated by an irrotational approximation of the velocity. For large amplitude waves the parcel paths in the neighborhood of the free surface exhibit increased dispersion and lingering transport due to the generation of vorticity. Armed with this understanding it is possible to formulate a simple Lagrangian model which captures the transport qualitatively for a large range of wave amplitudes. The effect of wave breaking on the mean transport is accounted for by parametrizing dispersion via a simple stochastic model of the parcel path. The stochastic model is too simple to capture dispersion, however, it offers a good starting point for a more comprehensive model for mean transport and dispersion. -
Dispersion of Tsunamis: Does It Really Matter? and Physics and Physics Discussions Open Access Open Access S
EGU Journal Logos (RGB) Open Access Open Access Open Access Advances in Annales Nonlinear Processes Geosciences Geophysicae in Geophysics Open Access Open Access Nat. Hazards Earth Syst. Sci., 13, 1507–1526, 2013 Natural Hazards Natural Hazards www.nat-hazards-earth-syst-sci.net/13/1507/2013/ doi:10.5194/nhess-13-1507-2013 and Earth System and Earth System © Author(s) 2013. CC Attribution 3.0 License. Sciences Sciences Discussions Open Access Open Access Atmospheric Atmospheric Chemistry Chemistry Dispersion of tsunamis: does it really matter? and Physics and Physics Discussions Open Access Open Access S. Glimsdal1,2,3, G. K. Pedersen1,3, C. B. Harbitz1,2,3, and F. Løvholt1,2,3 Atmospheric Atmospheric 1International Centre for Geohazards (ICG), Sognsveien 72, Oslo, Norway Measurement Measurement 2Norwegian Geotechnical Institute, Sognsveien 72, Oslo, Norway 3University of Oslo, Blindern, Oslo, Norway Techniques Techniques Discussions Open Access Correspondence to: S. Glimsdal ([email protected]) Open Access Received: 30 November 2012 – Published in Nat. Hazards Earth Syst. Sci. Discuss.: – Biogeosciences Biogeosciences Revised: 5 April 2013 – Accepted: 24 April 2013 – Published: 18 June 2013 Discussions Open Access Abstract. This article focuses on the effect of dispersion in 1 Introduction Open Access the field of tsunami modeling. Frequency dispersion in the Climate linear long-wave limit is first briefly discussed from a the- Climate Most tsunami modelers rely on the shallow-water equations oretical point of view. A single parameter, denoted as “dis- of the Past for predictions of propagationof and the run-up. Past Some groups, on persion time”, for the integrated effect of frequency dis- Discussions the other hand, insist on applying dispersive wave models, persion is identified. -
Coastal Circulation and Water-Column Properties in The
Coastal Circulation and Water-Column Properties in the War in the Pacific National Historical Park, Guam— Measurements and Modeling of Waves, Currents, Temperature, Salinity, and Turbidity, April–August 2012 Open-File Report 2014–1130 U.S. Department of the Interior U.S. Geological Survey FRONT COVER: Left: Photograph showing the impact of intentionally set wildfires on the land surface of War in the Pacific National Historical Park. Right: Underwater photograph of some of the healthy coral reefs in War in the Pacific National Historical Park. Coastal Circulation and Water-Column Properties in the War in the Pacific National Historical Park, Guam— Measurements and Modeling of Waves, Currents, Temperature, Salinity, and Turbidity, April–August 2012 By Curt D. Storlazzi, Olivia M. Cheriton, Jamie M.R. Lescinski, and Joshua B. Logan Open-File Report 2014–1130 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Acting Director U.S. Geological Survey, Reston, Virginia: 2014 For product and ordering information: World Wide Web: http://www.usgs.gov/pubprod Telephone: 1-888-ASK-USGS For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment: World Wide Web: http://www.usgs.gov Telephone: 1-888-ASK-USGS Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Suggested citation: Storlazzi, C.D., Cheriton, O.M., Lescinski, J.M.R., and Logan, J.B., 2014, Coastal circulation and water-column properties in the War in the Pacific National Historical Park, Guam—Measurements and modeling of waves, currents, temperature, salinity, and turbidity, April–August 2012: U.S. -
Arxiv:2002.03434V3 [Physics.Flu-Dyn] 25 Jul 2020
APS/123-QED Modified Stokes drift due to surface waves and corrugated sea-floor interactions with and without a mean current Akanksha Gupta Department of Mechanical Engineering, Indian Institute of Technology, Kanpur, U.P. 208016, India.∗ Anirban Guhay School of Science and Engineering, University of Dundee, Dundee DD1 4HN, UK. (Dated: July 28, 2020) arXiv:2002.03434v3 [physics.flu-dyn] 25 Jul 2020 1 Abstract In this paper, we show that Stokes drift may be significantly affected when an incident inter- mediate or shallow water surface wave travels over a corrugated sea-floor. The underlying mech- anism is Bragg resonance { reflected waves generated via nonlinear resonant interactions between an incident wave and a rippled bottom. We theoretically explain the fundamental effect of two counter-propagating Stokes waves on Stokes drift and then perform numerical simulations of Bragg resonance using High-order Spectral method. A monochromatic incident wave on interaction with a patch of bottom ripple yields a complex interference between the incident and reflected waves. When the velocity induced by the reflected waves exceeds that of the incident, particle trajectories reverse, leading to a backward drift. Lagrangian and Lagrangian-mean trajectories reveal that surface particles near the up-wave side of the patch are either trapped or reflected, implying that the rippled patch acts as a non-surface-invasive particle trap or reflector. On increasing the length and amplitude of the rippled patch; reflection, and thus the effectiveness of the patch, increases. The inclusion of realistic constant current shows noticeable differences between Lagrangian-mean trajectories with and without the rippled patch. -
Test of Self-Organization in Beach Cusp Formation Giovanni Coco,1 T
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. C3, 3101, doi:10.1029/2002JC001496, 2003 Test of self-organization in beach cusp formation Giovanni Coco,1 T. K. Burnet, and B. T. Werner Complex Systems Laboratory, Cecil and Ida Green Institute of Geophysics and Planetary Physics, University of California, San Diego, La Jolla, California, USA Steve Elgar Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA Received 4 June 2002; revised 6 November 2002; accepted 13 November 2002; published 29 March 2003. [1] Field observations of swash flow patterns and morphology change are consistent with the hypothesis that beach cusps form by self-organization, wherein positive feedback between swash flow and developing morphology causes initial development of the pattern and negative feedback owing to circulation of flow within beach cusp bays causes pattern stabilization. The self-organization hypothesis is tested using measurements from three experiments on a barrier island beach in North Carolina. Beach cusps developed after the beach was smoothed by a storm and after existing beach cusps were smoothed by a bulldozer. Swash front motions were recorded on video during daylight hours, and morphology was measured by surveying at 3–4 hour intervals. Three signatures of self- organization were observed in all experiments. First, time lags between swash front motions in beach cusp bays and horns increase with increasing relief, representing the effect of morphology on flow. Second, differential erosion between bays and horns initially increases with increasing time lag, representing the effect of flow on morphology change because positive feedback causes growth of beach cusps. Third, after initial growth, differential erosion decreases with increasing time lag, representing the onset of negative feedback that stabilizes beach cusps. -
Intracratonic Asthenosphere Upwelling and Lithosphere Rejuvenation
Earth and Planetary Science Letters 260 (2007) 482–494 www.elsevier.com/locate/epsl Intracratonic asthenosphere upwelling and lithosphere rejuvenation beneath the Hoggar swell (Algeria): Evidence from HIMU metasomatised lherzolite mantle xenoliths ⁎ L. Beccaluva a, , A. Azzouni-Sekkal b, A. Benhallou c, G. Bianchini a, R.M. Ellam d, M. Marzola a, F. Siena a, F.M. Stuart d a Dipartimento di Scienze della Terra, Università di Ferrara, Italy b Faculté des Sciences de la Terre, Géographie et Aménagement du Territoire, Université des Sciences et Technologie Houari Boumédienne, Alger, Algeria c CRAAG (Centre de Recherche en Astronomie, Astrophysique et Géophysique), Alger, Algeria d Isotope Geoscience Unit, Scottish Universities Environmental Research Centre, East Kilbride, UK Received 7 March 2007; received in revised form 23 May 2007; accepted 24 May 2007 Available online 2 June 2007 Editor: R.W. Carlson Abstract The mantle xenoliths included in Quaternary alkaline volcanics from the Manzaz-district (Central Hoggar) are proto-granular, anhydrous spinel lherzolites. Major and trace element analyses on bulk rocks and constituent mineral phases show that the primary compositions are widely overprinted by metasomatic processes. Trace element modelling of the metasomatised clinopyroxenes allows the inference that the metasomatic agents that enriched the lithospheric mantle were highly alkaline carbonate-rich melts such as nephelinites/melilitites (or as extreme silico-carbonatites). These metasomatic agents were characterized by a clear HIMU Sr–Nd–Pb isotopic signature, whereas there is no evidence of EM1 components recorded by the Hoggar Oligocene tholeiitic basalts. This can be interpreted as being due to replacement of the older cratonic lithospheric mantle, from which tholeiites generated, by asthenospheric upwelling dominated by the presence of an HIMU signature. -
Global Ship Accidents and Ocean Swell-Related Sea States
Nat. Hazards Earth Syst. Sci. Discuss., doi:10.5194/nhess-2017-142, 2017 Manuscript under review for journal Nat. Hazards Earth Syst. Sci. Discussion started: 26 April 2017 c Author(s) 2017. CC-BY 3.0 License. Global ship accidents and ocean swell-related sea states Zhiwei Zhang1, 2, Xiao-Ming Li2, 3 1 College of Geography and Environment, Shandong Normal University, Jinan, China 2 Key Laboratory of Digital Earth Science, Institute of Remote Sensing and Digital Earth, Chinese Academy of Sciences, 5 Beijing, China 3 Hainan Key Laboratory of Earth Observation, Sanya, China Correspondence to: X.-M. Li (E-mail: [email protected]) Abstract. With the increased frequency of shipping activities, navigation safety has become a major concern, especially when economic losses, human casualties and environmental issues are considered. As a contributing factor, sea state conditions play 10 a significant role in shipping safety. However, the types of dangerous sea states that trigger serious shipping accidents are not well understood. To address this issue, we analyzed the sea state characteristics during ship accidents that occurred in poor weather or heavy seas based on a ten-year ship accident dataset. The sea state parameters, including the significant wave height, the mean wave period and the mean wave direction, obtained from numerical wave model data were analyzed for selected ship accidents. The results indicated that complex sea states with the co-occurrence of wind sea and swell conditions represent 15 threats to sailing vessels, especially when these conditions include close wave periods and oblique wave directions. 1 Introduction The shipping industry delivers 90% of all world trade (IMO, 2011). -
Hydrothermal Vent Fields and Chemosynthetic Biota on the World's
ARTICLE Received 13 Jul 2011 | Accepted 7 Dec 2011 | Published 10 Jan 2012 DOI: 10.1038/ncomms1636 Hydrothermal vent fields and chemosynthetic biota on the world’s deepest seafloor spreading centre Douglas P. Connelly1,*, Jonathan T. Copley2,*, Bramley J. Murton1, Kate Stansfield2, Paul A. Tyler2, Christopher R. German3, Cindy L. Van Dover4, Diva Amon2, Maaten Furlong1, Nancy Grindlay5, Nicholas Hayman6, Veit Hühnerbach1, Maria Judge7, Tim Le Bas1, Stephen McPhail1, Alexandra Meier2, Ko-ichi Nakamura8, Verity Nye2, Miles Pebody1, Rolf B. Pedersen9, Sophie Plouviez4, Carla Sands1, Roger C. Searle10, Peter Stevenson1, Sarah Taws2 & Sally Wilcox11 The Mid-Cayman spreading centre is an ultraslow-spreading ridge in the Caribbean Sea. Its extreme depth and geographic isolation from other mid-ocean ridges offer insights into the effects of pressure on hydrothermal venting, and the biogeography of vent fauna. Here we report the discovery of two hydrothermal vent fields on theM id-Cayman spreading centre. The Von Damm Vent Field is located on the upper slopes of an oceanic core complex at a depth of 2,300 m. High-temperature venting in this off-axis setting suggests that the global incidence of vent fields may be underestimated. At a depth of 4,960 m on the Mid-Cayman spreading centre axis, the Beebe Vent Field emits copper-enriched fluids and a buoyant plume that rises 1,100 m, consistent with > 400 °C venting from the world’s deepest known hydrothermal system. At both sites, a new morphospecies of alvinocaridid shrimp dominates faunal assemblages, which exhibit similarities to those of Mid-Atlantic vents. 1 National Oceanography Centre, Southampton, UK. -
Safe Boating Through the St. Lucie Inlet
Information: Florida Fish & Wildlife Commission 850-488-4676 SAFE BOATING US Coast Guard - Ft. Pierce 772-461-7606 THROUGH THE ST. LUCIE INLET US Coast Guard Auxiliary 772-465-8128 US Army Corps of Engineers 772-221-3349 St. Lucie Inlet Coastal 772-225-2300 Weather Station HERE ARE SOME THINGS TO REMEMBER: • Listen to the most recent weather forecast for the times you plan to go out AND come back in the inlet. • Look in the Tide Tables or local newspapers for the times St. Lucie Inlet of predicted high and low tides for the day you plan to go out. Remember the outgoing (ebb) tital current at low Newcomers tide is the worst time to make a passage through the St. Lucie Inlet. If you are a boater new to this area, it is highly • Safe boating practices are even more important in inlets. recommended that you make your first passage of Check your boat before you head out. Life preservers the St. Lucie Inlet as an observer. An experienced should be worn when going through inlets. boater with local knowledge at the helm can point • Expect the unexpected. Watch the clouds to anticipate out various hazards and conditions to avoid. This is severe weather such as thunderstorms. Be on the lookout for shifting shoals and changing channels. especially important if you have no prior experience • Engine failure is common in small boats in rough seas. with any ocean inlets. The extra roughness agitates gasoline and settled dirt or water in the fuel system, which can cause engine failure Notes on Navigation at Night at a crtical time. -
Waves and Weather
Waves and Weather 1. Where do waves come from? 2. What storms produce good surfing waves? 3. Where do these storms frequently form? 4. Where are the good areas for receiving swells? Where do waves come from? ==> Wind! Any two fluids (with different density) moving at different speeds can produce waves. In our case, air is one fluid and the water is the other. • Start with perfectly glassy conditions (no waves) and no wind. • As wind starts, will first get very small capillary waves (ripples). • Once ripples form, now wind can push against the surface and waves can grow faster. Within Wave Source Region: - all wavelengths and heights mixed together - looks like washing machine ("Victory at Sea") But this is what we want our surfing waves to look like: How do we get from this To this ???? DISPERSION !! In deep water, wave speed (celerity) c= gT/2π Long period waves travel faster. Short period waves travel slower Waves begin to separate as they move away from generation area ===> This is Dispersion How Big Will the Waves Get? Height and Period of waves depends primarily on: - Wind speed - Duration (how long the wind blows over the waves) - Fetch (distance that wind blows over the waves) "SMB" Tables How Big Will the Waves Get? Assume Duration = 24 hours Fetch Length = 500 miles Significant Significant Wind Speed Wave Height Wave Period 10 mph 2 ft 3.5 sec 20 mph 6 ft 5.5 sec 30 mph 12 ft 7.5 sec 40 mph 19 ft 10.0 sec 50 mph 27 ft 11.5 sec 60 mph 35 ft 13.0 sec Wave height will decay as waves move away from source region!!! Map of Mean Wind