DOCSLIB.ORG

Earth Sciences Research Journal Simulation of Near-Surface Layer of the Colombian Pacific Ocean

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Earth Sciences Research Journal Simulation of Near-Surface Layer of the Colombian Pacific Ocean EARTH SCIENCES RESEARCH JOURNAL Earth Sci. Res. J. Vol. 9, No. 2 (Dec. 2005): 110-122 SIMULATION OF NEAR-SURFACE LAYER OF THE COLOMBIAN PACIFIC OCEAN Lev Karlin1 and Nancy Villegas2 1 Russian State Hydrometeorological University, San Petersburg, Russia, e-mail: [email protected] 2 Departamento de geociencias, Universidad Nacional de Colombia, Sede Bogotá, e-mail:[email protected] RESUMEN Este artículo muestra los resultados obtenidos en el estudio de la estructura fina termohalina de la capa sub-superficial realizado en la Cuenca del Pacífico colombiano. Se formularon modelos matemáticos para diferentes regímenes de capas sub-superficiales. Basado en tres estaciones se realizó un análisis horario de información meteorológica, variación de espesor, temperatura y salinidad de la capa fina. Las leyes de formación de la estructura fina termohalina para la capa sub-superficial en la Cuenca del Pacífico colombiano están relacionadas con convección nocturna, mezcla viento-ondas, absorción de energía radiante y precipitación. Palabras clave: Capa sub-superficial, estructura termohalina fina, termoclina, haloclina, mezcla viento- ondas, mezcla convectiva. ABSTRACT This paper presents the results provided by the fine-scale thermohaline structure of near-surface layer (NSL) study done in the Colombian Pacific Ocean (CPO). Mathematical models for different regimes of the near- surface layer are formulated. Based on three stations, an hourly analysis of meteorological data, thickness change, temperature and salinity of this layer was done. The principles of formation of the thermohaline structure for NSL over CPO are related to night convection, wind-wave mixing, volume absorption of radiant energy and precipitation. Key words: Near-surface layer, fine-scale thermohaline structure, thermocline, halocline, wind-wave mixing, convective mixing. © 2005 ESRJ - Unibiblos INTRODUCTION 8 m/s), intensive convection (night, autumn-winter, Fedorov and Ginsburg (1988) found for thermohaline during the cooling or rise of salinity in ocean), structure formation in the Ocean-NSL, the following Langmuir circulation (wind speed between 3 and regimes: intensive wind-wave mixing (wind speed > 10 m/s) and desalt due to precipitation. Manuscript received August 2004, Paper accepted June 2005 110 Simulation of near-surface layer of the Colombian Pacific Ocean First, Karlin et al. (1988) and later Rodhe (1991) Wind-wave mixing regime found another regime related to horizontal advection. Finally, the regime connected to special features The quasi-homogeneity in temperature and salinity of the offshore thermohaline structure in polar and vertical distribution of the mixed layer in diurnal circumpolar regions was determined (Timokhov, time, simplify the differential simulation without loss 1989; Timokhov et.al, 1993). of accuracy, using integral methods. It is assumed We described four mathematical models used the presence of mixed layer during the calculation for NSL regimes over CPO provided by data period. The simplified expression of NSL thickness analysis in 3 stations. Hourly weather data and is: vertical thermohaline profiles at these stations were 3 2mU* examined in detail, obtaining NSL thickness values, h = T (1) g q0 top and bottom boundaries and the corresponding a p temperature and salinity (Villegas, 2003). In where, m is an empirical constant of proportion- conclusion, the predominant NSL regimes of ality; h is the upper mixed layer thickness, m; CPO are night convection, wind-wave mixing, the tac p uv U* = c volume absorption of radiant energy and regime t is the dynamic speed, m/s; p is the with precipitation. resistance coefficient; uv is the wind speed, m/s; a p T is the thermal expansion coefficient, 1/°C; q0 is the METHODOLOGY heat flux through water-air boundary, °Cm/s. The equation to calculate temperature evolution with The former data was obtained at hydrometeorological constant heat flux is: stations 14 (4° N , 78° W), 49 (2° N, 80° W) and 111(3° N, 84° W), in August and September, 2001 T q0 = (Otero and Pineda, 2001), recording data during 24 dT0 h dt (2) hours, trying to verify the models that describe the different NSL regimes, see Figure 1. These stations where, dT0 is the change of upper mixed layer tem- covered the coastal (station 14), the offshore (station perature for the calculated step on the time dt, °C. 111) and the mixing water zone (station 49), being Equation (1) determines the upper mixed layer thick- selected according to the quasi-homogeneous ness in wind-wave mixing regime, in the case of its classification zones (Villegas, 2002). decrease. This happens until maximum heat flux is observed, when diurnal thermocline is formed. Thickness remain constant until the heat flux in air- water boundary decreases, then thickness increases and expansion of diurnal mixing layer is observed. In this case, the temperature and thickness evolution formulas of mixed layer must consider the formed T diurnal thermocline thickness and heat flux qh on mixed layer bottom boundary. In accordance with the Similarity Theory of profile T in the thermocline (Kitaygorodskiy, 1970; Miropolskiy, 1970 and Gar- nich and Kitaygorodskiy, 1978), we have: 3 T 2h 2mU* q0 = - 2t gap h TT0 - H at TT0 - H aT ^ h ^ h (3) T 3 2q0 2mU* H-- h 1 aT -- 2 ] g] g ; d h gh a p n TT0 - HTa ^ h T 3 2T0 2q0 2mU* = - 2 (4) 2t h gh a p Figure 1. CPO hydrometeorological station locations. 111 Lev Karlin and Nancy Villegas T where, T0 is the water temperature in upper mixed bottom boundary of convective layer, °Cm/s; q0R layer, °C; TH is the water temperature in bottom is the heat flux through ocean surface caused by boundary of mixed layer, °C; aT is the dimension- evaporation, turbulent heat exchange and long-wave less coefficient of Self-Similarity determined ac- radiation, °Cm/s. cording to observed data and H is the thermocline Equation (7) requires the expression of turbulent depth, m. energy balance integrated in limits of convective Formulas (1), (2), (3) and (4) calculate the thickness layer. The production of energy (generated due to and temperature evolution of mixed layer in wind- forces of Archimedes) is made until z depth with wave mixing regime. the Bouguer’s law (radiation flux determined expo- nentially) and considering dissipation according to Convective mixing regime works of Zilitinkevich and Dearfor (1974); Dearfor et al. (1980); Dearfor and Willis (1985); Kofi (1985) This type of convection, in absence of dynamic fac- and Zilitinkevich (1987), it is possible to write the tors on water-air boundary, is also called free con- energy balance turbulence equation integrated in the vection. In this work, convective-wind mixing took limits of convective layer as follows: place at night, when heat flux on water-air boundary is negative, the mixed layer descends and heat flux T T q0R + qh h -rh 1 -rh h+ qS 1 + e --1 e 8) through mixed layer bottom boundary becomes de- 2: 2 ]]g r gD fined by the involvement hypothesis (Karlin, 1988). T The equations of thickness h ad temperature T evlu- = 0. 4 q0R h tion of NSL in convective mixing regime are: where, qS is the short wave emission flux to ocean T 3 2h kq q0 2mU* surface, °Cm/s; r is the effective coefficient of weak- =- + ; 5) -1 2t TT0 - H ga p h TT0 - H ening solar energy in sea water, m . ^ h T In expression (8), qh is undetermined doing neces- T 3 2T q0 U* =1. 2 - 2m 2 . 6) sary to analyze two stages of NSL evolution, in 2t h ga p h the first one, layer thickness increases when solar energy flux decreases or decreases when heat loss where, kq is dimensionless coefficient for free con- vection (Woods and Barkmann, 1986, Varfolomeyev increases; causing heat exchange (involvement), the T and Sutyrin, 1981). previous processes make necessary to estimate qh . Convective mixing regime is characterized by In the second stage, when solar energy flux increases layer mixed deepening even for weak wind, due to or heat loss decreases, the mixed layer thickness negative heat flux in water-air boundary. These two decreases, i.e., a new convective mixing layer takes factors together (intensive refreshing and strong place with a thickness smaller than previous one. T wind) contribute to the deepening of layer, causing When h decreases qh =0 then: the diurnal thermocline vanish. 2 1 - e-rh rh = 9) ] gqT Sunny and weak wind weather regime 1+e-rh + 0.2 0R c qS m If in the ocean surface exists a convective mixed Because rh is dimensionless, it is necessary to use the layer and the mixture of this layer is so strong that the expression h* = 1/ r in order to calculate it. Defining temperature vertical gradient is zeroed, then we use hr =h/ h* = h as the thickness of the mixed con- U heat equation in vertical direction, integrating from vective layer, so h= h/r. From (9), h is depending T U U surface to inferior boundary of convective layer h: on q0 /; qSSq has important role because its value is maximum at noon and practically zero at night. In 2T0 T T consequence h* decreases in sunrise to noon interval, h= q0 + qSo -- qh qh 7) 2t R producing a minimum convective layer thickness. After noon, mixed convective layer thickness in- here, qSo is the radiation flux through ocean-atmo- T creases and qh ! 0, which is defined as: sphere boundary, °Cm/s; qh is the radiation flux on 112 Simulation of near-surface layer of the Colombian Pacific Ocean T 2h after rain. When rain stops, salt flux through surface qh =TT0 - Z 10) 2t ^ h is equal to zero and thickness of freshened layer increases. Then, its characteristic can be defined as where, TT0 - Z – is the difference between water ^ h follows (Karlin et.
Load more

Recommended publications
  • NWS Melbourne Marine Web Letter August 2013 (For Marine Forecast Questions 24/7: Call 321-255-0212, Ext
    NWS Melbourne Marine Web Letter August 2013 (For Marine Forecast Questions 24/7: call 321-255-0212, ext. 2) Marine Links relevant to East Central Florida Buoy 41010 It is hoped that this buoy, which went adrift in February, will be redeployed by mid to late September. Additional Marine Observations I’ve added a web page that has most of the marine observations along the east coast. http://www.srh.noaa.gov/mlb/?n=marob Note that wind/wave data became available at Sebastian Inlet via the National Data Buoy Center earlier this year. There are also some web cams with wind data. One, at Jensen Beach, has wave data too. Upwelling Some on again, off again upwelling occurred over the continental shelf this summer. This is not unusual. South to southeast winds (near shore parallel) are the primary cause of periodic upwelling. In some years, these winds are persistent and stronger than normal, which produces more prolific upwelling. In 2003, water temps in the upper 50s occurred in mid August at Daytona Beach! Typically the upwelling diminishes by late August or September. Nearshore Wave Prediction System We will soon upgrade our nearshore wave model (SWAN) to the Nearshore Wave Prediction System (NWPS). One enhancement is that Gulf Stream data will be incorporated back into the wave model. This will allow us to give better estimates for the position of the west wall of the Gulf Stream. The wave model will again be able to generate higher wave heights in the Gulf Stream during northerly wind surges. Hopefully, this functionality will be ready by Fall when cold fronts start moving through again.
    [Show full text]
  • Caverns Measureless to Man: Interdisciplinary Planetary Science & Technology Analog Research Underwater Laser Scanner Survey (Quintana Roo, Mexico)
    Caverns Measureless to Man: Interdisciplinary Planetary Science & Technology Analog Research Underwater Laser Scanner Survey (Quintana Roo, Mexico) by Stephen Alexander Daire A Thesis Presented to the Faculty of the USC Graduate School University of Southern California In Partial Fulfillment of the Requirements for the Degree Master of Science (Geographic Information Science and Technology) May 2019 Copyright © 2019 by Stephen Daire “History is just a 25,000-year dash from the trees to the starship; and while it’s going on its wild and woolly but it’s only like that, and then you’re in the starship.” – Terence McKenna. Table of Contents List of Figures ................................................................................................................................ iv List of Tables ................................................................................................................................. xi Acknowledgements ....................................................................................................................... xii List of Abbreviations ................................................................................................................... xiii Abstract ........................................................................................................................................ xvi Chapter 1 Planetary Sciences, Cave Survey, & Human Evolution................................................. 1 1.1. Topic & Area of Interest: Exploration & Survey ....................................................................12
    [Show full text]
  • Circulation-Wave Coupling with a Wave Parameterization for the Idealized California Coastal Region
    Circulation-Wave Coupling With a Wave Parameterization For the Idealized California Coastal Region Le Ly and Curt Collins Dept. of Oceanography Naval Postgraduate School Monterey, CA 93043 1. Introduction atmospheric model), POM (Princeton Ocean Momentum and energy transfers across the air- Model; Blumberg and Mellor, 1987), and WAM sea interface under realistic ocean conditions are wave model (Wilczak et al., 1999), and an important not only in theoretical studies, but also atmosphere-POM-WAM for the Mediterranean in many applications including marine region (Lionello et al., 1999). atmospheric and oceanic forecasts and climate Based on a new concept of oceanic turbulence modeling on all scales. Surface breaking waves and a wave breaking condition of the linear wave are believed to be an important supplier of theory, a surface wave parameterization is turbulent energy besides shear production of the developed and presented. This wave classical turbulence theory. Waves contain a parameterization with wave-dependent roughness considerable amount of momentum and energy, is tested against available data on wave- and they redistribute these quantities over great dependent turbulence dissipation, roughness distances. Wind waves supply energy for length, drag coefficient, and momentum fluxes turbulence due to breaking. Ocean waves strongly using a coupled air-wave-sea model. We also effect the air-sea system on all scale. A part of the present a circulation-wave coupling study using a energy and momentum is transferred directly wave dependent roughness (Ly and Garwood, from the atmosphere to ocean currents while 2000) and taking the wind-wave-turbulence- another part is transferred to surface waves. The current relationship into account.
    [Show full text]
  • D5.3 Interaction Between Currents, Wave, Structure and Subsoil
    Downloaded from orbit.dtu.dk on: Oct 05, 2021 D5.3 Interaction between currents, wave, structure and subsoil Christensen, Erik Damgaard; Sumer, B. Mutlu; Schouten, Jan-Joost; Kirca, Özgür; Petersen, Ole; Jensen, Bjarne; Carstensen, Stefan; Baykal, Cüneyt; Tralli, Aldo; Chen, Hao Total number of authors: 19 Publication date: 2015 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Christensen, E. D., Sumer, B. M., Schouten, J-J., Kirca, Ö., Petersen, O., Jensen, B., Carstensen, S., Baykal, C., Tralli, A., Chen, H., Tomaselli, P. D., Petersen, T. U., Fredsøe, J., Raaijmakers, T. C., Kortenhaus, A., Hjelmager Jensen, J., Saremi, S., Bolding, K., & Burchard, H. (2015). D5.3 Interaction between currents, wave, structure and subsoil. General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your
    [Show full text]
  • The Effects of Haloclines on the Vertical Distribution and Migration of Zooplankton
    Journal of Experimental Marine Biology and Ecology 278 (2002) 111–134 www.elsevier.com/locate/jembe The effects of haloclines on the vertical distribution and migration of zooplankton Laurence A. Lougee *, Stephen M. Bollens1, Sean R. Avent 2 Romberg Tiburon Center for Environmental Studies and the Department of Biology, San Francisco State University, 3150 Paradise Drive, Tiburon, CA 94920, USA Received 28 April 2000; received in revised form 29 May 2002; accepted 18 July 2002 Abstract While the influence of horizontal salinity gradients on the distribution and abundance of planktonic organisms in estuaries is relatively well known, the effects of vertical salinity gradients (haloclines) are less well understood. Because biological, chemical, and physical conditions can vary between different salinity strata, an understanding of the behavioral response of zooplankton to haloclines is crucial to understanding the population biology and ecology of these organisms. We studied four San Francisco Bay copepods, Acartia (Acartiura) spp., Acartia (Acanthacartia) spp., Oithona davisae, and Tortanus dextrilobatus, and one species of larval fish (Clupea pallasi), in an attempt to understand how and why zooplankton respond to haloclines. Controlled laboratory experiments involved placing several individuals of each species in two 2-m-high tanks, one containing a halocline (magnitude varied between 1.4 and 10.0 psu) and the other without a halocline, and recording the location of each organism once every hour for 2–4 days using an automated video microscopy system. Results indicated that most zooplankton changed their vertical distribution and/or migration in response to haloclines. For the smaller taxa (Acartiura spp., Acanthacartia spp., and O.
    [Show full text]
  • Download Download
    I DEIA EDIÇÃO Imprensa da Universidade de Coimbra Email: [email protected] URL: http//www.uc.pt/imprensa_uc Vendas online: http://livrariadaimprensa.uc.pt DIREÇÃO Maria Luísa Portocarrero Diogo Ferrer CONSELHO CIENTÍFICO Alexandre Franco de Sá | Universidade de Coimbra Angelica Nuzzo | City University of New York Birgit Sandkaulen | Ruhr ‑Universität Bochum Christoph Asmuth | Technische Universität Berlin Giuseppe Duso | Università di Padova Jean ‑Christophe Goddard | Université de Toulouse‑Le Mirail Jephrey Barash | Université de Picardie Jerôme Porée | Université de Rennes José Manuel Martins | Universidade de Évora Karin de Boer | Katholieke Universiteit Leuven Luís Nascimento |Universidade Federal de São Carlos Luís Umbelino | Universidade de Coimbra Marcelino Villaverde | Universidade de Santiago de Compostela Stephen Houlgate | University of Warwick COORDENAÇÃO EDITORIAL Imprensa da Universidade de Coimbra CONCEÇÃO GRÁFICA Imprensa da Universidade de Coimbra IMAGEM DA CAPA Raquel Aido PRÉ ‑IMPRESSÃO Margarida Albino PRINT BY KDP ISBN 978‑989‑26‑1971‑2 ISBN DIGITAL 978‑989‑26‑1972‑9 DOI https://doi.org/10.14195/978‑989‑26‑1972‑9 Projeto CECH‑UC: UIDB/00196/2020 ‑ Centro de Estudos Clássicos e Humanísticos da Universidade de Coimbra © JULHO 2020, IMPRENSA DA UNIVERSIDADE DE COIMBRA RELENDO O PARMÉNIDES DE PLATÃO REVISITING PLATO’S PARMENIDES ANTÓNIO MANUEL MARTINS MARIA DO CÉU FIALHO (COORDS.) (Página deixada propositadamente em branco) In memoriam Samuel Scolnicov (Página deixada propositadamente em branco) Í NDICE Prefácio, Maria do Céu Fialho, António Manuel Martins .................. 9 Introdução, A. M. Martins ................................................................ 11 The ethical dimension of Plato’s Parmenides, Samuel Scolnicov .... 27 ”El engañoso dialogo de Platón consigo mismo en la primera parte del Parménides”, Néstor Luis Cordero ...............................
    [Show full text]
  • Determination of Wave Characteristics
    Guidance for Flood Risk Analysis and Mapping Determination of Wave Characteristics February 2019 Requirements for the Federal Emergency Management Agency (FEMA) Risk Mapping, Assessment, and Planning (Risk MAP) Program are specified separately by statute, regulation, or FEMA policy (primarily the Standards for Flood Risk Analysis and Mapping). This document provides guidance to support the requirements and recommends approaches for effective and efficient implementation. Alternate approaches that comply with all requirements are acceptable. For more information, please visit the FEMA Guidelines and Standards for Flood Risk Analysis and Mapping webpage (https://www.fema.gov/guidelines-and-standards-flood-risk-analysis-and- mapping). Copies of the Standards for Flood Risk Analysis and Mapping policy, related guidance, technical references, and other information about the guidelines and standards development process are all available here. You can also search directly by document title at https://www.fema.gov/library. Wave Determination February 2019 Guidance Document 88 Page iii Document History Affected Section or Subsection Date Description First Publication February Initial version of new transformed guidance. The content was 2019 derived from the Guidelines and Specifications for Flood Hazard Mapping Partners, Procedure Memoranda, and/or Operating Guidance documents. It has been reorganized and is being published separately from the standards. Wave Determination February 2019 Guidance Document 88 Page iv Table of Contents 1.0 Overview
    [Show full text]
  • Downloaded 10/03/21 08:00 PM UTC
    MAY 2005 P I N K E L 645 Near-Inertial Wave Propagation in the Western Arctic ROBERT PINKEL Marine Physical Laboratory, Scripps Institution of Oceanography, La Jolla, California (Manuscript received 11 April 2003, in final form 8 October 2004) ABSTRACT From October 1997 through October 1998, the Surface Heat Budget of the Arctic (SHEBA) ice camp drifted across the western Arctic Ocean, from the central Canada Basin over the Northwind Ridge and across the Chukchi Cap. During much of this period, the velocity and shear fields in the upper ocean were monitored by Doppler sonar. Near-inertial internal waves are found to be the dominant contributors to the superinertial motion field. Typical rms velocities are 1–2 cm sϪ1. In this work, the velocity and shear variances associated with upward- and downward-propagating wave groups are quantified. Patterns are detected in these variances that correlate with underlying seafloor depth. These are explored with the objective of assessing the role that these extremely low-energy near-inertial waves play in the larger-scale evolution of the Canada Basin. The specific focus is the energy flux delivered to the slopes and shelves of the basin, available for driving mixing at the ocean boundaries. The energy and shear variances associated with downward-propagating waves are relatively uniform over the entire SHEBA drift, independent of the season and depth of the underlying topography. Variances associated with upward-propagating waves follow a (depth)Ϫ1/2 dependence. Over the deep slopes, vertical wavenumber spectra of upward-propagating waves are blue-shifted relative to their downward counterparts, perhaps a result of reflection from a sloping seafloor.
    [Show full text]
  • The Contribution of Wind-Generated Waves to Coastal Sea-Level Changes
    1 Surveys in Geophysics Archimer November 2011, Volume 40, Issue 6, Pages 1563-1601 https://doi.org/10.1007/s10712-019-09557-5 https://archimer.ifremer.fr https://archimer.ifremer.fr/doc/00509/62046/ The Contribution of Wind-Generated Waves to Coastal Sea-Level Changes Dodet Guillaume 1, *, Melet Angélique 2, Ardhuin Fabrice 6, Bertin Xavier 3, Idier Déborah 4, Almar Rafael 5 1 UMR 6253 LOPSCNRS-Ifremer-IRD-Univiversity of Brest BrestPlouzané, France 2 Mercator OceanRamonville Saint Agne, France 3 UMR 7266 LIENSs, CNRS - La Rochelle UniversityLa Rochelle, France 4 BRGMOrléans Cédex, France 5 UMR 5566 LEGOSToulouse Cédex 9, France *Corresponding author : Guillaume Dodet, email address : [email protected] Abstract : Surface gravity waves generated by winds are ubiquitous on our oceans and play a primordial role in the dynamics of the ocean–land–atmosphere interfaces. In particular, wind-generated waves cause fluctuations of the sea level at the coast over timescales from a few seconds (individual wave runup) to a few hours (wave-induced setup). These wave-induced processes are of major importance for coastal management as they add up to tides and atmospheric surges during storm events and enhance coastal flooding and erosion. Changes in the atmospheric circulation associated with natural climate cycles or caused by increasing greenhouse gas emissions affect the wave conditions worldwide, which may drive significant changes in the wave-induced coastal hydrodynamics. Since sea-level rise represents a major challenge for sustainable coastal management, particularly in low-lying coastal areas and/or along densely urbanized coastlines, understanding the contribution of wind-generated waves to the long-term budget of coastal sea-level changes is therefore of major importance.
    [Show full text]
  • Distribution of Convective Lower Halocline Water in the Eastern
    Kikuchi et al.: cLHW Distribution Distribution of Convective Lower Halocline Water In the Eastern Arctic Ocean Takashi Kikuchi, Kiyoshi Hatakeyama, Japan Marine Science and Technology Center 2-15, Natsushima-cho, Yokosuka, 237-0061, JAPAN and James H. Morison PSC/APL, University of Washington Seattle, WA 98105-6698, U.S.A. Submitted to JGR-Oceans on Nov.21 2003 Revised on May 31, 2004 1 Kikuchi et al.: cLHW Distribution Abstract We investigate the distribution of convectively formed Lower Halocline water (cLHW) in the eastern Arctic Ocean using observational and climatological data. The cLHW can be defined as the water mass in the cold halocline layer formed by winter convection. The presence of cLHW is indicated by temperatures close to the freezing point and a sharp bend in the Θ-S curve near the salinity of cLHW. Results from ice drifting buoy observations in 2002 show differences in water mass characteristics in the upper ocean among the Amundsen Basin, over the Arctic Mid Ocean Ridge, and in the Nansen Basin. In 2000-2002 cLHW was present over the Arctic Mid Ocean Ridge and the Nansen Basin, but was largely absent from the Amundsen Basin. Using climatological data, we find that cLHW was confined to the Nansen Basin prior to 1990. In the early 1990s, cLHW still covered only the Nansen Basin, but extended to the northern side of the Arctic Mid Ocean Ridge in the mid 1990s and covered the whole of the Amundsen Basin by the late 1990s. In the early 2000s, the area of cLHW moved back to its present boundary on the northern side of the Arctic Mid Ocean Ridge.
    [Show full text]
  • Deep Ocean Wind Waves Ch
    Deep Ocean Wind Waves Ch. 1 Waves, Tides and Shallow-Water Processes: J. Wright, A. Colling, & D. Park: Butterworth-Heinemann, Oxford UK, 1999, 2nd Edition, 227 pp. AdOc 4060/5060 Spring 2013 Types of Waves Classifiers •Disturbing force •Restoring force •Type of wave •Wavelength •Period •Frequency Waves transmit energy, not mass, across ocean surfaces. Wave behavior depends on a wave’s size and water depth. Wind waves: energy is transferred from wind to water. Waves can change direction by refraction and diffraction, can interfere with one another, & reflect from solid objects. Orbital waves are a type of progressive wave: i.e. waves of moving energy traveling in one direction along a surface, where particles of water move in closed circles as the wave passes. Free waves move independently of the generating force: wind waves. In forced waves the disturbing force is applied continuously: tides Parts of an ocean wave •Crest •Trough •Wave height (H) •Wavelength (L) •Wave speed (c) •Still water level •Orbital motion •Frequency f = 1/T •Period T=L/c Water molecules in the crest of the wave •Depth of wave base = move in the same direction as the wave, ½L, from still water but molecules in the trough move in the •Wave steepness =H/L opposite direction. 1 • If wave steepness > /7, the wave breaks Group Velocity against Phase Velocity = Cg<<Cp Factors Affecting Wind Wave Development •Waves originate in a “sea”area •A fully developed sea is the maximum height of waves produced by conditions of wind speed, duration, and fetch •Swell are waves
    [Show full text]
  • Swell and Wave Forecasting
    Lecture 24 Part II Swell and Wave Forecasting 29 Swell and Wave Forecasting • Motivation • Terminology • Wave Formation • Wave Decay • Wave Refraction • Shoaling • Rouge Waves 30 Motivation • In Hawaii, surf is the number one weather-related killer. More lives are lost to surf-related accidents every year in Hawaii than another weather event. • Between 1993 to 1997, 238 ocean drownings occurred and 473 people were hospitalized for ocean-related spine injuries, with 77 directly caused by breaking waves. 31 Going for an Unintended Swim? Lulls: Between sets, lulls in the waves can draw inexperienced people to their deaths. 32 Motivation Surf is the number one weather-related killer in Hawaii. 33 Motivation - Marine Safety Surf's up! Heavy surf on the Columbia River bar tests a Coast Guard vessel approaching the mouth of the Columbia River. 34 Sharks Cove Oahu 35 Giant Waves Peggotty Beach, Massachusetts February 9, 1978 36 Categories of Waves at Sea Wave Type: Restoring Force: Capillary waves Surface Tension Wavelets Surface Tension & Gravity Chop Gravity Swell Gravity Tides Gravity and Earth’s rotation 37 Ocean Waves Terminology Wavelength - L - the horizontal distance from crest to crest. Wave height - the vertical distance from crest to trough. Wave period - the time between one crest and the next crest. Wave frequency - the number of crests passing by a certain point in a certain amount of time. Wave speed - the rate of movement of the wave form. C = L/T 38 Wave Spectra Wave spectra as a function of wave period 39 Open Ocean – Deep Water Waves • Orbits largest at sea sfc.
    [Show full text]