DOCSLIB.ORG

EAS/BIOEE 154 Lecture 12 Introduction to Oceanography Waves Fundamental Principles Ideally, Waves Represent a Propagation of Energy, Not Matter

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

EAS/BIOEE 154 Lecture 12 Introduction to Oceanography Waves Fundamental Principles Ideally, waves represent a propagation of energy, not matter. (but ocean waves are not always ideal). Three kinds: Longitudinal (e.g., sound wave) Transverse (e.g., seismic “S” wave) - only in solids Surface, or orbital wave Occur at the interfaces of two different densities. These are the common wind-generated waves. Some Definitions Wave Period: Time it Takes a Wave Crest to Travel one Wavelength (units of time) Wave Frequency: Number of Crests Passing A Fixed Location per Unit Time (units of 1/time) Frequency = 1/Period Wave Speed: Distance a Wave Crest Travels per Unit Time (units of distance/time) Wave Speed = Wave Length / Wave Period for deep water waves only Wave Amplitude: Wave Height/2 Wave Steepness: Wave Height/Wavelength Wave Interference Crossing waves can “interfere” to create either a bigger wave (constructive interference) or smaller wave (destructive interference). Generation of Waves Most surface waves generated by wind; therefore called wind waves Waves are also generated by Earthquakes, landslides — tsunamis Atmospheric pressure changes (storms) Gravity of the Sun and Moon — tides Height of Wind-Generated Waves depends on: Wind Speed Duration of Wind Event Fetch - the distance over which wind can blow without obstruction Waves and Swell Once generated, waves can propagate as swell without wind Dispersion: Large waves travel faster than small ones Because waves are not ideal, energy is dissipated and waves die out Small ones die out, or damp out, faster. Wave Speed and Water Depth Deep-Water waves travel in water that is deeper than 1/2 the wave’s wavelength; Depth > L/2 Speed is function of wavelength only – long wavelengths move faster Waves have nearly ideal shape and thus propagate energy but very little mass EAS/BIOEE 154 Lecture 2 Shallow-Water waves travel in water that is shallower than 1/20 of the wave’s wavelength; Depth <L/2 Wave speed is function of water depth only Waves are not ideal and propagate both Energy and Mass (Stokes Drift) Intermediate waves neither purely “deep” or “shallow”; L/20 < Bottom Depth < L/2 wave speed depends on both wavelength and water depth Breaking Waves As waves approach the shore, wavelength decreases, while height and steepness increase. As waves approach the shore, drag of the bottom slows the water motion near bottom Consequently, there is net forward transport at the surface as the waves steepens Once height reaches 1/7 wave length, the wave becomes unstable and breaks. Wave Refraction & Reflection Shallow-Water Wave change direction due to changes in speed; which are in turn due to changes in depth The net result is a rotation of wave fronts to become parallel with bottom depth contours. Wave may also be reflected Consequence of Wave Refraction: wave energy is focused on headlands and away from bays – nature likes a straight coast! Waves striking beach at an angle produce Longshore transport of sediment Transport Obstructed by Groins Other Waves Tsunamis Storm Surges & Sieches Internal Waves Planetary Waves Tsunamis Tsunamis (sometimes improperly called tidal waves) are large amplitude, long wavelength waves that propagate on the ocean surface Tsunamis can be generated by Earthquakes Landslides Volcanic Eruptions Meteorite/Asteroid Impact Properties of Tsunamis Tsunamis have long periods and long waves lengths (as long as 1 hour and 100 km respectively). For tsunamis, wavelength is always greater than twice the water depth. Therefore, tsunamis always behave as shallow water waves (speed 2 EAS/BIOEE 154 Lecture 2 depends on depth). In water of average depth (4000 m), a tsunami will travel at 700 km/hr. The December, 26 2004 Sumatran Earthquake and Tsunami Generated by a magnitude 9.3 earthquake as the Indian Plate thrust under the Sunda Plate Calculated vertical displacements were as much as 5 meters The fault ruptured along more than 1200 km One of the largest earthquakes in past 100 years. May have generated submarine landslides Extensive damage and loss of life throughout the Eastern Indian Ocean Can we predict tsunami’s and save lives? Generating a Tsunami Warning Earthquake occurs Seismic waves travel through the Earth (at about 8 km/sec) to seismometers Earthquake detected by seismometers Determine location - did it occur in the sea? Determine size - is it big enough to generate a tsunami? Pacific Tsunami Warning Center issues bulletin About 75% are false alarms - most earthquakes don’t generate damaging tsunamis Governments must then take action to warn & evacuate Detect tsunamis using seabed detectors - NOAA’s DART system: only 6 detectors deployed so far – most in the northeast Pacific; 32 planned for the Pacific by 2007 (at a cost of over $1 million a piece). What areas are vulnerable to tsunamis? Pacific Rim is most vulnerable Hawaii is particularly vulnerable Japan, Alaska, S. America Pacific Northwest The plate boundary system in the Pacific NW is behaves very similarly to the Indonesia one, with very large, very infrequent earthquakes. Geologic evidence and Japanese historical records indicate a very large tsunami generated there in 1700. Indian Ocean Atlantic and Caribbean Many of the Caribbean islands are subduction zone volcanoes - in addition to earthquakes, volcanic eruptions and volcanic landslides could generate tsunamis Eastern Mediterranean Both volcanically and seismically active Salt beds beneath Mediterranean are particularly subject to landslides. Other Waves Seiches – resonant oscillations Internal Waves – waves that propagate along density boundaries within 3 EAS/BIOEE 154 Lecture 2 the ocean Kelvin and Rossby waves: Low amplitude, long wavelength waves related to wind changes – notably El Niño Some Study Questions How deep must the water be for a wave with a 100 m wavelength to behave as a strictly deep water wave? How shallow must the water be for that same wave to behave as a strictly shallow water wave? What is the restoring force for capillary waves? If a wave has a period of 10 seconds, what is the frequency of that wave? Describe what happens as waves move out from a storm? How does the distribution of short and long wavelength waves change? Why would wave refraction cause headlands to erode, and sediment to be deposited in bays? Explain how waves can transport sediment along the coast in “longshore drift”. Why are tsunamis considered “shallow water waves”? About how long did it take the Dec. 26 tsunami to reach Sri Lanka? What role do NOAA’s DART buoys play in the Pacific Tsunami Warning System? How do the DART instruments detect a tsunami? How does water motion differ between tsunamis and wind-driven waves? 4 .
Recommended publications
  • Wind-Caused Waves Misleads Us Energy Is Transferred to the Wave

    Wind-Caused Waves Misleads Us Energy Is Transferred to the Wave

    WAVES IN WATER is quite similar. Most waves are created by the frictional drag of wind blowing across the water surface. A wave begins as Tsunami can be the most overwhelming of all waves, but a tiny ripple. Once formed, the side of a ripple increases the their origins and behaviors differ from those of the every­ day waves we see at the seashore or lakeshore. The familiar surface area of water, allowing the wind to push the ripple into waves are caused by wind blowing over the water surface. a higher and higher wave. As a wave gets bigger, more wind Our experience with these wind-caused waves misleads us energy is transferred to the wave. How tall a wave becomes in understanding tsunami. Let us first understand everyday, depends on (1) the velocity of the wind, (2) the duration of wind-caused waves and then contrast them with tsunami. time the wind blows, (3) the length of water surface (fetch) the wind blows across, and (4) the consistency of wind direction. Once waves are formed, their energy pulses can travel thou­ Wind-Caused Waves sands of kilometers away from the winds that created them. Waves transfer energy away from some disturbance. Waves moving through a water mass cause water particles to rotate in WHY A WIND-BLOWN WAVE BREAKS place, similar to the passage of seismic waves (figure 8.5; see Waves undergo changes when they move into shallow water­ figure 3.18). You can feel the orbital motion within waves by water with depths less than one-half their wavelength.
  • Transport Due to Transient Progressive Waves of Small As Well As of Large Amplitude

    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.
  • Arxiv:2002.03434V3 [Physics.Flu-Dyn] 25 Jul 2020

    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.
  • The Stokes Drift in Ocean Surface Drift Prediction

    The Stokes Drift in Ocean Surface Drift Prediction

    EGU2020-9752 https://doi.org/10.5194/egusphere-egu2020-9752 EGU General Assembly 2020 © Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. The Stokes drift in ocean surface drift prediction Michel Tamkpanka Tamtare, Dany Dumont, and Cédric Chavanne Université du Québec à Rimouski, Institut des Sciences de la mer de Rimouski, Océanographie Physique, Canada ([email protected]) Ocean surface drift forecasts are essential for numerous applications. It is a central asset in search and rescue and oil spill response operations, but it is also used for predicting the transport of pelagic eggs, larvae and detritus or other organisms and solutes, for evaluating ecological isolation of marine species, for tracking plastic debris, and for environmental planning and management. The accuracy of surface drift forecasts depends to a large extent on the quality of ocean current, wind and waves forecasts, but also on the drift model used. The standard Eulerian leeway drift model used in most operational systems considers near-surface currents provided by the top grid cell of the ocean circulation model and a correction term proportional to the near-surface wind. Such formulation assumes that the 'wind correction term' accounts for many processes including windage, unresolved ocean current vertical shear, and wave-induced drift. However, the latter two processes are not necessarily linearly related to the local wind velocity. We propose three other drift models that attempt to account for the unresolved near-surface current shear by extrapolating the near-surface currents to the surface assuming Ekman dynamics. Among them two models consider explicitly the Stokes drift, one without and the other with a wind correction term.
  • Tsunami, Seiches, and Tides Key Ideas Seiches

    Tsunami, Seiches, and Tides Key Ideas Seiches

    Tsunami, Seiches, And Tides Key Ideas l The wavelengths of tsunami, seiches and tides are so great that they always behave as shallow-water waves. l Because wave speed is proportional to wavelength, these waves move rapidly through the water. l A seiche is a pendulum-like rocking of water in a basin. l Tsunami are caused by displacement of water by forces that cause earthquakes, by landslides, by eruptions or by asteroid impacts. l Tides are caused by the gravitational attraction of the sun and the moon, by inertia, and by basin resonance. 1 Seiches What are the characteristics of a seiche? Water rocking back and forth at a specific resonant frequency in a confined area is a seiche. Seiches are also called standing waves. The node is the position in a standing wave where water moves sideways, but does not rise or fall. 2 1 Seiches A seiche in Lake Geneva. The blue line represents the hypothetical whole wave of which the seiche is a part. 3 Tsunami and Seismic Sea Waves Tsunami are long-wavelength, shallow-water, progressive waves caused by the rapid displacement of ocean water. Tsunami generated by the vertical movement of earth along faults are seismic sea waves. What else can generate tsunami? llandslides licebergs falling from glaciers lvolcanic eruptions lother direct displacements of the water surface 4 2 Tsunami and Seismic Sea Waves A tsunami, which occurred in 1946, was generated by a rupture along a submerged fault. The tsunami traveled at speeds of 212 meters per second. 5 Tsunami Speed How can the speed of a tsunami be calculated? Remember, because tsunami have extremely long wavelengths, they always behave as shallow water waves.
  • Tsunamis in Alaska

    Tsunamis in Alaska

    Tsunami What is a Tsunami? A tsunami is a series of traveling waves in water that are generated by violent vertical displacement of the water surface. Tsunamis travel up to 500 mph across deep water away from their generation zone. Over the deep ocean, there may be very little displacement of the water surface; but since the wave encompasses the depth of the water column, wave amplitude will increase dramatically as it encounters shallow coastal waters. In many cases, a El Niño tsunami wave appears like an endlessly onrushing tide which forces its way around through any obstacle. The image on the left illustrates how the amplitude of a tsunami wave increases as it moves from the deep ocean water to the shallow coast. Over deep water, the wave length is long, and the wave velocity is very fast. By the time the wave reaches the coast, wave length decreases quickly and wave speed slows dramatically. As this takes place, wave height builds up as it prepares to inundate the shore. Why do Tsunamis occur in Alaska? Subduction-zone mega-thrust earthquakes, the most powerful earthquakes in the world, can produce tsunamis through fault boundary rupture, deformation of an overlying plate, and landslides induced by the earthquake (IRIS, 2016). Megathrust earthquakes occur along subduction zones, such as those found along the ring of fire (see image to the right). The ring of fire extends northward along the coast of western North America, then arcs westward along the southern side of the Aleutians, before curving southwest along the coast of Asia.
  • Part II-1 Water Wave Mechanics

    Part II-1 Water Wave Mechanics

    Chapter 1 EM 1110-2-1100 WATER WAVE MECHANICS (Part II) 1 August 2008 (Change 2) Table of Contents Page II-1-1. Introduction ............................................................II-1-1 II-1-2. Regular Waves .........................................................II-1-3 a. Introduction ...........................................................II-1-3 b. Definition of wave parameters .............................................II-1-4 c. Linear wave theory ......................................................II-1-5 (1) Introduction .......................................................II-1-5 (2) Wave celerity, length, and period.......................................II-1-6 (3) The sinusoidal wave profile...........................................II-1-9 (4) Some useful functions ...............................................II-1-9 (5) Local fluid velocities and accelerations .................................II-1-12 (6) Water particle displacements .........................................II-1-13 (7) Subsurface pressure ................................................II-1-21 (8) Group velocity ....................................................II-1-22 (9) Wave energy and power.............................................II-1-26 (10)Summary of linear wave theory.......................................II-1-29 d. Nonlinear wave theories .................................................II-1-30 (1) Introduction ......................................................II-1-30 (2) Stokes finite-amplitude wave theory ...................................II-1-32
  • 2018 NOAA Science Report National Oceanic and Atmospheric Administration U.S

    2018 NOAA Science Report National Oceanic and Atmospheric Administration U.S

    2018 NOAA Science Report National Oceanic and Atmospheric Administration U.S. Department of Commerce NOAA Technical Memorandum NOAA Research Council-001 2018 NOAA Science Report Harry Cikanek, Ned Cyr, Ming Ji, Gary Matlock, Steve Thur NOAA Silver Spring, Maryland February 2019 NATIONAL OCEANIC AND NOAA Research Council noaa ATMOSPHERIC ADMINISTRATION 2018 NOAA Science Report Harry Cikanek, Ned Cyr, Ming Ji, Gary Matlock, Steve Thur NOAA Silver Spring, Maryland February 2019 UNITED STATES NATIONAL OCEANIC National Oceanic and DEPARTMENT OF AND ATMOSPHERIC Atmospheric Administration COMMERCE ADMINISTRATION Research Council Wilbur Ross RDML Tim Gallaudet, Ph.D., Craig N. McLean Secretary USN Ret., Acting NOAA NOAA Research Council Chair Administrator Francisco Werner, Ph.D. NOAA Research Council Vice Chair NOTICE This document was prepared as an account of work sponsored by an agency of the United States Government. The views and opinions of the authors expressed herein do not necessarily state or reflect those of the United States Government or any agency or Contractor thereof. Neither the United States Government, nor Contractor, nor any of their employees, make any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, product, or process disclosed, or represents that its use would not infringe privately owned rights. Mention of a commercial company or product does not constitute an endorsement by the National Oceanic and Atmospheric Administration.
  • Stokes Drift and Net Transport for Two-Dimensional Wave Groups in Deep Water

    Stokes Drift and Net Transport for Two-Dimensional Wave Groups in Deep Water

    Stokes drift and net transport for two-dimensional wave groups in deep water T.S. van den Bremer & P.H. Taylor Department of Engineering Science, University of Oxford [email protected], [email protected] Introduction This paper explores Stokes drift and net subsurface transport by non-linear two-dimensional wave groups with realistic underlying frequency spectra in deep wa- ter. It combines analytical expressions from second- order random wave theory with higher order approxi- mate solutions from Creamer et al (1989) to give accu- rate subsurface kinematics using the H-operator of Bate- man, Swan & Taylor (2003). This class of Fourier series based numerical methods is extended by proposing an M-operator, which enables direct evaluation of the net transport underneath a wave group, and a new conformal Figure 1: Illustration of the localized irrotational mass mapping primer with remarkable properties that removes circulation moving with the passing wave group. The the persistent problem of high-frequency contamination four fluxes, the Stokes transport in the near surface re- for such calculations. gion and in the direction of wave propagation (left to Although the literature has examined Stokes drift in right); the return flow in the direction opposite to that regular waves in great detail since its first systematic of wave propagation (right to left); the downflow to the study by Stokes (1847), the motion of fluid particles right of the wave group; and the upflow to the left of the transported by a (focussed) wave group has received con- wave group, are equal. siderably less attention.
  • Atlantic Hurricane Activity During the Last Millennium

    Atlantic Hurricane Activity During the Last Millennium

    www.nature.com/scientificreports OPEN Atlantic hurricane activity during the last millennium Michael J. Burn1 & Suzanne E. Palmer2 Received: 13 February 2015 Hurricanes are a persistent socio-economic hazard for countries situated in and around the Accepted: 10 July 2015 Main Development Region (MDR) of Atlantic tropical cyclones. Climate-model simulations have Published: 05 August 2015 attributed their interdecadal variability to changes in solar and volcanic activity, Saharan dust flux, anthropogenic greenhouse gas and aerosol emissions and heat transport within the global ocean conveyor belt. However, the attribution of hurricane activity to specific forcing factors is hampered by the short observational record of Atlantic storms. Here, we present the Extended Hurricane Activity (EHA) index, the first empirical reconstruction of Atlantic tropical cyclone activity for the last millennium, derived from a high-resolution lake sediment geochemical record from Jamaica. The EHA correlates significantly with decadal changes in tropical Atlantic sea surface temperatures (SSTs; r = 0.68; 1854–2008), the Accumulated Cyclone Energy index (ACE; r = 0.90; 1851–2010), and two annually-resolved coral-based SST reconstructions (1773–2008) from within the MDR. Our results corroborate evidence for the increasing trend of hurricane activity during the Industrial Era; however, we show that contemporary activity has not exceeded the range of natural climate variability exhibited during the last millennium. The extent to which the climate dynamics of the Main Development Region (MDR) of Atlantic tropical cyclone activity are controlled by natural or anthropogenic climatic forcing factors remains unclear1,2. This uncertainty has arisen because of the reliance on historical meteorological records, which are too short to capture the natural long-term variability of climatic phenomena as well as a lack of understand- ing of the physical link between tropical Atlantic SSTs and tropical cyclone variability3,4.
  • EARTH SCIENCE ACTIVITY #1 Tsunami in a Bottle

    EARTH SCIENCE ACTIVITY #1 Tsunami in a Bottle

    EARTH SCIENCE ACTIVITY #1 Grades 3 and Up Tsunami in a Bottle This activity is one of several in a basic curriculum designed to increase student knowledge about earthquake science and preparedness. The activities can be done at any time in the weeks leading up to the ShakeOut drill. Each activity can be used in classrooms, museums, and other educational settings. They are not sequence-bound, but when used together they provide an overview of earthquake information for children and students of various ages. All activities can be found at www.shakeout.org/schools/resources/. Please review the content background (page 3) to gain a full understanding of the material conducted in this activity. OBJECTIVE: For students to learn that tsunamis can be caused by earthquakes and to understand the effects of tsunamis on the shoreline MATERIALS/RESOURCES NEEDED: 2-liter plastic soda bottles Small gravel (fish tank gravel) Water source Empty water bottle (16 oz) Overhead projector Transparency of Tsunami Facts “What Do I See?” handout PRIOR KNOWLEDGE: In order to conduct this activity, students need to know how fault slippage can generate earthquakes. ACTIVITY: Set-Up (Time varies) Collect as many 2-liter soda bottles as possible or ask students to bring in bottles for this activity (3 students can share one bottle). Obtain an empty water bottle (about 16 oz). Remove labels from all bottles. Purchase or gather enough small gravel to fit through the mouth of the soda bottles. Students will fill up their soda bottles with gravel to create at least a 2 inch layer on the bottom of the bottle.
  • Final Program

    Final Program

    Final Program 1st International Workshop on Waves, Storm Surges and Coastal Hazards Hilton Hotel Liverpool Sunday September 10 6:00 - 8:00 p.m. Workshop Registration Desk Open at Hilton Hotel Monday September 11 7:30 - 8:30 a.m. Workshop Registration Desk Open 8:30 a.m. Welcome and Introduction Session A: Wave Measurement -1 Chair: Val Swail A1 Quantifying Wave Measurement Differences in Historical and Present Wave Buoy Systems 8:50 a.m. R.E. Jensen, V. Swail, R.H. Bouchard, B. Bradshaw and T.J. Hesser Presenter: Jensen Field Evaluation of the Wave Module for NDBC’s New Self-Contained Ocean Observing A2 Payload (SCOOP 9:10 a.m. Richard Bouchard Presenter: Bouchard A3 Correcting for Changes in the NDBC Wave Records of the United States 9:30 a.m. Elizabeth Livermont Presenter: Livermont 9:50 a.m. Break Session B: Wave Measurement - 2 Chair: Robert Jensen B1 Spectral shape parameters in storm events from different data sources 10:30 a.m. Anne Karin Magnusson Presenter: Magnusson B2 Open Ocean Storm Waves in the Arctic 10:50 a.m. Takuji Waseda Presenter: Waseda B3 A project of concrete stabilized spar buoy for monitoring near-shore environement Sergei I. Badulin, Vladislav V. Vershinin, Andrey G. Zatsepin, Dmitry V. Ivonin, Dmitry G. 11:10 a.m. Levchenko and Alexander G. Ostrovskii Presenter: Badulin B4 Measuring the ‘First Five’ with HF radar Final Program 11:30 a.m. Lucy R Wyatt Presenter: Wyatt The use and limitations of satellite remote sensing for the measurement of wind speed and B5 wave height 11:50 a.m.