MAR 352 Exam 2

langmuir

langmuir

circulation that affects the surface layer of the ocean. small scale response, but bigger than surface waves. leads to observable wind rows at convergence zones

ekman spiral

describes the transport of water perpendicular to direction of wind stress assuming steady state conditions. surface layer pushes next layer down slightly the right, and slightly weaker current. next layer pushes next layer, slightly to right and slightly weaker current, producing a “spiral” of the current vectors, to right in northern hemisphere, decreasing speed with increasing depth

wave

a disturbance traveling through a medium by which energy is transferred from one particle of the medium to another without causing any permanent displacement of the medium itself. a disturbance that travels through space and time, accompanied by a transfer of energy

waves

causes of these include wind, tectonics, tides, and objects moving through water

restoring forces

forces that dissipate waves. for most waves dissipation is caused by gravity or surface tension

capillary waves

waves small enough to be restored by surface tension. important for surface gas exchange

sea state

describes the wind field being encountered, measure of the size of waves. controlled by wind speed, duration, and fetch (distance over which the wind blows)

fully developed sea

term for the maximum steady state waves under current conditions

southern

the ocean with the largest sea state

rossby number

this value relates the importance of nonlinear forces to coriolis forces. for surface wave calculations, we assume this is large

forerunners

waves with periods of 15-30s that often arrive before storms

Hmax

variable for maximum wave height in a given time period, good for knowing the energy to withstand

H1/3

variable for significant wave height, measured as the average value of the height of the highest 1/3 of waves in a given time period

lambda/2

the ocean bottom must be greater than this value for a wave to be considered a deep water wave

deep water waves

waves in deep enough water that they do not interact witht he bottom, have circular orbitals

lambda/20

the ocean bottom depth must be less than this value for a wave to be considered a shallow water wave

shape

this feature of a wave changes as it approaches shore, its bottom orbitals slow and water piles up

dispersion

the separation of wave groups due to wave speeds

kinetic

the energy transferred by wave motion is this type

potential

the energy resulting from the elevation of water in a wave is this type

wave drift

the small net forward motion of particles in a wave

wave speed

this is a function of wave depth, wavelength, and gravity

x

when x is very small, tanh(x) is approximately equal to what?

constructive

this interference occurs when waves are in phase with each other

rogue waves

dangerous waves that occur under a lot of constructive interference

direction

reflection, refraction, and diffraction can all change this feature of a wave's motion

reflection

waves bounce off of a structure. the size of the angle of waves coming in relative to the boundary is the same as after they have hit it

refraction

when a wave crest turns/bends because one part is moving faster than another. usually due to differences in shoreline shape, uneven bottom topography, or offshore land features

diffraction

occurs when a wave travels through an opening in a boundary, redistributes wave crests from a straight line (parallel) to radiating outward (radial) from the opening. can lead to interference if it happens in multiple nearby locations

snell's law

used for quantifying wave refraction

seiche

also called a standing wave, occurs in partially enclosed bodies of water when the system is driven at, or near, its natural frequency. wave oscillates vertically around a fixed position, no translational movement

node

position along a seiche wave with no vertical movement

natural frequency

feature of a seiche wave also called resonance frequency, driven by the size of the water body

period

when waves interact with currents, this remains constant

speed

when waves interact with currents and this increases, wavelength increases and height decreases

tides

these are shallow water waves with the longest wavelengths of any waves in the ocean. an energy source for vertical mixing in the deep ocean and an important stirring mechanism in coastal oceans

tides

between tides and wind-generated waves, which has larger heights, longer period and wavelengths, and is more predictable?

tidal range

the difference in height between consecutive tidal cycles (low to high or high to low)

spring tide

period where tidal range is maximized. occurs when the sun and moon are at the same or opposite angles from each other, adding tidal bulges

mean high water

what does MHW stand for?

mean tide level

what does MTL stand for?

tide producing forces

what does TPF stand for?

tide generating forces

gravitational attraction and conservation of angular momentum constitute these

declination

this feature of the moon describes the angle between equatorial plane and plane of moon’s orbit, leads to tidal variation

bathymetry

this local feature of an area can play a role in tidal variation

tidal constituents

these add up to create the tide at a given place. the different responses and strengths of each vary with location and make the total tide different

tidal asymmetry

occurs when tidal range ~ water depth, common in estuaries. higher tides move with faster speeds, bending predictions

perpendicular

geostrophic currents move in a direction ____ to forces such as pressure gradients

estuary

a semi-enclosed body of water that has a free connection with the open sea. the seawater here is measurably diluted with freshwater deriving from land drainage. very biologically productive and areas of large anthropogenic disruption

geomorphology

coastal plain, bar built, tectonic, and fjord are the four types of estuaries based on this

coastal plain

also called drowned river valleys, have low-lying coasts with drowned river systems caused by rising of sea level. examples: chesapeake bay, delaware bay

bar built

estuaries in shallow coastal regions separated from open ocean by bars at the mouth. examples: great south bay, pamlico sound

tectonic

estuaries caused by sea filling in a “hole” or basin formed by sinking land caused by tectonic forcing. examples: san francisco bay, gulf of california

fjord

estuaries cut by glaciers, narrow and steep-sided. has sill from glacial deposits near mouth. examples: coasts of chile, alaska, norway, western US

estuary convective flow

two-layered flow in which seaward-moving, low-salinity water is at the surface and landward-moving, high-salinity water is subsurface. KNOW: the mixing between layers depends on magnitude of river flow and tidally-induced mixing

salinity

based on this property, estuaries can be highly stratified, partially stratified, or well-mixed. determined by bottom and coastal topography, ratio of tidal energy to river flow

highly stratified

in this estuary type, there is a low tidal to river flow ratio. horizontal isohalos, weak vertical mixing

salt wedge

in this highly stratified estuary type, there is large freshwater influx and a strong halocline

fjord

in this highly stratified estuary type, there is fresh river water moving seaward as glacial sill blocks returning deep-water flow. little vertical mixing, deeper water below sill level stagnates

partially mixed

in estuaries of this type, there are tilted isohalos, a weaker halocline than salt wedge. coastal plain estuaries tend to be this type

well mixed

in estuaries of this type, there is high tidal to river flow ratio and vertical isohalos

inverse

these estuaries can occur where there is high evaporation with little river input. have saline outflow. examples: mediterranean sea, red sea

right

facing the sea in a broad estuary of the northern hemisphere subject to coriolis force, which side of the estuary will the outflow tend to hug?

semienclosed

in these seas, bottom topography plays a key role in oceanographic characteristics. deep basins can have typical oceanographic processes

dilution basin

a semienclosed sea where freshwater input exceeds evaporation, such as the arctic ocean or black sea

concentration basin

a semienclosed sea where evaporation exceeds freshwater input, such as the mediterranean sea

parameters

wave ___ include wavelegth, period, frequency, angular frequency, and speed

sound

the speed of this varies depending on the medium and is affected by density, temperature, pressure, and several other factors

1530m/s

speed of sound in water

342m/s

speed of sound in air

pressure

these waves are the basis of all acoustic signals

fourier series

allow any periodic signal to be approximated by summing sine waves of different wavelengths/frequencies/phases. signals are combinations of different frequencies

broad band

these sounds have large bandwidths and short durations

spectrograph

a plot of energy/frequency

acoustics

in general, these can be plotted as amplitude over time or pressure over time

analog

this type of acoustic signal is continuous (think record, wax cylinder). beneficial in that they record the "true" signal, not a sub-sample, and contain all of the original signal's information

digital

this type of acoustic signal is discrete (think mp3s). beneficial in that exact copies can be produced and they are easier to transport/distribute

sampling

the process where a continuous (analog) signal is converted to a discrete (digital) signal. two key parameters: rate and quantization

sampling rate

the separation (in time) of where the signal is sampled. a higher rate will better recreate the signal, but requires more data storage

nyquist frequency

sampling rate / 2. the highest frequency that is “stored” in the digital signal without aliasing (mistakes). you must sample your signal at a rate twice that of the highest frequency component you are interested in

quantization

how accurately you measure the amplitude of the original signal when you sample it. more bits more accurately recreate the signal, but more bits requires more data storage space

8

how many bits are in one byte?

duty cycle

the percent of the time that an instrument is actually recording, continuous recording often not feasible. depends on recording system capabilities such as storage and battery life, and should also consider patterns of organism activity, length of sounds produced

acoustic resistance

the product of the medium's density and sound speed. a way of describing how “difficult” it is to create a pressure wave in the medium

hearing ranges

these are similar between species but not well known for most animals. driven by what wavelengths propagate well in the environmental medium and general size similarity in hearing mechanisms (small bones in ear)

log

sounds and hearing operate on this scale. allows you to examine differences occurring at different scales

octave

one of these equates to a doubling in sound frequency

deciBel

a logarithmic unit to express the ratio of two quantities. often used for power or intensity, always need to provide a reference level when reporting

1

reference value (in microPascals) for sound measurements in water

transmission

spreading or absorbing a sound leads to loss of this. sound gets less intense farther from its source

increases

speed of sound in water increases with increasing water temperature, increasing salinity, and increasing depth

beer's law

describes exponential decay of light intensity with depth

light

ocean water transmits this poorly. transmission is best in blue-green

sound intensity

energy per area per time, proportional to amplitude^2

sound level

a deciBel version of intensity

more

higher-amplitude sound waves carry ___ energy

sonar

this equation tells how loud an acoustic signal will be at a given distance

deep sound channel

also called SOFAR channel, can be used to transmit low-frequency sound around the earth

el nino

a disruption of the ocean-atmosphere system in the tropical pacific having important consequences for weather around the globe, with a period of roughly 3-4 years. occurs when usual winds diminish or switch direction, warm water leaks back eastwards, and upwelling stops. sea surface becomes nearly level and thermocline becomes nearly level or depressed in the east

sir gilbert walker

began piecing together widespread el nino effects in his effort to understand and predict monsoons in india and avoid famines. claimed that southern oscillation was connected to various meteorological events throughout the globe, but did not prove it