oceanography

semidiurnal tide

2 highs 2 lows of same heights, common on Atlantic coast, 12hr25m period.

north atlantic, south atlantic, north pacific, south pacific, Indian Ocean

5 major subtropical gyres

seiche

A standing wave (2 waves of the same wavelength going in opposite directions yielding a net zero movement, no circular motion) of an enclosed or semi enclosed body of water that may have a period ranging from a few minutes to a few hours, depending on the dimension of the basin. The wave motion continues after the initiating force has ceased.

constructive/ destructive interference

Constructive is when wave trains having the same wavelength come together in phase, meaning crest to crest and trough to trough (wave height = sum of the 2). Destructive is when wave trains of the same wavelength come together out of phase, meaning the crest from one wave coincides with the trough of the 2nd (wave height = 0)

California Current

Cool-water eastern boundary current in the North Pacific Subtropical Gyre that flows south along the coast of California to complete the loop of the North Pacific

suptropical convergence

Ekman transport deflects surface water to the right in the northern hemisphere, so a clockwise rotation develops within an ocean basin and produces--- of water in the middle of the gyre (causing water to pile up in the center of the subtropical gyre). It can be a hill of up to 2m.

ENSO

El Niño-Southern Oscillation includes El Niño and the east-west atmospheric pressure seesaw that accompanies the warm current (known as Southern Oscillation). Alternates between warm and cold phases (la Niña) and causes huge environmental changes

estuary plume

Formation of water resulting from the discharge of low-salinity water into marine waters of the ocean, forming a distinct layer of water on top of the seawater due to its lower density, higher in nutrients, turbidity and productivity than the surrounding seawater and can gradually deliver those water quality characteristics to the adjacent ocean water.

Walker Circulation

High pressure and sinking air cause the coastal region of South America to have clear, fair, dry weather, while on the other side of the Pacific a low pressure region and rising air create clouds and rain in Indonesia, Australia, etc. This pressure difference causes the strong southeast trade winds to blow across the equatorial South Pacific. The resulting atmospheric circulation cell in the South Pacific Ocean is this

Ekman spiral

It describes the speed and direction of flow of surface water at various depths. After an immediate column of of water is set in motion by wind, the Coriolis Effect causes the surface water to move in a direction 45 degrees to the right of the wind ( in the northern hemisphere). As this happens, deeper water is set in motion in a spiraling manner. Eventually, the water can move in a direction perpendicular to the original wind (pg. 205 graph)

tsunami

Japanese term for large destructive waves ; a seismic sea wave; a long period gravity wave generated by a submarine earthquake or volcanic event

gyre

Large circular loops of water driven by the major wind belts of the world

North Atlantic Deep Water

Large masses of deep water form in the Norwegian Sea and deep water flows as a subsurface current into the North Atlantic forming this. It also comes from the Irminger Sea off southern eastern Greenland, the Labrador Sea, and the Mediterranean Sea. Spreads to all ocean basins

Western Boundary Current

One of the 4 main currents that makes up the Gyres. When the equatorial currents reach the western portion of an ocean basin, they must turn because they can't cross land. The Coriolis Effect deflects them away from the equator as western boundary currents (they travel along the western boundary of an ocean basin) (carry warm water to high latitudes)

La Niña

The cool phases of ENSO is similar to normal, but intensified because of larger pressure changes that create stronger Walker Circulation and strong trade winds, which create more upwelling and shallow thermocline. They usually follow El Niño

Western Intensification

The top of this hill is closer to the western boundary than the center of the gyre. As a result, the western boundary currents within the gyre are faster, narrower, and deeper than the eastern boundary. This happens EVEN IN THE SOUTHERN HEMISPHERE.

upwelling

The vertical movement of cold, deep, nutrient-rich water to the surface that increases productivity

el Niño

The warm water current near Peru that reduces anchovies and therefore marine life. The high pressure along the coast of South America weakens, reducing the difference between the high and low pressure regions of the walker circulation and southeast trade winds diminish (sometimes even go reverse!), causes upwelling to cease

Gulf Stream

Western boundary current. The world's best studied current that moves northward along the East Coast of the US, warming coastal states and moderating winters in these and northern European countries

plunging breaker

a curling crest that moves over an air pocket (good for surfing).

Coriolis effect

a mass moving in a rotating system (Earth) experiences a force acting perpendicular to the direction of motion. In the northern hemisphere, it deflects objects to the right and in the southern hemisphere it deflects wind to the left (counterclockwise)

estuary

a partially enclosed coastal body of water in which freshwater runoff from a river dilutes the input of salty ocean water

medium

a substance that carries a wave (ex. A coil in a slinky)

spilling breaker

a turbulent mass of air and water that runs down the front slope of the wave as it breaks. They result from a gently sloped ocean bottom and have a longer life span than other breakers (long, but less exciting surf ride)

backshore

above high tide zone and covered with water only during storms

sea

area where wind-driven waves are generated (choppiness and waves move in many directions)

coastal wave refraction

bending of waves as they approach the shore bc wave feels bottom first and slows rest of wave so they orient themselves nearly parallel to shore

offshore

beyond lowtide breakers, deep enough that waves rarely affect the bottom

orbital wave

both traverse and longitudinal; ocean waves

equilibrium Theory of Tides

causes "tidal bulges" on opposite sides of globe, deforming the ocean sphere- reason behind 2 high/low tides per day 12 hrs apart (land masses can get in the way and mess this up a bit)

sea arch

caves erode through to other side from pounding waves forming openings.

sea cave

caves in base of cliff formed by waves.

mixed tide

characteristics of both, highs and lows may not be same heights, most common in world, generally 12h25m period but sometimes 2450.

transitional wave

characteristics of deep and shallow water waves

Thermohaline Circulation

deep ocean circulation; density variations cause differences in temperature and salinity

highly stratified

deep, upper layer salinity increases head to mouth and flows head to mouth, deep water layer has steady salinity, same circulation patterns.

hypoxia

deficiency in oxygen.

beach

deposit of shore area, from coastline to line of breakers, entire area of coast that experiences changes due to breaking waves.

levees

elongated ridge, regulates water levels and prevents coastal flooding of rivers

coast

extends inland from shore

nearshore

extends seaward from low tide shoreline to low tide breaker line, never exposed to atmosphere but affected by waves that touch bottom

barrier island

extremely long offshore deposits of sand parallel to coast.

restoring force

for water-water is medium and resorting force is surface tension or gravity-simple harmonic motion, directed toward equilibrium of system

wave train

groups of waves

still water line

halfway between the crest and trough

Antarctic Bottom Water

high density water sinks down to the continental slope of Antarctica (densest water in the open ocean). Spreads to all ocean basins

king tides

highest tides of year, in winter when sun and moon are aligned

wavelength

horizontal distance between 2 corresponding points on successive waveforms (crest to crest OR trough to trough)

wind duration

how long the wind blows

spit

linear ridge of sediment extending in direction of longshore drift from land into deeper water near mouth of bay.

relative sea level change

local sea level change

rogue wave

massive, solitary, spontaneous ocean waves that can reach enormous heights and often occur at times when normal ocean waves are not unusually large

spring tides

maximum tidal range (dif between high and low tide), Earth moon and sun are aligned- constructive interference

wind driven current (surface)

move water horizontally and occur primarily in the ocean's surface waters

longshore drift

movement of sediment in a zigzag fashion caused by longshore currents in surf zone

density driven current (deep)

moves water vertically and accounts for the thorough mixing of deep masses of ocean water; when surface water becomes high density (through low temperature or high salinity) it sinks and spreads slowly beneath the surface.

anoxia

no oxygen

surging breakers

occurs when the ocean bottom has an abrupt slope and the wave energy is compressed into a shorter distance and the wave surges forward (build up and break at shoreline)

diurnal tide

one high tide one low tide per lunar day, common in shallow inland areas, 24h50m period

seawall

parallel to shore, armors the coastline and protects landward developments from ocean waves (often collapse)

breakwater

parallel to shore, traps sand.

groin

perpendicular to coastline, trap sand moving in longshore transport.

jetty

perpendicular, protects harbor entrances from waves and secondarily sand, can cause upcoast deposition and downcoast erosion.

foreshore

portion exposed at low tide and submerged at high tide.

dynamic theory of tides

push and pull of ocean water in response to various forces, explains predictable tidal periods

longitudinal wave

push-pull waves; the particles that vibrate "push-pull" in the same direction that the energy is traveling, like a spring whose coils are compressed and expanded

mechanical waves

requires the presence of a material medium in order to transport their energy from one location to another. Sound waves are examples of mechanical waves. (Ex. slinky waves require the medium of a coil to exist)

beach replenishment

sand is added to the beach to replace lost sediment, alternative to hard stabilization

tombolo

sand ridge that connects island or sea stack to mainland or two islands, oriented perpendicular to direction of incoming waves.

coastal environments

shallow, affected by onland processes, halocline, thermocline, pycnocline, home to a lot of life

vertical mixing

shallow, low volume estuary where net flow is from head to mouth and salinity is uniform top to bottom but increases head to mouth.

transverse wave

side-to-side waves; energy travels at right angles to the direction of the vibrating particles

delta subsidence

soil in wetlands naturally compresses under its own weight; plants and fresh sediment can offset this

river delta (tide/wave/river dominated)

some rivers carry more sediment to the ocean than longshore currents can distribute- when river mouth fills with sediment

slightly stratification

somewhat deeper, salinity increases head to mouth, 2 layers in water (less saline/dense on top, more saline/dense on bottom), separated by zone of mixing, circulation of less saline towards ocean, more saline towards head.

rip current

strong narrow surface currents from backlash of breaking waves, flow away from shore perpendicular to beach

hard stabilization

structures built to protect a coast from erosion or to prevent the movement of sand on a beach (bad)

dams

suppress floods

wind wave

surface waves that occur on the free surface of oceans, seas, lakes, rivers, etc. and result from wind being blown over a surface

fetch

the area of the open ocean over which the wind blows with constant speed and direction, thereby creating a wave system; distance over the water that a wind blows in a single direction

subtropical gyre

the center of these coincides with 30 degrees north or south latitude. They rotate clockwise in the northern hemisphere and counterclockwise in the southern. Each one is composed of 4 main currents that flow into one another.

Disturbing Force

the energy that causes ocean waves to form

Ekman transport

the net movement of water is 90 degrees to the right (in the northern hemisphere) of the original direction of the wind

wave frequency

the number of wave crests passion a fixed location per unit of time (1/period)

wind speed

the rate at which wind moves per unit of time

wave period

the time it takes on full wave (wavelength) to pass a fixed position

deep-water wave

the wave depth is greater than the wave base (point where the circular orbit movement is negligible in the wave)

sea stack

tops of arches crumble to make these

equatorial currents

travel westward with the trade winds

wave height

vertical distance between the crest and trough (H)

tidal bore

wall of water that moves up certain low-lying rivers due to incoming tide

coastal upwelling

water rises from below to replace water moving away from the shore

swell

waves generated in the sea area move towards its margins, wind speeds diminish and the waves eventually move faster than wind. When this occurs, waves steepness decreases and waves become long-crested waves called ---

shallow-water wave

waves where depth is less than 1/20 of the wavelength (tough the ocean floor)

electromagnetic waves

waves which transmit energy through a vacuum (empty space); they are created by the vibration of an electric charge (ex. Light energy emitted by the sun that travels through the vacuum of outer space)

salt wedge

wedge of salty water comes beneath river water, deep, high volume, horizontal salinity gradient at depth and pronounced vertical halocline.

Eastern Boundary Current

when currents flow back across the ocean basin, the Coriolis effect and continental barriers turn them toward the equator that come along the eastern boundary of ocean basins (come from high latitude to low bringing cool water)

capillary wave

wind blows over waves and creates pressure and stress that deform the ocean surface into small, rounded waves with V shapes troughs and wavelengths less than 1.74 cm (ripples). As the wind increase from left to right, the heigh and wavelength of waves increase beginning as capiallary wave ripples and turning into gravity waves (exceed 1.74cm). Once the H/L ratio exceeds 1/7, the wave crashes

neap tides

working at right angle to moon's, small tidal range (lower high tides and higher low tides)- destructive interference. These alternate about a week apart

eustatic sea level change

world wide (seafloor spreading rates, etc)