ocean Flashcards
how much of the earth’s surface does the ocean cover
70%
how many oceans are there and how many basics
1 ocean with 5 basins (atlantic, pacific, indian, southern, arctic)
what light penetrates deepest into the ocean
blue light penetrates deeper than red light
the 3 ocean layers
sunlight zone, twilight zone, midnight zone
sunlight zone
is the surface layer also known as the euphotic or epipelagic zon, or the mixed layer. the upper 200 meters of the ocean. important layer for photosynthesis with enough sunlight and 90% of all marine life live here.
twilight zone
also known as the mesopelagic or dysphotic zone. little light penetration, 200-1000m. little photosynthesis occurs here
midnight zone
also known as the bathpelagic or aphotic zone. receives no sunlight, little light penetration from bioluminescent organisms. unusual organisms can survive in this, dark, harsh and high pressure environment
what are of the earth gets the most sunlight
the sun shines directly at the equator and tropics where most of the solar energy gets absorbed.
3 temperature layers
mixed layer, transition layer, deep layer
mixed layer
the temperature varies according to season and latitude. wind, waves, tides and convection mix this layer. the sun warms up this layer
transition layer
the temperature rapidly changes. also known as pycnocline, thermocline, or halocline.
deep layer
temperature is cool and about the same temp all the time
sunlight zone (surface of ocean) temp at high lats (polar)
as cold as -2, ocean water freezes at -194 so sea ice forms at high lats
sunlight zone temp at low latitudes (tropics)
as warm as 36
thermocline
layer of water where temperature changes rapidly with depth, also known as the transition layer (twilight zone area). separates warm surface water with the cool deep water. depth and strength of thermocline varies with season and lat. strongest at the tropics and nonexistent at the poles. found in low lats
thermocline seasonal variations in winter
weather/climate cold and stormy, no thermocline and layers well mixed
thermocline seasonal variations in spring
weather/climate is warming, reduced wind. reducsed mixing and thermocline is growing
thermocline seasonal variations in summer
weather/climate warmest and low wind. no mixing and a strong thermocline
thermocline seasonal variations in autumn
weather/climate cooling, increasing wind. thermocline decays and mixing begins
the densest water
cold, salty water
thermocline changes with latitude
the closer to the equator the more pronounced the thermocline is.
composition of seawater
96.5% water. 3.5% salt (made up of chloride, sodium, sulfate, magnesium, calcium, potassium and other minor constituents)
salinity
the mass of dissolved salt in water. most salt in the ocean comes from water running over rocks containing salt carrying it to sea
salinity reduced by
rainfall (tropics and mid lats) and river runoff adding large amounts of water changing the concentration
salinity increased by
evaporation (in tropics) and ice formation (polar) cause they remove large amounts of water while leaving salt behind.
why is polar water the densest
when seawater freezes salt is left behing in the ocean forming very dense water that sinks. cold and salty
halocline
layer of water where salinity rapidly changes with depth. varies around the earth prominent at the poles. found in high lats
halocline in high lats
water is less dense at the surface cause ice has formed and the cold salty dense water sinks. with depth salinity increases
halocline at low lats
salinity is high at the surface because of evaporation but because the water is warm it stays on the surface, halocline to the left as with depth salinity decreases
density
mass/volume.
density in the ocean
- the saltier the water the denser it is
- the colder the water the denser it is
-the least dense water is warm fresh water - densest is cold salty water
ocean is divided into 3 laters
surface layer, pycnocline layer, deep layer
pycnocline
layer where density changes rapidly. 18% of ocean. density changes due to temperature or vertical changes in salinity. its the barrier between surface and deep zones.
does salinity increase or decrease with water depth
increases with water depth
does temperature increase or decrease with water depth
decreases
does density increase or decrease with water depth
increases
the 3 density layers
the surface layer, pyncocline, deep ocean
surface mixed zone in density
(2% of the ocean) least dense water, mixed by wind, waves, tides and ocean currents. same salinity and temp throughout whole layer. temp changes due to sun and local weather. salinity varies due to evaporation, ice formation, run off and precipitation. non-existent in high lats.
deep zone density
80% of ocean, the bottom layer. the water is always cold and dense. cold dense water sinks at poles carrying o2, co2 and nutrients downward
ocean pressure
the deeper you go the greater the pressure of water
what determines density
pressure, salinity, and temperature
the thermohaline circulation (thc)
also known as the ocean’s conveyer belt is a global scale circulation that occurs over 100-1000 years. a giant convection current with many branches transports energy (heat), matter (nutrients, oxygen and co2) deep into the ocean and around the globe
what is the thc’s impact on the climate
it moves warmer waters towards the poles and cold water to the equator. the cold waters are nutrient rich with lots of dissolved co2 while warm waters are oxygenated less nutrients
how is the thc connected
the southern ocean connects all other oceans, it links major surface and deep water currents in atlatnic, indian, pacific and southern oceans
downwelling
occures when surface currents converge, the water has no where to go but down and surface water sinks. leading to low productivity zones as surface waters are low in nutrients
upwelling
process which deep, cold, nutrient rich water rises towards the surface replacing diverging surface water
how thermohaline circulation happens
- warm tropical water travels on the surface of the ocean towards the arctic and antartica (replacing cold water that has sunk)
- very cold winds blow off the ice and cool and freeze warm water
- latent heat released into atmoshere and lost in ocean
- as sea water freezes water immediately below ice becomes cold and dense. this dense water is called brine and sinks (downwells) to the ocean bottom driving the thc
- some of the deep water rises up to the surface in pacific and indian ocean after 1600-2000 years
- deep water eventually makes its way to the surface in the tropics (upwelling)
what is AABW
antartic bottom water, the densest water layer produced in antarctica (extreme south). this water is so dense it creeps along the ocean floor
what is NADW
north atlantic deep water produced in the artic (exterme north). less dense than AABW
how does the thc impact the earth’s climate
because of the circulation of heat- warm water moves to the poles, cold water moves to the equator
how does thc impact the carbon cycle
co2 is dissolved best in cold water, this cold water sinks at the poles taking co2 with it. vast amounts of carbon is stored in deep ocean for 1000s of years
thc impacts/importance to life
it carries ocean and nutrients to the deep oceans.
surface currents
10% of oceans flow in surface currents. waters flows horizontally like rivers in the ocean. transfer water and heat from tropical to polar regions, influence weather and climate, and distribute nutrients and scatter organisms.
what forces form the ocean’s currents
- gravity
- suns heat, solar radiation
- winds and wind friction
- coriolis effect (earth’s rotation)
gyres
a large system of rotating ocean currents. surface currents circulate in giant loops called gyres due to the earth’s spin (coriolis effect)
winds effects on ocean surface/ surface currents
winds, driven by uneven solar heating and coriolis effect drive the movement of the ocean’s surface.
what are the main winds that move the ocean
the easterlies and westerlies
effects of wind on the ocean surface
friction between the wind and water causes the water to move. some of the energy of the wind is transferred to the water to make waves and some is transfered to create surface currents
the coriolis effect on surface currents
wind blows and friction causes ocean surface to move, but because of the coriolis effect the surface waters move to the right of the wind direction in the NH and to the left of the wind direction in the SH
ekman spiral in the SH
a consequence of the coriolis effect. when surface water molecules move by force of the wind, dragging deeper layers of water molecules below them. the rotating column of water that forms when water moves at an angle to the wind direction due to coriolis. 90degrees to the left
ekman spiral in the NH
a consequence of the coriolis effect. when surface water molecules move by force of the wind, dragging deeper layers of water molecules below them. the rotating column of water that forms when water moves at an angle to the wind direction due to coriolis. 90degrees to the right
ekman spiral and transport
formed in the mixed layer. surface water moved by wind, drags deeper layers of water below. each layer moved by friction from the shallower layer above. the deeper the layer, the slower it moves than the layer above due the loss of energy. the movement ceases at 100m
how are surface currents influenced by gravity
winds and gravity move water, currents are effected by coriolis effect so currents arent parallel to wind or straight down to the steepest surface, run at an angle. currents run down slopes due to pull of gravity
what distinct currents are gyres subdivided into
transverse currents, eastern boundary currents and western currents
what is ACC
antartic circumpolar current, the strongest surface current and carries the largest volume of water per second of all surface currents. intense westerly winds over the southern ocean drive the ACC and with no continental land masses in the way to slow it down
coastal upwelling
where water from deep sea travels to the surface from depths of 200-300m, cold and rich in nutrients. often happens where wind blows along a coastline. the wind causes water at the surface to move away from the coast, due to ekman transport and water from deeper oceans rises and takes its place (upwelling).
coastal downwelling
opposite of upwelling where surface waters pushing down into deeper areas of the ocean, happens when winds cause ekman transport pushes water towards the coast and deeper into the ocean
how do ocean currents transport greak amounts of heat around the globe
water has a high heat capacity meaning that once it is heated up by the sun it takes months or years to release the heat and cool down. making the ocean an immense heat reservoir retaining energy from the sun over a long time. transfer of heat also influences climate
heat transfer ocean and atmosphere
the equator receives more heat from the sun than earth’s surface releases. higher lats have less heat from the sun than is released by the surface. the ocean releases much of this heat. atmos and ocean transport heat north and south to compensate for the imbalance.
thc transport of heat through the ocean
thc transports more heat than wind driven surface currents due because warm water from tropics flows north and south to polar regions where the water cools and releases heat into the environment, water becomes denser, sinks to greater depths, and flows towards the equator to pick up more heat
how are ocean waves generated
-gentle breezes (capillary waves)
-wind (wind waves)
-earthquakes, volcanoes or landslide causing sudden displacement of water (tsunami)
-gravitational attraction (tides)
waves
affect only the ocean’s surface layer but tsunamis move the whole water column. waves go from shortest to longest wavelengths (slowest and fastest)
capillary waves
small, tiny rippples, short-wave length waves. equilibrium between the force of gravity and surface tension of a fluid
wind waves
formed by transfer of wind energy to water. grow from friction of the wind and surface water. fetch, wind speed and wind duration increase the height of a wave. small wavelength and only affect surface of the ocean.
fetch
the unobstructed distance that wind can travel over water in a constant direction
what do wind waves move
energy. not matter! ocean waves move energy across the ocean. energy is moved at the speed of the water but water is not moving with the wave. wave moves in circules, each circule equal in diameter to the wave’s height
how do waves move forward
wind waves grow from friction of wind of surface causing capillary waves that deflect and slow the surface wind causing some of the winds energy to be transferred into the water driving waves forward
3 factors affecting growth of wind waves
- wind strength
- wind duration
- fetch
wind strength
wind must be moving faster than the wave crest for energy to transfer from air to sea and grow wind waves
wind duration
length of time wind blows; high winds blow only a short time dont generate large winds
where do the largest waves occur
at the southern ocean cause virtually nothing stops winds and waves get 11m high.
why dont waves grow in cyclones
cause the circular motion of air means there isnt a lot of fetch
what is the maximum ratio of wave to heigh length
1:7. waves 7 eters long will not be more than 1 metre high. if it gets bigger than this waves will break, excess energy becomes whitecaps and turbulence.
internal waves
form between water of different densities especially at the base of pycnocline. wave different wavelengths from surface waves and only seen from air
what affects the way waves travel
wave refraction, wave diffraction and wave reflection
wave refraction
the slowing and changing direction of waves in shallow water
wave diffraction
bending of wave around an obstacle.
wave reflection
occurs when waves bounce back from an obstacle they encouter. cause interferene with oncoming waves creating standing waves, waves that arent travelling
tides
the longest of all waves with the wavelength of half the circumference of earth. occur cause sun and moon gravitationally pull more strongly on one side of the earth than the other.
how do height of tides get affected
the earth and moons orbits arent complete circles they are elliptical meaning that sometimes the moon is closer to the earth and sometimes earth close to the sun affecting the heigh of tides.
spring and king tides
at new and full moons, solar and lunar tides reinforce each other. spring tides are the highest high and lowest low tides. the king tides are the highest spring tides when the moon is closest to the earth. sun and moon pulling in parallel directions. unusually large tidal range
neap tide
first and third quarter moons. the sun and earth and moon form a right angle creating neap tides, the lowest high and highest low tides. unusually small tidal range
how does the moon rotate relative to the earth
not at the center. rotate at a center of mass about 1,650 kilometers beneath earth’s surface
how does the moon’s gravity affect the ocean
the moon’s gravity attracts the ocean towards it, causing tidal bulges
where is carbon found
everywhere. in the atmosphere as ch4 and co2, in bodies of all living things as sugars proteins fats and dna. in fuels plastics clothing wood concrete. in rocks like limestone marble diamonds and graphite etc
carbon as an element
forms strong bonds with 4 other elements. making methane, carbon dioxide, glucose, graphite and diamonds. many other c compounds called organic compounds
how is carbon released into the atmosphere
by many things, respiration, burning of fuel, burning of forests, volcanic eruptions, methane from animal burp and flatulence, methane released from melting permafrost, decay of dead material, making concrete and warming of oceans
how is carbon removed from the atmosphere
photosynthesis, phytoplankton (also photosynthesis), absorbed by water
carbon absorbed by water
stormy cold water absorbs more than fresh and salt water cause of wind agitation. makes weak carbonic acid. co2 gas enters the ocean by dissolving in the sea surface, the amount of co2 dissolved depends on wind waves and temp of the water
long term carbon sink/storage
millions of years in the ocean deep wate circulation, sediment, limestone, marble, fossils and fossil fuels
short term carbon sink/storage
minutes to years in forests, phytoplankton, soil, permafrost, atmosphere and all plants and animals
is co2 a ghg
yes, it traps some of the suns heat and keeps the earth warm, but the increase in co2 emissions increases the co2 in the atmosphere increasing earth warming. and also increases co2 in ocean causing ocean acidification…
physical carbon pump
co2 dissolved into ocean from the atmosphere. when water warms up co2 released back into the atmos. dissolved co2 and carbon compounds can be transported to deep ocean to be stored in sediment for hundreds of years. strong in polar regions due to downwelling. deep currents also a longterm sink
biological carbon pump
biological sequestration of carbon from atmosphere and land runoff. marine organsims synthesize c compounds to photosynthesise or make calcium carbonate shells etc. the abundance of planktonic species is essential for photosynthesis, the death of phytoplankton either eaten or turned into sediment etc. marine matter /’snow’ drifting downward consisting of dead bodies and faecal matter. decomposition and c cycle
the importance of phytoplankton
not only on the marine food web as producers, but these phytoplankton photosynthesise and obtain co2 from dissolved co2 in the water, others like coccolithophores make plates from calcium carbonate
thc moving carbon
through upwelling and downwelling
what is the pH scale
measures acidity and alkalinity determines by the amount of H+ in the seawater. increase in H+ leads to seawater to be less basic increasing aciditiy. scale from 0 (acid) 7 (neutral) and 14 (alkaline)
ocean acidification
pH has been slightly basic with an average of 8.2 in last 300 years but now its 8.1 representing a 25% increase in acidity showing an increase in H+ in water. co2 in atmos increased due to human industrialization, ocean absorbs more co2 an advantage to get the co2 out of the atmosphere but a disadvantage as equilibrium reactions result in more H+ being produced
carbonate chemistry
water H20
carbon dioxide CO2
carbonic acid H2CO3
bicarbonate ion H+
carbonate ion CO32-
calcium Ca2+
calcium carbonate CaCO3
how is more H+ produced and how does this affect marine life
more co2 dissolved in oceans changing equilibrium reaction where there are extra H+ produced. this extre h+ combines with carbonate ions to form bicarbonate ions. now there are less carbonate ions available for those marine creates that make calcium carbonate shells and skeletons. now these organisms require more energy to produce these shells reducing energy for other life processes. increased acidity also dissolved calcium carbonate as h+ react with the solid calcium carbonate converting it into bicarbonate.
how is human activity affecting co2 levels
the ocean can adjust its own ph but the rate the co2 is being put into the air and absorbed by the ocean is too fast right now for this to happen
carbonate chemistry, co2 from atmos absorbed by ocean reacting with seawater and forms carbonic acid
co2+h20-> h2co3
carbonic acid dissociates (breaks up) forming bicarbonate ions and h+
h2co3-> h+ + hco3-
some h+ reacts with bicarbonate to form carbonate ions and more h+
h+ + HCO3- -> 2H+ CO32-
carbonate chemistry equilibrium
equations that go both ways depending on concentration of relevent molecules and ions
co2+h2o <-> h2co3 <-> h+hco3- <-> 2h+ + co32-
el nino
warm ocean phase, occurs when there is higher air pressure in west low in east (opposite of normal conditions). temps higher than normal by 3 degrees. trade winds weaken and sometimes reverse direction causing westerlies to blow. ocean water kinda piles up off south america in the east. thermocline pushes deeper, upwelling decreases cutting off supplies of nutrient. less water moves to the surface. rainfall in central pacific. western pacific becomes dry, draughts. flooding in the east.
la nina
cold ocean phase, occurs when lower air surface pressure in the west. NE trade winds stronger than usual increasing upwelling in the east and temps are lower than normal by 3degrees. rain shifts farther west than normal. winds pile up warm surface water in the west. strong upwelling
southern oscillation
coherent interannual fluctuations of atmospheric pressure over tropical indo pacific regions. normal conditions air pressure in the west (at darwin) is lower than the east (tahiti). normally sea surface temps are 7degrees higher in western pacific than eastern. warm rising air in the west causes low pressure, rising air condenses into clouds and rain falls. the colder east is relatively dry. due to differences in air pressure between east and west pacific, a convection cell called the walker circulation cell is formed. warm ocean phase is el nino, cold ocean phase is la nina. these change in normal surface temps have large scale impacts on ocean pressure, global temp and climate
walker circulation/pacific circulation cell
trade winds blow in a westerly direction along the equator and push ocean water west, piling water up higher in the western pacific than eastern. air pressure is lower in the west, sea temps higher in the west. surface layer of ocean heats up as it travels across the pacific and becomes deeper causing thermocline to be deeper. east warm layer more shallow causing thermocline to be more shallow wih the deeper layer is nearer he surface at west. this results in upwelling in the east
ENSO
el nino southern oscillation
