Oceanography is the study of the world’s oceans. In the late 1800s, the British
Challenger the first research to study the oceans. In the 1920s, the German research
ship Meteor used sonar for the first time to map the seafloor features of the South
Atlantic Ocean. Sonar,(sound navigation and ranging) echo and the known velocity
of sound in water to determine water depth.
–The velocity of sound in water is 1500 m/s.
–To calculate the distance to the ocean floor, multiply the time by 1500 m/s, then
divide by 2.
Earth’s Oceans
70% of Earth’s Surface
97% is salt water
5 Main Bodies
Pacific Ocean –
largest & deepest
Atlantic Ocean –
½ size of Pacific
Indian Ocean –
3rd largest
Southern Ocean –
4th largest – ice all year
Arctic Ocean smallest & shallowest
ice for part of the year
Earth’s ocean began to
form 4.2 BYA Large
amounts of H2O with
CO2 & other gases
formed early
atmosphere.
Condensation lead to
forming the oceans.
A second source for
the water was from
asteroids & comets
that hit the earth
during its early
formation.
The volume of water
has stayed the same
over time.
Composition of Sea Water
Salinity - Expressed in ppt
Avg. is 35 ppt
Ocean Layers – Temperature
 Water cools with depth esp.
250m to 900m in tropics due to
radiation from the sun
 Polar water all cold due to lack
of much radiant energy
Ocean Layers – Density
 Cold water is denser than hot
 Salt water is denser than fresh
 Ocean has layered density
 Polar density is constant.
 Densest layer is on bottom.
Brackish – fresh/seawater
Between 1-17 ppt
Ocean Layers – Salinity
 Top 500m of warm H2O is saltier
 Warm water evaporates faster
 Warmer water saltier from the
results of evaporation.
 Cold, polar water is diluted by
glaciers.
 Cold, salty water is the densest.
Ocean Light Zones
 Surface Zone – sunlit zone 200m
greatest amt. of sunlight & area
where most organisms live.
 Middle Zone – twilight zone 1000m
most of light’s wavelenghts are
absorbed so light is blue-green.
 Deep Zone – midnight zone >1000m
animals make their own light by
bioluminescence & no
photosynthesis occurs.
euphotic zone
disphotic zone
aphotic zone
http://www.montereyinstitute.org/noaa/lesson03/l3la2.htm
http://www.seasky.org/deep-sea/ocean-layers.html
Seafloor
 Continental Margins – from shore to
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deep ocean consists of continental shelf,
slope, & rise.
Abyssal Plains – large, flat areas in the
deepest part with sediment/volcanoes.
Ocean Trenches – forms along the
abyssal plain where an oceanic plate
collides with a continental plate. (avg.
depth 4,000m, Mariana 11,000m.
Deep Ocean Exploration – submersibles
& ROV (Remote Operated Vehicles are
cheaper & able to withstand the pressure)
Energy Resources – Oil, nat gas, methane
Mineral Resources – Mg, Au, Zn
http://www.classzone.com/books/earth_science/terc/content/investigations/es0802/es0802page03.cfm
Surface Waves – made by wind
•Trough is the lowest part of the wave
•Crest is the highest part of the wave
Wave pattern moves in a circular pattern.
Waves change shape & size as it nears the shore because it
drags on the seafloor & collapses in on itself & reaches the
beach (breaker).
Tides – rise & fall of ocean surface due to gravitational
force between the earth & the moon & between the
earth & the sun.
Moon & Topography
Spring & Neap Tides
 Moon – causes the biggest
 Spring - When the earth, sun,
bulge on the ocean surface
on the side away from the
moon (high tide).
 Tidal range is between 115m. It varies due to the
shape, size, & depth of the
ocean basin.
& moon line up it creates a
strong gravitational pull, so
the tide has a higher than
normal range (both higher &
larger).
 Neap – When the moon is at
90 angle, the pull is the
weakest, so it has a smaller
range than normal.
Surface Currents
Ex. Gulf Stream (warm) & California Current (cold)
 Friction of the wind creates currents.
 Currents move in the direction of the wind currents until
deflected by a continent into loops.
1. Tropical Winds
2. Trade Winds
3. Polar Winds
 Some carry warm & cold water horizontally across the ocean.
 Other currents cause upwelling (vertical movement along a coast)
that brings cold nutrient rich water to the surface.
 Density currents also move vertically, moving surface water &
circulating energy, nutrients, & gases.
 Currents can go to 400m below the surface.
 Currents move about 100km/day.
Gyres – Great Ocean Conveyor Movements
*1,000 years to complete cooling & warming cycle.
–The continents deflect ocean currents to the north and
south causing closed circular current systems, called gyres.
–There are 5 major gyres: the North Pacific, the North
Atlantic, the South Pacific, the South Atlantic, and the
Indian Ocean.
–The parts of all gyres closest to the equator move towards
the west as equatorial currents until they are deflected
toward the poles by a landmass.
–After cooling in the polar regions, the current, deflected
by landmasses, moves back toward the equator.
Environmental Impacts
 Sources –
 Climate Change - Warming
*Point – oil spill
*Nonpoint – sewage, runoff of
chemicals, & air pollution
 Effects –
*Solid waste – Pacific trash
*Excess sediments – block light
*Excess nutrients – algal bloom
http://www.pbs.org/wnet/need
-to-know/environment/anocean-of-plastic/2686/
*Coral Bleaching - algae
killed
*Sea level rise - risk of flood
*Dissolved O2 – organism
need this to survive
*More CO2 dissolved in sea
makes the H2O acidic. This
reduces the absorption of
Ca by animals for shells &
skeletons, disrupting food
webs.