Transcript Oceanography

Waves are a result of wind.
As wind blows longer and
harder, more waves will be
produced.
 Surface currents move
warm water toward the
poles and cold water
toward the equator. An
example of a warm surface
current would be the Gulf
Stream.
 Tides are the daily rise and
fall of sea level due to the
gravitational attraction
between the Moon, Sun,
and Earth.
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New and full moons create
spring tides: highest high tide,
lowest low tide
First and third quarter moons
create neap tides: lowest high
tide, highest low tide
High tides are found on
whatever side of the Earth the
Moon is on due to gravity. The
exact opposite side of the Earth
will also have high tide due to
inertia.
The tidal bulges follow the Moon
where ever it goes.
The difference between sea
level at high tide and sea level
at low tide is called the tidal
range.
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High oceanic productivity
occurs in areas of
upwelling in the ocean,
particularly along
continental shelves
The coastal upwelling in
these regions is the result
of deep oceanic currents
colliding with sharp
coastal shelves, forcing
nutrient-rich cool water to
the surface and pushing
surface waters offshore.
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The ocean is the largest reservoir of heat at the Earth’s surface.
The stored heat in the ocean drives much of the Earth’s weather.
This stored heat also cases the climate near the ocean to be
milder than the climate of the interior of continents.
Since water absorbs and releases heat energy relatively slowly,
water has a moderating effect on climate, and it also helps
organisms regulate their body temperature. This high heat
capacity causes a body of water to stay warmer or cooler longer
than the surrounding earth and air.
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Why are there land and
sea breezes? Because
land heats up and cools
down much faster than
the water, creating
temperature and
pressure differences.
Warm air is less dense
and rises over the land
during the day, creating
an onshore breeze from
the sea.
Cool air is more dense
and sinks over the land
at night, creating an
offshore breeze from the
land.
The submerged extension of the continent below sea
level is the continental margin.
 Mid-ocean ridges, trenches, volcanic island arcs, and
seamounts are the result of tectonic activity.
 Chemosynthesis does not require sunlight. This occurs at
hydrothermal vents near mid-ocean ridges.
 Photosynthesis is how plants and cyanobacteria (bluegreen algae) near the ocean surface produce oxygen.
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El Niño is marked by warmer water in the
Pacific off the coast of South America. It alters
weather patterns in the United States and
around the world.
During La Niña conditions (normal) , the
tradewinds blow toward the west across the
tropical Pacific, away from South America.
These winds pile up warm surface water in the
west Pacific, so that the sea surface is about
1-2 feet (about 0.5 meter) higher at Indonesia
than at Ecuador (in South America).
The sea-surface temperature is about 8
degrees Celsius higher in the west, with cool
temperatures off South America, due to an
upwelling of cold water from deeper levels.
This cold water is nutrient-rich, supporting high
levels of primary productivity, diverse marine
ecosystems, and major fisheries.
During El Niño, the tradewinds relax in the
central and western Pacific. Surface water
temperatures off South America warm up,
because there is less upwelling of the cold
water from below to cool the surface. This
cuts off the supply of nutrients, resulting in a
drastic decline in the food chain, including
commercial fisheries in this region.
Evidence shows that
human activities, including
intense fishing around the
world, are altering ocean
ecosystems beyond their
natural state.
 A recent study which has
mapped the total human
impact on the seas for the
first time has revealed that
the picture is far worse
than the scientists
imagined.
 40% of the world's oceans
have been heavily
affected by human
activities, including fishing,
coastal development, and
pollution from shipping.
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