Download OCEANOGRAPHY MORE OCEANOGRAPHY

4/18/2012
OCEANOGRAPHY
The Tides
Tides are the daily rise and fall of
ocean water level caused by the
moon & sun’s gravitational pull
(mainly the moon)
2 high and 2 low tides occur daily
Spring — greatest tidal range
because the moon, sun, and Earth
are in alignment (full/new moon)
Neap — lowest tidal range
worldwide; happens during quarter
moon phases
MORE OCEANOGRAPHY
Waves are generated by
the wind
The ocean is the largest
reservoir of heat…therefore, it
drives most of the Earth’s
weather systems
Current systems are created by the Coriolis Effect and
Wind. In the Northern Hemisphere, currents turn
clockwise and warm water moves toward the poles and
cold water moves toward the equator (convection
currents)
Sea level can change. Sea level rises when polar ice
caps melt and sea level goes down when more ice is
created.
1
4/18/2012
MORE OCEANOGRAPHY
Upwelling occurs when cold water
sink and forces the water on the
bottom to be pushed to the surface,
resulting in cold bottom water rising to
fill the gap. This nutrient-rich water
provides extreme amounts of food for
fish, therefore upwelling areas are
known for rich biological activity.
Estuaries — areas where fresh water rivers
meet salt water areas. The Chesapeake
Bay is an example. There are variations in
salinity (salt content) and diverse biological
life.
MORE OCEANOGRAPHY
Salinity, Element Concentrations, and Density Currents
Salinity is the amount of salt in the
water. Average salinity is 3.5%.
Because of the salt, ocean water is
more dense than fresh water. The
salt is washed off the continents by
runoff & concentrated in the ocean.
Concentration of elements in the ocean
(contains 70 elements, here are the top 3):
55% chloride (from volcanoes)
31% sodium (from rivers)
4% magnesium
Density currents occur when dense
seawater moves to a less dense area.
Cold water moves to warm areas
Water with salt is more dense.
Evaporation or the formation of ice may
cause the salinity of water to increase.
Rainfall & melting of ice causes salinity of
water to decrease.
2
4/18/2012
AND YET EVEN MORE OCEANOGRAPHY
Species types in the oceans
Pelagic
Species—
live in
seawater
Benthic
species—
live on the
bottom
Phytoplankton – Primary Producers of the Oceanic Food Web
Source of energy is sunlight
They include diatoms, coccolithophores, cyanobacteria especially
synechococcus and prochlorococcus, and dinoflagellates.
Overall, they are called algae.
Phytoplankton are primary producers because they use solar
energy to convert CO and nutrients into carbohydrates and other
molecules used by life. This is called photosynthesis. Together,
they account for about 95% of the primary productivity in the
ocean and about half of all primary productivity on earth.
2
Features of Ocean Floor
Extending out from a continent's edge is a gently sloping, shallow area called the
continental shelf (F). At the edge of the shelf, the ocean floor drops off in a steep incline
called the continental slope (A). The continental slope marks the true edge of the
continent, where the rock that makes up the continent stops and the rock of the ocean
floor begins. Beyond this slope is the abyssal plain (C), a deep, smooth and nearly flat
area of the ocean floor. In some places, deep, steep-sided canyons called trenches (G)
cut into the abyssal plain. These indicate a convergent boundary. A continuous range of
mountains called the mid-ocean ridge (D) winds around Earth. These indicate a
divergent boundary. There are mountains on the abyssal plain, too. Some reach above
the ocean surface to form volcanic islands (E). Others, called seamounts (B), are
volcanoes completely under water.
3