OCEAN CURRENTS:
CURRENT:
Continuous and directed
movement of ocean water

TWO TYPES:
Surface Currents
 Deep Water Currents

SURFACE CURRENTS:
10% of water in ocean
 The upper 400m of the ocean

DEEP WATER CURRENTS:
90% of water in ocean
 Waters move around the ocean
basins by density differences
 Density differences a function of
different temperatures and salinity

TWO TYPES OF FORCES:
Primary Forces: Start the water
moving:

 Solar
Heating
 Winds
 Gravity
 Coriolis Effect
Secondary Forces: Influence
where the current goes

SOLAR HEATING:
Causes water to expand
 Water is about 8 cm higher than
middle latitudes, thus water wants
to flow down slope

WINDS:
Winds blowing on surface of the
ocean push the water
 Water piles up in the direction the
wind is blowing

GRAVITY
Will pull water “down the hill”
when water mounds up

CORIOLIS EFFECT:
An inertial effect due to the
spinning of the earth

When going towards pole you
are coming from an area that is
moving faster, thus the
deflection with the direction of
the Earth’s rotation
When going to the equator, the
deflection goes against the spin
of the Earth, due to the spin of
the Earth
GYRES:
The effect of winds and Coriolis
effect results in circular flows of
water made of several currents

EKMAN TRANSPORT:
Surface water is
blown away by winds,
dragging the water
beneath it
 The deflection due to
Coriolis Effect creates
a spiral pattern and a
net current to the
right or left of wind
 Results in upwelling

UPWELLING:
Nutrient rich water from the
deeper parts of the ocean rises to
the surface to replace the water
blown away
 Animation:

DEEP WATER CIRCULATION:
Occur where the temperature is
cold and relatively high in salinity
 Thermohaline Circulation
Thermo = heat, haline = salt

EARTH CONVEYOR BELT
Salt rich, warm water is blown north
by the Gulf Stream, where is cools
and sinks
 This provides heat to the polar
regions and nutrients everywhere
 Possibly disrupted by global warming

LOCAL CURRENTS:
formed by a combination of tides,
winds, waves, and rivers/streams
 Longshore currents and rip
currents

LONGSHORE CURRENTS:
When waves strike the shoreline
at an oblique angle, causing
resultant waves to move parallel
with the shoreline

RIP CURRENTS:
Formed when waves push the
water in front of it sideways till it
can find a path out to sea
