How does the Coriolis effect influence the wind?
How do you think this would affect currents in the
ocean?
Journal 2: WED 1/11
What role do currents play in transporting heat? How
do currents affect climate?
WEBSITE FOR WEBQUEST:
http://www.oar.noaa.gov/k12/html/elnino2.html
Highways in the Sea
Causes of Currents
What forces are
responsible for currents?
Wind: transfers energy
through friction on
surface; causes currents
and waves
Sea level: steeper
slope=greater pressure
gradient=drives a larger,
faster current
Water density: greater
density in one area causes
pressure gradient to drive a
current below the surface
What influences the
direction and nature of
these currents?
- Ocean boundaries force
currents in various
directions;
- Trade winds and the
westerlies account for
most of the wind’s energy
that drives currents
Gyres
What is a gyre?
Combo of the westerlies
pushing water eastward,
the trade winds
pushing it westward, and
the Coriolis effect
resulting in the circular
flow in each ocean basin
5 major gyres
What is an eddie?
Friction against water’s surface that causes swirling
currents
Important because they can profoundly affect local
temperatures and water conditions.
Commercial fishing vessels use eddies to locate fish
Can also influence the speed of a ship
Can affect local climates by redistributing heat
Western Boundary Currents
& Eastern Boundary Currents
How do Western
Boundary Currents differ
from Eastern Boundary
Currents?
- Eastern Currents: carry
cool water towards
equator; tend to be wide
and shallow; not
common to have eddies
spin off these currents
- Western Currents:
much stronger; western
intensification: Coriolis
effect is a major
contributor; there is weak
flow of water toward the
equator; flow of western
boundary currents
balances this slow drift;
Trade winds also
contribute to the strong
western currents
Upwelling vs. Downwelling
Wind-driven currents that flow vertically
Upwelling: upward vertical current that brings deep
water to the surface
Downwelling: downward vertical current that pushes
surface water deep into the ocean
What kind of biological effect does this have?
-nutrients to shallow waters and to deeper waters
-weather patterns
El Nino Southern Oscillation
(ENSO)
Buildup of warm water in the Central and Eastern
Equatorial Pacific
Tremendously affects world weather patterns
El Niño = warm surface current in equatorial eastern
Pacific that occurs periodically around Christmastime
Southern Oscillation = change in atmospheric
pressure over Pacific Ocean accompanying El Niño
ENSO describes a combined oceanic-atmospheric
disturbance
Normal Conditions in the PO
El Nino Conditions
El Nino Effect on weather, marine
habitats, and human activity
Most severe events of ENSO caused flooding,
tornados, drought; 23,000 deaths and $33 billion in
damages
Ruins kelp beds by warming the water b/c kelp only
thrives in moderate to cold waters
This also affects local fish populations and other
marine ecosystems
La Nina
Powerful upwellings bring deep cooler waters to the
surface
This colder than normal condition is called La Nina
(opposite of El Nino)
Scientists still trying to determine what exactly causes
these warm and cold phases
Ocean Conveyor Belt
The interconnected flow of currents that
redistribute heat
Earth’s “air conditioner”
Moderates the world’s climate
Ocean Conveyor Belt Animation:
http://bcs.whfreeman.com/thelifewire/content/chp58/5
802003.html
Examples of Instruments/Methods
that scientists use to study currents
1. Drogue: float that determines the drift of currents
2. Argo Float: float that transmits data to satellites
3. Various Flow Meters: measure and record current
speed and direction (Eulerian study method)
4. Doppler Acoustic Current Meter: determines
current direction and speed
5. Flotsam method: accidental opportunities to study
currents; ships losing cargo that wash up on beaches
and can improve computer models of currents
CFA: SO3b: Explain the influence of the Coriolis
effect on winds, ocean currents, and on weather
and climate.
1.
2.
3.
4.
5.
6.
What is the difference between an upwelling and
downwelling?
How does El Nino (ENSO) effect the Earth’s climate
and weather?
What is an eddie? How does it effect Earth’s climate?
What forces are responsible for currents? Explain.
What is the Ocean Conveyor Belt?
Use a Venn Diagram to differentiate between western
boundary and eastern boundary currents.
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