PowerPoint Presentation Upwelling in the world ocean (PowerPoint)

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					Upwelling in the World Ocean
        Presentation Points
 Mechanisms that create ocean upwelling
 Types of upwelling
 Identifying upwelling on satellite-derived
  maps
 Ecological and economic effects of
  upwelling
    Mechanisms that create
       ocean upwelling
 Wind
 Coriolis
         Effect
 Ekman Transport
Upwelling refers to deep water
that is brought to the surface.




Areas of upwelling are created by surface winds
that pull water away from an area. This deficit of
water on the surface invites water to come up
from deeper regions.
To understand upwelling, you must be familiar with how
the Coriolis Force affects ocean surface currents. The
 Coriolis Effect acts on moving water, because it is not
 attached to the rotating Earth. As water flows over the
  rotating earth, it appears to deflect to the right in the
   Northern Hemisphere and the left in the Southern.
Due to friction between the layers of water in the ocean
  and the Coriolis Effect, the net result of wind blowing
  across the surface of the water is transportation of a
 layer of water 90 degrees to the direction of the wind.
           This is known as Ekman Transport.
        Types of Upwelling
 Equatorial
 Coastal
 Seasonal
1. Equatorial Upwelling




                     Upwelling
Look at the equator in the
     Pacific Ocean.
2. Coastal Upwelling
 (follow the black arrows)
What’s the difference between
 Peru(A) and Columbia (B)?

             B

            A
     3. Seasonal upwelling

        Wind                        Wind




Onshore winds pile        Offshore winds take
water up on shore,        water away from
thus surface water will   shore, thus water
be forced downward.       from depth will
This is ‘downwelling’.    upwell to the surface.
 The Monsoonal wind shifts in
  Oman create very different
        conditions.




April, 1999                  August, 1999
Onshore winds: Downwelling   Offshore winds: Upwelling
  Identifying upwelling on
   satellite-derived maps

 SeaSurface Temperature
 Ocean Color
The deep water that surfaces in upwelling is
cold; by looking at Sea Surface Temperature
 maps we can identify cool upwelled water
         versus hotter surface water.
  Upwelled water also contains nutrients
(nitrate, phosphate, silicate) and dissolved
 gases (oxygen and carbon dioxide) that
are not utilized at depth because of a lack
                 of sunlight.

 Now on the surface, these nutrients and
  gases help to fuel photosynthesis by
   small algae called phytoplankton.
    Phytoplankton photosynthesize using
specialized color pigments called chlorophyll.
Thus, “Ocean Color” maps are another way to
  identify areas of upwelling. Where on this
   ocean color map are high phytoplankton
                concentrations?
    Ecological and Economic
      effects of upwelling:
 Upwelling leads to more phytoplankton
 More phytoplankton leads to more fish
 More fish lead to commercial fishing jobs
  and to more seafood
Phytoplankton come in many shapes
and forms. Collectively they form the
     base of oceanic food webs.




     Without upwelling many of the
     world’s fisheries would not thrive.
Some climatic events can reduce
         upwellings.


       El Nino   ~
     Along Peru’s coast, an El Nino event decreases
       the coastal winds. Thus the upwelling from
                    below is slowed.




An El Nino condition results from weakened trade winds in the western Pacific
Ocean near Indonesia, allowing piled-up warm water to flow toward South America.
  Even though upwelling areas
account for only 1% of the ocean
surface, they support 50% of the
        worlds fisheries.
    Productivity (phytoplankton growth)
    of an area is determined by the rate
    and the duration of upwelling.

   Rate of upwelling       Duration of upwelling
    determines               determines the total
    phytoplankton cell       amount of
    size.                    phytoplankton.




    small vs. large             few vs. many
 Classification of upwelling systems in terms of
                rate and duration:
                       RATE
         Low          Medium           High
 Short
Long




                                       After Thurman, H.V. (1994)
•Moderate rates of upwelling for long
duration (8 months or longer) provide the
ultimate combination for a large fishery.

•With too low or too high a rate,
phytoplankton are small, so there is a
trophic level between the algae and the
fish….therefore the fish receive less
energy.
             Upwelling and Fisheries
                             January                                           April




                              July                                            October




Using this series of Sea Surface Temperature Maps from 1999, can
you determine areas/times for possible fisheries?

(Hint: Look at Peru’s coast in January and April. Look at the northwestern tip of Africa in
July and October.)

				
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