El Nino/Southern Oscillation by s981nv

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									El Niño / Southern Oscillation
(ENSO)
            By Sagar Bora
        University of Bremen
                          Outline

   Motivation/History
   El – Niño/La Niña definition
   Normal Conditions in the Pacific Ocean
   El – Niño Conditions
   La-Niña Conditions
   Effects of El – Niño and La-Niña
   El – Niño facts
   Summary
11/4/2012                Presented by Sagar Bora   2
                                          El Niño
       From the mid 18th century,
        Peruvian fisherman noticed
        that their harvest completely
        failed every few years.
       This periodic event was
        associated with unusually
        warm waters off the coast of
        Peru.
       Since the periodic warming
        almost always occurred
        around December, the
        fisherman named it El Niño,
        in reference to the Christ
        child.


    11/4/2012                            Presented by Sagar Bora                                 3

Motivation      Definitions   Normal conditions     El Nino        La Nina   Effects   Facts   Summary
                              Southern Oscillation
                                        In the late 19th century Gilbert Walker,
                                         the head of the Indian Meteorological
                                         Service notices that the Indian monsoon
                                         fails periodically every few years, leading
                                         to drought and famine in India.
                                        Search for a way to predict the Indian
                                         monsoon.
                                        Identified a peculiar see-saw relationship
                                         between pressure over the maritime
                                         continent and India and the Pacific near
                                         South America.
                                        He called this relationship the Southern
                                         Oscillation.

    11/4/2012                            Presented by Sagar Bora                                 4

Motivation      Definitions   Normal conditions     El Nino        La Nina   Effects   Facts   Summary
                                           ENSO

                                     In 1969, UCLA professor Jacob Bjerknes
                                      was the first to recognize that El Niño and
                                      the Southern Oscillation are actually
                                      manifestations of the same physical
                                      phenomenon and that it results from an
                                      unstable interaction between the
                                      atmosphere and the ocean. This resulted in
                                      the term ENSO to refer to this
                                      phenomenon.




    11/4/2012                            Presented by Sagar Bora                                 5

Motivation      Definitions   Normal conditions     El Nino        La Nina   Effects   Facts   Summary
                  Why should we study El Niño?

       Reduced upwelling off the coast of South America. So
        periodic failure of fishery near Peru, which normally is
        responsible for one-fifth of global fish production.
        High coral mortality
       Drought in South-east Asia, India, Australia and
        Africa
       Heavy rainfall in the South Americas



    11/4/2012                            Presented by Sagar Bora                                 6

Motivation      Definitions   Normal conditions     El Nino        La Nina   Effects   Facts   Summary
                               El – Niño definition




                        From: www.weathersa.co.za

          El Niño : When the three-month running mean of the Sea Surface
             Temperature anomalies in the Nino 3.4 region are greater than or
             equal to 0.5°C, an El Niño event is assumed to be taking place.


    11/4/2012                               Presented by Sagar Bora                                 7

Motivation      Definitions    Normal conditions       El Nino        La Nina   Effects   Facts   Summary
                               La Niña definition




                     From: www.weathersa.co.za

       La Niña : When the three-month running mean of the Sea
         Surface Temperature anomalies in the Nino 3.4 region are
         greater than or equal to -0.5°C, an La Nina event is
         assumed to be taking place.
    11/4/2012                            Presented by Sagar Bora                                 8

Motivation      Definitions   Normal conditions     El Nino        La Nina   Effects   Facts   Summary
       Normal Conditions in the Pacific Ocean
                                                            Nutrient rich cool water
                                                             along the Peruvian coast
                                                             (eastern pacific) due to
                                                             upwelling;
                                                             good for marine life;
                                                            Shallow mixed layer;
                                                             thermocline raised
                                                            3 to 8 °C warmer water in the
                                                             west Pacific near Australia,
                                                             Indonesia
                                                            Deep mixed layer;
                                                             thermocline pushed down
    From: www.weathersa.co.za

    11/4/2012                              Presented by Sagar Bora                                 9

Motivation        Definitions   Normal conditions     El Nino        La Nina   Effects   Facts   Summary
        Normal Conditions in the Pacific Ocean




   Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz



    11/4/2012                                                 Presented by Sagar Bora                                 10

Motivation          Definitions             Normal conditions            El Nino        La Nina   Effects   Facts   Summary
          Normal Conditions in the atmosphere

                                                                   High pressure in the east above the
                                                                    cold water, low pressure in the west
                                                                    above the warmer water
                                                                   Pressure gradients result in easterly
                                                                    trade winds which in turn results in
                                                                    upwelling along the Peruvian coast
                                                                   Trade winds brings moist warm air
                                                                    towards Indonesian region which rises
                                                                    and travels eastward before sinking in
                                                                    the east. This is a thermally direct
                                                                    circulation found by Sir G. Walker.

        From: www.weathersa.co.za




    11/4/2012                                  Presented by Sagar Bora                                 11

Motivation       Definitions        Normal conditions     El Nino        La Nina   Effects   Facts   Summary
       El – Niño Conditions in the atmosphere

                                                                  Easterly winds weakens, even
                                                                  changes directions sometimes and
                                                                  becomes westerlies due to change
                                                                  in the sign of pressure gradient. Sir
                                                                  Walker called this east-west seesaw
                                                                  in southern Pacific pressure
                                                                  “Southern Oscillation”


        From: www.weathersa.co.za




    11/4/2012                                  Presented by Sagar Bora                                 12

Motivation       Definitions        Normal conditions     El Nino        La Nina   Effects   Facts   Summary
       El Niño conditions in the Pacific Ocean
                                                             Due to change in the wind
                                                              direction, the currents on the ocean
                                                              also slows down or changes
                                                              direction from westward to
                                                              eastward.
                                                             SST rises in the eastern pacific and
                                                              the western pacific cools down a
                                                              bit; Downwelling occurs off the
                                                              coast of Peru; nutrient-less warm
                                                              surface water leads to decline in
                                                              marine life
                                                             Rainy conditions move with the
                                                              warmer SST and dry conditions
                                                              move with the cold
     From: www.weathersa.co.za

    11/4/2012                               Presented by Sagar Bora                                 13

Motivation        Definitions    Normal conditions     El Nino        La Nina   Effects   Facts   Summary
      El Niño Conditions in the Pacific Ocean




      Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz




    11/4/2012                                                Presented by Sagar Bora                                 14

Motivation         Definitions             Normal conditions            El Nino        La Nina   Effects   Facts   Summary
                A normal year and an El Niño year




                      Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz

    11/4/2012                                                Presented by Sagar Bora                                    15

Motivation      Definitions            Normal conditions                        El Nino   La Nina   Effects   Facts   Summary
                                          La Niña conditions
                                                                     During La Niña years, the
                                                                      upwelling off the Peruvian coast is
                                                                      enhanced and the SSTs in the Nino
                                                                      regions become cooler than usual.
                                                                     The Walker Circulation operates in
                                                                      the same way as described for
                                                                      normal years, but because of the
                                                                      larger area of colder water off the
                                                                      South American coast and the
                                                                      displacement of warmer water to
                                                                      the west, the atmospheric pattern
                                                                      also shifts accordingly. Heavier
                                                                      rainfall over Australia and
                                                                      Indonesia and dry spans over
                                                                      South Americas
             From: http://www.wrh.noaa.gov/


    11/4/2012                                        Presented by Sagar Bora                                 16

Motivation         Definitions            Normal conditions     El Nino        La Nina   Effects   Facts   Summary
       La Niña conditions in the Pacific Ocean




        Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz



    11/4/2012                                               Presented by Sagar Bora                                 17

Motivation        Definitions             Normal conditions              El Nino      La Nina   Effects   Facts   Summary
                                Global impacts of El Niño




    Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz



    11/4/2012                                                 Presented by Sagar Bora                                 18

Motivation          Definitions             Normal conditions            El Nino        La Nina   Effects   Facts   Summary
                               Global impacts of La Niña




    Source: http://www.wrh.noaa.gov/fgz/science/elnino.php?wfo=fgz




    11/4/2012                                                 Presented by Sagar Bora                                 19

Motivation          Definitions             Normal conditions            El Nino        La Nina   Effects   Facts   Summary
                                    El Niño facts

            ENSO is not a weather anomaly, it’s a part of a cycle.
            Every weather anomaly throughout the world that
             occurs during an El Niño year is not caused by that El
             Niño.
            The impact of global warming on El Niño is not as
             yet known, speculation notwithstanding.
            Forecasting El Niño’s onset does not tell us much
             about its other characteristics (e.g., intensity,
             frequency, duration).


    11/4/2012                            Presented by Sagar Bora                                 20

Motivation      Definitions   Normal conditions     El Nino        La Nina   Effects   Facts   Summary
                        Summary and conclusions

       El Niño , La Nina and the Southern Oscillations are coupled
        phenomenon that occurs periodically at the Pacific Ocean.
       Normally, SST and SSH at the eastern pacific is lower than the western
        pacific.
       During El Niño , it’s the opposite of the normal conditions. SST and SSH
        rises in the eastern pacific and easterlies slows down or changes direction.
       La Niña is the extreme of the normal conditions. SST at the east coast
        decreases more than usual.
       Both La Niña and El Niño effects the global climate and the economy of
        many countries.



    11/4/2012                            Presented by Sagar Bora                                 21

Motivation      Definitions   Normal conditions     El Nino        La Nina   Effects   Facts   Summary
            Thank you for Listening!!
                  Questions?




11/4/2012           Presented by Sagar Bora   22

								
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