2. What is El Nino?
• El Nino is the name given to a southerly, warm
ocean current off the coast of Ecuador is a
Spanish term “the Christ child”, so called as it
generally occurs after Christmas.
• El Nino is a naturally occurring event in the
equatorial region which causes temporary
changes in the world climate.
• It is not a regular event.
• The average period length is five years.
3. What is ENSO?
• ENSO is the "El Nino-Southern Oscillation,". The
Southern Oscillation is a see-saw shift in surface
air pressure between the eastern and western
halves of the Pacific. When pressure rises in the
east, it falls in the west and vice versa. In the
1950's scientists realized that El Nino and the
Southern Oscillation were parts of the same
event.
4. The ENSO Cycle
• Naturally occurring phenomenon.
• Equatorial Pacific fluctuates between warmer
than average (El Nino ) and colder than average
(La Nina) condition.
• The changes in SSTs(Sea surface temperature)
affect the distribution of tropical rainfall.
• Changes in intensity and position of jet streams
and storm activity occur at higher latitudes
5. The first signs of an El Nino
• A rise in air pressure in the Indian Ocean,
Indonesia,and Australia.
• A fall in air pressure over Tahiti and rest of the
central and eastern Pacific Ocean.
• Warm air rises in Peru.
• The trade winds in the south Pacific or hard east
6. Normal year
• In normal years,Eastern winds push the warm
surface waters westwards across equtorial south
pacific,causing warm surface water to accumulate
near Indonesia.
• This helps in the formation of clouds,which give
heavy rainfall in North Australia.
• Cold current carries oxygen & nutrients that
sustain fish.
8. El Nino year
• El Nino years,Easterly winds even reverse.Warm
surface water flows from west to east,increasing
the depth of warm water off the South American
coast.
• Heavy rainfall due to warm water.
• warm water suppresses the nutrient-rich Peru
current
• Fish & seabirds move away or die.
10. • Increased precipitation over parts of South
America,western and southern U.S.
• Severe flooding.
• Drought in Australia,Indonesia,phillipenes.
• Reduction in annual monsoons in India.
• Severe crop damage.
Effects of El Nino
12. Impact of El Nino on India
• Dry conditions and deficient monsoon.
• Alter the climate.
• Development of warm conditions.
• It will result drought /heavy rainfall situation.
• It reduces the production of summer crop.
13. Indian monsoon
• ENSO-induced warm zones in the Pacific cause
the warm air over them to rise and initiate
circulation cells. Such cells along northern
Australia, Indonesia and the eastern edge of the
Indian Ocean could have their downdraft sides
over a nascent monsoon circulation cell in the
Indian Ocean, which would disrupt its formation,
causing poor monsoon rains over the
subcontinent. This model implies that El Nino
years should coincide with deficient monsoon
rains.
