EL NIÑO SOUTHERN OSCILLATION - GEOGRAPHY
News: What is El Nino and how it impacts the monsoon
What is in the news?
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Recently, some Meteorological
experts said that This year’s monsoon is also progressing under the cloud of an
El Nino in the Pacific Ocean.
What is El Nino Southern Oscillation?
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The opposite phase, La
Nina, which is the abnormal cooling of sea surface waters in the same region,
is known to aid rainfall over India.
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There is a third, neutral
phase, as well in which the sea surface temperatures remain roughly in line
with long-term averages.
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Together, these three
phases in the Pacific Ocean are referred to as El Nino Southern Oscillation, or
ENSO.
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The ocean part of the
ENSO is measured by what is known as the Oceanic Nino Index or ONI.
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The atmospheric part is
monitored through the Southern Oscillation Index, or SOI.
What is the Oceanic Nino Index?
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It Measures the oceanic
component of El Nino Southern Oscillation (ENSO).
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Tracks the departure from
average sea surface temperatures in the tropical Pacific Ocean.
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Helps quantify the
intensity and duration of El Nino or La Nina events.
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Typically based on a
rolling three-month average of sea surface temperature anomalies in specific
regions.
What is the Southern Oscillation Index (SOI)?
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Measures the atmospheric
component of ENSO.
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Quantifies the difference
in air pressure between two locations: Tahiti and Darwin.
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Positive
SOI values indicate higher pressure in the eastern Pacific and lower pressure
in the western Pacific.
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Negative
SOI values indicate lower pressure in the eastern Pacific and higher pressure
in the western Pacific.
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Reflects the strength and
changes in the atmospheric circulation patterns associated with ENSO.
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Used to assess the phase
and strength of ENSO and its impact on global weather and climate patterns.