"Historic El Niño forecast raises concerns for India's monsoon and agriculture"
ENSO
El Niño–Southern Oscillation; ocean-atmosphere coupled climate cycle in the tropical Pacific with warm (El Niño), cool (La Niña), and neutral phases.
Niño 3.4 Region
Central-eastern equatorial Pacific zone used as the benchmark for measuring SST anomalies to define El Niño/La Niña events.
El Niño is the warm phase of the El Niño–Southern Oscillation (ENSO), a naturally recurring ocean-atmosphere coupled phenomenon centred in the tropical Pacific Ocean. Scientifically, El Niño is declared when sea-surface temperatures (SSTs) in the Niño 3.4 region of the central-eastern equatorial Pacific exceed the climatological mean by +0.5°C for five consecutive overlapping three-month periods. ENSO cycles through three phases — El Niño, neutral, and La Niña — roughly every two to seven years. The atmospheric pressure see-saw between the eastern and western Pacific is measured by the Southern Oscillation Index (SOI), which turns negative during El Niño events.
India's Southwest Monsoon (June–September) delivers approximately 75% of the country's annual rainfall, with a Long Period Average (LPA) of roughly 887 mm. Below-normal rainfall is defined as less than 90% of the LPA. The monsoon's strength is intimately linked to ENSO dynamics: El Niño events weaken the land-sea temperature gradient between the Indian subcontinent and the Indian Ocean, suppressing the moisture-laden winds that drive monsoon precipitation. Historically, roughly 60% of strong El Niño years have coincided with below-normal monsoon rainfall in India, though the relationship is not deterministic. Modulating factors — particularly the Indian Ocean Dipole (IOD) and the Madden-Julian Oscillation (MJO) — can offset or amplify El Niño's suppressive effect.
Under normal Pacific conditions, strong easterly trade winds push warm surface water westward toward the Indo-Pacific Warm Pool, sustaining the Walker Circulation — a zonal atmospheric loop in which air rises over the western Pacific and subsides over the eastern Pacific. During El Niño, trade winds weaken or reverse, warm water shifts eastward, and the Walker Circulation weakens. This causes anomalous subsidence over the Indian Ocean, suppressing convection and reducing the moisture flux that feeds the Indian monsoon.
The Indian Ocean Dipole (IOD) is the Indian Ocean's counterpart to ENSO. In its positive phase, the western Indian Ocean warms relative to the eastern Indian Ocean, strengthening the moisture gradient toward the Indian subcontinent and partly offsetting El Niño's suppressive influence. A negative IOD, by contrast, can compound El Niño's adverse effects. …
In the South Atlantic and South-Eastern Pacific regions in tropical latitudes, cyclone does not originate. What is the reason?
With reference to "Coriolis force", which of the following statements is/are correct?
1.It increases with increase in wind velocity.
2.It is maximum at the poles and is absent at the equator.
Select the answer using the code given below:
With reference to El Niño, consider the following statements:
1.El Niño is declared when sea-surface temperatures in the Niño 3.4 region exceed the climatological mean by +0.5°C for five consecutive overlapping three-month periods.
2.The Southern Oscillation Index (SOI) turns positive during El Niño conditions.
3.El Niño events weaken the Walker Circulation, causing anomalous subsidence over the Indian Ocean.
Which of the statements given above is/are correct?
Which of the following best explains why a positive Indian Ocean Dipole (IOD) can partially offset El Niño's adverse effect on India's Southwest Monsoon?
Consider the following statements about India's Southwest Monsoon:
1.The Long Period Average (LPA) for the Southwest Monsoon is approximately 887 mm.
2.Below-normal monsoon is defined as rainfall less than 90% of the LPA.
3.The Southwest Monsoon delivers approximately 60% of India's annual rainfall.
Which of the statements given above is/are correct?
With reference to NOAA's ENSO monitoring, which of the following is the primary sea-surface temperature region used to classify El Niño and La Niña events?
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