Why is it in the News?

The US National Oceanic and Atmospheric Administration (NOAA) has recently forecasted an 83% likelihood that the Oceanic Niño Index (ONI) will move into a neutral range between April and June 2024.

What is the Oceanic Niño Index?

• The Oceanic Niño Index (ONI) is the National Oceanic and Atmospheric Administration's (NOAA) primary indicator for monitoring El Niño and La Niña, which are opposite phases of the climate pattern called the El Niño-Southern Oscillation, or “ENSO” for short.
  • NOAA is a US governmental agency responsible for monitoring and researching the Earth's oceans, atmosphere, and climate, and providing weather forecasts and environmental data.
• The ONI is the difference between a three-month running average of the sea surface temperature averaged over an area of the ocean from 120 West to 170 West longitude along the equator and the long-term average for the same three months.
• NOAA considers El Niño conditions to be present when the Oceanic Niño Index is +0.5 or higher, indicating the east-central tropical Pacific is significantly warmer than usual.
• La Niña conditions exist when the Oceanic Niño Index is -0.5 or lower, indicating the region is cooler than usual.

What is El Niño and La Niña?

• El Niño and La Niña are two natural climate phenomena that occur in the Pacific Ocean, characterized by fluctuations in ocean surface temperatures.
• They are part of the El Niño-Southern Oscillation (ENSO) cycle, which impacts global weather patterns.
  • El Niño refers to the warming of ocean surface temperatures in the eastern tropical Pacific.
    • This warming causes changes in atmospheric pressure and wind patterns, which can lead to drought conditions in parts of South America and heavy rainfall in other regions, such as the southern United States.
  • La Niña is the opposite phase of the ENSO cycle, characterized by cooler-than-average ocean surface temperatures in the eastern tropical Pacific.
    • This results in the strengthening of normal trade winds, causing increased rainfall in some regions, such as Indonesia and northern Australia, and drier conditions in other areas, including the southwestern United States.

Effects of El Niño and La Niña on India:

• Both El Niño and La Niña have significant impacts on India's climate, particularly during the monsoon season.
• El Niño events often lead to weaker monsoon winds and reduced rainfall in India, causing droughts and impacting agricultural production.
• On the other hand, La Niña events typically result in stronger monsoon winds and higher rainfall, leading to better agricultural yields.
  • However, excessive rainfall can also cause floods and landslides in some regions.
• Monitoring and predicting the occurrence of El Niño and La Niña events is crucial for India's weather forecasting and agricultural planning.
• Accurate predictions enable authorities to take necessary measures to mitigate potential adverse effects on agriculture and infrastructure.