Oceanic Niño Index

About Oceanic Niño Index

• It is the National Oceanic and Atmospheric Administration’s (NOAA) primary indicator for monitoring the ocean part of the seasonal climate pattern called the El Niño-Southern Oscillation, or “ENSO”.
• The ONI tracks the running 3-month averagesea surface temperatures in the east-central tropical Pacific between 120°-170°W, near the International Dateline, and whether they are warmer or cooler than average.
• Index values of +0.5 or higher indicate El Niño and values of -0.5 or lower indicate La Niña.

What are El Nino and La Nina?

• El Nino and La Nina are two opposing climate trends that deviate from the normal conditions and normally run nine to twelve months, but can often extend.
• These events occur every two to seven years on average (El Nino is more frequent than La Nina), but not on a regular basis and together are referred to as the El Nino-Southern Oscillation (ENSO) cycle by scientists.
• El Nino is typically known as the warm phase (a band of warmer water spreading from west to east in the equatorial Pacific Ocean) and La Nina is identified as the cold phase (a band of cooler water spreads east-west) of ENSO.
• Both El Nino and La Nina can have global effects on weather, wildfires, ecosystems and economics.

Q1: What is Southern Annular Mode?

It is the north-south movement of Southern Westerly Winds over timescales of 10s to 100s of years. It is also known as the Antarctic Oscillation.They blow almost continuously in the mid- to high-latitudes of the southern hemisphere.

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