Double-Dip La NiƱa | 21 Oct 2021
Why in News
Recently, the National Oceanic and Atmospheric Administration (NOAA, an American scientific agency) has declared that La Niña has re-developed. Consecutive La Niña is called Double-Dip.
Key Points
- About:
- La Nina is one part of the El Nino Southern Oscillation (ENSO) cycle, which is characterized by opposing warm and cool phases of oceanic and atmospheric conditions in the tropical Pacific Ocean.
- Consecutive La Ninas following a transition through ENSO neutral conditions are not uncommon and can be referred to as a “Double-Dip.”
- In 2020, La Nina developed during the month of August and then dissipated in April 2021 as ENSO-neutral conditions returned.
- For the upcoming winter season, which extends from December 2021 through February 2022, there is an 87% chance of La Nina.
- Previous La Ninas occurred during the winter of 2020-2021 and 2017-2018, and an El Nino developed in 2018-2019. When neither climate pattern is present, ENSO is neutral and does not influence global climate patterns.
- ENSO:
- It is a periodic fluctuation in sea surface temperature (El Niño) and the air pressure of the overlying atmosphere (Southern Oscillation) across the equatorial Pacific Ocean.
- El Nino and La Nina are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region. They are opposite phases of what is known as the ENSO cycle.
- El Nino and La Nina episodes typically last nine to 12 months, but some prolonged events may last for years.