Climate Oscillations: ENSO, NAO and PDO
First published: 2025
Brief summary
Accessible explanation of major climate oscillations and their weather effects.
Article
El Niño–Southern Oscillation, the North Atlantic Oscillation and the Pacific Decadal Oscillation are large-scale patterns of ocean and atmospheric variability. They influence temperature, precipitation, storm tracks and seasonal weather across regions far from their centres of action.
ENSO develops in the tropical Pacific through linked changes in sea-surface temperature, trade winds and atmospheric pressure. El Niño is associated with unusually warm central and eastern equatorial Pacific waters, while La Niña is associated with unusually cool conditions in the same region.
The North Atlantic Oscillation reflects changes in the pressure difference between the subtropical Atlantic and the region near Iceland. Its positive and negative phases alter the strength and position of westerly winds, affecting winter temperature and rainfall across eastern North America, Europe and the Mediterranean.
The Pacific Decadal Oscillation describes a longer-lived pattern of North Pacific sea-surface temperature variability. It can resemble ENSO spatially but persists on decadal timescales, and its phase can reinforce or weaken regional effects associated with shorter-term climate variations.
Source details and credits
- Source / publisher: University of Illinois Extension
- Source type: Educational article
- URL type: WWW
- Credits: University of Illinois Extension
- URL: https://extension.illinois.edu/blogs/get-growing/2025-01-23-climate-oscillations-enso-nao-and-pdo