Pacific decadal oscillation

The Pacific decadal oscillation (PDO) is a robust, recurring pattern of ocean-atmosphere climate variability centered over the mid-latitude Pacific basin. The PDO is detected as warm or cool surface waters in the Pacific Ocean, north of 20°N. Over the past century, the amplitude of this climate pattern has varied irregularly at interannual-to-interdecadal time scales, meaning time periods of a few years to as much as time periods of multiple decades.

Source: Wikipedia — Pacific decadal oscillation (CC BY-SA 4.0)