The Pacific Decadal Oscillation (PDO) is a low-frequency seesaw (ENSO-like) pattern of sea surface temperature in the Pacific Ocean, but varies on decadal (20 to 30 year) time scales. On decadal time-scales the PDO has been identified as a source of ocean-atmosphere climate variability that has impacts over the U.S. Recent studies have shown that ENSO and PDO can reinforce or weaken each other's effects.
A long-lived El Niño-like pattern of Pacific climate variability. The Pacific Decadal Oscillation operates at something on the order of a 20- to 30-year time scale, while El Niño/La Niña events are typically on the order of 6 to 18 months in length. Both phenomena correlate with relatively wetter or drier periods in the western portion of North America.
cyclic variations in sea-surface temperature in the Northern Pacific—an example of natural climate variability. These occur on decadal timescales and affect the weather in places like the U.S. Pacific Northwest region.