Pacific Decadal Oscillation
The Pacific Decadal Oscillation (PDO) is a long-term, El Niño-like pattern of climate variability in the Pacific Ocean that persists for 20-30 years at a time. It has both warm and cold phases that have related impacts on Pacific region weather.
Differences from ENSO
While the PDO is similar to the El Niño-Southern Oscillation (ENSO), key differences include:
- The PDO persists for decades while ENSO persists for 1-2 years
- PDO primary climatic fingerprints are in the North Pacific while ENSO’s are in the tropics
- Warm PDO resembles El Niño conditions while cool PDO resembles La Niña
The mechanisms behind the PDO are also currently unknown.
PDO Phases
The PDO has two distinct climate phases:
- Warm phase: More El Niño-like – Favors warmer temperatures in the north Pacific and stronger Aleutian Low pressure system.
- Cool phase: More La Niña-like – Leads to cooler north Pacific Ocean temperatures and weaker Aleutian Low.
Influence on Regional Climate
Shifts in the PDO influence climate variables like temperature and precipitation. Effects include:
- Warmer Alaska temperatures and altered marine ecosystem productivity during warm phase
- Cooler Alaska coastal waters and temperatures during cool phase
- Potential links to decadal precipitation variations across North America
Ongoing research aims to better understand PDO mechanisms and predictability for improved climate forecasting.