The North Pacific Oscillation (NPO) is a

teleconnection Teleconnection in atmospheric science refers to climate anomalies being related to each other at large distances (typically thousands of kilometers). The most emblematic teleconnection is that linking sea-level pressure at Tahiti and Darwin, Austr ...

pattern first described by

Walker Walker or The Walker may refer to: People * Walker (given name) *Walker (surname) * Walker (Brazilian footballer) (born 1982), Brazilian footballer Places In the United States *Walker, Arizona, in Yavapai County *Walker, Mono County, California ...

and Bliss and characterized by a north–south seesaw in sea-level pressure over the North Pacific Ocean.
Rogers, using surface atmospheric temperature from St. Paul, Alaska, and

Edmonton Edmonton ( ) is the capital city of the Canadian province of Alberta. Edmonton is situated on the North Saskatchewan River and is the centre of the Edmonton Metropolitan Region, which is surrounded by Alberta's central region. The city an ...

, identified two phases of the NPO, an Aleutian below (AB) phase that correspond to a deepened and eastward shifted

Aleutian Low The Aleutian Low is a semi-permanent low-pressure system located near the Aleutian Islands in the Bering Sea during the Northern Hemisphere winter. It is a climatic feature centered near the Aleutian Islands measured based on mean sea-level press ...

and an Aleutian above (AA) phase that is the opposite. During the positive (AB) phase, sea-level pressure is enhanced over a large region in the

subtropics The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° nort ...

that extend poleward to 40N° and reduced at higher latitudes, westerlies are enhanced over the central Pacific and winter temperature are mild along much of the North America west coast but cooler than usual over Eastern Siberia and the United States South-West, precipitations are higher than usual over

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...

and the Great Plains. The effects of the NPO propagate into the subtropics and

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also refer ...

through another climate mode, the Pacific Meridional Mode.
The North Pacific Gyre Oscillation (NPGO) is the oceanic expression of the NPO.

References

External links

NPGO/NPO website
Regional climate effects Pacific Ocean {{climate-stub