North Pacific Oscillation

{{Short description|Climatic cycle affecting North America and East Asia}}

Image:North Pacific Oscillation.png

The North Pacific Oscillation (NPO) is a teleconnection pattern first described by Walker and Bliss{{cite journal |last=Walker |first=Gilbert T.|author2=E.W. Bliss |year=1932|title=World weather V|journal=Memoirs of the Royal Meteorological Society|volume=4|pages=53–84|url=http://www.rmets.org/pdf/ww5.pdf|access-date=2010-10-09 }} 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, identified two phases of the NPO, an Aleutian below (AB) phase that correspond to a deepened and eastward shifted Aleutian Low and an Aleutian above (AA) phase that is the opposite.{{cite journal |last=Rogers |first=Jeffery C.|year=1981|title=The North Pacific Oscillation|journal=International Journal of Climatology|volume=1|issue=1|pages=39–57|doi=10.1002/joc.3370010106|bibcode=1981IJCli...1...39R}}

During the positive (AB) phase, sea-level pressure is enhanced over a large region in the subtropics 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 and the Great Plains. The effects of the NPO propagate into the subtropics and tropics through another climate mode, the Pacific Meridional Mode.{{cite journal |last=Linkin|first=Megan E.|author2=Sumant Nigam |year=2008|title=The North Pacific Oscillation–West Pacific Teleconnection Pattern: Mature-Phase Structure and Winter Impacts|journal=Journal of Climate|volume=21|issue=9|pages=1979–1997|doi=10.1175/2007JCLI2048.1|bibcode=2008JCli...21.1979L|doi-access=free}}

The North Pacific Gyre Oscillation (NPGO) is the oceanic expression of the NPO.{{cite journal |last=Ceballos |first=Lina |author2=Emanuele Di Lorenzo |author3=Carlos D. Hoyos |author4=Niklas Schneider |author5= Bunmei Taguchi |year=2009|title=North Pacific Gyre Oscillation Synchronizes Climate Fluctuations in the Eastern and Western Boundary Systems|journal=Journal of Climate|volume=22 |issue=19|pages=5163–5174|doi=10.1175/2009JCLI2848.1|url=http://journals.ametsoc.org/doi/full/10.1175/1520-0442(1997)010%3C1821%3AATOICV%3E2.0.CO%3B2|access-date=2010-10-07 |bibcode=2009JCli...22.5163C |hdl=1853/26552 |s2cid=53349832 |hdl-access=free }}