Ocean Circulation Signatures of North Pacific Decadal Variability. Issue 3 (11th February 2019)

• Record Type: Journal Article
• Authors: Wills, Robert C. J.; Battisti, David S.; Proistosescu, Cristian; Thompson, LuAnne; Hartmann, Dennis L.; Armour, Kyle C.
• Is Part Of: Geophysical research letters. Volume 46:Issue 3(2019)
• Page Start: 1690
• Page End: 1701
• Publication Date: 2019-02-11
• Subjects: Pacific Decadal Oscillation -- climate variability -- climate dynamics -- atmosphere‐ocean coupling -- ocean gyre circulation -- sea level; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1029/2018GL080716
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: The Pacific Decadal Oscillation (PDO) is the dominant pattern of observed sea surface temperature variability in the North Pacific. Its characteristic pattern of eastern intensified warming and cooling within the Kuroshio‐Oyashio Extension is pervasive across timescales. We investigate the mechanisms for its decadal persistence in coupled climate models, focusing on the role of ocean circulation changes. We use low‐frequency component analysis to isolate the mechanisms relevant at decadal and longer timescales from those acting at shorter timescales. The PDO warm phase is associated with strengthening and expansion of the North Pacific subpolar gyre in response to a deepening of the Aleutian Low. The subpolar gyre takes several years to respond to wind stress forcing through baroclinic ocean Rossby wave adjustment, such that white noise atmospheric forcing is integrated into red noise, increasing variability at long timescales. Sea level anomalies within the Kuroshio‐Oyashio Extension provide an observable ocean circulation signature of North Pacific decadal variability. Plain Language Summary: North Pacific sea surface temperatures vary from decade to decade with a characteristic pattern, where temperature anomalies near North America are opposite to those off the coast of Japan. These ocean changes influence fish populations as well as climate over the surrounding land regions. Here we investigate the physical mechanisms for this sea surface temperature variability using global climate models that include interactions between the atmosphere and ocean. We find that ocean currents change together with the changes in sea surface temperature and that the time it takes for these ocean currents to adjust to changes in the prevailing wind patterns gives this variability its persistence from decade to decade. Key Points: Decadal sea surface temperature variability in the North Pacific is linked to variability of the ocean gyre circulation The gyre circulation integrates white noise Aleutian Low forcing, giving variability that is strongest at decadal and longer timescales Sea level anomalies illustrate the ocean';s role in North Pacific decadal variability