Anatomy of North Pacific Decadal Variability

Abstract In the low-resolution version of the Community Climate System Model, version 3 (CCSM3), the modeled North Pacific decadal variability is demonstrated to be independent of the epoch for which a statistically steady control simulation is constructed, either preindustrial or modern; however, it is demonstrated to be significantly affected by the different global warming scenarios investigated. In the control simulations, the North Pacific basin is shown to be dominated by sea surface temperature (SST) variability with a time scale of approximately 20 yr. This mode of variability is in close accord with the observed characteristics of the Pacific decadal oscillation (PDO). A detailed analysis of the statistical equilibrium runs is performed based on other model variables as well [sea surface salinity (SSS), barotropic circulation, freshwater and heat fluxes, wind stress curl, sea ice, and snow coverage]. These analyses confirm that the underlying mechanism of the PDO involves a basin-scale mode of ocean adjustment to changes of the atmospheric forcing associated with the Aleutian low pressure system. However, they also suggest that the observed sign reversal of the PDO arises from a feedback in the northern part of the basin. In this novel hypothesis, the advection to the Bering Sea of “spice” anomalies formed in the central and western Pacific sets up a typical 10-yr time scale for the triggering of the PDO reversal. In all of the global warming simulations described in this paper, the signal represented by the detrended SST variability in the North Pacific displays significant power at multidecadal frequencies. In these simulations, the natural North Pacific decadal variability, as characterized in the control simulations (the PDO), remains the leading mode of variability only for moderate forcing. If the warming is too strong, then the typical 20-yr time scale of the canonical PDO can no longer be detected, except in terms of SSS variability and only prior to a significant change that occurs in the Bering Strait Throughflow.

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North Pacific decadal variability: insights from a biennial ENSO environment

Climate Dynamics ◽

10.1007/s00382-016-3391-1 ◽

2016 ◽

Vol 49 (4) ◽

pp. 1379-1397 ◽

Cited By ~ 4

Author(s):

Deepthi Achuthavarier ◽

Siegfried D. Schubert ◽

Yury V. Vikhliaev

Keyword(s):

North Pacific ◽

Decadal Variability ◽

Pacific Decadal Variability

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The response of the North Pacific Decadal Variability to strong tropical volcanic eruptions

Climate Dynamics ◽

10.1007/s00382-012-1373-5 ◽

2012 ◽

Vol 39 (12) ◽

pp. 2917-2936 ◽

Cited By ~ 44

Author(s):

Tao Wang ◽

Odd Helge Otterå ◽

Yongqi Gao ◽

Huijun Wang

Keyword(s):

North Pacific ◽

Decadal Variability ◽

Volcanic Eruptions ◽

The North ◽

Pacific Decadal Variability ◽

The North Pacific

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Influence of ENSO on Pacific Decadal Variability: An Analysis Based on the NCEP Climate Forecast System

Journal of Climate ◽

10.1175/jcli-d-11-00573.1 ◽

2012 ◽

Vol 25 (18) ◽

pp. 6136-6151 ◽

Cited By ~ 25

Author(s):

Hui Wang ◽

Arun Kumar ◽

Wanqiu Wang ◽

Yan Xue

Keyword(s):

North Pacific ◽

Time Scale ◽

Decadal Variability ◽

Interannual Time Scale ◽

Forecast System ◽

Climate Forecast System ◽

Decadal Time Scale ◽

The North ◽

Pacific Decadal Variability ◽

The North Pacific

Abstract The influence of El Niño–Southern Oscillation (ENSO) on Pacific decadal variability (PDV) is investigated by comparing two 500-yr simulations with the National Centers for Environmental Prediction (NCEP) Climate Forecast System coupled model. One simulation is a no-ENSO run, in which model daily sea surface temperature (SST) in the tropical Pacific Ocean is relaxed to the observed climatology. The other simulation is a fully coupled run and retains ENSO variability. The PDV considered in this study is the first two empirical orthogonal functions of monthly SST anomalies in the North Pacific: the Pacific decadal oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO). The PDO in the no-ENSO run can be clearly identified. Without ENSO, the PDO displays relatively higher variance at the decadal time scale and no spectral peak at the interannual time scale. In the ENSO run, the PDO variability increases slightly. ENSO not only enhances the variability of the PDO at the interannual time scale, but also shifts the PDO to longer time scales—both consistent with observations. ENSO modulates the Aleutian low and associated surface wind over the North Pacific. The latter, in turn, helps establish a more persistent PDO in the ENSO run. The results also indicate a PDO modulation of global ENSO impacts and the linearity in the superposition of the ENSO-forced and PDO-related atmospheric anomalies. Compared to observations, the NPGO in both simulations lacks power at the time scale longer than 30 yr. On the decadal time scale, the variability of the NPGO is weaker in the ENSO run than in the no-ENSO run.

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Supplementary material to "Influence of North Pacific Decadal Variability on the Western Canadian Arctic over the past 700 years"

10.5194/cp-2016-118-supplement ◽

2016 ◽

Author(s):

François Lapointe ◽

Pierre Francus ◽

Scott F. Lamoureux ◽

Mathias Vuille ◽

Jean-Philippe Jenny ◽

...

Keyword(s):

North Pacific ◽

Decadal Variability ◽

Canadian Arctic ◽

The Past ◽

Pacific Decadal Variability ◽

Supplementary Material

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Role of Stochastic Atmospheric Forcing from the South and North Pacific in Tropical Pacific Decadal Variability

Journal of Climate ◽

10.1175/jcli-d-18-0536.1 ◽

2019 ◽

Vol 32 (13) ◽

pp. 4013-4038 ◽

Cited By ~ 5

Author(s):

Tianyi Sun ◽

Yuko M. Okumura

Keyword(s):

North Pacific ◽

Large Scale ◽

Decadal Variability ◽

South Pacific ◽

Tropical Pacific ◽

Ocean Dynamics ◽

The South ◽

Pacific Decadal Variability ◽

Sst Anomalies ◽

The Tropical Pacific

Abstract Stochastic variability of internal atmospheric modes, known as teleconnection patterns, drives large-scale patterns of low-frequency SST variability in the extratropics. To investigate how the decadal component of this stochastically driven variability in the South and North Pacific affects the tropical Pacific and contributes to the observed basinwide pattern of decadal variability, a suite of climate model experiments was conducted. In these experiments, the models are forced with constant surface heat flux anomalies associated with the decadal component of the dominant atmospheric modes, particularly the Pacific–South American (PSA) and North Pacific Oscillation (NPO) patterns. Both the PSA and NPO modes induce basinwide SST anomalies in the tropical Pacific and beyond that resemble the observed interdecadal Pacific oscillation. The subtropical SST anomalies forced by the PSA and NPO modes propagate to the equatorial Pacific mainly through the wind–evaporation–SST feedback. This atmospheric bridge is stronger from the South Pacific than the North Pacific due to the northward displacement of the intertropical convergence zone and the associated northward advection of momentum anomalies. The equatorial ocean dynamics is also more strongly influenced by atmospheric circulation changes induced by the PSA mode than the NPO mode. In the PSA experiment, persistent and zonally coherent wind stress curl anomalies over the South Pacific affect the zonal mean depth of the equatorial thermocline and weaken the equatorial SST anomalies resulting from the atmospheric bridge. This oceanic adjustment serves as a delayed negative feedback and may be important for setting the time scales of tropical Pacific decadal variability.

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