The Forcing of the Pacific Decadal Oscillation

The Pacific decadal oscillation (PDO), defined as the leading empirical orthogonal function of North Pacific sea surface temperature anomalies, is a widely used index for decadal variability. It is shown that the PDO can be recovered from a reconstruction of North Pacific sea surface temperature anomalies based on a first-order autoregressive model and forcing by variability of the Aleutian low, El Nino–Southern Oscillation (ENSO), and oceanic zonal advection anomalies in the Kuroshio–Oyashio Extension. The latter results from oceanic Rossby waves that are forced by North Pacific Ekman pumping. The SST response patterns to these processes are not orthogonal, and they determine the spatial characteristics of the PDO. The importance of the different forcing processes is frequency dependent. At interannual time scales, forcing from ENSO and the Aleutian low determines the response in equal parts. At decadal time scales, zonal advection in the Kuroshio–Oyashio Extension, ENSO, and anomalies of the Aleutian low each account for similar amounts of the PDO variance. These results support the hypothesis that the PDO is not a dynamical mode, but arises from the superposition of sea surface temperature fluctuations with different dynamical origins.

[1]  C. Deser,et al.  Understanding the persistence of sea surface temperature anomalies in midlatitudes , 2003 .

[2]  Eduardo Zorita,et al.  A Simple Model of the Decadal Response of the Ocean to Stochastic Wind Forcing , 1997 .

[3]  Franco Biondi,et al.  North Pacific Decadal Climate Variability since 1661 , 2001 .

[4]  Naomi Naik,et al.  Wind-Driven Shifts in the Latitude of the Kuroshio–Oyashio Extension and Generation of SST Anomalies on Decadal Timescales* , 2001 .

[5]  B. Qiu,et al.  Kuroshio Extension Variability and Forcing of the Pacific Decadal Oscillations : Responses and Potential Feedback , 2022 .

[6]  A. Barnston,et al.  Predictive Skill of Statistical and Dynamical Climate Models in SST Forecasts during the 1997-98 El Niño Episode and the 1998 La Niña Onset. , 1999 .

[7]  Ze'ev Gedalof,et al.  A multi‐century perspective of variability in the Pacific Decadal Oscillation: new insights from tree rings and coral , 2002 .

[8]  T. Barnett,et al.  Connections between the Pacific Ocean Tropics and Midlatitudes on Decadal Timescales , 2000 .

[9]  N. Graham.  Decadal-scale climate variability in the tropical and North Pacific during the 1970s and 1980s: observations and model results , 1994 .

[10]  T. Barnett,et al.  Origins of the midlatitude Pacific decadal variability , 1999 .

[11]  M. Alexander.  Midlatitude Atmosphere–Ocean Interaction during El Niño. Part I: The North Pacific Ocean , 1992 .

[12]  D. Vimont,et al.  Footprinting: A seasonal connection between the tropics and mid‐latitudes , 2001 .

[13]  Hisashi Nakamura,et al.  An active role of extratropical sea surface temperature anomalies in determining anomalous turbulent heat flux , 2003 .

[14]  M. Latif,et al.  Analysis of observed and simulated SST spectra in the midlatitudes , 2002 .

[15]  H. Nakamura,et al.  Decadal changes in the North Pacific oceanic frontal zones as revealed in ship and satellite observations , 2003 .

[16]  Bin Wang,et al.  The Forced and Intrinsic Low-Frequency Modes in the North Pacific* , 2005 .

[17]  R. Sutton,et al.  Atmospheric GCM Response to Extratropical SST Anomalies: Synthesis and Evaluation* , 2002 .

[18]  C. Deser,et al.  Evidence for a Wind-Driven Intensification of the Kuroshio Current Extension from the 1970s to the 1980s , 1999 .

[19]  D. Battisti,et al.  The Basic Effects of Atmosphere–Ocean Thermal Coupling on Midlatitude Variability* , 1998 .

[20]  D. Battisti,et al.  Interannual (ENSO) and Interdecadal (ENSO-like) Variability in the Southern Hemisphere Tropospheric Circulation* , 1999 .

[21]  Michael D. Dettinger,et al.  North–South Precipitation Patterns in Western North America on Interannual-to-Decadal Timescales , 1998 .

[22]  John R. Lanzante,et al.  The Atmospheric Bridge: The Influence of ENSO Teleconnections on Air-Sea Interaction over the Global Oceans , 2002 .

[23]  Kevin E. Trenberth,et al.  Recent Observed Interdecadal Climate Changes in the Northern Hemisphere , 1990 .

[24]  N. Mantua,et al.  The Pacific Decadal Oscillation , 2002 .

[25]  A. Miller,et al.  Interdecadal climate regime dynamics in the North Pacific Ocean: theories, observations and ecosystem impacts , 2000 .

[26]  Alexey Kaplan,et al.  Predictability of El Niño over the past 148 years , 2004, Nature.

[27]  S. Minobe.  Spatio-temporal structure of the pentadecadal variability over the North Pacific , 2000 .

[28]  W. Sturges,et al.  Wind Forcing of the Atlantic Thermocline along 32°N at Low Frequencies , 1995 .

[29]  N. Graham,et al.  Decadal Variability of Precipitation over Western North America , 1998 .

[30]  David W. Pierce,et al.  Distinguishing coupled ocean–atmosphere interactions from background noise in the North Pacific , 2001 .

[31]  D. Lluch-Cota,et al.  Sea surface temperature variability in coastal areas of the northeastern Pacific related to the El Niño‐Southern Oscillation and the Pacific Decadal Oscillation , 2001 .

[32]  D. Pierce,et al.  Anatomy of North Pacific Decadal Variability , 2002 .

[33]  W. White,et al.  A westward-intensified decadal change in the North Pacific thermocline and gyre-scale circulation , 1998 .

[34]  Bin Wang,et al.  Global patterns of decadal-scale variability observed in sea surface temperature and lower-tropospheric circulation fields , 2001 .

[35]  T. Yamagata,et al.  Decadal Climate Variability in the North Pacific during the Recent Decades , 1997 .

[36]  T. Barnett,et al.  Interdecadal interactions between the tropics and midlatitudes in the Pacific Basin , 1999 .

[37]  Russ E. Davis,et al.  Monthly Mean Sea-Level Variability Along the West Coast of North America , 1982 .

[38]  The Role of Sea Surface Temperatures in Interactions between ENSO and the North Pacific Oscillation. , 2002 .

[39]  Mathew Barlow,et al.  ENSO, Pacific Decadal Variability, and U.S. Summertime Precipitation, Drought, and Stream Flow , 2001 .

[40]  T. Barnett,et al.  Interdecadal modulation of ENSO teleconnections , 1998 .

[41]  A. J. Clarke,et al.  Remotely Driven Decadal and Longer Changes in the Coastal Pacific Waters of the Americas , 1999 .

[42]  Matthew Newman,et al.  ENSO-Forced Variability of the Pacific Decadal Oscillation , 2003 .

[43]  Masato Sugi,et al.  Pacific decadal oscillation and variability of the Indian summer monsoon rainfall , 2003 .

[44]  P. B. Liebelt.  An Introduction To Optimal Estimation , 1967 .

[45]  M. Alexander.  Midlatitude Atmosphere–Ocean Interaction during El Niño. Part II: The Northern Hemisphere Atmosphere , 1992 .

[46]  T. Barnett,et al.  Modeling of North Pacific Climate Variability Forced by Oceanic Heat Flux Anomalies. , 2001 .

[47]  T. Yamagata,et al.  Recent Decadal SST Variability in the Northwestern Pacific and Associated Atmospheric Anomalies , 1999 .

[48]  E. Kamen,et al.  Introduction to Optimal Estimation , 1999 .

[49]  A. Miller,et al.  Predicting Western North Pacific Ocean Climate , 2001 .

[50]  C. Deser,et al.  Pacific Interdecadal Climate Variability: Linkages between the Tropics and the North Pacific during Boreal Winter since 1900 , 2004 .

[51]  J. Wallace,et al.  A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production , 1997 .

[52]  James W. Hurrell,et al.  Decadal atmosphere-ocean variations in the Pacific , 1994 .

[53]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.

[54]  D. Schrag,et al.  Support for tropically‐driven pacific decadal variability based on paleoproxy evidence , 2001 .

[55]  I. Bladé.  The Influence of Midlatitude Ocean–Atmosphere Coupling on the Low-Frequency Variability of a GCM. Part I: No Tropical SST Forcing* , 1997 .

[56]  Russ E. Davis,et al.  Predictability of Sea Surface Temperature and Sea Level Pressure Anomalies over the North Pacific Ocean , 1976 .

[57]  T. Nitta,et al.  Recent Warming of Tropical Sea Surface Temperature and Its Relationship to the Northern Hemisphere Circulation , 1989 .

[58]  J. Wallace,et al.  The Seasonal Footprinting Mechanism in the Pacific: Implications for ENSO(. , 2003 .

[59]  David W. Pierce,et al.  The role of ocean dynamics in producing decadal climate variability in the North Pacific , 2001 .

[60]  K. Hasselmann.  Stochastic climate models Part I. Theory , 1976 .

[61]  J. Wallace,et al.  ENSO-like Interdecadal Variability: 1900–93 , 1997 .

[62]  T. Barnett,et al.  Interdecadal variability of the Pacific Ocean: model response to observed heat flux and wind stress anomalies , 1994 .

[63]  H. Nakamura,et al.  Interannual and Decadal Modulations Recently Observed in the Pacific Storm Track Activity and East Asian Winter Monsoon , 2002 .

[64]  S. Xie,et al.  Interdecadal Thermocline Variability in the North Pacific for 1958–97: A GCM Simulation* , 2000 .

[65]  P. Imkeller,et al.  Stochastic climate models , 2001 .