Nutrient and salinity decadal variations in the central and eastern North Pacific

Long‐term timeseries of upper ocean salinity and nutrients collected in the Alaskan Gyre along Line P exhibit significant decadal variations that are shown to be in phase with variations recorded in the Southern California Current System by the California Cooperative Oceanic Fisheries Investigation (CalCOFI). We present evidence that these variations are linked to the North Pacific Gyre Oscillation (NPGO)—a climate mode of variability that tracks changes in strength of the central and eastern branches of the North Pacific gyres and of the Kuroshio‐Oyashio Extension (KOE). The NPGO emerges as the leading mode of low‐frequency variability for salinity and nutrients. We reconstruct the spatial expressions of the salinity and nutrient modes over the northeast Pacific using a regional ocean model hindcast from 1963‐2004. These modes exhibit a large‐scale coherent pattern that predicts the in‐phase relationship between the Alaskan Gyre and California Current timeseries. The fact that large‐amplitude, low‐frequency fluctuations in salinity and nutrients are spatially phase‐locked and correlated with a measurable climate index (the NPGO) open new avenues for exploring and predicting the effects of long‐term climate change on marine ecosystem dynamics.

[1]  N. Bond,et al.  Recent shifts in the state of the North Pacific , 2003 .

[2]  J. McWilliams,et al.  Dynamically balanced absolute sea level of the global ocean derived from near‐surface velocity observations , 2003 .

[3]  James C. McWilliams,et al.  The Warming of the California Current System: Dynamics and Ecosystem Implications , 2005 .

[4]  James C. McWilliams,et al.  North Pacific Gyre Oscillation links ocean climate and ecosystem change , 2008 .

[5]  W. Collins,et al.  The NCEP–NCAR 50-Year Reanalysis: Monthly Means CD-ROM and Documentation , 2001 .

[6]  W. Hsieh,et al.  Variations in nutrients, carbon and other hydrographic parameters related to the 1976/77 and 1988/89 regime shifts in the sub-arctic Northeast Pacific , 2007 .

[7]  Thomas M. Smith,et al.  Improved Extended Reconstruction of SST (1854–1997) , 2004 .

[8]  James C. McWilliams,et al.  Equilibrium structure and dynamics of the California Current System , 2003 .

[9]  Emanuele Di Lorenzo,et al.  North Pacific Gyre Oscillation Synchronizes Climate Fluctuations in the Eastern and Western Boundary Systems , 2009 .

[10]  Bunmei Taguchi,et al.  Decadal Variability of the Kuroshio Extension: Observations and an Eddy-Resolving Model Hindcast* , 2006 .

[11]  Steven J. Bograd,et al.  CalCOFI: a half century of physical, chemical, and biological research in the California Current System , 2003 .

[12]  Steven J. Bograd,et al.  The biological response to the 1977 regime shift in the California Current , 2003 .

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

[14]  Alexander F. Shchepetkin,et al.  The regional oceanic modeling system (ROMS): a split-explicit, free-surface, topography-following-coordinate oceanic model , 2005 .

[15]  Andrew C. Thomas,et al.  Interannual variability in chlorophyll concentrations in the Humboldt and California Current Systems , 2009 .

[16]  W. Crawford,et al.  Line P ocean temperature and salinity, 1956–2005 , 2007 .

[17]  Thomas M. Powell,et al.  Results from a three-dimensional, nested biological-physical model of the California Current System and comparisons with statistics from satellite imagery , 2006 .

[18]  H. Freeland,et al.  Variability of the North Pacific Current and its bifurcation , 2007 .

[19]  John C. Warner,et al.  Ocean forecasting in terrain-following coordinates: Formulation and skill assessment of the Regional Ocean Modeling System , 2008, J. Comput. Phys..

[20]  D. Varela,et al.  Seasonal and interannual variability in phytoplankton and nutrient dynamics along Line P in the NE subarctic Pacific , 2007 .

[21]  Steven J. Bograd,et al.  Time series of the northeast Pacific , 2007 .

[22]  S. Josey A comparison of ECMWF, NCEP-NCAR, and SOC surface heat fluxes with moored buoy measurements in the subduction region of the Northeast Atlantic , 2001 .

[23]  Howard J. Freeland,et al.  Persistently declining oxygen levels in the interior waters of the eastern subarctic Pacific , 2007 .

[24]  N. Schneider,et al.  Forcing of low-frequency ocean variability in the Northeast Pacific. , 2009 .

[25]  S. Nigam,et al.  The North Pacific Oscillation–West Pacific Teleconnection Pattern: Mature-Phase Structure and Winter Impacts , 2008 .

[26]  E. Di Lorenzo,et al.  Decadal variations in the California Current upwelling cells , 2007 .

[27]  H. Freeland A short history of Ocean Station Papa and Line P , 2007 .