Di Lorenzo, E., J. Fiechter, N. Schneider, A. Bracco, A. J. Miller, P. J. S. Franks,
S. J. Bograd, A. M. Moore, A. C. Thomas, W. Crawford, A. Pena and A. J. Hermann, 2009:
Nutrient and salinity decadal variations in the
central and eastern North Pacific.
Geophysical Research Letters, 36, L14601, doi:10.1029/2009GL038261.
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 adequately predicts the in-phase relationship
between the Alaskan Gyre and California Current timeseries. The fact that large-amplitude, lowfrequency
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.