Newman, M., M. A. Alexander, T. R. Ault, K. M.
Cobb, C. Deser, E. Di Lorenzo, N. J. Mantua, A. J.
Miller, S. Minobe, H. Nakamura, N. Schneider,
D. J. Vimont, A. S. Phillips, J. D. Scott and C. A.
The Pacific Decadal Oscillation, revisited
Journal of Climate, 29, 4399-4427.
The Pacific decadal oscillation (PDO), the dominant year-round pattern of monthly North
Pacific sea surface temperature (SST) variability, is an important target of ongoing
research within the meteorological and climate dynamics communities, and is central to
the work of many geologists, ecologists, natural resource managers, and social scientists.
Research over the last fifteen years has led to an emerging consensus: the PDO is not a
single phenomenon, but is instead the result of a combination of different physical
processes, including both remote tropical forcing and local North Pacific
atmosphere/ocean interactions, which operate on different timescales to drive similar
PDO-like SST anomaly patterns. How these processes combine to generate observed
PDO evolution, including apparent regime shifts, is shown using simple autoregressive
models of increasing spatial complexity. Simulations of recent climate in coupled GCMs
are able to capture many aspects of the PDO, but do so based on a balance of processes
often more independent of the Tropics than is observed. Finally, it is suggested that
assessment of PDO-related regional climate impacts, reconstruction of PDO-related
variability into the past with proxy records, and diagnosis of Pacific variability within
coupled GCMs should all account for the effects of these different processes, which only
partly represent direct forcing of the atmosphere by North Pacific Ocean SSTs.