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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, C03005, doi:10.1029/2004JC002398, 2005

Wave spectral energy variability in the northeast Pacific

Peter D. Bromirski

Integrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA


Daniel R. Cayan

Climate Research Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA


Reinhard E. Flick

California Department of Boating and Waterways, Integrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA


Abstract

The dominant characteristics of wave energy variability in the eastern North Pacific are described from NOAA National Data Buoy Center (NDBC) buoy data collected from 1981 to 2003. Ten buoys at distributed locations were selected for comparison based on record duration and data continuity. Long-period (LP) [T > 12] s, intermediate-period [6 ≤ T ≤ 12] s, and short-period [T < 6] s wave spectral energy components are considered separately. Empirical orthogonal function (EOF) analyses of monthly wave energy anomalies reveal that all three wave energy components exhibit similar patterns of spatial variability. The dominant mode represents coherent heightened (or diminished) wave energy along the West Coast from Alaska to southern California, as indicated by composites of the 700 hPa height field. The second EOF mode reveals a distinct El Niño-Southern Oscillation (ENSO)-associated spatial distribution of wave energy, which occurs when the North Pacific storm track is extended unusually far south or has receded to the north. Monthly means and principal components (PCs) of wave energy levels indicate that the 1997–1998 El Niño winter had the highest basin-wide wave energy within this record, substantially higher than the 1982–1983 El Niño. An increasing trend in the dominant PC of LP wave energy suggests that storminess has increased in the northeast Pacific since 1980. This trend is emphasized at central eastern North Pacific locations. Patterns of storminess variability are consistent with increasing activity in the central North Pacific as well as the tendency for more extreme waves in the south during El Niño episodes and in the north during La Niña.

Received 23 March 2004; accepted 19 January 2005; published 8 March 2005.

Keywords: wave spectral energy; climate variability; ENSO; atmosphere-ocean forcing; coastal waves; wind waves.

Index Terms: 4560 Oceanography: Physical: Surface waves and tides (1222); 4522 Oceanography: Physical: ENSO (4922); 4513 Oceanography: Physical: Decadal ocean variability (1616, 1635, 3305, 4215); 1616 Global Change: Climate variability (1635, 3305, 3309, 4215, 4513); 3339 Atmospheric Processes: Ocean/atmosphere interactions (0312, 4504).

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Citation: Bromirski, P. D., D. R. Cayan, and R. E. Flick (2005), Wave spectral energy variability in the northeast Pacific, J. Geophys. Res., 110, C03005, doi:10.1029/2004JC002398.