Wind-Wave Variability in the Northeast Pacific, 1981-2003

The dominant characteristics of wave energy variability in the eastern North Pacific are described from NOAA NDBC buoy data collected from 1981-2003. Ten buoys at distributed locations were selected for comparison based on record duration and data continuity. Long period, LP [T > 12] s, intermediate period, IP [6≤ T≤ 12] s, and short period, SP [T < 6] s wave spectral energy components are considered separately. Empirical orthogonal function (EOF) analyses of monthly wave energy anomalies reveals 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 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 1997-98 El Niño winter had the highest basin-wide wave energy within this record, substantially higher than the 1982-83 El Niño. An increasing trend in the dominant PC of LP wave energy suggests that storminess has increased in the NE Pacific since 1980. This trend is particularly emphasized at central eastern 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.