Wave power variability and trends across the North Pacific

Abstract

[1] Multiyear climate variations influence North Pacific storm intensity and resultant variations in wave energy levels. The timing of these decadal fluctuations and strong El Niño's have had a strong influence on long-term trends. Here we investigate variations in the North Pacific wave power, P W , determined from WAVEWATCH III (WW3) wave model significant wave height, Hs, and peak period data forced by NRA-1 winds spanning the 1948-2008 epoch. Over the entire hindcast, upward trends in Hs and P W , especially in winter, are observed over much of the North Pacific, strongly influenced by an apparent storm intensification after the mid-1970s regime shift. Heightened P W is concentrated in particular regions of the basin, and is associated with increased wave activity during the warm phase of the Pacific Decadal Oscillation (PDO). Wave power events, P E , defined as episodes when Hs exceeded the 90th percentile threshold for at least 12 h, exhibit significant upward trends along much of the U.S. Pacific coast during winter months. Importantly, the hindcast exhibits a recent decrease in P W across much of the North Pacific, in contrast to the long-term increase of P W and Hs. This recent decrease is associated with the prevalent PDO cool phase that developed after the late 1990s. Variability and intensification of coastal P W and P E have important practical implications for shoreline and beach erosion, coastal wetlands inundation, storm-surge flooding, and coastal planning. These considerations will become increasingly important as sea level rises.

Periodicity and patterns of ocean wind and wave climate

“…The broad-band signals of the EOFs support the dynamic nature of the North Atlantic Ocean [Sterl et al, 1998]. However, the climate cycles are often described by their inter-annual variability in the literature [e.g., Wang and Swail, 2001;Sterl and Caires, 2005;Fan et al, 2012;Stopa et al, 2013a;Bromirski et al, 2013]. The results show that the intra-annual and interannual oscillations have similar magnitude and comparable roles in basin-scale climate cycles.…”

“…Recent studies have applied climate indices to explain the inter-annual wave variability in the North Atlantic [Bacon and Carter, 1991;Swail and Cox, 2000;Woolf et al, 2002;Gulev and Grigorieva, 2006], North Pacific [Graham and Diaz, 2001;Tsai et al, 2012;Bromirski et al, 2013], Southern Ocean [Hemer et al, 2008[Hemer et al, , 2010Bosserelle et al, 2011], Northern Hemisphere [Shimura et al, 2013], and globally Sterl and Caires, 2005;Young, 1999;Izaguirre et al, 2011;Fan et al, 2012;Stopa et al, 2013a]. The EOF approach in the time domain allows comparison with findings from previous studies and provides a basis to relate the frequency domain results.…”

“…The Southern Pacific is connected to the Atlantic through the Indian Ocean allowing continuation of storm systems across the Westerlies and producing the most consistent and energetic waves observed globally [Hemer et al, 2010, Arinaga andCheung, 2012]. The tropics and subtropics have relatively mild Easterly trade winds, but can still generate appreciable wave activities especially in the Central North Pacific [Stopa et al, 2013b;Bromirski et al, 2013]. The North Pacific is largely seasonal with energetic waves in the boreal winter and relatively calm conditions in the summer.…”

“…Reanalysis wind and wave data sets have advantage over in situ and remotely sensed observations because they resolve multiscale processes by their high spatial and temporal resolution [Semedo et al, 2011;Rascle and Ardhuin, 2013]. This allows more intricate studies of the climate impacts from extratropical cyclones to nearshore processes [e.g., Wang et al, 2006;Bromirski et al, 2013]. The 30-plus years of reanalysis data have enabled studies of inter-annual climate cycles [Fan et al, 2012;Stopa et al, 2013a].…”

Adaptive Planning for Transportation Corridors Threatened by Sea Level Rise

“…Climate change is expected to result in accelerated rates of sea level rise (3) and changing seasonal wave conditions (4), further exposing the shorelines to impacts (5,6). Infrastructural and living systems adaptations will need to occur to avoid a wholesale change in the marshes, estuarine systems, low-lying urban areas, and exposed highway infrastructure along the US coast.…”