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Pacific Coastal and Marine Science Center

PCMSC Seminar Series

Large-scale atmospheric controls of multipeaked directional spectra along the Southern California coast

Christie Hegermiller
USGS/UC-Santa Cruz

Tuesday, January 11th at 1:00 pm

Photograph of the California coast with huge waves breaking.

abstract
Sediment dynamics along the California coast are largely influenced by spatial and temporal variability in nearshore wave energy. The vastness of the Pacific Ocean and the complexity of California’s nearshore bathymetry, which is rife with canyons and, in the case of Southern California, exhibits a wide shelf protected by islands, yields multimodal wave spectra that are difficult to model and therefore predict. Towards this goal, a statistical method was developed to downscale local multimodal wave conditions from large-scale atmospheric patterns. This work improves existing methods by partitioning wave spectra into wave systems, defined by discrete generation regions, and by considering the average wave speed of waves generated in different parts of those regions. For an example case offshore of Southern California, which experiences bimodal wave spectra, this new methodology yields improvements to the prediction of daily wave conditions over a reanalysis period. Statistical downscaling and a dynamical wave model were combined for a hybrid approach to assess the relative contribution of different wave systems to nearshore energy in Southern California. The relative contribution of wave energy by local seas, swell generated in the North Pacific, and swell generated in the South Pacific varies with large-scale atmospheric drivers, coastline orientation, and island shadowing. Surprisingly, swell generated in the Southern Hemisphere contributes nearly 40% of energy along some coasts during annual maximum events, with implications for alongshore sediment transport.

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Directions and Parking

Street map of our location.
[Larger version]

From the San Francisco Bay Area:
Take your favorite highway to Hwy 17 South to Hwy 1
At the Hwys 17+1 merge, keep right
Follow signs to “Hwy 1 North, Half Moon Bay, UC Santa Cruz”
Stay on Hwy 1 North (keep in right-most lanes)
Hwy 1 is also named Mission Street — Follow Mission for about 2 miles
At the Western Drive stop light, turn left onto Western Drive
The building right in front of you is the
USGS Pacific Coastal and Marine Science Center
2885 Mission Street

From the south coast or from Hwy 17:
Take Hwy 1 North to west Santa Cruz
At the Western Drive stop light, turn left onto Western
The building right in front of you is the
USGS Pacific Coastal and Marine Science Center
2885 Mission Street

From the north coast:
Take Hwy 1 South to west Santa Cruz
At the Western Drive stop light, turn right onto Western
The building right in front of you is the
USGS Pacific Coastal and Marine Science Center
2885 Mission Street

Parking:
Limited parking spaces may be available in the parking lot located on the NE corner of Western Drive and Mission Street
Limited parking is available along Mission Street and along Natural Bridges Drive
Entrance to PCMSC is at 2885 Mission Street

 Photograph of Natural Bridges, photo by Laura Torresan.

See a LIST of all Seminars previously presented.

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Schematic shows how to get to the PCMSC seminar room.

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URL: https://walrus.wr.usgs.gov/seminar/
Page Contact Information: Laura Zink Torresan
Page Last Modified: 10 January 2017 (lzt)