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Nearshore waves in southern California: hindcast, and modeled historical and 21st-century projected time series

November 7, 2016

As part of the Coastal Storm Modeling System (CoSMoS), time series of hindcast, historical, and 21st-century nearshore wave parameters (wave height, period, and direction) were simulated for the southern California coast from Point Conception to the Mexican border. The hindcast (1980-2010) time series represents reanalysis-forced offshore waves propagated to the nearshore, whereas the historical (1976-2005) and 21st-century (2012-2100) time series represent global climate model-forced offshore waves propagated to the nearshore. Changes in deep-water wave conditions directly regulate the energy driving coastal processes. However, a number of physical processes, for example, refraction on continental shelves and/or diffraction by islands, transform deep-water waves as they propagate to the coast, which complicates large-scale modeling efforts. In this work, a hindcast of nearshore waves was simulated by forcing a numerical wave model with hindcasted intermediate-water waves and reanalysis winds. A lookup table was created by relating corresponding offshore winds and waves with nearshore wave conditions. Using the lookup table, historical and 21st-century nearshore wave time series were generated for global climate model-forced offshore winds and waves.