MIultiple-Scale Variability Of Waves In The Southern California Bight

Waves play an important role in the process of sea-air interaction.Some research statistics show that 90%of the natural destructive power of the ocean originates from waves.Therefore,studying the distribution and propagation process of waves in the nearshore is of great significance to the maritime industry and ocean engineering.The development of wave models has reached the third generation.Many scholars used third generation models,which are based on energy balance equation,to simulate offshore waves.However,the establishment of a long time series wave model in the Southern California Bight(SCB)and the use of model data to investigate the multi-scale temporal and spatial characteristics of waves in the SCB remain few in number.In this thesis,the Simulating WAves Nearshore(SWAN)model is used to investigate medium-term wave processes from 2004 to 2013.The model is forced by an in-house Weather Research and Forecasting model(WRF)wind estimate.The currents field using the Regional Ocean Modeling System(ROMS)is further exploited to account for the feedback mechanisms of ambient currents on waves.The physical processes of bottom friction,white-capping,diffraction,triplet and quadruplet wave-wave interaction and depth-induced wave breaking are considered comprehensively.The comparison with the in-situ measurements shows that SWAN model can well reproduce the multiple-scale variation of waves in the SCB.The wave-current interaction and topography.effects(especially from islands)are analyzed.The results show that the wave field in the SCB has significant seasonal and intra-seasonal characteristics,with higher wave heights and wave periods in winter,and lower wave heights and period values in summer.The change in bathymetry and ocean currents has a significant impact on the dynamic mechanism of the wave propagation process in the sea The presence of islands has a dissipative effect on the propagation of wave energy and the changing flow field alters the size of the wave height.