Forecasting and Hindcasting Waves With the SWAN Model in the Southern California Bight
NAVAL RESEARCH LAB STENNIS SPACE CENTER MS OCEANOGRAPHY DIV
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The Naval Research Laboratory created a wave forecasting system in support of the Nearshore Canyon Experiment NCEX field program. The outer nest of this prediction system encompassed the Southern California Bight. This forecasting system is described in this paper, with analysis of results via comparison to the extensive buoy network in the region. There are a number of potential errors, two of which are poor resolution of islands in the Bight - which have a strong impact on nearshore wave climate and the use of the stationary assumption for computations. These two problems have straightforward solutions, but the solutions are computationally expensive, so an operational user must carefully consider their cost. The authors study the impact of these two types of error relative to other errors, such as error in boundary forcing using several hindcasts performed after the completion of NCEX. It is found that, with buoy observations as ground truth, the stationary assumption leads to a modest increase in root-mean-square error this is due to relatively poor prediction of the timing of swell arrivals and local sea growthdecay. The model results are found to be sensitive to the resolution of islands however, coarse resolution does not incur an appreciable penalty in terms of error statistics computed via comparison to buoy observations, suggesting that other errors dominate.
- Physical and Dynamic Oceanography