The effect of wind variability and domain size in the Persian Gulf on predicting nearshore wave energy near Doha, Qatar

Abstract

Wind-wave generation and propagation processes in the Persian Gulf during October and November 2010 were simulated with a third-generation numerical wave model. Several different numerical configurations were used, with output at an instrument pier near the Doha, Qatar coast used to examine the efficacy of these approaches. Three wind sources were used: two sets of wind hindcasts which span the extent of the Gulf; and 15-min averaged winds measured at the pier and distributed as a spatially constant wind field for the model. Domain size, and its nearshore effect, was examined by using three domains of varying sizes and resolutions. Boundary conditions from nesting between larger and smaller domains were also varied to determine how incoming wave conditions from larger domains located further offshore can affect nearshore wave conditions. The effect of wind field, boundary conditions and domain size were quantified by examining the histograms, correlation coefficient, and root-means-square differences, of various parameters (significant wave height, wave height due to swells, peak period, and mean approach direction) for each wave condition at the site. It is determined that significant wave heights at the pier are strongly dependent on the wind fields used and also have some dependence on the use of boundary conditions, while nearshore peak periods are very dependent on the use of boundary conditions. Furthermore, the distribution of wave mean angles tends to be narrower for cases in which hindcast winds and boundary conditions were used. These results are consistent with the sporadic appearance of a strong, unidirectional wind field over the Persian Gulf basin.