No abstract available.

We analyzed wave and wind data from 18 buoys in the Southern California Bight to characterize the spatial and temporal variability of the regional wave climate. Point Conception shelters most of the Bight from being directly impacted by North Pacific weather. The wave height inside the sheltered zone and to the east of the Channel Islands is less than half the wave height in the open ocean to the west. Within the sheltered Bight, storm waves (by proxy of being greater than the 95th percentile wave height for more than 6 hours) are mainly from the west, but long period swells ( T p >15 seconds) are mainly from the south-southwest. There are on average two to four storms during each winter month (November–March) and fewer than two storms per month for the rest of the year. The Channel Islands selectively block the westerly swells and make the wave climate in the Santa Barbara Channel different from the rest of the sheltered Bight. A statistically significant wave-height minimum exists in the area offshore Dana Point and Oceanside. The multiyear (2–23 years) wave-data records from all 18 buoys show negligible temporal trend, positive or negative. Like the wave climate, the long-term probability of sediment transport on the continental shelves of the Bight displays large difference between the sheltered and open-ocean (near Point Conception) sites. The return period of incipient sediment motion on the sheltered shelf breaks (one to five months) is at least two orders of magnitude longer than that on the Point Conception shelf break (0.6 day). Similar to the spatial distribution of wave heights, there is a systematic return-period maximum on the shelf off Dana Point and Oceanside.

In the past decade, several large programs that monitor currents and transport patterns for periods from a few months to a few years were conducted by a consortium of university, federal, state, and municipal agencies in the central Southern California Bight, a heavily urbanized section of the coastal ocean off the west coast of the United States encompassing Santa Monica Bay, San Pedro Bay, and the Palos Verdes shelf. These programs were designed in part to determine how alongshelf and cross-shelf currents move sediments, pollutants, and suspended material through the region. Analysis of the data sets showed that the current patterns in this portion of the Bight have distinct changes in frequency and amplitude with location, in part because the topography of the shelf and upper slope varies rapidly over small spatial scales. However, because the mean, subtidal, and tidal-current patterns in any particular location were reasonably stable with time, one could determine a regional pattern for these current fields in the central Southern California Bight even though measurements at the various locations were obtained at different times. In particular, because the mean near-surface flows over the San Pedro and Palos Verdes shelves are divergent, near-surface waters from the upper slope tend to carry suspended material onto the shelf in the northwestern portion of San Pedro Bay. Water and suspended material are also carried off the shelf by the mean and subtidal flow fields in places where the orientation of the shelf break changes abruptly. The barotropic tidal currents in the central Southern California Bight flow primarily alongshore, but they have pronounced amplitude variations over relatively small changes in alongshelf location that are not totally predicted by numerical tidal models. Nonlinear internal tides and internal bores at tidal frequencies are oriented more across the shelf. They do not have a uniform transport direction, since they move fine sediment from the shelf to the slope in Santa Monica Bay, but carry suspended material from the mid-shelf to the beach in San Pedro Bay. It is clear that there are a large variety of processes that transport sediments and contaminants along and across the shelf in the central Southern California Bight. However, because these processes have a variety of frequencies and relatively small spatial scales, the dominant transport processes tend to be localized and have dissimilar characteristics even in adjacent regions of this small part of the coastal ocean.