85th AMS Annual Meeting

Tuesday, 11 January 2005: 9:00 AM
Southern California Bight current system forced by 1996-2003 MM5 wind
Changming Dong, IGPP/UCLA, Los Angeles, CA; and M. Blaas, A. Hall, M. Hughes, and J. McWilliams
The Nested Regional Ocean Model System (ROMS/UCLA) is applied to study the equilibrium structure and dynamics of Southern California Bight (SCB) Current System. The model is configured to two-level nesting grids with the parent grid (20km) covering the whole US west coast and child grid (6.7km) covering the southern California Bight (The model configuration is also downscaled to more finer grids (2km and 0.7 km) for local region inside the SCB). Its external forcing is by momentum, heat, freshwater flux at the surface and adaptive nudging to gyre-scale fields at the boundaries. The momentum flux is 1996-2003 three-hourly nested MM5 wind (6km for the finest grid in the SCB). The model starts from an equilibrium state, which is obtained from a multiple-year cyclic run, and continue to be intergrated from 1996 to 2003. The eight-year solution shows realistic mean and seasonal mean circulation, seasonal and interannual variability and the mesoscale structure of the circulation in SCB, well compared with with CalCOFI data and some other observations. The strong possitive wind curl in the Santa Barbara Channel and the south of the Channel not only intentifies the local upwelling but also might introduce a domain scale pressure gradient which plays an important role in the SCB circulation. The relationships among the surface wind stress, wind stress curl, and SCB circulation and other physical variables are analyzed using Empirical Orthogonal Function. The interaction between wind-driven circulation, complicated SCB bottom topography is studied. The mesoscale eddy activies and energy balance is discussed.

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