Abstract. This process-oriented study of the California Current system (CCS) uses a high-resolution, multilevel, primitive equation ocean model on a/3 plane to isolate the response of that eastern boundary oceanic regime to temporal and spatially varying wind forcing. To study the generation, evolution, and maintenance of many of the observed features such as currents, meanders, and eddies in the CCS, the model is forced from rest with seasonal climatological winds. In response to the prevailing wind direction, surface equatorward currents develop, along with upwelling of cooler water along the coast and a poleward undercurrent. Baroclinic/barotropic instabilities in the equatorward surface current and poleward undercurrent result in the generation of meanders near the coast.As the meanders intensify, cold upwelling filaments develop along the coast and subsequently extend farther offshore. In time, the meanders form both cyclonic and anticyclonic eddies, which subsequently propagate farther offshore,, Longer. simulation

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A high-resolution, multi-level, primitive equation ocean model is used to examine the response to wind forcing of an idealized flat-bottomed oceanic regime along an eastern ocean boundary. A band of steady alongshore, upwelling favorable winds, either with or without alongshore variability, is used as forcing on both anf-plane and a ,a-plane. In each experiment a wind-driven equatorward coastal jet and a poleward undercurrent are generated. In time the coastal jet and undercurrent become unstable and lead to the development of eddies and jets with relatively strong onshore and offshore directed flows. The alongshore variation in alongshore wind stress plays a role in determining the location of eddy generation regions. A comparison of model results with available observations shows that the time-averaged model coastal jet and undercurrent are consistent in scale and magnitude with the observed data. Although the instantaneous eddies and jets are weaker than the corresponding observed features, they have horizontal scales typical of the observed scales. The results of this study support the hypothesis that steady wind forcing is one of several possible important generation mechanisms for eddies in the California Current System.

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Abstract. To investigate the northern Canary Current system (NCCS), results from four numerical experiments of increasing complexity are examined. Experiment 1, which uses seasonal wind forcing only, shows that as expected, wind forcing is the key generative mechanism for the current, upwelling, meander, eddy, and filament structures. Experiments 2 and 3, which have the additional effects of irregular coastline geometry, show the following: capes are areas for enhanced upwelling, extensive filaments, maximum current velocities, and enhanced growth of cyclonic meanders and eddies; an embayment like the Gulf of Cadiz is a primary region for anticyclonic meander and eddy development. The results from the complex flow regime of Experiment 4, which has the additional effects of thermohaline gradients and Mediterranean Outflow, highlights the major characteristics and unique features (such as the generation of Meddles) of the NCCS with relatively close similarities to field observations.

A high-resolution, multi-level, primitive equation ocean model has been used to investigate the combined role of seasonal wind forcing, seasonal thermohaline gradients, and coastline irregularities on the formation of currents, meanders, eddies, and filaments in the entire California Current System (CCS) region, from Baja to the Washington-Canada border. Additional objectives are to further characterize the meandering jet south of Cape Blanco and the seasonal variability off Baja. Model results show the following: All of the major currents of the CCS (i.e., the California Current, the California Undercurrent, the Davidson Current, the Southern California Countercurrent, and the Southern California Eddy) as well as filaments, meanders and eddies are generated. The results are consistent with the generation of eddies from instabilities of the southward current and northward undercurrent via barotropic and baroclinic instability processes. The meandering southward jet, which divides coastally-influenced water from water of offshore origin, is a continuous feature in the CCS, and covers an alongshore distance of over 2000 km from south of Cape Blanco to Baja. Off Baja, the southward jet strengthens (weakens) during spring and summer (fall and winter). The area off southern Baja is a highly dynamic environment for meanders, filaments, and eddies, while the region off Point Eugenia, which represents the largest coastline perturbation along the Baja peninsula, is shown to be a persistent cyclonic eddy generation region.

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As a guide for the choice of finite-difference schemes for use in ocean modding, different distributions of variables over the horizontal array of grid points in an ocean circulation model are investigated using the shallow water equations. Numerical and analytical techniques are used to study the types of computational noise present in each grid system. It is shown that the B-scheme (in which the horizontal velocity is carried at the center and the height field is carried at each corner of a rectangular grid) with diffusive dissipation successively suppresses numerical noise in a coarse grid (>I00 km) ocean model. For fine-scale resolution (