Citation: Haas, K. A., I. A. Svendsen, M. C. Haller, and Q. Zhao, Quasi-three-dimensional modeling of rip current systems,

[1] This paper describes the three-dimensional variation of rip currents through the use of experimental measurements of rip currents in a directional wave basin. The rip currents are unstable, appearing sporadically at any given location. The vertical profile of the rip current is found to vary from depth-uniform inside the channel to depth-varying further offshore. Offshore from the channel the rip current has much stronger velocities at the surface than near the bottom. The instantaneous profiles twist rapidly over depth farther offshore and are fairly uniform in the channel. The depth variations are shown to be sensitive to the total volume flux in the rip.

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In upwelling regions, wind relaxations lead to poleward propagating warm water plumes that are important to coastal ecosystems. The coastal ocean response to wind relaxation around Pt. Conception, CA is simulated with a Regional Ocean Model (ROMS) forced by realistic surface and lateral boundary conditions including tidal processes. The model reproduces well the statistics of observed subtidal water column temperature and velocity at both outer and inner‐shelf mooring locations throughout the study. A poleward‐propagating plume of Southern California Bight water that increases shelf water temperatures by ≈ 5°C is also reproduced. Modeled plume propagation speed, spatial scales, and flow structure are consistent with a theoretical scaling for coastal buoyant plumes with both surface‐trapped and slope‐controlled dynamics. Plume momentum balances are distinct between the offshore (>30 m depth) region where the plume is surface‐trapped, and onshore of the 30 m isobath (within 5 km from shore) where the plume water mass extends to the bottom and is slope controlled. In the onshore region, bottom stress is important in the alongshore momentum equation and generates vertical vorticity that is an order of magnitude larger than the vorticity in the plume core. Numerical experiments without tidal forcing show that modeled surface temperatures are biased 0.5°C high, potentially affecting plume propagation distance and persistence.

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