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Kelp forests are essential ecosystems in coastal regions around the world. They have large effects on flow structure, biogeochemical processes, and ecological dynamics. However, studies have yet to simulate these ecosystems in either regional ocean or global climate models. Here we describe and validate a model that simulates kelp forests in the water column for the ocean component of the Coupled Ocean-Atmosphere-Wave-Sediment-Transport model (COAWST V3.3) using a simple yet efficient linear regression approach to simulate kelp canopies. An in-situ dataset of 2-1/2 years, with and without kelp forest coverage around Isla Natividad (Baja CA, MX), allowed model validation for the main tidal constituents. We tested different vegetation drag coefficients and compared simulations with our canopy model against the standard vegetation module in COAWST. Results show that while both models simulate the velocities observed in the in situ dataset reasonably well, our model better represents turbulence kinetic energy through the water column as observed in laboratory experiments. This new kelp model can be helpful in ecology, physics, and biogeochemistry studies. [ABSTRACT FROM AUTHOR]

Kelp forests are essential ecosystems in coastal regions around the world. They have large effects on flow structure, biogeochemical processes, and ecological dynamics. However, studies have yet to simulate these ecosystems in either regional ocean or global climate models. Here we describe and validate a model that simulates kelp forests in the water column for the ocean component of the Coupled Ocean-Atmosphere-Wave-Sediment-Transport model (COAWST V3.3) using a simple yet efficient linear regression approach to simulate kelp canopies. An in-situ dataset of 2-1/2 years, with and without kelp forest coverage around Isla Natividad (Baja CA, MX), allowed model validation for the main tidal constituents. We tested different vegetation drag coefficients and compared simulations with our canopy model against the standard vegetation module in COAWST. Results show that while both models simulate the velocities observed in the in situ dataset reasonably well, our model better represents turbulence kinetic energy through the water column as observed in laboratory experiments. This new kelp model can be helpful in ecology, physics, and biogeochemistry studies. [ABSTRACT FROM AUTHOR]

We present a 1D model of the vertical structure of wave-driven flows on a shallow coral reef and compare that model to observations made on the reef flat on Ofu, American Samoa. This model is based on longstanding approaches to modeling flow structure in beach surf zones including the averaged effects of breaking and broken surface waves. Waves enter the model through an imbalance between the radiation stress and barotropic pressure gradients that exists below the troughs of the waves, which is offset by turbulent shear stress gradients. Assuming that the depth varying eddy viscosity takes the form found in open channel flows, i.e., a parabola, the horizontal momentum equation can be integrated twice with respect to height to derive the distribution with height of the velocity. The resulting theory is compared to observations made on a reef flat located on Ofu, American Samoa. Using a velocity scale in the eddy viscosity model that is proportional to the rms wave velocity, modeled profiles match observations reasonably well (average skill= 0.66), although there is some ambiguity introduced because matching observations and theory requires the addition of a correction that is found to depend on the square of the rms wave height. • Vertical flow structure for wave-driven flow on a shallow coral reef resembles surf-zone. • Shear in cross-reef flow can be modeled using a wave-based eddy viscosity. • The depth-averaged mean flow on the reef flat is not predicted a priori. [ABSTRACT FROM AUTHOR]