Details:

Journal Title:
Journal of Geophysical Research: Oceans
Personal Author:
Baker, Christine M. ; Moulton, Melissa ; Raubenheimer, Britt ; Elgar, Steve ; Kumar, Nirnimesh
Baker, Christine M. ; Moulton, Melissa ; Raubenheimer, Britt ; Elgar, Steve ; Kumar, Nirnimesh Less -
NOAA Program & Office:
OAR (Oceanic and Atmospheric Research) ; Sea Grant
OAR (Oceanic and Atmospheric Research) ; Sea Grant Less -
Sea Grant Program:
WHOI (Woods Hole Sea Grant)
Description:
Circulation in the nearshore region, which is critical for material transport along the coast and between the surf zone and the inner shelf, includes strong vortical motions. The horizontal length scales and vertical structure associated with vortical motions are not well documented on alongshore-variable beaches. Here, a three-dimensional phase-resolving numerical model, Simulating WAves till SHore (SWASH), is compared with surfzone waves and flows on a barred beach, and is used to investigate surfzone eddies. Model simulations with measured bathymetry reproduce trends in the mean surfzone circulation patterns, including alongshore currents and rip current circulation cells observed for offshore wave heights from 0.5 to 2.0 m and incident wave directions from 0 to 15° relative to shore normal. The length scales of simulated eddies, quantified using the alongshore wavenumber spectra of vertical vorticity, suggest that increasing wave directional spread intensifies small-scale eddies (urn:x-wiley:21699275:media:jgrc24622:jgrc24622-math-0001(10) m). Simulations with bathymetric variability ranging from alongshore uniform to highly alongshore variable indicate that large-scale eddies (urn:x-wiley:21699275:media:jgrc24622:jgrc24622-math-0002(100) m) may be enhanced by surfzone bathymetric variability, whereas small-scale eddies (urn:x-wiley:21699275:media:jgrc24622:jgrc24622-math-0003(10) m) are less dependent on bathymetric variability. The simulated vertical dependence of the magnitude and mean length scale (centroid) of the alongshore wavenumber spectra of vertical vorticity and very low-frequency (f ≈ 0.005 Hz) currents is weak in the outer surf zone, and decreases toward the shoreline. The vertical dependence in the simulations may be affected by the vertical structure of turbulence, mean shear, and bottom boundary layer dynamics.
Keywords:
[+]
Eddies Vorticity Waves
Source:
Journal of Geophysical Research: Oceans, 126, e2020JC016899
DOI:
https://doi.org/10.1029/2020JC016899
Document Type:
Journal Article
Funding:
Grant no. NA18OAR4170104
Rights Information:
Other
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:a6766c2dc20420f0049005a829f96640991baaabf5d0eebb1584fcb6df30a757
Download URL:
https://repository.library.noaa.gov/view/noaa/41630/noaa_41630_DS1.pdf
File Type:

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