Details:

Journal Title:
Journal of Geophysical Research: Oceans
Personal Author:
Wang, X. ; Kukulka, T. ; Plueddemann, A. J.
Wang, X. ; Kukulka, T. ; Plueddemann, A. J. Less -
NOAA Program & Office:
CINAR (Cooperative Institute for the North Atlantic Region)
Description:
Mixing processes in the upper ocean play a key role in transferring heat, momentum, and matter in the ocean. These mixing processes are significantly enhanced by wave-driven Langmuir turbulence (LT). Based on a paired analysis of observations and simulations, this study investigates wind fetch and direction effects on LT at a coastal site south of the island Martha’s Vineyard (MA, USA). Our results demonstrate that LT is strongly influenced by wind fetch and direction in coastal oceans, both of which contribute to controlling turbulent coastal transport processes. For northerly offshore winds, land limits the wind fetch and wave development, whereas southerly winds are associated with practically infinite fetch. Observed and simulated two-dimensional wave height spectra reveal persistent southerly swell and substantially more developed wind-driven waves from the south. For oblique offshore winds, waves develop more strongly in the alongshore direction with less limited fetch, resulting in significant wind and wave misalignments. Observations of coherent near-surface crosswind velocities indicate that LT is only present for sufficiently developed waves. The fetch-limited northerly winds inhibit wave developments and the formation of LT. In addition to limited fetch, strong wind–wave misalignments prevent LT development. Although energetic and persistent, swell waves do not substantially influence LT activity during the observation period because these relatively long swell waves are associated with small Stokes drift shear. These observational results agree well with turbulence-resolving large eddy simulations (LESs) based on the wave-averaged Navier–Stokes equation, validating the LES approach to coastal LT in the complex wind and wave conditions.
Keywords:
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Coasts Ocean Langmuir Turbulence Large Eddy Simulation (LES) Wind Fetch
Source:
Journal of Geophysical Research: Oceans, 127, e2021JC018222
DOI:
https://doi.org/10.1029/2021JC018222
Format:
PDF
Document Type:
Journal Article
Place as Subject:
Martha's Vineyard (Mass.)
Rights Information:
Other
Compliance:
Submitted
Main Document Checksum:
[+]
urn:sha256:8c6f466e7fd25f50f1f01d19d7267f24df5c66d4122803eec03c77ccfdb828fc
Download URL:
https://repository.library.noaa.gov/view/noaa/51833/noaa_51833_DS1.pdf
File Type:

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