Observations Of Nonlinear Internal Wave Run-Up To The Surfzone

Sinnett, Gregory; Feddersen, Falk; Lucas, Andrew J.; Pawlak, Geno; Terrill, Eric

doi:10.1175/JPO-D-17-0210.1

i

Observations Of Nonlinear Internal Wave Run-Up To The Surfzone

2018
By Sinnett, Gregory ; Feddersen, Falk ; Lucas, Andrew J. ; ...

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Journal Title:

Journal of Physical Oceanography
Personal Author:

Sinnett, Gregory ; Feddersen, Falk ; Lucas, Andrew J. ; Pawlak, Geno ; Terrill, Eric
NOAA Program & Office:

Sea Grant ; OAR (Oceanic and Atmospheric Research)
Sea Grant Program:

CASG/CUIMR (California Sea Grant)
Description:

The cross-shore evolution of nonlinear internal waves (NLIWs) from 8-m depth to shore was observed by a dense thermistor array and ADCP. Isotherm oscillations spanned much of the water column at a variety of periods. At times, NLIWs propagated into the surfzone, decreasing temperature by ≈1°C in 5 min. When stratification was strong, temperature variability was strong and coherent from 18- to 6-m depth at semidiurnal and harmonic periods. When stratification weakened, temperature variability decreased and was incoherent between 18- and 6-m depth at all frequencies. At 8-m depth, onshore coherently propagating NLIW events had associated rapid temperature drops (ΔT) up to 1.7°C, front velocity between 1.4 and 7.4 cm s−1, and incidence angles between −5° and 23°. Front position, ΔT, and two-layer equivalent height zIW of four events were tracked upslope until propagation terminated. Front position was quadratic in time, and normalized ΔT and zIW both decreased, collapsing as a linearly decaying function of normalized cross-shore distance. Front speed and deceleration are consistent with two-layer upslope gravity current scalings. During NLIW rundown, near-surface cooling and near-bottom warming at 8-m depth coincide with a critical gradient Richardson number, indicating shear-driven mixing.
Keywords:

Coastal Flows Internal Waves Coastal Flows Internal Waves
Source:

Journal of Physical Oceanography, 48(3), 531-554
DOI:

https://doi.org/10.1175/JPO-D-17-0210.1
Document Type:

Journal Article
Funding:

Grant no. NA14OAR4170075
Rights Information:

CC BY
Compliance:

Library
Main Document Checksum:

urn:sha256:bf718ea603931698446ac1c298fac9e268c1937533458384dc3ca7e2dc9e9591
Download URL:

https://repository.library.noaa.gov/view/noaa/33035/noaa_33035_DS1.pdf
File Type:

[PDF - 4.12 MB ]

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