Rip Current Observations via Marine Radar

Haller, Merrick C.; Honegger, D.; Catalán, Patricio A.

doi:10.1061/(asce)ww.1943-5460.0000229

Cited by 57 publications

(35 citation statements)

References 26 publications

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“…In this case, the model is correctly predicting a gyre‐like flow caused by a gap in the nearshore sandbar. This type of circulation was common during the experiment, and mainly occurred during low tide [ Haller et al ., ].…”

Section: Resultssupporting

confidence: 66%

“…This will be demonstrated using a rip current which appeared during low tides, at y ≈ 900 m, coincident with a gap in the nearshore bar/terrace. This rip, which occurred on multiple days, was well imaged by time‐averaged radar backscatter imagery [ Haller et al ., ], and was also detected by IR‐v measurements.…”

Section: Resultsmentioning

confidence: 99%

“…Measurements and forward model predictions for 13 September, 1800 EST (low tide). Background shading represents X‐band radar backscatter averaged over a 17 min collection period; high backscatter (green) corresponds to breaking waves, and/or surface roughness due to the presence of a rip current [ Haller et al ., ]. Red arrows are IR‐v measurements of currents (scale arrow in bottom‐right is 50 cm/s), which confirm the presence of a rip current at y ≈ 900 m. Red line is optical‐based shoreline position.…”

Section: Resultsmentioning

confidence: 99%

“…An X‐band marine radar, described by Haller et al . [], was mounted at the location

(x, y, z) = (17, 971, 14) m

. The system measured backscatter intensity in range bins spaced at 3 m to a maximum range of 927 m, and 270 azimuthal bins.…”

Section: Observationsmentioning

confidence: 99%

See 3 more Smart Citations

Surf zone bathymetry and circulation predictions via data assimilation of remote sensing observations

Wilson

Özkan-Haller

Holman

et al. 2014

J. Geophys. Res. Oceans

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Bathymetry is a major factor in determining nearshore and surf zone wave transformation and currents, yet is often poorly known. This can lead to inaccuracy in numerical model predictions. Here bathymetry is estimated as an uncertain parameter in a data assimilation system, using the ensemble Kalman filter (EnKF). The system is tested by assimilating several remote sensing data products, which were collected in September 2010 as part of a field experiment at the U.S. Army Corps of Engineers Field Research Facility (FRF) in Duck, NC. The results show that by assimilating remote sensing data alone, nearshore bathymetry can be estimated with good accuracy, and nearshore forecasts (e.g., the prediction of a rip current) can be improved. This suggests an application where a nearshore forecasting model could be implemented using only remote sensing data, without the explicit need for in situ data collection.

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Section: Resultssupporting

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…An X‐band marine radar, described by Haller et al . [], was mounted at the location

(x, y, z) = (17, 971, 14) m

. The system measured backscatter intensity in range bins spaced at 3 m to a maximum range of 927 m, and 270 azimuthal bins.…”

Section: Observationsmentioning

confidence: 99%

See 2 more Smart Citations

Surf zone bathymetry and circulation predictions via data assimilation of remote sensing observations

Wilson

Özkan-Haller

Holman

et al. 2014

J. Geophys. Res. Oceans

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show abstract

“…Time averaging is commonly used to remove noise and reveal spatial (flow) patterns in radar images (e.g. Dankert et al, 2003;Haller et al, 2013). At the Sand Motor, 5-minute time-averaged X-band radar images revealed signatures of the incoming fresh water lens, as well as spatial patterns associated with flow separation.…”

Section: Field Methodsmentioning

confidence: 99%

Field Observations of Tidal Flow Separation at a Mega-Scale Beach Nourishment

Radermacher¹,

Zeelenberg²,

Schipper³

et al. 2015

The Proceedings of the Coastal Sediments 2015

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Abstract:Large beach nourishments are often considered an efficient way to deal with coastal zone management issues, notably coastal erosion. Such large nourishments can act as a geometric perturbation, which might cause the tidal current to detach from the coastline. The Sand Motor is a mega-scale beach nourishment in the Netherlands. Field observations of the tidal flow field north of the Sand Motor are presented, showing evidence of flow separation and eddy formation during the flood phase of the tide. GPS-tracked drifters are transported offshore upon deployment near the tip of the nourishment. Flow convergence measured with nearshore current profilers is indicative of flow reversal at the lee side. Images of the temporal development of coherent patterns in time-averaged X-band radar backscatter align with in-situ observations of the flow field. Tidal flow separation at such large nourishments might have an impact on morphological development of the nourishment, as well as on swimmer safety.

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Cross‐shore tracer exchange between the surfzone and inner‐shelf

2014

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Cross-shore tracer exchange between the surfzone and inner-shelf is examined using temperature and dye measurements at an approximately alongshore-uniform beach. An alongshore-oriented plume is created by releasing dye continuously for 4.5 h in a surfzone alongshore current. The plume is sampled for 13 h from the release point to 700 m downstream, between the shoreline and 250 m offshore (6 m water depth). Within the surfzone ( 2 m depth), water is relatively warm, and dye is vertically well mixed. On the inner-shelf (3-6 m depth), alongshore currents are weak, and elevated temperature and dye co-occur in 25-50 m wide alongshore patches. Within the patches, dye is approximately depth-uniform in the warm upper 3 m where thermal stratification is weak, but decreases rapidly below 3 m with a strong thermocline. Dye and temperature vertical gradients are correlated, and dye is not observed below 18 C. The observations and a model indicate that, just seaward of the surfzone, thermal stratification inhibits vertical mixing to magnitudes similar to those in the ocean interior. Similar surfzone and inner-shelf mean alongshore dye dilution rates are consistent with inner-shelf dye properties being determined by local cross-shore advection. The alongshorepatchy and warm inner-shelf dye is ejected from the surfzone by transient rip currents. Estimated Stokes drift driven cross-shore exchange is small. The transient rip current driven depth-normalized heat flux out of the surfzone has magnitude similar to those of larger-scale shelf processes. Dye recycling, from the inner-shelf back to the surfzone, is suggested by relatively long surfzone dye residence times.

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Rip Current Observations via Marine Radar

Cited by 57 publications

References 26 publications

Surf zone bathymetry and circulation predictions via data assimilation of remote sensing observations

Surf zone bathymetry and circulation predictions via data assimilation of remote sensing observations

Field Observations of Tidal Flow Separation at a Mega-Scale Beach Nourishment

Cross‐shore tracer exchange between the surfzone and inner‐shelf

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