Infrared Signatures of Microbreaking Wave Modulation

Branch, Ruth; Jessup, Andrew T.

doi:10.1109/lgrs.2007.895688

Cited by 4 publications

(6 citation statements)

References 13 publications

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“…This phase discrepancy of the temperature modulation is related with a relative location between microbreaking and wave crest. The temperature modulation in the plunging region (Figure 15), showing the surface is renewed on the rear face of waves, is consistent with the laboratory experiments of Branch and Jessup [2007]. In the bore region, the bore front precedes the wave crest to disturb the forward surface, and therefore, the surface temperature rapidly decreases and the standard deviation pulsates earlier than the maximum surface elevation phase (see Figure 16).…”

Section: Transitions Of Surface Temperaturesupporting

confidence: 80%

“…Jessup and Hesany [1996] observed the maximum modulation occurs on a forward face of ocean swell in the case of wind and swell aligned. On the other hand, Branch and Jessup [2007] found the opposite phase modulations in both laboratory and ocean observations; the surface disruption occurs on the rear face of breaking waves. This phase discrepancy of the temperature modulation is related with a relative location between microbreaking and wave crest.…”

Section: Transitions Of Surface Temperaturementioning

confidence: 89%

“…[21] On the other hand, a series of studies on sea surface temperatures with infrared imagery by Jessup and his colleagues has revealed that wind-driven microbreaking of ocean waves has a primary role for renewing the surface owing to breaking turbulence, resulting in modulations of the surface temperature [Jessup and Hesany, 1996;Jessup et al, 1997;Wick and Jessup, 1998;Siddiqui et al, 2001;Branch and Jessup, 2007]. The temperature modulation has been observed to appear at different phases in open ocean, which is caused by microbreaking owing to short waves bounded on longer swell waves [Branch and Jessup, 2007].…”

Section: Small-scale Laboratory Experimentsmentioning

confidence: 99%

“…The temperature modulation has been observed to appear at different phases in open ocean, which is caused by microbreaking owing to short waves bounded on longer swell waves [Branch and Jessup, 2007]. For depth-induced breaking waves, identical turbulence in the bore is also formed in front of the wave crest to induce the temperature modulation.…”

Section: Small-scale Laboratory Experimentsmentioning

confidence: 99%

“…Jessup and his colleagues have also discussed the impact of wind-driven microbreaking at wave crests on the surface renewal process. They examined changes in surface temperature modulation and the size of the renewed surface in a series of laboratory experiments and observations made in the open ocean [Jessup and Hesany, 1996;Siddiqui et al, 2001;Zappa et al, 2004;Branch and Jessup, 2007].…”

Section: Introductionmentioning

confidence: 99%

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Infrared measurements of surface renewal and subsurface vortices in nearshore breaking waves

Watanabe

Mori

2008

J. Geophys. Res.

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[1] When ocean waves reach a surf zone, jets projecting from the breakers splash sequentially, producing horizontal roller vortices beneath the jets and longitudinal counterrotating vortices behind the rollers; these vortices organize into three-dimensional structures that evolve into a turbulent bore with wave propagation. This disrupts any uniform temperature distributions on the surface, creating heterogeneous patterns of surface temperatures. In this study, we extracted surface temperature distributions from infrared measurements in small-and large-scale wave flumes, then used those data to study the renewed surfaces created by subsurface vortices beneath spilling and plunging breakers. In our large-scale experiments, temporal and spatial scales of surface renewal and surface recovery were consistent with earlier work; however, in our small-scale experiments, the spatial scales showed significant deviations from earlier in situ observations. These inconsistencies may be attributed to scale effects for subsurface vortices, and we show that the Froude number (Fr) can be used to characterize the initial formation of longitudinal counterrotating vortices. Further, for turbulent flows fully developed by wave breaking in a bore region, the frequency of surface renewal correlates exponentially with Reynolds number (Re). The computed vorticity on the breaking wave surface exhibits local patterns which correlate strongly with the gravity induced counterrotating vortices, which in turn renew the rear-facing surface of the breaking waves. In contrast the turbulent bore which precedes the wave crest rapidly disturbs and renews the surface in front of the crest. These two different mechanisms for surface renewal, during the nearshore breaking process, lead to modulations in the surface temperature distribution and changes in thermal diffusivity during the propagation of the breaking wave.Citation: Watanabe, Y., and N. Mori (2008), Infrared measurements of surface renewal and subsurface vortices in nearshore breaking waves,

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Section: Transitions Of Surface Temperaturesupporting

confidence: 80%

Section: Transitions Of Surface Temperaturementioning

confidence: 89%

Section: Small-scale Laboratory Experimentsmentioning

confidence: 99%

Section: Small-scale Laboratory Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Infrared measurements of surface renewal and subsurface vortices in nearshore breaking waves

Watanabe

Mori

2008

J. Geophys. Res.

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Stereo imaging and X-band radar wave data fusion: An assessment

et al. 2018

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The use of spatial and spatio-temporal data is rapidly changing the paradigm of wind wave observations, which have been traditionally restricted to time series from single-point measurements (e.g. from buoys, wave gauges). Active and passive 2D remote sensors mounted on platforms, ships, airplanes and satellites are now becoming standards in the oceanographic community and industry. Given the covered area ranging from centimeters to kilometers, such sensors are now a valuable tool for ocean and coastal observations. In this paper, we intercompare spatio-temporal wind wave data acquired with two state-of-the-art techniques, namely the stereo wave imaging and the X-band marine radar. The comparison was performed by operating the two instruments on an oceanographic research platform during a crossing-sea condition. We analyzed the statistical properties of the wave field, and its directional and omni-directional energy distributions. From our analysis, we suggest that stereo data can be exploited to find the best radar Modulation Transfer Function and scale factor needed to estimate wave parameters. Moreover, the fusion of the two systems will allow to broaden the scales covered by any one measurement, and to retrieve reliable directional wave spectra from short (∼1 m) to midwavelengths (∼100 m). Highlights ► We compare spatio-temporal wave data from stereo imaging and X-band radar. ► We use stereo data to improve the radar Modulation Transfer Function (MTF) and scale factor. ► The fusion of the two systems will allow covering spatial scales broader than any one measurement. Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site.

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