A tide‐generated internal waveform in the western approaches to the Strait of Gibraltar

Violette, Paul E. La; Arnone, Robert

doi:10.1029/jc093ic12p15653

Cited by 49 publications

(18 citation statements)

References 7 publications

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“…[13] Semidiurnal tidal fluctuations in the Strait can reverse the flows [La Violette and Lacombe, 1988], and the periodic occurrence of nonlinear internal waves can support mixing that increases the N:Si:P ratio in the Atlantic and decreases it in the Mediterranean waters. Nonlinear internal wave packets are generated at the main bathymetric sill (the Camarinal sill) located in the western approaches to the Strait and have been found 200 km inside the Alboran Sea [Pistek and La Violette, 1999].…”

Section: Resultsmentioning

confidence: 99%

The N:Si:P molar ratio in the Strait of Gibraltar

Dafner

Boscolo

Bryden

2003

Geophysical Research Letters

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All existing descriptions of nutrient distributions in the Strait of Gibraltar suggest that the Atlantic water brings to the Mediterranean Sea nutrients in the Redfield ratio (N:Si:P = 16:15:1). Here, the N:Si:P molar ratios (±Standard Error), obtained in April 1998, are used to show that in the Atlantic water at the western entrance of the Strait this ratio is lower (13.8(±0.5):12.1(±1.0):1) than the classical Redfield ratio; it is close to the Redfield ratio in the middle of the Strait (15.6(±0.6):10.7(±0.9):1), and increases dramatically to 23.6(±3.4):29.1(±4.5):1 at the eastern entrance of the Strait. In the Mediterranean water, the N:Si:P ratio has a quite similar trend with 31.5(±6.0):26.5(±3.6):1 in the east, 20.4(±0.2):31.5(±11.1):1 in the middle and 18.1(±0.6):17.6(±0.7):1 in the west of the Strait. The physical and biological processes that account for the observed spatial variability of the N:Si:P ratio along the Strait are identified. We estimated that in the Atlantic water entering the Mediterranean Sea, about 84% of the variability in N:Si:P molar ratio is due to biological and 16% to physical processes.

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Section: Resultsmentioning

confidence: 99%

The N:Si:P molar ratio in the Strait of Gibraltar

Dafner

Boscolo

Bryden

2003

Geophysical Research Letters

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“…Further measurements of internal waves in the strait, together with simultaneous visual observations from aircraft and the space shuttle by bathythermograph, radar, infrared scanner collected in October 1982October , 1984October , and 1985, were presented by La Violette and Arnone (1988).…”

Section: "Shallow" Shelfmentioning

confidence: 99%

“…The date of the shot was defined with the method presented in Appendix A. It is necessary to mention that in another case of propagation of the tidally generated solitary wave over Camarinal Sill described by La Violette and Arnone (1988), the soliton propagates strictly eastward from the strait and does not turn to the north in the Alboran sea. The shear flow induced at the shelf in the Ceuta Bay and the Gibraltar Bay is much less pronounced, but may be still distinguished by means of remote sensing (see Fig.…”

Section: "Shallow" Shelfmentioning

confidence: 99%

“…Reviews on the internal solitary waves generation in both shallow and deep areas of the World Ocean are presented in Ostrovsky and Stepanyants (1989), Grimshaw et al (2004), Sabinin et al (2004), , and Helfrich and Mellville (2006). Examples of areas with strong internal tides are the Strait of Gibraltar (Ziegenbein, 1970;Armi and Farmer, 1988;La Violette and Arnone, 1988;Kinder, 1984;, the Mascarene Ridge (Konyaev et al, 1995;Morozov et al, 2009), Russian Polar Seas (Morozov, 1995;Serebryanyi, 2000), the continental shelf of the UK (Small et al, 1999(Small et al, , 2001(Small et al, , 2003, the Andaman Sea (Osborne and Burch, 1980;Vlasenko and Alpers, 2005), the Alboran Sea (Speich et al, 1996;Lafuente and Delgado, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Transformation of internal solitary waves at the "deep" and "shallow" shelf: satellite observations and laboratory experiment

Shishkina

Sveen

Grue

2013

Nonlin. Processes Geophys.

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Abstract. An interaction of internal solitary waves with the shelf edge in the time periods related to the presence of a pronounced seasonal pycnocline in the Red Sea and in the Alboran Sea is analysed via satellite photos and SAR images. Laboratory data on transformation of a solitary wave of depression while passing along the transverse bottom step were obtained in a tank with a two-layer stratified fluid. The certain difference between two characteristic types of hydrophysical phenomena was revealed both in the field observations and in experiments. The hydrological conditions for these two processes were named the "deep" and the "shallow" shelf respectively. The first one provides the generation of the secondary periodic short internal waves -"runaway" edge waves -due to change in the polarity of a part of a soliton approaching the shelf normally. Another one causes a periodic shear flow in the upper quasi-homogeneous water layer with the period of incident solitary wave. The strength of the revealed mechanisms depends on the thickness of the water layer between the pycnocline and the shelf bottom as well as on the amplitude of the incident solitary wave.

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“…These roughness bands are often sea surface manifestations of internal waves [1]. They can be captured by a variety of remote sensing instruments, e.g., by ship radar [2], by photographic cameras flown on air-or spacecrafts [3], by optical scanners flown on satellites [4], by ground-based radar [5], or by airborne and spaceborne imaging radars [6]- [9]. However, in the past, sea surface manifestations of internal waves have been used only sporadically in systematic studies on internal wave dynamics, e.g., by Watson [5] who monitored the passage of internal waves from the Rock of Gibraltar by a shore based radar, and by Richez [9] who tracked internal wave trains through the Strait of Gibraltar by an airborne synthetic aperture radar (SAR).…”

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confidence: 99%

Wavelet analysis in SAR ocean image profiles for internal wave detection and wavelength estimation

Rodenas

Garello²

1997

IEEE Trans. Geosci. Remote Sensing

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Oceanographers and remote sensing researchers have long recognized the potential of using satellite imagery for studying oceanic internal waves. Radars are able to image internal waves because they are particularly sensitive to changes in the small-scale surface roughness (i.e., the capillary and ultragravity waves) present on the ocean surface which are altered by the velocity field associated with the internal waves. If, as seems likely, the greytone patterns of these images can be confirmed to correspond to trough and crest patterns of internal waves, then a great deal can be learnt about internal waves from satellite data. In this paper, the utility of wavelet analysis as a tool for oceanic internal wave detection and wavelength estimation is examined using both continuous and discrete versions of the wavelet transform. The theoretical background of each procedure is briefly described and applied using a specific "wavelet" for each case. In this first approach, we only consider supervised detection for the internal wave train detection problem. Normally, an unsupervised method using the two-dimensional (2-D) wavelet transform is required for internal wave detection and orientation, including land-sea separation to avoid false alarms. We first present the construction of an appropriate wavelet basis, based on an oceanographic soliton internal wave analytical model, to detect and localize nonlinear wave signatures from SAR ocean image profiles. The structure of arbitrary wavelet basis derived from the compactly supported orthonormal B-splines wavelets is studied so as to obtain more optimal discrete wavelet decompositions. Comparisons are made for wavelet decompositions based on several families of compactly supported wavelets. Finally, the continuous wavelet transform is applied to estimate energies and wavelengths within soliton peaks from the detected internal wave trains. The advantages and drawbacks of the continuous and discrete wavelet transforms for the internal wave detection problem from SAR ocean image profiles are also discussed. The results from this study show that wavelet analysis is an excellent tool to detect internal waves against background noise, and to estimate, with a good degree of precision, soliton wavelengths from SAR ocean image profiles.Index Terms-B-splines, compactly supported orthonormal wavelets, continuous wavelet transform (CWT), discrete wavelet transform (DWT), ERS-1 SAR ocean images, Gaussian wavelet, internal waves, multiresolution analysis, scalogram, soliton model.

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A tide‐generated internal waveform in the western approaches to the Strait of Gibraltar

Cited by 49 publications

References 7 publications

The N:Si:P molar ratio in the Strait of Gibraltar

The N:Si:P molar ratio in the Strait of Gibraltar

Transformation of internal solitary waves at the "deep" and "shallow" shelf: satellite observations and laboratory experiment

Wavelet analysis in SAR ocean image profiles for internal wave detection and wavelength estimation

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A tide‐generated internal waveform in the western approaches to the Strait of Gibraltar

Cited by 49 publications

References 7 publications

The N:Si:P molar ratio in the Strait of Gibraltar

The N:Si:P molar ratio in the Strait of Gibraltar

Transformation of internal solitary waves at the &quot;deep&quot; and &quot;shallow&quot; shelf: satellite observations and laboratory experiment

Wavelet analysis in SAR ocean image profiles for internal wave detection and wavelength estimation

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Transformation of internal solitary waves at the "deep" and "shallow" shelf: satellite observations and laboratory experiment