Focusing and vertical mode scattering of the first mode internal tide by mesoscale eddy interaction

Dunphy, Michael; Lamb, Kevin G.

doi:10.1002/2013jc009293

Cited by 109 publications

(112 citation statements)

References 52 publications

(61 reference statements)

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“…The Amazon shelf break is particularly interesting because low-mode ITs generated at the shelf break and propagating into the open ocean may interact with eddies and the meandering field of steady currents such as the NBC and the NECC. Dunphy and Lamb (2014) showed that passing a mode-one IT through a mode-one baroclinic eddy results in IW scattering into higher modes -with implications for the…”

Section: J M Magalhaes Et Al: Internal Solitary Waves Off the Amazmentioning

confidence: 99%

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

et al. 2016

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Abstract. Synthetic aperture radar (SAR) imagery from the Amazon shelf break region in the tropical west Atlantic reveals for the first time the two-dimensional horizontal structure of an intense Internal Solitary Wave (ISW) field, whose first surface manifestations are detected several hundred kilometres away from the nearest forcing bathymetry. Composite maps and an energy budget analysis (provided from the Hybrid Coordinate Ocean Model -HYCOM) help to identify two major ISW pathways emanating from the steep slopes of a small promontory (or headland) near 44 • W and 0 • N, which are seen to extend for over 500 km into the open ocean. Further analysis in the SAR reveals propagation speeds above 3 m s −1 , which are amongst the fastest ever recorded. The main characteristics of the ISWs are further discussed based on a statistical analysis, and seasonal variability is found for one of the ISW sources. This seasonal variability is discussed in light of the North Equatorial Counter Current. The remote appearance of the ISW sea surface manifestations is explained by a late disintegration of the internal tide (IT), which is further investigated based on the SAR data and climatological monthly means (for stratification and currents). Acknowledging the possibility of a late disintegration of the IT may help explain the remote-sensing views of other ISWs in the world's oceans.

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Section: J M Magalhaes Et Al: Internal Solitary Waves Off the Amazmentioning

confidence: 99%

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

et al. 2016

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“…Although internal tides with u/c ( 1 propagate as linear waves, they can be steered (Rainville and Pinkel 2006;Park and Watts 2006;Zaron and Egbert 2014;Kelly and Lermusiaux 2016) and scattered (Dunphy and Lamb 2014;Kelly and Lermusiaux 2016) by subtidal flows. Several studies have found that these phenomena appear to be dominated by linearized tide-mean flow interactions, even in fully nonlinear models (Zaron and Egbert 2014;Dunphy and Lamb 2014;Kelly and Lermusiaux 2016).…”

Section: Mean Flow Effectsmentioning

confidence: 99%

“…Several studies have found that these phenomena appear to be dominated by linearized tide-mean flow interactions, even in fully nonlinear models (Zaron and Egbert 2014;Dunphy and Lamb 2014;Kelly and Lermusiaux 2016).…”

Section: Mean Flow Effectsmentioning

confidence: 99%

“…Observations of such tidal variability abound and have been associated with seasonal variations, three-dimensional structures, remote internal tide generation, and intermittent local mixing as reported, for example, by Holloway (1984), Lerczak et al (2003), Sharples et al (2007), Kurapov et al (2010), and Jackson (2012). Reviews by Huthnance (1995), Hollaway (1988), Ivey (2011), Nash et al (2012b), Lamb (2014), and others have emphasized that shelf-edge tidal dynamics are challenging to explain because many interconnected processes occur at the shelf break. Particularly strong variability has been documented in the Mid-Atlantic Bight (MAB) region (e.g., Colosi et al 2001;Nash et al 2012a).…”

Section: Introductionmentioning

confidence: 99%

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A Coupled-Mode Shallow-Water Model for Tidal Analysis: Internal Tide Reflection and Refraction by the Gulf Stream

Kelly

Lermusiaux

Duda

et al. 2016

Journal of Physical Oceanography

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A hydrostatic, coupled-mode, shallow-water model (CSW) is described and used to diagnose and simulate tidal dynamics in the greater Mid-Atlantic Bight region. The reduced-physics model incorporates realistic stratification and topography, internal tide forcing from a priori estimates of the surface tide, and advection terms that describe first-order interactions of internal tides with slowly varying mean flow and mean buoyancy fields and their respective shear. The model is validated via comparisons with semianalytic models and nonlinear primitive equation models in several idealized and realistic simulations that include internal tide interactions with topography and mean flows. Then, 24 simulations of internal tide generation and propagation in the greater Mid-Atlantic Bight region are used to diagnose significant internal tide interactions with the Gulf Stream. The simulations indicate that locally generated mode-one internal tides refract and/or reflect at the Gulf Stream. The redirected internal tides often reappear at the shelf break, where their onshore energy fluxes are intermittent (i.e., noncoherent with surface tide) because meanders in the Gulf Stream alter their precise location, phase, and amplitude. These results provide an explanation for anomalous onshore energy fluxes that were previously observed at the New Jersey shelf break and linked to the irregular generation of nonlinear internal waves.

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“…Based on linear wave theory, Cai et al (2008) studied internal waves in a shear background current, and found that in addition to the velocity shear across the pycnocline, the vertical structure of the horizontal velocity profile also had a significant influence on the evolution of internal waves. The interaction between mode-1 internal tides and mesoscale eddies was examined in Dunphy and Lamb (2014). The authors found that the interaction, essentially the bending of the paths followed by the wave energy, produced hot and cold spots of energy flux.…”

Section: Introductionmentioning

confidence: 99%

On the interaction of short linear internal waves with internal solitary waves

Stastna

2018

Nonlin. Processes Geophys.

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Abstract. We study the interaction of small-scale internal wave packets with a large-scale internal solitary wave using high-resolution direct numerical simulations in two dimensions. A key finding is that for wave packets whose constituent waves are short in comparison to the solitary wave width, the interaction leads to an almost complete destruction of the short waves. For mode-1 short waves in the packet, as the wavelength increases, a cutoff is reached, and for larger wavelengths the waves in the packet are able to maintain their structure after the interaction. This cutoff corresponds to the wavelength at which the phase speed of the short waves upstream of the solitary wave exceeds the maximum current induced by the solitary wave. For mode-2 waves in the packet, however, no corresponding cutoff is found. Analysis based on linear theory suggests that the destruction of short waves occurs primarily due to the velocity shear induced by the solitary wave, which alters the vertical structure of the waves so that significant wave activity is found only above (below) the deformed pycnocline for overtaking (head-on) collisions. The deformation of vertical structure is more significant for waves with a smaller wavelength. Consequently, it is more difficult for these waves to adjust to the new solitary-waveinduced background environment. These results suggest that through the interaction with relatively smaller length scale waves, internal solitary waves can provide a means to decrease the power observed in the short-wave band in the coastal ocean.

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Focusing and vertical mode scattering of the first mode internal tide by mesoscale eddy interaction

Cited by 109 publications

References 52 publications

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

Effect of the North Equatorial Counter Current on the generation and propagation of internal solitary waves off the Amazon shelf (SAR observations)

A Coupled-Mode Shallow-Water Model for Tidal Analysis: Internal Tide Reflection and Refraction by the Gulf Stream

On the interaction of short linear internal waves with internal solitary waves

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