Journal article

Degradation of an internal wave beam by parametric subharmonic instability in an upper ocean pycnocline

B Gayen, S Sarkar

JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS | AMER GEOPHYSICAL UNION | Published : 2013

Abstract

Numerical simulations are performed to investigate the interaction of a semidiurnal internal wave (IW) beam with the nonuniform stratification of an upper ocean pycnocline. During the initial stage of the interaction, higher harmonics originate after reflection of the IW beam at the caustic and are trapped in the pycnocline. In cases where the pycnocline thickness is sufficiently large (approximately larger than twice the dominant wavelength in the beam), the incoming beam undergoes a parametric subharmonic instability (PSI) during refraction through the pycnocline at later time. Consequently, there is significant energy transfer to subharmonic motions that exhibit exponential growth with a ..

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University of Melbourne Researchers

Grants

Awarded by ONR


Funding Acknowledgements

We are pleased to acknowledge discussions of internal wave beam observations and the present model results with Shaun Johnston, SIO. The support of ONR N000141110512, program monitor Terri Paluszkiewicz, is gratefully acknowledged.