Internal Kelvin wave frontogenesis on the equatorial pycnocline

Abstract

This study investigates the influence of the background stratification of the pycnocline on Kelvin wave frontogenesis on the equatorial beta plane using numerical simulations. The pycnocline is characterized by its depth and thickness. We analyzed the propagation of a nonlinear Kelvin wave on the equatorial pycnocline at different depths and thicknesses. Our numerical simulations show that the steepening of a nonlinear Kelvin wave develops in a similar manner for varying parameters of the pycnocline. We calculated and analyzed the dependence of the time of breaking on the pycnocline at different depths and thicknesses. We found that an increase in the thickness of the pycnocline results in a delay of Kelvin wave frontogenesis. However, an increase in the depth of the pycnocline results in a decrease of the time of the breaking of a nonlinear Kelvin wave. Our numerical results show that the nonlinear Kelvin wave would break after four months of evolution on the equatorial pycnocline in the Pacific Ocean.

Keywords:

• Equatorial Kelvin wave
• Nonlinearity
• Time of breaking
• Numerical modeling

Acknowledgments

This work was supported by the Russian Foundation for Basic Research Grant 10-05-00770 and by FEB RAS Grant 09-II-07-002. The authors thank the editor and anonymous referees for remarks which led to a substantial improvement of this article.