TITLE:
Features of Internal Waves in a Shoaling Thermocline
AUTHORS:
Vadim V. Navrotsky, Valeriy Yu. Liapidevskii, Elena P. Pavlova
KEYWORDS:
Shelf; Shoaling Thermocline; Internal Waves; Turbulence
JOURNAL NAME:
International Journal of Geosciences,
Vol.4 No.5,
July
17,
2013
ABSTRACT: Observations and numeric modeling of internal wave
generation and transformation in the
shelf zone of sea show that the main part of tidal energy is transported to
shores in form of internal gravitational waves. Long-term measurements of
temperature and current velocity fluctuations at many levels in the near-bottom
thermocline were carried out during the periods when stable seasonal
thermocline was present. Analysis of the measurements permits us to understand
mechanisms of internal wave destruction with turbulent motion generation and
corresponding rebuilding of velocity and density mean fields in the stratified
near-bottom layer. Spectral analysis of temperature fluctuations shows that in
shoaling internal waves the low-frequency maxima disappear, maxima at higher frequencies
appear, and the spectra slope in the high frequency range changes with depth.
Taking into account the concurrent analysis of near-bottom pressure
fluctuations and current velocity fluctuations from surface till bottom we come
to the conclusion that breaking internal waves in a near-bottom thermocline
generate not only small-scale three-dimensional turbulence, but also quasi-horizontal
turbulence of larger scales, which considerably contributes into mixing and
sediments, alluvium, and nutrients transport in the shelf zone of sea.