Internal wave weather in a stratified lake

Saggio, Angelo, and Jörg Imberger

Limnol. Oceangr. 43(8), 1998, 1780-1795 | DOI: 10.4319/lo.1998.43.8.1780

ABSTRACT: Thermistor chain data collected in Lake Biwa (Japan) during a period of strong stratification were used to determine the nature of the water column response to wind forcing. The evolution of the basin-scale waves in the lake were reproduced in three-dimensional numerical simulations and the time variability of the internal wave spectrum is discussed based on spectral analysis of the thermistor chain records. Severe winds associated with the passage of three typhoons during the sampling period excited basin-scale Kelvin and PoincarC waves, which, by interaction with the topography of the lake and non-linear effects, generate trains of high-frequency internal waves. Time-frequency analysis of the temperature signals suggests that the omega.lc.gif - 56 Bytes-2 slope of the internal wave spectrum is probably the result of the composition of groups of waves with high intermittence travelling through the wave guide. The observed rapid decay of internal wave energy after severe wind events seemed to be due mostly to high dissipation at the sloping boundaries of the lake.

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