Author(s): C. Rozas; A. De La Fuente; Y. Nino; H. Ulloa
Linked Author(s): Yarko Niño
Keywords: No Keywords
Abstract: Lake Villarrica, located in south central Chile, has a maximum depth of 167 m and a maximum fetch of about 20 km. The lake is monomictic, with a seasonal thermocline located at a depth of about 20 m. In this paper, results of a field study and numerical simulations of the response of the lake to wind are presented and discussed, focusing on the modal analysis of internal waves affected by Coriolis effects. The field data showed forced and free responses of the lake stratification in the form of tilting of the isopycnals and the presence of linear and nonlinear internal waves. A thermocline is identified, assuming a two-layer stratification of the system, which shows dominant frequencies of oscillation, corresponding to periods of 9,11,12.4, 18.2, 21.9, 26.9and 103 hours. Most of these frequencies are also predicted by the numerical simulations, which show a reasonably good agreement with observed internal waves. The numerical simulations identify the occurrence of a mode 1 Kelvin wave, with a period of about a day that coincides with the frequency of daily winds blowing on the lake. The simulations suggest that this mode of the Kelvin waves would be in a quasiresonant state, which in the field would be damped and controlled by friction effects.
Year: 2009