Multilayer models to estimate periods of natural oscillation modes in tropical lakes and reservoirs

Abstract

Internal waves are essential to energy transfer processes in stratified water bodies. Tonunderstand their effects and implications for the energy balance of a water body, it is necessarynto know its spatial structure and period. In tropical zones, the thermal stratification in the waterncolumn is not as strong as in zones with climatic seasons. In the latter zones, the stratificationncan be described with models having few layers because the epilimnion and hypolimnion areneasily distinguishable, while in tropical zones significant temperature gradients are observednthrough most of the water column, so describing the stratification with few layers can leadnto unreliable estimates. In this paper, a multilayer model is developed to calculate periods ofnnatural oscillation modes in lakes and reservoirs with stratification typical of tropical zones. The stratification is simplified by assuming uniform density layers and the water body is considered to have a horizontal flat bottom. The model solves the eigenvalues and eigenvectors problem corresponding to sets of celebrities and the spatial structures of natural modes of oscillation. It is shown that a three-layer model is inadequate to estimate the celebrities of the natural modes of oscillation of the Porce II tropical reservoir.