Dynamics of internal waves generated by mountain breeze in Alchichica Crater Lake, Mexico

Abstract

Hydrophysical measurements carried out in the deep tropical crater lake Alchichica, Mexico, showed the presence of intense internal waves with a one-day period, generated by the regular influence of a mountain breeze. The diurnal waves effectively generate semidiurnal internal waves that are close to the resonance oscillations of the lake. The internal waves brake close to the shoreline and into the lake's bottom, which generates baroclinic circulation and water masses mixing. According to the data obtained with a ADCP, two diurnal and two semidiurnal inclined waves propagate in the lake towards each other in depth and can form fluctuations of a vertical mode, if the depth of the lake is a multiple of one-half the vertical wavelength. This multiplicity applies to both the diurnal and semidiurnal waves. The simultaneous existence of horizontal and vertical modes corresponds to a volumetric mode, or resonant lake oscillation. The waves collapse near the shore slopes and the lake's bottom, inducing baroclinic circulation and local mixing.