FLOW CHARACTERISTICS OF A GRAVITY CURRENT-INDUCED BY DIFFERENTIAL COOLING IN A SMALL LAKE

Extensive field data of a density current driven by the differences in the cooling rates between the two lobes of a small lake are presented . These data illustrate the fact that this gravitational motion affect s the whole system and dominates its lakewide circulation. Moreover, d ata are used to evaluate the entrainment into the density current and also to discuss the regime of the flow from a scaling analysis of the horizontal momentum equations. This analysis is specifically applied t o the central area of the lake, where the density current flows from o ne lobe to the other. Results of this study show that in the longitudi nal direction there is a balance between the pressure gradient and the turbulent viscous term. Further, it is found that geostrophy correctl y describes the transversal pattern of the passage of the gravity curr ent from the northern lobe to the southern, where it flows confined to the western shoreline.