Patterns of Local Circulation in the Itaipu Lake Area: Numerical Simulations of Lake Breeze

Abstract

The lake-breeze circulation in the Itaipu region was investigated numerically using a nonhydrostatic version of the Topographic Vorticity Model. The area of study corresponds to a 100 km ? 180 km rectangle, located on the Brazil?Paraguay border, with Itaipu Lake in its center. The characteristics of the lake breeze generated by the numerical experiments were consistent with the observations available in the area. The numerical experiments have shown that the land use effect is important in the spatial distribution of the lake-breeze circulation and that the topography contributes to modulating the breeze intensity, with the daytime valley?mountain circulation intensifying the lake breeze. However, the circulation pattern observed during daytime over the region is mainly due to the Itaipu Lake presence. The numerical results indicated that Itaipu Lake is able to generate and sustain a lake breeze, with 3.5 m s?1 of maximum intensity and 1500-m depth, that propagates inland at 5.1 km h?1 under typical undisturbed and calm-wind summer conditions.