The South American Altiplano is a high altitude plateau located between 15°S and 22°S and lying between two mountain chains of the Central Andes. Within the plateau are two large features of surface discontinuity that influence local atmospheric circulations. Lake Titicaca, at the north end of the Altiplano is has an area of 8,300 square km making it the 2nd largest lake in South America. The Salar de Uyuni is the largest dry salt lake in the world with a surface area of 9000 square km. These features and their influences on local circulation can possibly change weather and climate of their surrounding areas. The aim of this study is to use pilot balloon soundings and rain gauge measurements to describe the influence of these features on their surroundings, and the impact on precipitation.

Large-scale results showed a relationship between upper-level easterly flow and wet days on the Altiplano, in addition to the opposite; westerly flow and dry days on the altiplano. With regards to Lake Titicaca, we observed a tendency for increased precipitation with proximity to the lake. The difference in flow on wet and dry days also modified the lake-breeze circulation. Analysis of morning and afternoon near-surface winds about both Lake Titicaca and the Salar de Uyuni indicated morning confluence and afternoon difluence. This appears to be associated with the observed increased morning convection over Lake Titicaca indicated by satellite imagery. Comparison of the Salar and Lake circulations indicated a stronger diurnal breeze signal at the salar, possibly a result of the resistance of the salt surface to heating, and the contrasting land cover surrounding the salar.