Intraseasonal Variability of Moisture and Rainfall over the South American Altiplano

Abstract

Abstract Precipitation over the South American Altiplano (about 4000 m above sea level) is mostly concentrated during the austral summer (December–January–February) when mean easterly flow in the middle and upper troposphere favors the moisture transport from the interior of the continent toward the central Andes. Within the wet season, rainy days tend to cluster in rainy episodes of about a week long, interrupted by somewhat longer dry periods. Based on one-site, research-quality observations over the western Altiplano, it has been suggested that occurrence of deep, moist convection is largely controlled by the availability of water vapor in the local boundary layer. In this work the author evaluates the representativeness of the observations in the western Altiplano in a regional context and investigates if the hypotheses derived from these data are generally applicable to the rest of the plateau. The study is based on surface synoptic data and atmospheric reanalysis. The relationship between moisture f...