Abstract

MOLINA-CARPIO, Jorge et al. Climate and spatial variability of the humid upper Andes. Ecología en Bolivia [online]. 2019, vol.54, n.1, pp.40-56. ISSN 1605-2528.

We present a characterization of the climate of the humid Andes region and its spatial variability, with emphasis on the altitude range from 2,000 to 4,000 m. Through the analysis of daily and hourly climate records we could identify the dominant atmospheric processes in the Andean basin of the Beni River and Yungas. It was found that most of the multiple rainfall maxima in the Subandino and Yungas are a consequence of the interaction between the South American low level jet (SALLJ) and the complex regional orography. However local circulation mechanisms, which facilítate the transport of moisture from the valleys to the hillslopes following a diurnal cycle, predomínate in the range of 2,000 to 4,000 m. This result in a perhumid and cold strip centered around 3,000 m of altitude, where the average rainfall reaches values 2 to 10 times larger than potential evapotranspiration (PET). This strip is characterized by exceptionally high relative humidity and number of rainy days, and very low values of solar radiation, PET and diurnal temperature range. The combination of regional and local atmospheric processes with the orography creates multiple perhumid biogeographic islands, smaller than the "rainfall hotspots" of Chapare and Alto Madre de Dios.

Keywords : Climate; Humid upper Andes; Orographic rainfall.

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