Annual and Daily Meteorological Cycles and Atmospheric Circulation Associated with Precipitation Events on Sajama Volcano, Bolivia.

Revista de Ecologia, La Paz, Bolivia (in press)
(In spanish; spanish abstract available here soon)

Mathias Vuille, Douglas R. Hardy, Carsten Braun, Frank Keimig, Raymond S. Bradley

    Dept. of Geosciences, University of Massachusetts, USA


In order to improve the calibration of an ice core recently recovered from the summit of Sajama Volcano, Bolivia, an automatic satellite-linked weather station was installed on the summit in October 1996. Here we present first results regarding the daily and annual meteorological cycle of barometric pressure, solar radiation, air temperature, specific humidity, wind speed, wind direction and snow accumulation (precipitation) over the time period October 96 - September 1997. The first year of measurements at the station has demonstrated that seasonal weather changes at the summit can occur abruptly, and the data further illustrate that climatic conditions are more episodic in nature than previously believed. This unique high altitude climatic data not only increases our knowledge in terms of ice core calibrations in the tropics, but also allows us to gain more insight into the climatic changes, currently under way in the high altitudes of the Tropics. Additional information regarding summer precipitation events results from the analysis of atmospheric circulation patterns, transport mechanisms and moisture sources associated with snowfall on Sajama. These circulation analyses show that highly variable patterns of atmospheric conditions can lead to snowfall on Sajama during the summer months. Overall 17 precipitation episodes were recorded on Sajama Volcano during the 1996/97 summer season (Nov. 96 - March 97) by snow depth sensors and additional measurements at our weather station.

Sajama volcano, Bolivia.

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