Mesoscale Atmospheric Processes Seminar: Marcos Andrade

Universidad Mayor de San Andres, La Paz, Bolivia

Abstract

The effects of anthropogenic atmospheric aerosols upon glaciers have been the object of great interest due to the observed rapid melting of the latter in different parts of the world. Studies in Asia, especially over the Himalayas, suggest that aerosol transport to this region might be playing an important role both in changing albedo properties of snow and ice as well as increasing local temperature of the atmosphere, contributing in this way to the rapid receding of the Himalayan glaciers. A fast decrease in area and volume of the ice mass in the Andean glaciers has also been reported in different studies over the last 20 years.

With the aim of studying transport of aerosol particles produced by biomass burning east of the Andes, a set of experiments has been conducted. Using a MOUDI cascade impactor to examine surface air aerosols with different aerodynamic sizes, samples were collected under clean conditions (June, 2010) and in the middle of the biomass burning season (September, 2010) at Mt. Chacaltaya (5200 masl; 16°21'S, 68°07'W) and La Paz, Bolivia. In order to better understand the type of particles collected at high altitude locations, samples at regions near the biomass fires (522 masl; 16°16'S, 62°30'W) were also collected. The analyses show a small increment in PM_2.5 concentration between clean and smoky conditions at Chacaltaya. In contrast, the concentration was almost 10-times larger in regions near the fires. Samples where aerodynamic size particle varies from 0.2 m to 0.6 m, show that under clean conditions there is no trace of potassium whereas during biomass season potassium is present not only in La Paz and Chacaltaya (the Andean region) but near the area where fires are produced.

The high altitude of Chacaltaya station, its long history as a scientific laboratory as well as the aforementioned interest in aerosol transport over the Andean region led this site to be accepted as a Global Atmosphere Watch regional station within the World Meteorological Organization. A joint project with European partners will allow continuous measurements of aerosol properties arriving at this site over the coming years. The current state of this project and following steps that are planned will be discussed in this talk.