Continuous measurements of optical properties of atmospheric aerosols in Mukteshwar, northern India

Particulate pollution of mainly anthropogenic origin is a widely spread phenomenon in southern Asia, influencing climate and causing adverse health effects on humans. In this paper, we analyze continuous measurements of aerosol scattering and absorption properties that were conducted in Mukteshwar, a remote site in the Himalayan Mountains in northern India, during September 2005-September 2007. While aerosol concentrations were somewhat lower than those measured closer to urban areas in India, some optical parameters had a noticeable resemblance to those measured elsewhere in India. The average value of the measured single-scattering albedo was 0.81 at 525 nm, being indicative of a substantial amount of absorbing material. Annually, there were two periods when aerosol scattering and absorption coefficients were relatively low. These were the rainy season during July and August and the winter months December and January when particulate pollution seemed to reside partly below the altitude of the measurement station. During December and January, local cooking and warming of houses by biomass burning, normally not visible in the data, became evident yet weak sources of absorbing material.