Collaborative Research: Measurement of Aerosol Chemical and Radiative Properties in Nepal

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This project supports an aerosol sampling program that will be carried out in collaboration between the University of New Hampshire, the University of Colorado/CIRES, and the Nepalese Department of Hydrology and Meteorology (DHM). The concentrations of soluble ionic species, organic carbon and elemental carbon in aerosol will be determined on a continuous basis (at a nominal 2-day resolution) at these stations for approximately two years. This filter sampling will be complemented by continuous multi-wavelength aerosol optical depth measurements at each station. One station will be situated near Kathmandu, and the other at an altitude of 4100 m. The primary objective is to determine the modifications in the aerosol content of air masses as they traverse Nepal from south to north and encounter the Himalayan Massif. The alternating influence of summer monsoon air from the Bay of Bengal and wintertime westerlies are expected to cause large seasonal variations in the concentration and composition of aerosols. Optical depth measurements will provide information on the relationships between surface-level air masses and the aerosol burden in the overlying column. Little is currently known about the atmospheric chemistry over much of central Asia due to a lack of systematic sampling in this broad region. The central Asian monsoon circulation is the primary source of water for densely populated regions of Asia, and is also a major component of the global climate system. Model predictions suggest that anthropogenic modifications of atmospheric composition could greatly modify regional climate, including the strength of the summer monsoon and therefore the amount of much needed precipitation.