| Although aerosol radiative effects have been known for sometime and are considered one of the major uncertainties in climate change modeling, most of the studies have focused on the forcing due to scattering and absorption of radiation in the uv-visible region.1 Infrared spectral information allows the confirmation of key functional groups that are responsible for enhanced absorption observations from secondary organics in the uv-visible region. This work evaluates the infrared absorption by aerosols, particularly organics that are now found to be a major fraction of urban and regional aerosols in the 0.1 to 1.0 micron size range and to help identify key types of organics that can contribute to aerosol absorption of solar and infrared radiation important in climate forcing. Aerosol filter samples have been characterized in the mid infrared spectral ranges using diffuse reflection spectroscopy. Samples were collected in Mexico City, Little Rock, Arkansas, and Chicago, Illinois for comparison of different urban sites. |
