Aerosol Radiative Forcing Observed from Natural and Anthropogenic Sources

In order to understand the impact of aerosols on our climate, we must first accurately quantify their radiative effect on the Earth's energy balance. Here we determine the radiative impact of aerosols at the surface and top of atmosphere directly from radiometric observations. Our objective is to determine the variability that exists in the forcing in diverse geographical regions, and between natural and anthropogenic sources. We achieve our goal by deriving the aerosol forcing from observations obtained from the Indian Ocean Experiment (INDOEX), and from the Atmospheric Radiation Measurement Program (ARM) sites in the continental US, and the Tropical Western Pacific. In addition to understanding the forcing variability, we note that these studies will also provide powerful constraints for aerosol models that are being developed for climate models and satellite retrieval algorithms.