Aerosol Direct Radiative Effects Over the Northwest Atlantic, Northwest Pacific, and North Indian Oceans: Estimates Based on In-situ Chemical and Optical Measurements and Chemical Transport Modeling

The largest uncertainty in the radiative forcing of climate change over the industrial era is that due to aerosols, a substantial fraction of which is the uncertainty associated with scattering and absorption of shortwave (solar) radiation by anthropogenic aerosols in cloud-free conditions (IPCC, 2001). Quantifying and reducing the uncertainty in aerosol influences on climate is critical to understanding climate change over the industrial period and to improving predic- tions of future climate change for assumed emission scenar- ios. Measurements of aerosol properties during major field campaigns in several regions of the globe during the past decade are contributing to an enhanced understanding of at- mospheric aerosols and their effects on light scattering and climate. The present study, which focuses on three regions