We recommend that the uncertainties in calculated aerosol forcing at the top of the atmosphere be reduced to within ±15 percent both globally and locally. This limit of uncertainty is equivalent to that required in estimating greenhouse gas forcing (IPCC, 1995a). Locally this would imply an uncertainty in forcing of less than 1.5 W m^-2 (by assuming a local aerosol effect of -10 W m^-2 in the diurnal mean).

This report presents our opinions about needed scientific studies (measurements, observations, model developments); the technologies required (satellites, computers, aircraft, instruments); the necessary resources; and an implementation plan for a U.S. multiagency program to answer these scientific questions and, thereby, to improve climate models. Chapters 3 and 4 contain our recommendations for implementing a focused, integrated research program. First, however, Chapter 2 describes needed research.