The First ISCCP Regional Experiments (FIRE) have been designed to improve data products and cloud/radiation parameterizations used in general circulation models (GCMs). Specifically, the goals of FIRE are (1) to improve the basic understanding of the interaction of physical processes in determining life cycles of cirrus and marine stratocumulus systems and the radiative properties of these clouds during their life cycles and (2) to investigate the interrelationships between the International Satellite Cloud Climatology Project (ISCCP) data, GCM parameterizations, and higher space and time resolution cloud data. To-date, four intensive field-observation (IFO) periods were planned and executed: a cirrus IFO (October 13 - November 2, 1986); a marine stratocumulus IFO off the southwestern coast of California (June 29 - July 20, 1987); a second cirrus IFO in southeastern Kansas (November 13 - December 7, 1991); and a second marine stratocumulus IFO in the eastern North Atlantic Ocean (June 1 - June 28, 1992). Each mission combined coordinated satellite, airborne, and surface observations with modeling studies to investigate the cloud properties and physical processes of the cloud systems. The Atlantic Stratocumulus Transition Experiment (ASTEX)/Marine Aerosol Gas Exchange (MAGE) experiment is a multinational effort to improve our capability for studying cloud-chemistry interactions and the air/sea fluxes that affect them. The primary purpose of ASTEX (with which MAGE collaborated) was to study the factors influencing the formation and dissipation of marine clouds. The specific goals of the MAGE atmospheric chemistry experiment in ASTEX included:- Develop and test a Lagrangian strategy for studying chemical and meteorological evolution in a tagged airmass, using ships, balloons, and aircraft.- Develop and test new techniques for estimating trace-gas and aerosol fluxes across the air/sea interface by comparison with traditional approaches.- Evaluate the impact of marine and continental aerosols on the formation and dissipation of stratocumulus clouds.- Compare the impacts of natural and anthropogenic sulphur, halogens, and hydrocarbons on marine aerosol chemistry.- Gain experience with multi-national and multi-agency field experiments as a means for addressing global tropospheric chemistry issues.