The atmospheric processes that bring about the conversion                  of the gases of sulfur dioxide, nitrogen oxides, and organic                    compounds to water soluble acids and salts are not well                         understood.  Laboratory and field observations have identified                  chemical processes that can affect and promote these                            transformations, but the relative importance of the several                     oxidizing and catalytic systems present in the atmosphere                       remains largely unknown.  Attempts to understand the                            relationships between gaseous emissions and remotely observed                   deposition of their oxidation products are frustrated by this                   lack of knowledge about the fundamental conversion processes                    occurring in nature.  There is currently great interest in                      clouds as potential "reaction chambers" for the oxidation of                    gases into less volatile and water soluble compounds.  Many                     fundamental aspects of sulfur chemistry in the remote marine                    environment are especially poorly understood.  The principal                    goals of the research project are:  1)   To measure vertical                    distributions of sulfur dioxide and dimethylsulfide over the                    Northeastern Pacific Ocean and to determine the primary factors                 responsible for the observed distributions; and 2) To determine                 the relationships between dimethylsulfide, sulfates, cloud                      condensation nuclei and cloud droplet size distributions in the                 remote marine environment.                                                                The first step in accomplishing these goals will be                   the development and testing of instrumentation for airborne                     studies of the sulfur chemistry in the marine atmosphere.                       Limited airborne measurements over the Northeastern Pacific                     Ocean will be carried out over the next two years.  The results                 of these studies should add significantly to our knowledge of                   sulfur in the marine environment and its role in global                         tropospheric chemistry and climate.