organigramme de trajectoires

CONT: In order to predict the atmospheric concentrations of sulphur dioxide and sulphates down wind of source regions several phenomena must be quantitatively accounted for: 1. atmospheric transport and diffusion [;] 2. precipitation scavenging [;] 3. dry deposition at the earth's surface [;] 4. conversion of SO [subscript 2] to sulphates. The simplest approach to solving this problem uses a ""trajectory box model"" with appropriate parameterization of items 2 to 4 above. This type of model has been applied in Europe and is presently being adopted to the North American scene by the Atmospheric Environment Service.