Aside from observational studies, developing numerical models for simulating various scales of atmospheric phenomena is another of our activities. Microphysical models have been developed for chemical and physical studies of minor atmospheric constituents. Regional scale models are for environmental assessment (particularly in the East-Asian region); global scale photochemical models are for studies of greenhouse gases and ozone loss related chemicals. Figure 3 is an example of results from a two-dimensional chemical model on distributions of a replacement compound for CFCs and its degradation products.