抄録
Present status of air pollution in Sendai is described and its local-climatological conditions are discussed in this paper, expecting the usefulness of air pollution as an indicator for urban climates. Sulphur oxide is picked up now as pollutant since its sources are easy to notice. Pollution sources of sulphur oxide are within the built-up area and at New Sendai Port (Fig 2). The results obtained are as follows;
1) Concentration of sulphur oxide in air shows peculiar seasonal and weekly pattern to each district of business, industrial and residential (Fig 3, Table 1).
2) Marked concentration of sulphur oxide expands to the leeward of the built-up area in winter, but not in summer (Fig 5). It indicates that built-up area works as strong pollution sources in winter, while it works faintly in summer.
3) Concentration of air pollution in and around the built-up area is mostly affected by wind direction rather than wind velocity.
4) When SE wind prevails over the city, plus anomaly of concentration appears not only in the leeward area of pollution sources but also in windward side, Shichigo and Nakano. The plus anomaly area in the windward side suggests the local circulation that carries polluted air to the coast.
5) Clear vertical difference of concentration is frequently observed at urban center in the night (Fig 8). It is thought to be caused by occurrence of surface inversion that confines the pollutants in the low layer.
The results 4) and 5) give the possibility that, looking upon the pollutants as a tracer in air, air flow and climatic characteristics in local-scale in and around the built-up area may be detected.
