Correlation between urban early ozone minimum and solar radiation

摘要

The surface ozone concentration measured in urban and semiurban atmospheres shows in its daily pattern an early morning minimum and an afternoon maximum. In some cases, it can be observed a second minimum after sunset. These variations can be attributed to the daily pattern of other pollutants. After the first minimum in O_3 daily variation, the increment of ozone concentration can be attributed to photochemical formation and to the transport from the higher layer, when the boundary layer is raised. In all cases the driver of both process is the solar radiation, therefore it should be a direct relation between them. We have find in our preliminary studies that the early morning ozone minimum has a seasonal variation in its time of occurrence. This variation can be attributed to some causes. A natural causes is the variation of level of radiation that reach the surface, which displace the balance between the mechanism of destruction and production of ozone in urban and semiurban areas.