Abstract
Based on the measurements by the Japan Meteorological Agency (JMA), in spite of the fact that the total ozone has been increasing at Sapporo, Tsukuba and Naha since the mid-1990s, the surface UV has not been decreasing. In order to understand this phenomenon, the surface UV spectroscopic data obtained by Brewer spectrophotometers at noon at Sapporo, Tsukuba and Naha were analyzed. The trends in the ratios between the UVA and UV indicies(UVA/UV)were analyzed. As a result, the ratio between the UVA index and UV index (UVA/UV) significantly increased only at Sapporo, and it showed a little change or a slight decrease at Tsukuba and Naha. Therefore, the effect of total ozone on the UV index was shown only at Sapporo. This effect was negligible or hidden by other effects at Tsukuba and Naha. To understand these results, the effects of the airmass factor and changes in the size distribution of the aerosols were discussed.
