JMA observes total ozone amount in the atmosphere over the station usings two types of measurement instruments, the Dobson spectrophotometer at Sapporo, Tsukuba, Naha and Syowa Station and the Brewer spectrophotometer at Minamitorishima. Total ozone is obtained by measuring the intensity ratios of solar light in some wavelengths showing great variation in absorption by ozone, which is made by dispersing the ultraviolet solar radiation. A prism is used for dispersion in the Dobson spectrophotometer, and a diffraction grating is used in the Brewer spectrophotometer.
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Fig. 7.2.7.1 Dobson spectrophotometer. |
GAW stations for the ozone layer and ultraviolet radiation observation | Total ozone observation | Umkehr observation | Ozonesonde observation | Calibration for total ozone observation