Surface ozone observation

7.2.6 Surface ozone observation

   Surface ozone is observed using a UV light absorption ozone monitor, utilizing the characteristics of UV radiation to be absorbed by ozone. The system models used at the observation stations are listed in Tables 7.1.1.2, 7.1.1.3, 7.1.1.4, and 7.1.1.5, with the appearance of the system shown in Figure 7.2.6.1.

   Air samples are introduced to the observation system from a dedicated intake on the observatory rooftop (ground heights: 8 m at Ryori and Minamitorishima, 10 m at Yonagunijima, and 4m at Syowa) at a rate of 10 litres per minute, which are partly diverted to the ozone monitor at a rate of 1.5 litres per minute. All the piping systems use Teflon®, on the surface of which ozone is not readily destroyed. Ozone monitors are calibrated using an ozone generator at the JMA headquarters (Section 7.3.5).

   The air samples are analyzed every 10 seconds for Ryori and Yonagunijima, every 15 seconds for Minamitorishima and every 12 seconds for Syowa Station, using a calibrated ozone monitor.

   The analyzed ozone concentrations are quality controlled and statistically processed at the JMA headquarters. Hourly mean values are calculated from all the observations excluding those during inspections or malfuction of the system. Daily and monthly mean values are produced from the hourly mean values when more than half the values are available during the period. Observations for surface ozone may contain local variations within the surface boundary layer. However, as concentrations of ozone in the atmosphere naturally vary from moment to moment as a result of photochemical formation and destruction, or destruction upon contact with ground surface, BG data ara not selected when calculating daily and monthly mean values.


Surface O3 observation system at Yonagunijima.

Fig. 7.2.6.1 Surface O3 observation system at Yonagunijima station.

Time series of hourly mean surface O3 concentrations at Ryori

Fig. 7.2.6.2 Time series of hourly mean surface O3 concentrations at Ryori in 2009.

Time series of hourly mean surface O3 concentrations at Minamitorishima

Fig. 7.2.6.3 Time series of hourly mean surface O3 concentrations at Minamitorishima in 2009.

Time series of hourly mean surface O3 concentrations at Yonagunijima

Fig. 7.2.6.4 Time series of hourly mean surface O3 concentrations at Yonagunijima in 2009.

Time series of hourly mean surface O3 concentrations at Syowa

Fig. 7.2.6.5 Time series of hourly mean surface O3 concentrations at Syowa in 2009.

Contents

GAW stations for greenhouse and reactive gas observation | Surface ozone observation | Calibration for surface ozone observation