2:00 PM - 2:15 PM
[AAS12-02] Estimation and trend analysis of the tropospheric baseline ozone and carbon monoxide concentrations at Mt. Happo
Keywords:Ozone, Carbon monoxide, Baseline level
In this study, we estimated baseline and polluted concentrations of O3 (1998–2014) and CO (1996–2014 and 2013–2014) at Mt. Happo by using the statistical method “REBS (Robust Extraction of Baseline Signal)” (Ruckstul et al., 2012), which is based on the robust local regression. Then, we analyzed these long-term trends. CO concentration (2013–2014) is significantly lower than CO concentration (1996–2004), and the degree is larger in summer and autumn than in spring. Recent baseline CO concentrations are decreasing in all season except for spring. Spring baseline concentration is slightly increasing. Polluted CO concentrations are decreasing in all season, and the degrees are larger than those of baseline concentration. On the other hand, O3 concentrations show decreasing trends with maximum in the mid-2000s in all season. The rate of decrease is characterized by a spring maximum and summer minimum. Both baseline and polluted O3 concentrations show decreasing trends in all season and both rates of decrease are the same degree. Hence it is considered that the decrease of springtime CO concentration at Mt. Happo is mainly caused by the decrease of polluted CO concentration, and that the decrease of O3 concentration is caused by the decreases of baseline and polluted O3 concentrations.