Development of an analytical method for the detection of NO_z and its application to the atmospheric analysis at a mountain site

Analytical methods for the detection of NO_z have been developed by using a laser-induced fluorescence spectroscopy (LIF) technique and a chemiluminescence (CL) method. NO_z (= NO_y – NO_x) represents NO_x oxidation products. The NO₂ concentrations are measured by LIF, which has a high sensitivity and no chemical interferences when a conversion technique to NO is applied by such as a CL method. The NO and NO_y concentrations are measured by an improved CL method. The NO_z concentrations are obtained by subtracting the concentrations of NO and NO₂ from NO_y. The NO_z concentrations in the atmosphere were measured at the top of Mt. Fuji in August, 2017. The average concentration of NO_z was 0.28±0.26 ppb. A back-trajectory analysis suggested that the air mass from the Asian continent showed a high concentration of NO_z, and the air mass from the Pacific Ocean showed a low concentration of NO_z. The concentrations of NO_z and O₃ showed a correlation, and ozone production efficiencies (OPE) were obtained from correlation plots. The obtained OPEs at a mountain site showed that the air mass from the Asian continent was 3 to 10 and from the Pacific Ocean was 18. An analytical method of NO_z in the atmosphere at a mountain site was established.