Analytical methods for the detection of NOz have been developed by using a laser-induced fluorescence spectroscopy (LIF) technique and a chemiluminescence (CL) method. NOz (= NOy – NOx) represents NOx 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 NOy concentrations are measured by an improved CL method. The NOz concentrations are obtained by subtracting the concentrations of NO and NO2 from NOy. The NOz concentrations in the atmosphere were measured at the top of Mt. Fuji in August, 2017. The average concentration of NOz was 0.28±0.26 ppb. A back-trajectory analysis suggested that the air mass from the Asian continent showed a high concentration of NOz, and the air mass from the Pacific Ocean showed a low concentration of NOz. The concentrations of NOz 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 NOz in the atmosphere at a mountain site was established.
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