Abstract
PANs (peroxyacyl nitrates) and ONs (organic nitrates) have been being observed using a thermal dissociation/cavity attenuated phase shift spectroscopy method since December 2012 at Suzu, the Noto Peninsula. In this article, observational results and analyses for the period from December 2012 to August 2013 are described, focusing on the seasonal variations of the PANs and ONs. Both the PANs and ONs showed seasonal variations with spring maxima and summer minima. The air mass origins arriving at Suzu were classified into the following five groups: Russia, North-East China, Middle China·Korea, Japan and Sea, using backward trajectory analyses. From winter to spring, both the PANs and ONs concentrations from Middle China·Korea were higher than those from the other air mass origins. From the spring to summer, their concentrations were independent of the air mass origins. No definite diurnal variations were observed from winter to spring. Meanwhile, the diurnal variations of the PANs and ONs concentrations had daytime maximum and nighttime minimum values from the spring to summer. We concluded that the PANs and ONs concentrations from winter to spring and those from spring to summer would be governed by the long-range transport and in-situ photochemical generation, respectively.
