Abstract
Peroxyacetyl Nitrate (PAN) measurement were made at Sapporo from July 1997 to September 1999 and at Mt. Teine (1000m altitude), a site near Sapporo urban area, from February to May 1999. Median concentrations of PAN for each month show seasonal variation. Maximum levels of about 0.3-0.4ppb were observed during winter months. On sunny days in summer PAN concentrations showed a distinct diurnal variation and local formation of PAN was apparent. Whereas, in winter PAN concentrations showed little diurnal variation and there was little difference between concentrations at Mt. Teine and surface concentrations in Sapporo, which indicate wintertime PAN in Sapporo were not formed by local photochemistry. Regional scale three-dimensional transport/chemistry simulations were performed for the period February 1999, The model results were compared to measured concentration and PAN levels were found to be influenced by continental outflow of air pollutants.
