TRACE GAS MEASUREMENTS AND AIR-MASS CLASSIFICATION FROM A GROUND STATION IN TAIWAN DURING THE PEM-WEST-A EXPERIMENT (1991)

Measurements of the ambient concentrations of O-3, NOx (NO + NO2), and PAN (peroxyacetyl nitrate) were collected at Kenting, a rural site ne ar the southern end of Taiwan, during the autumn of 1991 as part of th e Pacific Exploratory Mission - West A (PEM-West A) experiment. Two pr incipal component analyses (PCAs) were performed on the data. The resu lts of the PCA indicated that at least three different air mass types were observed at the site, including marine boundary layer, urban plum e, and continental outflow (from the Asian mainland). The average conc entrations determined for PAN and O-3 in the marine boundary Layer are 0.03 +/- 0.02 and 13 +/- 5 parts per billion by volume (ppbv), respec tively. In the continental outflow type air masses the average concent rations of PAN and O-3 were 0.33 +/- 0.41 and 46 +/- 7 ppbv, respectiv ely. The data collected indicate that a minimum of 100-150 parts per t rillion by volume (pptv) PAN is required in order to affect the produc tion of ozone in the marine boundary layer.