Transport of atmospheric carbon monoxide, ozone, and hydrocarbons from Chinese coast to Okinawa island in the Western Pacific during winter

CO, O3, and hydrocarbon measurements were conducted at Okinawa island, a southern Japanese island, during winter in 2000. The observed air was affected by the pollution transported from Chinese coastal area. Hydrocarbon concentration decreased as carbon number increased. This indicated that the measurement site was not affected by local anthropogenic sources. But negative correlation between O3 and sporadically high CO was observed. This indicated the fast transportation of polluted air from source region. Backward trajectory analyses showed that the air mass came from Chinese coastal area contained higher concentration of hydrocarbons than other trajectory categories. Transport time from source area to the observatory and observed hydrocarbon concentrations had negative correlations. The observed data at Okinawa were compared with the result obtained at Ogasawara island, a more remote island in the Western Pacific, in 1999. Their distance from the continent were different, however, the way of hydrocarbon decrease was same manner at these two sites. The standard deviation of the log natural of the mixing ratio for many hydrocarbons had more deviation at Okinawa than at Ogasawara. This indicated that Okinawa was more affected by polluted air which transported from the source region than Ogasawara.