The seasonal variation of atmospheric non-methane hydrocarbon at Cheju Island, South Korea

Non-methane hydrocarbon (NMHC) at Cheju Island, South Korea has been continuously measured since March 1994. The measurements are conducted two times per week. The general trend of the NMHC concentrations shows a seasonal cycle with a maximum in the winter and a minimum in the summer. The winter to summer ratios for reactive hydrocarbons varies as the rate constant for the reaction with hydroxyl radicals. This suggests that the rate of photochemical degraded by reaction with hydroxyl radical contributes in a significant way to remove hydrocarbons from the atmosphere. The relative concentrations of hydrocarbons in ambient air are valuable atmosphere tracers which can provide useful information such as the roles of photochemical reaction, source contributions and atmospheric transport process. The natural logarithms of the ratio of n-butane to ethane is plotted against the ratio of propane to ethane concentrations along with the data from the urban measurements, such as Tokyo and Sydney. Compared to these urban data sets, Cheju shows a range of ratios smaller than those of the urban site and this indicates a strong role for chemical destruction during the long range transport process. The data is combined with supporting data on aerosol and meteorology to provide insightsmore » into the behavior of the abundance, composition, source distribution and long range transport processes of trace species in this region.« less