Variation of CH, Concentsation In Atmosphere Yearly Trend for 10 Years at National Air Monitoring Station

Abstract

Variation for 10 years of CH₄ concentration was analyzed b y use of yearly mean, monthly mean, monthly 1 h max. and monthly 1 h min. value, mesured at 16 national air mon itoring stations. CH_∼4 concentration tended to yearly increase. For yearly mean value, increasing ratio was 0.003-0.021 ppm (mean 0.011 ppm) per year. Monthly 1 h max. was in the range of 1.60∼4.53 ppm. High concentrations were measured at urbanized area, that was affe cted by local emission sources. Monthly 1 h min., which was considered as background value, showed yearly increase from 1.58∼1.59 ppm in 1979 to 1.72∼1.73 ppm in 1988.