On the Regional Background Levels of $CH_4$ Observed Peninsula in Korea during 1990~1992

한국의 태안반도에서 관측된 $CH_4$의 지역적 배경농도에 관한 연구 -1990~1992년 자료를 중심으로-

Since November 1990, the observations of methane (CH4) level have been carried out at Tae-ahn Peninsula (TAP) in Korea. Analysis on atmospheric data obtained in the period from November 1990 to August 1992 is carried out and the results are included in this study. We 임ole that CIL does not have a clear seasonal cycle with a minor maximum in August- september and with a minimum in June-July. The variations in monthly average level are much larger with 1765.01∼ 1857.21 pub (amplitude 92.20 ppb). The occurrence of a minimum in June-July is due to the inflow of the North Pacific air, an increase of OH radical and due to a decrease in CH4 emission from rice paddy. A maximum in August and September appears to result from an increase in organic materials in agriculture (rice paddy) and forests, inputs of local sources due to weak airflows, stagnation of the warm and moist air and from a decrease in OH radical.'rho present analysis indicates that according to CH4 data from Mongolia and from several sites in North Pacific TAP is influenced as much as 31 pub in average from the inputs of Chinese omission. When the atmospheric CH4 of TAP is compared with data observed at Korea National University of Education (KNU), the values of KNU are higher (127 ppb) than those of TAP. It is clear that air samples taken at KNU are influenced strongly by local sources in central Korea than those at TAP. According to analysis of trajectories and airflows, we find that there are 4 types in classification. Firstly, when an air flow is originated mainly in China values of CH4 gas are in medium ranges. Secondly, when an airflow is from both local (Korea) and China we find higher values. Thirdly, with an airflow from both local (Korea) and Japan origins medium values are recorded. Fourths)r, when an airflow of maritime origin arrives low values of atmospheric CH4 are observed at TAP.