2000 Volume 35 Issue 3 Pages 170-182
This study was performed to evaluate the influence of non-point sources of methane on the concentration of atmospheric methane in the southern region of Okayama prefecture, analyzing data measured at air pollution monitoring stations.
Diurnal variation of the atmospheric methane concentration was well correlated with the diurnal change in the lapse rate of temperature in the atmospheric surface layer, which is an indicator of atmospheric stability. The difference between the hourly averaged concentration of atmospheric methane at 3: 00 and at 15: 00, was used to localize and characterize methane sources in the atmosphere. High methane concentrations were closely related with the land use ratio within a radius of 3 km of each monitoring station. Because the maximum levels were shown in July, the major source of atmospheric methane is presumed to rice paddy fields. We have been able to detect the influence of global-scale abnormal weather on atmospheric methane concentration at air pollution monitoring stations in Okayama prefecture.
