大気中メタンの季節変化及び日変化の観測と解析

Abstract

Regular observation data show that lowest concentration varies gradually inaccordance with seasonal variation, though sudden high concentrations are oftenobserved. We assume that sudden high concentrations are due to local atmosphericconditions, and exclude such data to get the seasonal variation of backgroundconcentration, which is higher in early winter and lower in summer.We found that diurnal variation is comparable to seasonal variation inmagnitude. We observed simultaneously time-height variations of temperature, humidity, wind speed and wind direction by kytoon from 31th Aug. to 1st Sep.1988 and from 1st to 2nd Dec. 1980. Applying the vertical diffusion process, weestimated the methane flux from the ground to be 26.5 (g/ (m2 * yr)) or 19.7 (g/(m2 * yr)), which is in good agreement with directly measured data.