Cross-correlation analysis of atmospheric trace concentrations of N_2O, CH_4 and CO_2 determined by continuous gas-chromatographic monitoring

摘要

Recently, the concentration of nitrous oxide (N_2O) has been studied, because N_2O is a greenhouse gas whose effect per molecule is more significant than that of carbon dioxide (CO_2), and also like chloro-fluorocarbons (CFCs) and other ozone-destroying chemical elements it can cause ozone layer depletion. From 1996, the continuous monitoring of N_2O has been done by gas-chromatography with an electron capture detector at our institute at Nagoya University (RAN) in Japan. Data of N_2O were analyzed together with monitoring data of CO_2 and methane (CH_4) at the same university, by applying power spectral density, auto-correlation and cross-correlation techniques. As a result, weak correlations between N_2O and CO_2 or CH_4 were found though their origins are thought to be different. This suggests that they are affected by the same phenomena at least partially. Moreover, correlations with the meteorological elements probably associated with the N_2O data are investigated. We will discuss the origins of N_2O in a suburb of Nagoya on the basis of temporal variations and correlations with various elements.