CONTINUOUS MONITORING OF THE CARBON-DIOXIDE CONCENTRATION IN THE URBAN ATMOSPHERE OF NAGOYA, 1991-1993

The present paper is a preliminary report concerning a continuous moni toring experiment for the atmospheric carbon dioxide (CO2) concentrati on conducted since November, 1990, in Nagoya. Even though Nagoya is an urban area, the annual variation of the atmospheric CO2 concentration shows a seasonal oscillation (lower in the summer and higher in the w inter), as observed in the global atmosphere. In addition to the seaso nal oscillation, a daily change in which the atmospheric CO2 concentra tion was lower during the day and higher during the night was also obs erved. Furthermore, additional peak concentrations, which might arise from the exhaust gases of automobiles, were observed during the mornin g and evening rush hours. The annual mean CO2 concentration was 381 pp mv in 1991, 382 ppmv in 1992 and 377 ppmv in 1993. These values were s ignificantly higher than those of the global mean concentration (353 p pmv) in 1990. The annual rate of increase for three years(from January , 1991, to December, 1993) was -1.29 ppmv/year, which corresponds to - 0.34%/year.