Time and space variations of tropospheric carbon dioxide over Japan

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Abstract
Aircraft measurements of atmospheric CO2 concentration over Japan, initiated in January 1979, have been continued to the present. The average seasonal variation of atmospheric CO2 showed maximum concentration early in April and early in May, and minimum concentration in mid-August and mid-September for the lower-most and the upper-most layers of the troposphere, respectively. The peak-to-peak amplitudes of the seasonal variation were 14.5, 9.0 and 7.8 ppmv for the lower, middle and upper tropospheres, respectively. The average rate of annual increase of the C02 concentration over the last 6 years was about 1.3 ppmv yr-1 with considerable variation with time. The vertical profile of the annual mean value of the CO2 concentration was almost the same from year to year; the CO2 concentration decreased gradually with height and the concentration difference between the lowest and highest layers of the troposphere was about 2 ppmv. DOI: 10.1111/j.1600-0889.1987.tb00265.x