Abstract
The concentration of atmospheric CO2 was measured continuously, 300m offshore of the main island of Okinawa, Japan for the period from February, 1983 to February, 1985. A diurnal variation of CO2 concentration was found during the warm months of March through October, with an enhanced magnitude in the summer season, strongly depending on the atmospheric stability. The CO2 concentration, obtained by applying a statistical data selection scheme, showed that the seasonal CO2 variation reaches a maximum in late April and a minimum in mid-September with the peak-to-peak amplitude of 7.2ppmv. During these measurements, the rate of secular CO2 increase was about 1.6 ppmv/year. These results are consistent with those of our aircraft measurements in the lower troposphere over Okinawa for the same period.
