LONGITUDINALLY DIFFERENT VARIATIONS OF LOWER TROPOSPHERIC CARBON-DIOXIDE CONCENTRATIONS OVER THE NORTH PACIFIC-OCEAN

To elucidate temporal and spatial variations of the atmospheric CO2 concentration over the North Pacific Ocean, air samples have been collected systematically using 4 container ships for 3 years from 1984 to 1986. The seasonal CO2 cycle was most enhanced at high latitudes and decreased gradually going southward with a phase delay. North of 30-degrees-N, the seasonal amplitude was larger in the western part than in the eastern part; however, to the south the situation was reversed. The southward phase shift of the seasonal CO2 cycle was much reduced in the eastern part, as compared with that in the western part. In the western part, the annual mean values of the CO2 concentration in respective years were high at middle latitudes and decreased going southward and northward; those in the eastern part were rather constant at middle and high latitudes, but increased slightly with decreasing latitude. As a result, yearly mean CO2 concentrations between 50-degrees and 25-degrees-N were always higher in the western part than in the eastern part and those at lower latitudes showed the opposite distribution. Differences of the CO2 concentration between the eastern and western parts depended on season and latitude.