ABSTRACT

Methane concentrations were determined for air samples collected over the western Pacific and the Antarctic Ocean in the years from 1978 to 1986. The latitudinal distribution from 35°N to 65°S revealed a decrease in methane concentration towards south, with two sharp gradients around 20°N and the intertropical convergence zone (ITCZ). The methane concentrations south of ITCZ were much lower than those in the Northern Hemisphere. The average concentrations of methane in samples collected over the western North Pacific (9°N–24°N) indicate an almost linear increase from 1978 to 1986 with no significant fluctuation of the annual rate of methane increase. The average rate of the increase from 1978 to 1986 was calculated to be 17 ± 2 ppb/yr over the western North Pacific, and that over the Antarctic Ocean was estimated to be 16–17 ppb/yr from 1978 to 1984.