Abstract
Ozone plays also an important role in the acidification of atmospheric depositions as well as global warming and the reduction of ultraviolet radiation. In order to characterize the ozone distribution in the surface atmosphere over the ocean, an analysis has been made of on-board observations made in the Western Pacific Ocean along cruising routes between Japan and Australia in every August from 1993 to 1998 and in February 1998.The diurnal variation of the ozone concentration was not found because of the poor influence of the photochemical reaction. In August, the mean ozone concentration is 12 ppbv at 30° N. It increases toward the equatorial area and is 19 ppbv in the equatorial area. It continues to increase toward the southern hemisphere, reaching a value of 27 ppbv at 30° S. In February, the mean ozone concentrations reveals a reverse trend: beginning at 47 ppbv at 30° N, it decreases to 22 ppbv in the equatorial area, and reaches 11 ppbv at 20° S. The variation between mean ozone concentrations in August and February increases with latitude, and is larger in the northern hemisphere than in the southern one.In order to analyze the origin of ozone, a 5-day backward isentropic trajectory analysis was performed. The ozone concentration was found to be proportional to the maximum height reached by the air mass over the previous 5 days.
