PCO<sub>2</sub> and δ<sup>13</sup>C in the air and surface sea water in the western North Pacific

Abstract

In order to ascertain yearly variability, the pCO2 in the air and surface sea water was measured during the winter season in and over the western North Pacific from 1981 to 1985, and δ13C measurements were taken from 1982. The seasonality was also studied in the area off Japan’s coast. The distribution of pCO2 in the surface sea water was found to vary with geographical location; it is low in the mid-latitudes and high in the equatorial region. During the El Niño Event in 1982/1983, the horizontal distribution of pCO2 was greatly disturbed, with a relatively low temperature and a high pCO2 level in the equatorial region in the western North Pacific.Surface sea water in the temperate zone shows a seasonal variation in pCO2, which is low in winter and high in summer.It was found that pCO2 in the air over the ocean decreases with distance from the Japanese islands, and south of 15°N it is nearly constant. Between 1982 and 1985, the δ13C of CO2 in the air south of 15°N decreased at 0.022 ± 0.006%, yr-1 and the pCO2 increased at 1.11 ± 0.04 ppm yr-1. The secular variation of pCO2 and δ13C in the surface sea water with the CO2 increase in the air, was not ascertainable from observations from 1981 to 1985.