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An automatic measuring system for the partial pressure, pCO 2 , of atmospheric and oceanic carbon dioxide was developed.The system was mounted on a moored buoy for routine observation of maritime meteorology in the East China Sea. CO 2 observations were conducted from 29 June 1997 to 6 January 1998. During the observation period, the atmospheric pCO 2 showed little variation (341 to 365 µatm), whereas pCO 2 in the surface water varied significantly (308 to 408 µatm). In the summer, pCO 2 was higher in the surface water than in the overlying atmosphere, implying that this area was a source for atmospheric CO 2 , though it became a sink after late September. Time series data clearly exhibited significant short-term variations in the oceanic pCO 2 , i.e., sudden variations during the passage of typhoons, and diurnal variations driven by the diurnal variations in the sea-surface temperature under calm conditions. The effects of typhoons on ocean-atmosphere CO 2 exchange at the surface could differ, depending on the relative position of the mooring site with respect to the center of the moving typhoons. These differences result from the different contributions of sea-surface cooling, entrainment, and upwelling. The efflux enhanced by three typhoons accounted for 60% of the efflux of CO 2 in the warm season. It is suggested that typhoons have a significant impact on the carbon cycle in the western subtropical NorthPacific.

A 44‐year mean distribution of tropical cyclone heat potential (TCHP), a measure of the oceanic heat content from the surface to the 26°C‐isotherm depth, shows that TCHP is locally high in the western North Pacific (WNP). TCHP varies on interannual time scales and has a relationship with tropical cyclone (TC) activity. The third mode of an empirical orthogonal function analysis of TCHP shows that an increase in the total number of TCs is accompanied with a warm central Pacific and cool WNP. Negative TCHP anomalies in the WNP suggest that an increase in total number of TCs results in cooling due to their passages. On the other hand, the first mode shows that the number of super typhoons increases in mature El Niño years. An increase in accumulated TCHP is related to the increase in the number of super typhoons due to long duration.

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