Summary of Data Presented

The data presented in this report are from PMEL cruises conducted in the Pacific and Indian Oceans during 1986-1989. The data files provide a complete listing of the calculated fugacities, the warming-corrected mole fraction CO₂ concentrations, and the data required to convert between in situ mole fraction and fugacity.

The fugacities were calculated according to equations given in Murphy et al. (1994). The fugacity calculations use observations of dry gas concentrations in units of parts per million, sea surface temperature, equilibrator temperature, sea surface salinity, and atmospheric pressure. The relative humidity is assumed to be 100% at the sea surface. The vapor pressure of seawater is calculated from temperature and salinity, and the functional relationship between gas solubility and temperature used is from Weiss et al. (1982). The fugacity values given in the data files are the in situ fugacities which have been corrected for the warming of the seawater in transiting to the equilibrator.

The mole fraction values given in the data files are the dry gas concentrations at the in situ temperature. For the air values, the reported concentration, X(CO₂)_air, is the mole fraction of the dried air pumped from the bow line. For the water values, the reported concentration, X(CO₂)_sw, is the mole fraction of the dried vapor drawn from the equilibrator headspace which has been converted to fugacity, corrected for warming, and converted back to mole fraction.

The warming values provided in the data files indicate the degrees of warming (°C) for seawater as it transited from the intake line to the analysis site. The warming values were derived from the regression of hourly warming on hourly sea surface temperature. Detailed information on the temperature data and analyses for each of these cruises are provided in Murphy et al. (1993).

Table 2 presents statistics on the fugacity of CO₂ in the atmosphere [f(CO₂)_air] and in the surface seawater [f(CO₂)_sw] for each leg of the PMEL 1986-1989 cruises. All maximums and minimums for f(CO₂)_air and f(CO₂)_sw, their sample locations, and dates are given. Highlighted values indicate maximum of maximums and minimum of minimums for fugacities of CO₂ for the 12 PMEL legs.

Table 2. Statistics on the fugacity of CO₂ in the atmosphere [f(CO₂)_air] and in surface seawater [f(CO₂)_sw] for each leg of the PMEL cruises from 1986-1989.