National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 1998

Variability of ΔpCO2 in the subarctic north Pacific. A comparison of results from four expeditions

Murphy, P.P., D.E. Harrison, R.A. Feely, T. Takahashi, R.F. Weiss, and R.H. Gammon

Tellus, 50B(2), 185–204, doi: 10.1034/j.1600-0889.1998.t01-1-00006.x (1998)

Time-space variability of surface seawater pCO2 is examined over the region (150°W-180°, 46°N-50°N) of the subarctic North Pacific where large meridional gradients of temperature and nutrient concentrations exist. The data were collected during four trans-Pacific expeditions in three different years (1985-1987), but within the same 30-day period of the year (August-September). Systematic measurement differences between the four data sets are estimated as <10 µatm. The inter-expedition comparison suggests that surface seawater pCO2 in the study area is quite variable, with mean differences of up to 25 µatm and local differences up to 60 µatm. Spatial and interannual variability of surface seawater pCO2 were found to contribute significant uncertainty to estimates of the mean ΔpCO2 for the study area. Fluxes were calculated using ΔpCO2 values from the four expeditions combined with gas exchange coefficients calculated from four different wind fields giving a range of -0.94 to +4.1 mmol CO2 m–2 d–1. The range of fluxes from the study area is scaled to a larger area of the North Pacific to address how this variability can translate into uncertainties in basin-wide carbon air-sea exchange fluxes.

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