Capturing the seasonal cycle of surface ocean pCO2 is a challenge for ocean biogeochemical models in the high latitude North Pacific (McKinley et al. 2006). Models are particularly challenged to capture the full amplitude of wintertime DIC supply to the surface ocean and the seasonal drawdown of DIC associated with the spring bloom in regions where data suggest this cycle is particularly vigorous. This is a concern because the same mechanisms that determine the seasonal cycle also control interannual to decadal timescale variability, but data is scarce to act as a direct longer-term constraint. We have begun to investigate seasonal pCO2 processes using a North Atlantic regional model at ½ degree resolution with an embedded 2 functional group ecosystem that includes explicit cycling of phosphorus, silicate, iron, oxygen, carbon and alkalinity. We report on initial model – data comparisons and efforts to improve the model’s pCO2 seasonal cycle.