Comparing the Sensitivity and Distribution of the Southern Ocean Surface Water pH to Mixing in a High Resolution Coupled Climate Model and the CMIP5 Earth System Models

Chair: Kumiko Azetsu-Scott

Joellen Russell (1)

1 University of Arizona, Tucson, AZ 85721, USA

We examine the relationships between the distribution of pH in the surface waters of the Southern Ocean, the air/sea flux of carbon dioxide, and the upwelling of old, low pH water. Efforts to determine the relative effects of these two processes have been hampered by the enormous computational resources required to simulate ocean biogeochemistry in eddy-resolving coupled climate models. Using observationally-based metrics and the Southern Ocean State Estimate, we first assess the relationship between upwelling and uptake on the distribution of surface pH in the CMIP5 ESM historical simulations. We then compare these moderate resolution simulations to that from a high resolution eddy-resolving coupled climate model (GFDL-CM2.6) simulation. We then assess the simulated surface pH changes in the models in response to an atmospheric CO2 doubling scenario.