Plattner1, Gian-Kasper, Hartmut Frenzel1, Nicolas Gruber1, Patrick Marchesiello1, James C. McWilliams1 , Gernot E. Friedrich2 and Francisco P. Chavez2

1Institute of Geophysics and Planetary Physics, University of California, Los Angeles, 5839 Slichter Hall, Los Angeles, CA 90095, Tel: (310) 206-5445, Fax:(310) 206-3051, E-mail: plattner@igpp.ucla.edu, 2Monterey Bay Aquarium Research Institute, 7700 Sandholdt Rd., Moss Landing, CA 95039-9644

 

Dynamics of CO2 air-sea gas exchange along the U.S. West Coast

 

The processes controlling the variability and magnitude of coastal biogeochemical cycles are not yet well understood. In particular, the contribution of the coastal oceans to the net flux of CO2 between the ocean and atmosphere remains unclear.

 

We investigate the dynamics of the CO2 air-sea gas exchange and its controlling processes for the U.S. West Coast on the basis of an eddy-resolving coupled physical-biogeochemical model. This region is dominated by intense coastal upwelling, highly turbulent flow, and a high biological production. The model is based on the Regional Ocean Modeling System, which has been coupled to an NPDZ-type ecosystem model with a simple formulation of the carbon cycle.

 

Preliminary results suggest that upwelling-driven CO2 outgassing occurs in a narrow band close to the coast, whereas biologically-driven CO2 uptake dominates the air-sea CO2 fluxes further offshore. The open ocean CO2 gas exchange is found to be determined by the CO2 solubility in seawater, mainly driven by sea surface temperatures.

 

We compare the modeling results to the available observations of the air-sea partial pressure difference of CO2 from in- and off-shore Monterey Bay as well as from Santa Monica Bay.