Basin-Scale Carbon Monoxide Distributions in the Parallel Ocean Program

Abstract

As a primary photochemical constituent in upper-ocean and tropospheric geocycling, carbon monoxide is of interest to a variety of global change research communities. Dynamic three-dimensional simulations of its marine concentration patterns, emphasizing Pacific surface waters, are presented. Calculations were driven by nitrogen/iron ecodynamics within the Parallel Ocean Program (POP) transport framework. Photoproduction was estimated following broadband transfer of ultraviolet A radiation down to and penetrating the mixed layer. Quantum efficiency, absorption, the chromophoric fraction of dissolved organics, and related microchemical parameters were all varied, in some cases collectively. Bacterial uptake was parameterized through stages of refinement ranging from a single global average time constant to the application of steady-state zooplanktonic grazing pressure. Major features of basin-spanning ship track data can be reproduced including tropical to gyre and temperate frontal ratios. Evidence for ecosystem structural influence upon the removal kinetics is reviewed and investigated. Polar waters exhibit unique processing modes and the periphery of the ocean requires specialized handling of organic and bacterial behavior. Large-scale budgets are consistent with recent independent determinations both with respect to internal turnover and flux to the atmosphere. A parsimonious mechanism involving optimized yield is recommended for early system model efforts. Areas awaiting improvement include resolution of UV and the segregation of both light-interacting carbon compounds and microbial populations as tracers.