Dependence of DMS global sea-air flux distribution on transfer velocity and concentration field type

Large-scale transport of marine reduced sulfur to the troposphere is a key to climate and global change, due to the influence of dimethyl sulfide (DMS) on aerosol/condensation nucleus fields. The sensitivity of DMS fluxes to sea-air transfer scheme has previously been studied using established climatologies or local simulations. However, planetary level sulfur cycle models are now coming on line, and roughly coincident, eddy correlation measurements indicate that interfacial behavior of the compound may be distinct from less soluble gases. Variation of the overall sulfur flux distribution is explored here for an historical sampling of piston velocities expressed as functions of the reference height wind, plus a composite reflecting the new transfer estimates. Dissolved concentrations are derived alternately from a current generation biogeochemistry model or the standard compilation. Comparisons of simulation and data-driven fields show that both have advantages. Modeling captures fine resolution features along frontal systems and provides a natural, biogeographic extrapolation across the general circulation. Climatology is free from physical or biotic computational biases and also is relatively strongly supported by coastal measurements. Contrast among the piston formulas includes integrated mass transfer differences as large as a factor of two. Working from the composite scheme, potential is demonstrated for improvements to shift marine DMS outputs from the Southern Ocean toward the equator. Complexities deriving from atmospheric stability, bubble enhancement, and surfactant chemistry may temper these results. Global budgets fall within the envelope of earlier work, 15 to 35 Tg S a(-1).