24 November 2015

Global Ocean Organosulfur Cycling: DMS in ACME


Global Ocean Organosulfur Cycling: DMS in ACMEDimethyl sulfide acts as a thermostat on climate but regional effects depend on fine scale eco-structural aspects of the marine system, e.g. phytoplanktonic class sulfur content, various stressors plus microbial demand and volatile yield during decomposition. ACME now carries the biochemical resolution needed to assess flux shifts over the era of global change. Unique DOE schemes for the simulation of dynamic DMS have been fully tested and benchmarked. Production in the model occurs alongside protein synthesis, so that connections to macromolecular primary organic aerosol sourcing can soon be made. The models carry sulfur levels for multiple taxa, the immediate precursor DMSP in the water column, stressors such as oxidants, and bacterial uptake as a function of sulfur demand. Recent runs show that the existence of Arctic sea ice depends critically on cloud reflectivity as controlled by DMS. We are now linking regional planktonic emission to global cloud classes. Our latest estimates: DMS modulates 10-20 W/m2 of reflected short wave radiation over the Southern Ocean in summer and large quantities elsewhere. But in the next century, stratification due to global warming will shift marine ecosystem structures and also surfactant trace gas transfer barriers, altering the relevant fluxes.

References from the Chemistry@Interfaces Working Group:Wang, S., Elliott, S., Maltrud, M., Cameron-Smith, P. 2015. Influence of dimethyl sulfide on marine ecosystems and the carbon cycle. Journal of Geophysical Research –Biogeosciences, in prep. Wang, S., Elliott, S., Cameron-Smith, P., Maltrud, M. 2015. Influence of explicit Phaeocystis parameterizations on global distributions of marine dimethyl sulfide. Journal of Geophysical Research –Biogeosciences, 10.1002/2015/2015JG003017. McCoy, D. with Burrows, S., Elliott, S. and 4 others. 2015. Natural aerosols explain seasonal and spatial patterns of Southern Ocean cloud albedo. Science Advances 6, 10.1126/sciadv.1500157. Elliott, S. 2015. Comment on marine emissions and atmospheric distributions of halocarbons and DMS, Atmospheric Chemistry and Physics Discussions 15, C5070-C5073.

Scott Elliott

DOE OBER ACME and Benchmarking