24 November 2015

Marine Macromolecules: Planetary Scale 2D Chemistry


Marine Macromolecules: Planetary Scale 2D Chemistry.Oceanic food webs release families of lipids and biopolymers into mixed layer water which function primarily as surfactants, quickly coating bubbles, the sea-air interface and nascent spray aerosol particles. The organics thus determine spray number fluxes, Kohler CCN effects and gas transfer, and all of this at the global scale. ACME and HiLAT have recently become the first community system models to deal in such processes. ACME and MPAS-O distribute the biomacromolecules via their full reactive transport, from injection via cell disruption to heterotrophic consumption. Sources include grazing and senescence then removal by bacteria and free enzymes. Validation and benchmarking exercises indicate fidelity relative to available data. Gibbs-Langmuir adsorption is already incorporated, with the treatment of new phases such as colloids and gels coming next. In the context of coupled DOE Earth System Models, full feedbacks from oceanic aerosol precursor emissions are now within reach. Estimates of forcing uncertainty from the marine biogenics are wide, and their influence is strong in remote areas such as the Southern Hemisphere. We will explore and narrow the range via further seawater organic chemistry mechanism development, validation of our new approaches and sensitivity testing in the unique DOE model family.

References from the Chemistry@Interfaces Working Group: Ogunro, O., Burrows, S., Elliott, S., Moore, K., Russell, L. and 3 others 2015. Global distribution and surface activity of macromolecules in offline simulations of marine organic chemistry. Biogeochemistry, 10.1007/s10533-015-0136-x. 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., Burrows, S., Deal, C., and 3 others 2014. Simulating macromolecular surfactant chemistry at the ocean atmosphere boundary. Environmental Research Letters 9, 10.1088/1748-9326/9/064012. Burrows, S., Ogunro, O., Russell, L., Rasch, P. and Elliott, S. 2014. A physically based framework for modeling the organic fractionation of sea spray aerosol from bubble film Langmuir equilibria. Atmospheric Chemistry and Physics, ACP-2014-32. Frossard, A. with Elliott, S. and 7 others, 2014. Composition of submicron organic mass in marine aerosol particles. Journal of Geophysical Research –Atmospheres, 2014JD021913.

Scott Elliott
Los Alamos National Laboratory
Elliott, S., Burrows, S., Deal, C., et al. "Prospects for Simulating Macromolecular Surfactant Chemistry at the Ocean-Atmosphere Boundary." Environmental Research Letters (2014). [10.1088/1748-9326/9/6/064012].

DOE OBER ACME and Benchmarking