Mathew Einar Maltrud

Energy and enstrophy transfer in numerical simulations of two‐dimensional turbulence

Numerical simulations of statistically steady two‐dimensional (2‐D) turbulence are analyzed to determine the relative importance of the types of wave‐vector triad interactions that transfer energy and enstrophy in the both the energy and enstrophy inertial ranges. In the enstrophy inertial range, it is found (in agreement with previous studies [J. Fluid Mech. 72, 305 (1975); Phys. Fluids A 2, 1529 (1990)]) that the important triads (i.e., those associated with the highest transfer rates) are typically very elongated. On the average, nearly all of the enstrophy transfer within these triads is directed from the intermediate to the largest wave‐number mode (i.e., downscale transfer). Energy, too, is transferred downscale in this manner, but is also transferred upscale due to the interaction of the intermediate with the smallest wave‐number mode of the triad, resulting in no net flux of energy in the enstrophy inertial range. Analysis of the geometry of the important triads indicates they are not of similar s...

Impacts of Marine Ecodynamics on the Dimethyl Sulfide(DMS) Production

March 4 th @ noon – Jones Annex 101 Dimethyl sulfide (DMS) is a biogenic organosulfur compound which contributes strongly to marine aerosol mass and the determination of cloud condensation nuclei over the remote oceans. DMS concentrations are directly controlled by marine ecosystems. Various marine mircoorganisms play different roles in the DMS production. Changes in phytoplankton production and community composition can alter the production and distributions of DMS. Observation based estimates showed significant changes in phytoplankton biomass in the last few decades; and climate models also project a reduced marine primary production and shifts in the plankton community structure in the future climate. Here we investigate the contribution of individual phytoplankton functional groups to the DMS production and fluxes to the atmosphere using the improved marine ecosystem-biogeochemical module of the Community Earth System Model (CESM). We will examine the impacts of shifts in phytoplankton community composition on DMS distributions in a RCP climate scenario. We will show changes in the DMS flux due to individual phytoplankton groups, and the subsequent impacts on cloud radiative forcing.