Dynamic Green Ocean Project
Marine production of DMS and the interaction with climate PhD project of Meike Vogt, Max-Planck-Institute for Biogeochemistry, Jena, Germany The most recent climate models include representations of ecosystem processes, both on land and in the oceans. Ecosystem processes are now seen as vital to a better understanding of the various climate feedbacks. Here we propose to investigate the feedback between climate and oceanic phytoplankton through the sulfur cycle. This work will be undertaken in the framework of the Dynamic Green Ocean Project (http://www.bgc-jena.mpg.de/bgc_prentice/projects/green_ocean/start.html), an international project aimed at developing a community model of ocean biogeochemistry for applications to Earth system problems. Dimethylsulphide (DMS) is a volatile sulfur compound produced indirectly by marine phytoplankton and transfered to the atmosphere. DMS affects the radiative properties of the atmosphere by reflecting solar radiations and by affecting the concentration of cloud condensation nuclei (CNN). It is the main natural source of sulphate aerosol and the major route by which sulphur is recycled from the ocean to the continents. The production of dimethylsulfoniopropionate (DMSP, a precursor for DMS) in the ocean is strongly dependant on the phytoplanktonic species. The transformation of DMSP into DMS occurs when phytoplanktonic cells are decomposed in the water, either following natural death or grazing by zooplankton. This project would study the impact of marine biology on the DMS cycle, and the potential effect of DMS on climate with a special focus on the natural changes in atmospheric DMS on glacial-interglacial time scales which have left their marks in ice-core records of the stable end-products, methane sulphonate and non-sea-salt sulphate. The project includes: 1) the implementation of a sulfur cycle with species-dependent production of DMSP in the Dynamic Green Ocean Model, 2) the inclusion of ocean DMS fluxes in a climate model, 3) doing climate simulations for pre-industrial Holocene and glacial times. The Ph.D. student will gain experience in modeling marine biogeochemistry and global climate, and with the analysis of satellite observations and paleoceanographic and ice-core proxies for model validation. The student will work as part of a small but dynamic and highly international group and in collaboration with a worldwide network of marine ecologists and ocean modelers.