Projekt: Reactions of small-scale and meso-scale processes in the upper ocean mixed layer to atmospheric forcing

a. Construction and analysis of a fully coupled 1D model for the upper ocean and the lower atmosphere. This model will be based on the General Ocean Turbulence Model (GOTM) for which a first feasibility study for a coupling is to be carried out in the first phase of SOPRAN. The coupled model will include the same turbulence closure models for the ocean and the atmosphere side and will resolve the ocean skin layer including a parameterization for breaking surface waves. Similar models have been described in the literature for example by Eifler and Donlon (2001) (including the skin layer) and Steiner (et al. 2006, 2007) and Steiner and Denman (2008) (in the framework of the Canadian SOLAS program, using GOTM for the oceanic part). The coupled model (General Ocean Atmosphere Turbulence Model, GOATM) will include the full functionality of GOTM for biogeochemical modules, such that coupled biogeochemical modeling in ocean and atmospheric boundary layers will be supported.
b. Quantification of the effect of meso-scale and sub-meso-scale lateral dynamics on the depth of the oceanic mixed layer, the surface heat flux and the ocean-atmosphere exchange. A refined version of the parameterization for the re-stratifying effect by ageostrophic sub-meso-scale lateral instabilities on mixed layer dynamics after Fox-Kemper et al. (2008) will be combined with an existing higher order parameterization for mesoscale eddy mixing in the interior of the ocean (Eden and Greatbatch, 2008). This parameterization for the re-stratifying effect of meso- and sub-meso-scale eddies will be implemented in an existing ocean model of the North Atlantic to estimate and to quantify the effect on mixed layer depth, vertical buoyancy and trace gas fluxes, surface heat fluxes and air-sea gas exchange.