Abstract: The vertical turbulent fluxes of dissolved oxygen and heat will be measured continuously in the littoral zone of Lake Konstanz by using the eddy-correlation method. The measurements will not only allow to characterize the turbulent transport within the water column, but will also provide an estimate of the sediment-water oxygen flux, which is a major process in determining water quality. Both phenomena will be investigated continuously over a seasonal cycle with a temporal resolution of minutes, and hence the method will resolve the entire natural variability of the fluxes. Based on background profiles of temperature and dissolved oxygen the measured turbulent fluxes of oxygen and heat will be converted to estimates of turbulent diffusivities from which the transport of other constituents, such as methane and phosphorus, will be calculated. The turbulent flux measurements will be accompanied by continuous measurements of vertical profiles of current velocity, turbulent kinetic energy dissipation rates, and wind. This will allow correlating the estimated fluxes with the observed physical forcing (e.g. wind, waves, currents, turbulence...). Parameterizations and deterministic relationships between fluxes and forcing will be developed to provide a generalization (up-scaling) of the results for larger-scale budgets and for a potential implementation in water quality models. Further attempts will be made to expand the eddy correlation method to measure turbulent fluxes of suspended material in the bottom-boundary layer (BBL). The intension of the particle flux measurements is to support the estimation of re-suspension and its impact on sediment-water fluxes of dissolved constituents. As vertical mixing in stratified waters (lakes, oceans) occurs mainly along the boundaries, the exchange between the bottom-boundary layer and the interior as well as the exchange between the littoral and pelagic zones has become one of the most important questions in Physical Oceanography and Limnology. The proposed project attempts to characterize such exchange process in a lake under consideration of the fully resolved natural variability.
