Das Projekt "Exploring the role of estuarine circulation for transport of suspended particulate matter (SPM) in the Wadden Sea by means of field observations and numerical modelling. Acronym: ECOWS" wird vom Umweltbundesamt gefördert und von Leibniz-Institut für Ostseeforschung durchgeführt. It is the aim of this project to investigate the role of estuarine circulation for suspended particulate matter (SPM) transport in the Wadden Sea. Major hypotheses are that (i) estuarine circulation is relevant to SPM transports in the Wadden Sea, that (ii) tidal straining (i.e. the correlation between vertical shear and eddy viscosity due to tidal asymmetry caused by horizontal density gradients) is the major process contributing to estuarine circulation, and (iii) that wind straining (i.e. the subtidal vertical shear generated by surface wind stress) is an important episodic contribution to estuarine circulation. These hypotheses will be tested by means of targeted field observations in three tidal channels (Hörnum Deep, Jade Bay and Otzumer Balje), idealised process-oriented numerical model simulations and realistic hindcast simulations for the focal areas and for the entire Wadden Sea. Confirmation of these hypotheses will lead to a paradigm shift in understanding Wadden Sea dynamics which so far has been widely assumed to be unaffected by density gradients.