SMuK 2021 – scientific programme

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UP: Fachverband Umweltphysik

UP 1: Oceanography and Climate Modelling

UP 1.2: Talk

Thursday, September 2, 2021, 11:15–11:30, H3

Thermohaline circulation - the role of advection in dynamics and stability — •Leonie Neitzel and Edeltraud Gehrig — RheinMain University of Applied Science, Germany

In recent years ongoing research of climate and environmental problems reveal the importance of thermohaline circulation on climate changes. The large-scale ocean circulation is driven by density gradients created by global surface salinity and temperature distributions. It can be modelled with box-models for the polar and equatorial regions of the earth. The boxes are coupled by deep water currents and surface currents that, in turn, depend on the parameter values of salinity and temperature. The dynamic system represented by the boxes and the currents typically exhibits a characteristic dynamics including e.g. bifurcations revealing critical regimes and consequently abrupt changes in the climate. In our approach we couple the model quations to an advection equation describing the changes in the density distribution within a box. This allows to investigate the role of local density changes induced by e.g. environmental influences or pollution. Our results demonstrate that local density changes created by e.g. an initial perturbation enter the thermohaline circulation via the currents and additionally affect the dynamics and stability of the system. Our comparative study of selected box models (Stommel, Marotzke and Welander model) reveals an influence of the dynamics on advective processes as well as dependencies on parameters and model approach.