Head of the Research Unit:
GEOMAR | Helmholtz Centre for Ocean Research Kiel
West shore campus
Düsternbrooker Weg 20
Small-scale mixing processes are an essential component of the ocean circulation and the ocean‘s climate. Mixing processes transport heat, salt and other dissolved substances between layers of different densities. The associated diapycnal heat flux is an important driver of the meridional overturning circulationand impacts heat uptake by the ocean. Mixing processes also contribute to the uptake and emission of anthropogenic greenhouse gases and play an important role in biogeochemical cycling of carbon and nutrients. Within physical oceanography, we aim at advancing the understanding of mixing processes in the ocean and developing physically-based parameterizations needed for improving ocean and climate models.
The strength of ocean mixing varies over several orders of magnitude. Elevated mixing rates are found at the ocean boundaries where energy input by the winds and tidal energy is predominately dissipated. Other “hot spots” for mixing processes include mid-ocean ridges and seamounts, the Southern Ocean and the upper equatorial oceans.
GEOMAR has established comprehensive infrastructure for integrated ocean mixing observations. The temporal and spatial variability of mixing can be observed by particularly fast-sampling microstructure probesMicrostructure. These probes are used as loosely-tethered profilers or are mounted to gliders and otherautonomous underwater vehicles (AUVs). An accurate method to determine temporally and spatially averaged mixing rates are deliberate tracer release experiments.
Banyte, D., T. Tanhua, M. Visbeck, D. W. R. Wallace, J. Karstensen, G. Krahmann, A. Schneider, L. Stramma and M. Dengler (2012), Diapycnal diffusivity at the upper boundary of the tropical North Atlantic oxygen minimum zone, J. Geophys. Res., 117, C09016, doi: 10.1029/2011JC007762.
Fischer, T., D. Banyte, P. Brandt, M. Dengler, G. Krahmann, T. Tanhua, and M. Visbeck (2013) Diapycnal oxygen supply to the tropical North Atlantic oxygen minimum zone, Biogeosciences, 10, pp. 5079-5093, doi: 10.5194/bg-10-5079-2013.
Hummels, R., M. Dengler, and B. Bourlés (2013), Seasonal and regional variability of upper ocean diapycnal heat flux in the Atlantic Cold Tongue, Prog. Oceanogr., 111, 52-74, doi: 10.1016/j.pocean.2012.11.001.
Tippenhauer, S., M. Dengler, T. Fischer, and T. Kanzow (2015) Turbulence and finestructure in a deep ocean channel with sill overflow on the Mid-Atlantic Ridge, Deep-Sea Res. I, 99,10-22, doi: 10.1016/j.dsr.2015.01.001