Marine systems, ranging in size from entire ocean basins down to the small scales of estuaries, may be viewed as mixing machines. Large-scale ocean currents such as the Gulf Stream or the Kuroshio become unstable and loose energy to mesoscale eddies, which in turn interact with internal waves, sub-mesoscale motions, and other processes. Also these motions may become unstable and decay into three-dimensional turbulence, triggering mixing at the smallest scales of motion in the ocean. In coastal regions, upwelled dense water masses form fronts, which may become unstable and loose energy due to a similar cascade of processes. In estuaries and river plumes, fresh river water is mixed by shear-induced turbulence with ocean water to form brackish water masses. In polar regions, fresh and cold water masses from subglacial discharge entrain warm and salty ambient water which is then cooled and freshened due to glacial melting. The weak but still important mixing in the ocean interior is dominated by breaking of internal waves and double diffusive processes. While in these examples, mixing is viewed as a result of dynamical processes in marine systems, the inverse may also true: the dynamics of these systems may be affected by mixing (one example being the role of diapycnal mixing for the global overturning circulation). In this case, the efficiency of mixing is a key parameter that may, however, strongly vary among different systems, with no agreement on a consistent description at the moment.
The 9th Warnemünde Turbulence Days are an attempt to share knowledge about turbulence and mixing in marine systems ranging from estuaries, shelf seas, marginal seas, up to the scale of the global ocean. Process studies based on observational, experimental, and modeling work as well as on theoretical investigations will be discussed. Methodological studies focusing on innovative instrumentation and modeling tools are also welcome. We especially encourage contributions from related fields like physical limnology and atmospheric sciences.
Qing Li (Los Alamos National Laboratory, NM, USA, confirmed)