Coherent structures (Young investigator group), Leader Dr. Katja Träumner

Organization of convergence zones
Coherent structures in the horizontal wind field
The atmospheric boundary layer is the lowest part of the troposphere. It extends from the ground up to a height of about 1 to 2 km thus being the part of the atmosphere where we live. The wind in the boundary layer is characterized by turbulence, i.e. random, unpredictable motions. In this chaotic wind field, however, distinct patterns, so-called coherent structures, may occur. The figures in the left show examples.

Although the occurrence of coherent structures in turbulent fluids has been explored since the 1930s, we know little about their characteristics, their occurrence, and their influence within the atmospheric boundary layer. This is due to the lack of methods for detecting this multi-dimensional phenomenon.

Innovative Dual-Doppler lidar methods can now be used to capture coherent structures and investigate them. On the one hand, process studies can be conducted in that way, for example to give information on the initiation of convection or on the cause of damage at roughness steps such as forest edges under high-wind conditions. On the other hand, it is possible to identify the influence of these structures on material and energy flows within the boundary layer and to improve their representation in atmospheric models.