Jun.-Prof. Nikki Vercauteren, Multiskalen Geodatenanalyse, FB Mathematik und Informatik, FU Berlin

Monday, June 6th 2017, 3:45 pm, LG3A room 352

The quiet atmosphere – Data-driven ideas for modeling different regimes of nighttime turbulent flows.


Boundary-layer turbulence at night, in stably stratified weak-wind conditions, is typically intermittent and generated partly by shear associated with propagating non-turbulent motions on the so-called submesoscales (corresponding roughly to scales smaller than 2km). These non-turbulent motions can include ramp-cliff patterns, waves or microfronts and are commonly denoted as submesomotions. The diversity of submesomotions complicates the identification of specific physical mechanisms that would potentially trigger intermittent turbulence, making the representation of nocturnal turbulence in weather forecasting models a challenging task. In this context, recently developed methods of nonstationary data analysis represent a promising tool to extract knowledge about yet unknown turbulence triggering mechanisms from observational datasets of atmospheric turbulence. In this seminar I will introduce the stable boundary layer, its specificities and associated modeling challenges. I will show that a combination of clustering methods or statistical methods developed for nonstationary data analysis and taking into account external influences can identify different flow regimes and give insights about the patterns of flow motions susceptible to influence turbulent mixing. Such insights are a necessary step to derive new modeling ideas.