Title: Stochastic simulation and time series analysis of nocturnal atmospheric boundary layers
Scientific field: Meteorology, Mechanical Engineering, Applied, Mathematics, Computational Fluid Dynamics
Key words: CFD, Boundary layers, Atmosphere, Time Series Analysis
Scientific Context:
Even stable stratifications can get locally (in space and time) unstable due to forcing from sub-mesoscale
motion. The correlation of the forcing and the generated turbulence is observed in field studies, but not fully
understood from a theoretical point of view. Just adapting existing similarity theory does not seem useful and
thus developing a stochastic parameterization for sub-mesoscale motions or their effect on turbulence could
represent an appropriate solution.
Research subject:
In this project the expertise of (i) flow modeling via recent stochastic approaches like ODTLES (on one-
dimensional turbulence (ODT) based large eddy simulationen (LES)) and (ii) mathematical time series analysis
shall be combined in an interdisciplinary fashion to investigate the former mentioned correlations in a broad
parameter space.
The first objective will be to apply an existing stand-alone ODT code (C++) to Ekman flows. ODT velocity and
buoyancy statistics will be compared with available reference data. The neutrally stratified case is considered
for various Reynolds numbers for validation of the lower-order formulation. After that we move on to the
stably-stratified cases for varying Richardson and Prandtl numbers. Some of the computations will be
repeated with ODTLES.
As a second objective, ODT and ODTLES are used to numerically study the nocturnal boundary layer.
Stratification and types of forcing are varied in a systematic way.
The third objective is the data analysis which will be done in cooperation with colleagues from FU Berlin.
Duration and Payment:
The project duration is 36 months. You will be paid in form of a tax free stipend. The amount is at least of the
order of DFG Ph.D. stipends, but might be higher depending on the qualification of the candidate.
Application:
Only via email using only one pdf document.
References:
[1] Vercauteren, N., Mahrt, L., and Klein, R. (2016). Investigation of interactions between scales of motion in
the stable boundary layer. Quarterly Journal of the Royal Meteorological Society 142:2424–2433.
[2] Vercauteren, N. and Klein, R. (2015). A clustering method to characterize intermittent bursts of turbulence
and interaction with submeso motions in the stable boundary layer. J. Atmos. Sci., 72:1504–1517
[3] Kang, Y and Belusic, D and Smith-Miles, Kate. (2015) Classes of structures in the stable atmospheric
boundary layer. Quarterly Journal of the Royal Meteorological Society 141:2057–2069.
[4] Glawe C, Medina M. JA, Schmidt H. IMEX based multi‐scale time advancement in ODTLES. Z Angew Math
Mech. 2018;98:1907–1923. https://doi.org/10.1002/zamm.201800098
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