LES study on turbulent dust deposition and its dependence on atmospheric boundary-layer stability

It is increasingly recognized that atmospheric boundary-layer stability (ABLS) plays an important role in aeolian processes. While the effects of ABLS on dust emission have been documented in several studies, those on dust deposition are less well studied. By means of large-eddy simulation, we investigate how ABLS influences the probability distribution of surface shear stress and hence dust deposition. Statistical analysis of the model results reveals that the shear stress can be well approximated by using a Weibull distribution and the ABLS influences on dust deposition can be estimated by considering the shear stress fluctuations. The model-simulated dust depositions are compared with the predictions of a dust-deposition scheme and measurements, and the findings are then used to improve the dust-deposition scheme. This research represents a further step towards developing dust schemes that account for the stochastic nature of dust processes.

On the Use of Probability-Based Methods for Estimating the Aerodynamic Boundary-Layer Thickness

In this paper, known probabilistic methods for estimating the thickness of the boundary layer of a two-dimensional laminar flow of viscous incompressible fluid are extended to three-dimensional laminar flows of a viscous compressible medium. Their applicability to the problems of boundary-layer stability is studied with the LOTRAN3 software package, which allows us to compute the position of laminar-turbulent transition in three-dimensional aerodynamic configurations.

Wind profile correction algorithm based on Atmospheric Boundary Layer stability profile

<p>In recent years, the use of radar wind profilers (RWP) at airports has grown significantly with the aim of supporting decision makers to maintain the safety of aircraft landings and takeoffs.</p><p>The RWP provide vertical profiles of averaged horizontal wind speed and direction and vertical wind velocity for the entire Atmospheric Boundary Layer (ABL) and beyond. In addition, RWP with Radio-Acoustic Sounding System (RASS) are able to retrieve virtual temperature profiles in the ABL.</p><p>RWP data evaluation is usually based on the so-called Doppler Beam Swinging method (DBS) which assumes homogeneity and stationarity of the wind field. Often, transient eddies violate this homogeneity and stationarity requirement. Hence, incorrect wind profiles can relate to transient eddies and present a problem for the forecast of high-impact weather phenomena in airports. This work intends to provide a method for removing outliers in such profiles based on historical data and other variables related to the Atmospheric Boundary Layer stability profile in the study region.</p><p>For this study, a dataset of almost one year retrieved from a RWP LAP3000 with RASS Extension is used for a wind profile correction algorithm development.</p><p>The algorithm consists of the detection of outliers in the wind profiles based on the thermodynamic structure of the ABL and the generation of the corrected profiles.</p><p>Results show that the algorithm is capable of identifying and correcting unrealistic variations in speed caused by transient eddies. The method can be applied as a complement to the RWP data processing for better data reliability.</p><p> </p><p>Keywords: atmospheric boundary layer; stability profile; wind profile</p>