- Turbulence as related to measurement techniques in the atmospheric surface layer, with particular emphasis on scintillometry. In order to understand the observed signal, a thorough knowledge of the underlying turbulent field is needed. This knowledge can be obtained by analysis of observations (tower, aircraft) or by numerical simulation: large eddy simulation for the turbulence on boundary-layer scale and direct numerical simulation for the study of turbulence down to the dissipation scales.
- Turbulence in the stable boundary-layer. We explore the use of direct numerical simulation and large-eddy simulation to learn lessons on stable atmospheric flows and we use analytical techniques to understand the occurrence of collapse and intermittency in the stable boundary-layer. The subject of dispersion in the stable boundary-layer is currently being explored.
- Turbulence in the convective boundary layer, with particular emphasis on (dis-)similarities between different scalars. Since many parameterizations for scalar transport are based on the assumption that all scalars have been created equal, any dissimilarity may undermine those parameterizations.My work focuses on heterogeneity in surface properties and the effect of dissimilar entrainment ratios.
- The practical link between turbulent transport and the surface energy balance. This work encompasses the estimation of the surface evapotranspiration from remote sensing data, land-surface models in atmospheric models and the use of forecasted meteorological data in the prediction of the spread of plant diseases.
- Member of the editorial board of Boundary-Layer Meteorology (since 2010).
- Member of the AMS Committee on Boundary Layer Turbulence (since 2012).
- Authored (together with Jos van Dam, also of Wageningen University) a text-book on 'Transport in the Atmosphere-Vegetation-Soil continuum' , published in 2014 by Cambridge University Press.
- Reviewer of papers for a wide range of journals.
- I developped the rubric for the asssessment of MSc-theses, now used throughout Wageningen University (the rubric and the user manual)
- I co-authored the course module Summer in the City, developed for the secondary school subject Nature, Life and Technology.
- I participated in the development of a simulation tool for secondary school students on the topic of boundary-layer clouds (investigative learning).