My current research focuses on the evaluation of the
WRF limited area model, and especially on the newly introduced schemes.
We use a nationwide network of ceilometers and scintillometers in The Netherlands for model evaluation.
In addition we model the urban heat island effect and heat stress in cities using the mesoscale model WRF (see figure below) and we participate in the Urban Met model intercomparison for urban canopy models. More of our work on urban meteorology is covered by the KvR program See here)
I just finished my PhD research on the understanding and
prediction of stable boundary layers over land. This is a key issue in
boundary layer meteorology at the moment, since the stable boundary layer is not
well understood, but it plays a key role in weather forecasting
(e.g. fog and frost prediction). The work mainly focuses on the modeling of
stable boundary layers (both in 3D as in column mode) to gain insight in the relevant physical processes and
their interaction. Several studies has been done. At first the output of the meso scale model
MM5,
with different planetary boundary layer schemes, was tested against observations from the
CASES99
-experiment.
Because of the high quality data, this may lead to better understanding and
parameterizations for the nocturnal boundary layer in GCMs (parameterizations in atmospheric models).
Secondly, a series of three CASES-99 nights was
modeled with very high resolution in the atmosphere and in the soil, with very
promising results. Currently I am working on a parameterization of the height of
the stable boundary layer for air quality models. Furthermore I am involved in
GABLS,
a LES and single-column model intercomparison project. At the moment we set up a new (GABLS3 case study) that will focus on the representation of the diurnal cycle over land and the low-level jet at Cabauw
Also we developed a new formula for the stable boundary layer height for use in operational dispersion models. Atmospheric dispersion at night is small, so high concentrations
can occur in case of an emergency. Just then high concentrations can occur, and the stable boundary layer height is a very critical parameter. Based on Dimensional Analysis, a new formula was obtained and
evaluated against a range of landuse and latitudes, where it shows a robust performance.
Publications
Poster on the Climate in the Urban Environment in The Netherlands,International Conference on Climate Changes Spatial Planning, 27 Oct. 2008, Rotterdam
Analysis of the Re-Intensification of Tropical Cyclone Erin over Land with the Numerical Model MM5
Presentation at NOAA-ESRL: Evaluation of the WRF model using scintillometery and ceilometry
Poster on the evaluation of the WRF model using the scintillometry technique,International Conference on Climate Changes Spatial Planning, 12-13 Sept. 2007, The Hague
Presentation for iLeaps-GABLS-GLASS symposium on "Land-Atmosphere interaction in the Earth System": Advances in the representation of the Stable Boundary Layer in Large Scale Models
Presentation for 6th Annual Meeting European Met. Soc.:On the possible role of gravity wave drag in the stable atmospheric boundary-Layer
Boundary-Layer Research at Meteorology and Air Quality Group, Wageningen University:
Modellering en Parameterizaties (in Dutch)
A Formula for the Depth of the Stable Boundary Layer: Evaluation and Dimensional Analysis
Mesoscale Model Intercomparison and Observational Evaluation for Three Contrasting Diurnal Cycles in CASES99: Focus on the Stable Boundary Layer
Poster presentation Modeling Drag in the Stable Boundary Layer:
the Possible Role of Orographic Gravity Wave Drag
Modeling the Evolution of the Atmospheric
Boundary layer for three contrasting nights in CASES-99
Revisiting
the height of the stable boundary layer in practical applications
Poster presentation on
the
modeling of the height of the stable boundary layer in practical applications
An evaluation of the mesoscale model MM5 for CASES99
Poster presentation on the horizontal extent of temperature and wind speed
oscillations in the stable boundary layer in The Netherlands
Modelling the evolution of the boundary layer for three contrasting nights in CASES-99 - How robust are the results?
1) The second study concerned the convective
boundary layer.
The main aim was to find out whether a currently used gradient relationship from
LES behaves correctly in the surface layer, compared with data and with
similarity theory. A budget study of potential temperature appeared to have
problems to close the budget, especially when eddy covariance fluxes are used
for surface flux determination. The gradients functions we checked appeared to
compare quite well with other LES formulations and similarity functions. The
paper is
here
2) During my trainee period that I spent at the
Atmospheric Research
group of
KNMI I
worked on a sensitivity analysis of a plant
physiological method to determine the evapotranspiration of forests.
The method is also known as the
A-gs model. It uses plant physiological
relationships and crop growth models to determine transpiration and thus the CO2
flux.
After some re-calibration of the main coefficients with data from a coniferous
forest, I performed a MONTE CARLO simulation while changing the relevant
parameters each time. The main conclusion was that for forests the model was not
as robust as it is for grasses. For natural vegetations the nutrient status
should be taken into account explicitly. Here you can find the report
(KNMI, Tech. rep 242)
More about
A-gs
