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Post-Docs, Research, and Visiting Scientists

Gert-Jan Duine

Postdoctoral research associate

Contact Information

Gert-Jan

Degrees
PhD University of Toulouse, France
MSc Meteorology & Air Quality, Wageningen University, the Netherlands
BSc Soil, Water & Atmosphere, Wageningen University, the Netherlands

My academic research focuses mainly on atmospheric boundary layers in complex terrains. The atmospheric boundary layer is the lowest layer of the atmosphere, in which most of our daily life occurs, and takes care of the horizontal and vertical transport of heat, momentum, moisture and tracer gases. During the day, as a result of the Earth’s surface being heated up by the Sun, a vertically extended unstable mixed layer develops and can reach up to 1-3 km, and takes care of atmospheric transport of pollutants from the surface to the free atmosphere. During the night, as a result of surface cooling, a stable layer develops, increasing for example surface concentrations of tracer gases, pollutants. Mountainous terrain exerts influences on boundary layers, modifies horizontal and vertical flows, and so the transport of pollutants.

My PhD was focused on valley winds in the nocturnal boundary layer. As vertical mixing is limited during (cloudless) nights, surface concentrations of pollutants may rise, and local (valley) flows take care for transport of these plumes. Characterization of valley flows is necessary for local and regional sanitary purposes. Therefore we carried out a field campaign KASCADE in southeastern France (https://kascade.sedoo.fr), and performed modeling studies using a state-of-the-art atmospheric numerical model (WRF). More information can also be found at https://tel.archives-ouvertes.fr/tel-01263986/

For my postdoc I focus on daily convective boundary layer processes in complex terrains. Together with Prof. De Wekker, I look at the spatio-temporal variability of convective boundary layer (CBL) depths over complex (mountainous) terrains in global transport models (e.g. TM5). These models are typically run on coarse grid spacing and therefore smoothen mountainous terrains. CBLs vary considerably over mountainous terrain, but for a correct estimation of carbon fluxes, the simulation of CBLs is a crucial parameter. As a consequence of the terrain smoothing there is a large uncertainty in the representation of CBLs in the global models, and how these biases translate to uncertainties in the CO2 concentrations near the surface. We evaluate the performance of coarse global models in their simulation of PBL depths, hope to improve the representation of CBLs, and then we should be able to assess the improvement of CO2-budgets in such models. We try to achieve these goals by using a combination of high-resolution numerical models like WRF, and existing observational data sets and studies.

Publications

5. Duine, G-J., T. Hedde, P. Roubin, P. Durand, M. Lothon, F. Lohou, P. Augustin, and M. Fourmentin, 2017: Characterisation of valley flows within two confluent valleys under stable conditions: observations from the KASCADE field experiment. Q. J. Roy. Meteor. Soc., 143, 1886-1902. doi: http://onlinelibrary.wiley.com/doi/10.1002/qj.3049/full

4. Duine, G-J., T. Hedde, P. Roubin, P.Durand, 2016: A simple method based on routine observations to nowcast down-valley flows in shallow, narrow valleys. J. Appl. Meteor. Climatol., 55(7), 1497-1511. doi: http://dx.doi.org/10.1175/JAMC-D-15-0274.1

3. Kalverla, P.C., Duine G.-J., Steeneveld, G-J and T. Hedde, 2016: Evaluation of the Weather Research and Forecasting model for contrasting diurnal cycles in the Durance Valley complex terrain during the KASCADE field campaign. J. Appl. Meteor. Climatol., 55(4), 861-882. doi: http://dx.doi.org/10.1175/JAMC-D-15-0258.1

2. Duine, G-J. and SFJ De Wekker, 2017: The effects of horizontal grid spacing on simulated daytime boundary layer depths in an area of complex terrain in Utah, Environ. Fluid Mech., under review.

1. Dupuy, F., G.-J. Duine, P. Durand, T. Hedde, P. Roubin and E. Pardyjak, 2017: Valley-winds at the local scale: A downscaling method based on an artificial neural network applied to routine weather forecasting. Submitted to J. Appl. Meteorol. Climatol.