Abstract
Original language  English 

Qualification  Doctor of Philosophy 
Awarding Institution 

Supervisors/Advisors 

Award date  15 May 2002 
Place of Publication  S.l. 
Publisher  
Print ISBNs  9789058086174 
Publication status  Published  2002 
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Keywords
 mathematical models
 evapotranspiration
 precipitation
 soil energy relations
 boundary layer
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Modeling the exchange of water and energy over natural land surfaces = Het modelleren van de uitwisseling van water en energie over natuurlijke landschappen. / Ronda, R.J.
S.l. : S.n., 2002. 119 p.Research output: Thesis › internal PhD, WU
TY  THES
T1  Modeling the exchange of water and energy over natural land surfaces = Het modelleren van de uitwisseling van water en energie over natuurlijke landschappen
AU  Ronda, R.J.
N1  WU thesis 3198 Met lit. opg.  Met samenvatting in het Nederlands Proefschrift Wageningen
PY  2002
Y1  2002
N2  This thesis deals with the modeling of the surface energy balance and the atmospheric boundary layer over natural land surfaces, on scales of the grid cell of largescale atmospheric models. In the first part, a model to calculate the canopy conductance as a function of environmental variables evaluated at leaf level is developed and validated. The parameter values of this approach are retained from plantphysiological theory. For a C 4 prairie grass in Kansas and a C 3 soybean crop in southern France, the plantphysiological approach gives better estimates of the canopy conductance, compared to a traditional JarvisStewart approach which relates the canopy conductance to environmental variables at a reference level, using empiricalstatistical functions. For a C 3 grassland in the Netherlands, both the plantphysiological approach and the JarvisStewart approach give comparable estimates of the latent heat flux density. In the second part, two approaches to calculate the impact of soil moisture stress on the surface flux densities over natural, heterogeneous areas are compared: a bulk approach where the soil moisture content is assumed to be uniform in a grid cell, and a distributed approach which takes account of the spatial variation of the soil moisture content. In wet conditions, the bulk approach gives larger predictions of the latent heat flux density than the distributed approach. In dry conditions the bulk approach gives lower predictions than the distributed approach. Especially for dry climates the bulk approach predicts during the dry season a severe suppression of the latent heat flux density. In the third part, using three cases that occur frequently in nature it is shown that only a tiling approach can provide estimates of the averaged surface flux densities that are consistent with the averaged temperature difference over the surface layer, the layer of air adjacent to the surface, in all situations.
AB  This thesis deals with the modeling of the surface energy balance and the atmospheric boundary layer over natural land surfaces, on scales of the grid cell of largescale atmospheric models. In the first part, a model to calculate the canopy conductance as a function of environmental variables evaluated at leaf level is developed and validated. The parameter values of this approach are retained from plantphysiological theory. For a C 4 prairie grass in Kansas and a C 3 soybean crop in southern France, the plantphysiological approach gives better estimates of the canopy conductance, compared to a traditional JarvisStewart approach which relates the canopy conductance to environmental variables at a reference level, using empiricalstatistical functions. For a C 3 grassland in the Netherlands, both the plantphysiological approach and the JarvisStewart approach give comparable estimates of the latent heat flux density. In the second part, two approaches to calculate the impact of soil moisture stress on the surface flux densities over natural, heterogeneous areas are compared: a bulk approach where the soil moisture content is assumed to be uniform in a grid cell, and a distributed approach which takes account of the spatial variation of the soil moisture content. In wet conditions, the bulk approach gives larger predictions of the latent heat flux density than the distributed approach. In dry conditions the bulk approach gives lower predictions than the distributed approach. Especially for dry climates the bulk approach predicts during the dry season a severe suppression of the latent heat flux density. In the third part, using three cases that occur frequently in nature it is shown that only a tiling approach can provide estimates of the averaged surface flux densities that are consistent with the averaged temperature difference over the surface layer, the layer of air adjacent to the surface, in all situations.
KW  wiskundige modellen
KW  evapotranspiratie
KW  neerslag
KW  bodemenergierelaties
KW  grenslaag
KW  mathematical models
KW  evapotranspiration
KW  precipitation
KW  soil energy relations
KW  boundary layer
M3  internal PhD, WU
SN  9789058086174
PB  S.n.
CY  S.l.
ER 