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Project properties |
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| Title | Sources and sinks in vegetation canopies: key to the understanding of covariances of passive and reactive compounds
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| Group | Meteorology and Air Quality Group |
| Project type | thesis |
| Credits | 36 |
| Supervisor(s) | dr. Arnold Moene |
| Examiner(s) | Prof. dr. A.A.M. Holtslag |
| Contact info | arnold.moene@wur.nl |
| Begin date | 2018/01/01 |
| End date | 2019/02/01 |
| Description | Vegetation cover strongly modifies the interaction between the land surface and the atmosphere: radiative and aerodynamic properties of plants are different from those of bare soil and plants also provide a unique pathway for water transport from the soil to the atmosphere. Hence plants provide much more water vapour to the atmosphere than bare soil surfaces. Plant stomata are also the pathway for the uptake of CO2 which in turn affects the composition of the atmosphere. For the atmosphere, vegetated surfaces could be considered as single surface as long as one is only interested in the resulting surface scalar fluxes (e.g. water vapour flux). However, if one needs to understand how these surface fluxes originate, vegetation canopies should be viewed as essentially three-dimensional. In such a three-dimensional control volume each scalar can have various sources and sinks, which will also be different for different scalars.
Some important applications are: the use of above-canopy correlation between concentrations of CO2 and H2O to infer soil– and vegetation-related fluxes of carbon and water; the impact of the degree of correlation between various compounds on their reaction rate (intensity of segregation). Aims / questions To determine how above-canopy correlation between scalars is affected by their source distribution within the canopy (only soil, only vegetation, or some mixture of both). To determine how this relation depends on properties of the atmospheric flow (stability) and the canopy (distribution of foliage). Methods The study will mainly rely on numerical simulations using the Dutch Atmospheric Large-Eddy Simulation model (DALES) which was recently extended with a description for canopy processes. Observations from the CHATS field campaign that took place in an walnut orchard are available for validation (spring 2007, in Dixon, California). |
| Used skills | You should not be afraid to handle large data sets and to do (and/or learn) some programming. |
| Requirements | Some understanding of atmospheric turbulence and land-atmosphere interaction processes is required. |