Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Evaluating the performance of land surface model ORCHIDEE-CAN v1.0 on water and energy flux estimation with a single-and multi-layer energy budget scheme
Chen, Yiying ; Ryder, James ; Bastrikov, Vladislav ; McGrath, Matthew J. ; Naudts, Kim ; Otto, Juliane ; Ottlé, Catherine ; Peylin, Philippe ; Polcher, Jan ; Valade, Aude ; Black, Andrew ; Elbers, Jan A. ; Moors, Eddy ; Foken, Thomas ; Gorsel, Eva Van; Haverd, Vanessa ; Heinesch, Bernard ; Tiedemann, Frank ; Knohl, Alexander ; Launiainen, Samuli ; Loustau, Denis ; Ogeé, Jérôme ; Vessala, Timo ; Luyssaert, Sebastiaan - \ 2016
Geoscientific Model Development 9 (2016)9. - ISSN 1991-959X - p. 2951 - 2972.

Canopy structure is one of the most important vegetation characteristics for land-atmosphere interactions, as it determines the energy and scalar exchanges between the land surface and the overlying air mass. In this study we evaluated the performance of a newly developed multi-layer energy budget in the ORCHIDEE-CAN v1.0 land surface model (Organising Carbon and Hydrology In Dynamic Ecosystems-CANopy), which simulates canopy structure and can be coupled to an atmospheric model using an implicit coupling procedure. We aim to provide a set of acceptable parameter values for a range of forest types. Top-canopy and sub-canopy flux observations from eight sites were collected in order to conduct this evaluation. The sites crossed climate zones from temperate to boreal and the vegetation types included deciduous, evergreen broad-leaved and evergreen needle-leaved forest with a maximum leaf area index (LAI; all-sided) ranging from 3.5 to 7.0. The parametrization approach proposed in this study was based on three selected physical processes-namely the diffusion, advection, and turbulent mixing within the canopy. Short-term sub-canopy observations and long-term surface fluxes were used to calibrate the parameters in the sub-canopy radiation, turbulence, and resistance modules with an automatic tuning process. The multi-layer model was found to capture the dynamics of sub-canopy turbulence, temperature, and energy fluxes. The performance of the new multi-layer model was further compared against the existing single-layer model. Although the multi-layer model simulation results showed few or no improvements to both the nighttime energy balance and energy partitioning during winter compared with a single-layer model simulation, the increased model complexity does provide a more detailed description of the canopy micrometeorology of various forest types. The multi-layer model links to potential future environmental and ecological studies such as the assessment of in-canopy species vulnerability to climate change, the climate effects of disturbance intensities and frequencies, and the consequences of biogenic volatile organic compound (BVOC) emissions from the terrestrial ecosystem.

Effect of spatial sampling from European flux towers for estimating carbon and water fluxes with artificial neural networks
Papale, Dario ; Black, T.A. ; Carvalhais, Nuno ; Cescatti, Alessandro ; Chen, Jiquan ; Jung, Martin ; Kiely, Gerard ; Lasslop, Gitta ; Mahecha, Miguel D. ; Margolis, Hank ; Merbold, Lutz ; Montagnani, Leonardo ; Moors, Eddy ; Olesen, J.E. ; Reichstein, Markus ; Tramontana, Gianluca ; Gorsel, Eva Van; Wohlfahrt, Georg ; Ráduly, Botond - \ 2015
Journal of Geophysical Research: Biogeosciences 120 (2015)10. - ISSN 2169-8953 - p. 1941 - 1957.
artificial neural networks - gross primary production - latent heat - representativeness - uncertainty - upscaling

Empirical modeling approaches are frequently used to upscale local eddy covariance observations of carbon, water, and energy fluxes to regional and global scales. The predictive capacity of such models largely depends on the data used for parameterization and identification of input-output relationships, while prediction for conditions outside the training domain is generally uncertain. In this work, artificial neural networks (ANNs) were used for the prediction of gross primary production (GPP) and latent heat flux (LE) on local and European scales with the aim to assess the portion of uncertainties in extrapolation due to sample selection. ANNs were found to be a useful tool for GPP and LE prediction, in particular for extrapolation in time (mean absolute error MAE for GPP between 0.53 and 1.56 gC m-2 d-1). Extrapolation in space in similar climatic and vegetation conditions also gave good results (GPP MAE 0.7-1.41 gC m-2 d-1), while extrapolation in areas with different seasonal cycles and controlling factors (e.g., the tropical regions) showed noticeably higher errors (GPP MAE 0.8-2.09 gC m-2 d-1). The distribution and the number of sites used for ANN training had a remarkable effect on prediction uncertainty in both, regional GPP and LE budgets and their interannual variability. Results obtained show that for ANN upscaling for continents with relatively small networks of sites, the error due to the sampling can be large and needs to be considered and quantified. The analysis of the spatial variability of the uncertainty helped to identify the meteorological drivers driving the uncertainty. Key Points Uncertainty due to spatial sampling is evaluated using ANNs and FLUXNET data GPP and LE budgets and IAV are analyzed with different site networks The uncertainty in upscaling due to spatial sampling is highly heterogeneous

Estimating noctural ecosystem respiration from the vertical turbulent flux and change in storange of CO2
Gorsel, E. van; Delpierre, N. ; Leuning, R. ; Black, A. ; Munger, J.W. ; Wofsy, S. ; Aubinet, M. ; Feigenwinter, C. ; Beringer, J. ; Bonal, D. ; Chen, B. ; Chen, J. ; Clement, R. ; Davis, K.J. ; Desai, A.R. ; Dragoni, D. ; Etzold, S. ; Grünwald, T. ; Gu, L. ; Heinesch, B. ; Hutyra, L.R. ; Jans, W.W.P. ; Kutsch, W. ; Law, B.E. ; Leclerc, Y. ; Mammarella, I. ; Montagnani, L. ; Noormets, A. ; Rebmann, C. ; Wharton, S. - \ 2009
Agricultural and Forest Meteorology 149 (2009)11. - ISSN 0168-1923 - p. 1919 - 1930.
ecosystemen - ademhaling - meettechnieken - nacht - kooldioxide - eddy-covariantie - micrometeorologie - luchtstroming - netto ecosysteem koolstofbalans - ecosystems - respiration - measurement techniques - night - carbon dioxide - eddy covariance - micrometeorology - air flow - net ecosystem carbon balance - eddy covariance measurements - temperate deciduous forest - carbon-dioxide exchange - ponderosa pine forests - long-term measurements - douglas-fir stand - old-growth forest - soil respiration - pacific-northwest - difficult conditions
Micrometeorological measurements of nighttime ecosystem respiration can be systematically biased when stable atmospheric conditions lead to drainage flows associated with decoupling of air flow above and within plant canopies. The associated horizontal and vertical advective fluxes cannot be measured using instrumentation on the single towers typically used at micrometeorological sites. A common approach to minimize bias is to use a threshold in friction velocity, u*, to exclude periods when advection is assumed to be important, but this is problematic in situations when in-canopy flows are decoupled from the flow above. Using data from 25 flux stations in a wide variety of forest ecosystems globally, we examine the generality of a novel approach to estimating nocturnal respiration developed by van Gorsel et al. (van Gorsel, E., Leuning, R., Cleugh, H.A., Keith, H., Suni, T., 2007. Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u*-threshold filtering technique. Tellus 59B, 397–403, Tellus, 59B, 307-403). The approach is based on the assumption that advection is small relative to the vertical turbulent flux (FC) and change in storage (FS) of CO2 in the few hours after sundown. The sum of FC and FS reach a maximum during this period which is used to derive a temperature response function for ecosystem respiration. Measured hourly soil temperatures are then used with this function to estimate respiration RRmax. The new approach yielded excellent agreement with (1) independent measurements using respiration chambers, (2) with estimates using ecosystem light-response curves of Fc + Fs extrapolated to zero light, RLRC, and (3) with a detailed process-based forest ecosystem model, Rcast. At most sites respiration rates estimated using the u*-filter, Rust, were smaller than RRmax and RLRC. Agreement of our approach with independent measurements indicates that RRmax provides an excellent estimate of nighttime ecosystem respiration.
The Energy Balance Experiment EBEX-2000. Part I: Overview and energy balance
Oncley, S.P. ; Foken, T. ; Vogt, R. ; Kohsiek, W. ; Debruin, H.A.R. ; Bernhofer, C. ; Christen, A. ; Gorsel, E. van; Grantz, D. ; Feigenwinter, C. ; Lehner, I. ; Liebethal, C. ; Liu, H. ; Mauder, M. ; Pitacco, A. ; Ribeiro, L. ; Weidinger, T. - \ 2007
Boundary-Layer Meteorology 123 (2007)1. - ISSN 0006-8314 - p. 1 - 28.
atmospheric surface-layer - frequency-response corrections - relaxed eddy accumulation - water-vapor transfer - flux measurements - sonic anemometer - heat-flux - sensible heat - land-surface - exchange
An overview of the Energy Balance Experiment (EBEX-2000) is given. This experiment studied the ability of state-of-the-art measurements to close the surface energy balance over a surface (a vegetative canopy with large evapotranspiration) where closure has been difficult to obtain. A flood-irrigated cotton field over uniform terrain was used, though aerial imagery and direct flux measurements showed that the surface still was inhomogeneous. All major terms of the surface energy balance were measured at nine sites to characterize the spatial variability across the field. Included in these observations was an estimate of heat storage in the plant canopy. The resultant imbalance still was 10%, which exceeds the estimated measurement error. We speculate that horizontal advection in the layer between the canopy top and our flux measurement height may cause this imbalance, though our estimates of this term using our measurements resulted in values less than what would be required to balance the budget.
Koelen in de veilingfase : invloed van de doorlooptijd en de temperatuur in de veilingfase op de vochtproduktie, rijpheid en houdbaarheid van snijbloemen
Ravesloot, M.B.M. ; Gorsel, R. van - \ 1992
Aalsmeer : Proefstation voor de Bloemisterij (Rapport / Proefstation voor de Bloemisterij 173) - 70
snijbloemen - systemen na de oogst - koelen - houdbaarheid (kwaliteit) - nederland - cut flowers - postharvest systems - cooling - keeping quality - netherlands
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