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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    Influence of Atmospheric Transport on Estimates of Variability in the Global Methane Burden
    Pandey, Sudhanshu ; Houweling, Sander ; Krol, Maarten ; Aben, Ilse ; Nechita-Banda, Narcisa ; Thoning, Kirk ; Röckmann, Thomas ; Yin, Yi ; Segers, Arjo ; Dlugokencky, Edward J. - \ 2019
    Geophysical Research Letters 46 (2019)4. - ISSN 0094-8276 - p. 2302 - 2311.
    atmospheric burden - atmospheric transport - CH emissions - interhemispheric difference - methane - TM5

    We quantify the impact of atmospheric transport and limited marine boundary layer sampling on changes in global and regional methane burdens estimate using tracer transport model simulations with annually repeating methane emissions and sinks but varying atmospheric transport patterns. We find the 1σ error due to this transport and sampling effect on annual global methane increases to be 1.11 ppb/year and on zonal growth rates to be 3.8 ppb/year, indicating that it becomes more critical at smaller spatiotemporal scales. We also find that the trends in inter-hemispheric and inter-polar difference of methane are significantly influenced by the effect. Contrary to a negligible trend in the inter-hemispheric difference of measurements, we find, after adjusting for the transport and sampling, a trend of 0.37 ± 0.06 ppb/year. This is consistent with the emission trend from a 3-D inversion of the measurements, suggesting a faster increase in emissions in the Northern Hemisphere than in the Southern Hemisphere.

    Off-line algorithm for calculation of vertical tracer transport in the troposphere due to deep convection
    Belikov, D.A. ; Maksyutov, S. ; Krol, M.C. ; Fraser, A. ; Rigby, M. ; Bian, H. ; Agusti-Panareda, A. ; Bergmann, D. ; Bousquet, P. ; Cameron-Smith, P. ; Chipperfield, M.P. ; Fortems-Cheiney, A. ; Gloor, E. ; Haynes, K. ; Hess, P. ; Houweling, S. ; Kawa, S.R. ; Law, R.M. ; Loh, Z. ; Meng, L. ; Palmer, P.I. ; Patra, P.K. ; Prinn, R.G. ; Saito, R. ; Wilson, C. - \ 2013
    Atmospheric Chemistry and Physics 13 (2013)3. - ISSN 1680-7316 - p. 1093 - 1114.
    general-circulation model - observed radon profiles - cumulus convection - atmospheric transport - climate simulations - meteorological data - cloud ensemble - precipitation - rn-222 - parameterization
    A modified cumulus convection parametrisation scheme is presented. This scheme computes the mass of air transported upward in a cumulus cell using conservation of moisture and a detailed distribution of convective precipitation provided by a reanalysis dataset. The representation of vertical transport within the scheme includes entrainment and detrainment processes in convective updrafts and downdrafts. Output from the proposed parametrisation scheme is employed in the National Institute for Environmental Studies (NIES) global chemical transport model driven by JRA-25/JCDAS reanalysis. The simulated convective precipitation rate and mass fluxes are compared with observations and reanalysis data. A simulation of the short-lived tracer Rn-222 is used to further evaluate the performance of the cumulus convection scheme. Simulated distributions of Rn-222 are evaluated against observations at the surface and in the free troposphere, and compared with output from models that participated in the TransCom-CH4 Transport Model Intercomparison. From this comparison, we demonstrate that the proposed convective scheme in general is consistent with observed and modeled results.
    Impact of transport model errors on the global and regional methane emissions estimated by inverse modelling
    Locatelli, R. ; Bousquet, P. ; Chevallier, F. ; Fortems-Cheney, A. ; Szopa, S. ; Saunois, M. ; Agusti-Panareda, A. ; Bergmann, D. ; Bian, H. ; Cameron-Smith, P. ; Chipperfield, M.P. ; Gloor, E. ; Houweling, S. ; Kawa, S.R. ; Krol, M.C. ; Patra, P.K. ; Prinn, R.G. ; Rigby, M. ; Saito, R. ; Wilson, C. - \ 2013
    Atmospheric Chemistry and Physics 13 (2013)19. - ISSN 1680-7316 - p. 9917 - 9937.
    general-circulation model - atmospheric transport - tracer transport - co2 inversions - boundary-layer - vertical profiles - data assimilation - climate-change - growth-rate - part i
    A modelling experiment has been conceived to assess the impact of transport model errors on methane emissions estimated in an atmospheric inversion system. Synthetic methane observations, obtained from 10 different model outputs from the international TransCom-CH4 model inter-comparison exercise, are combined with a prior scenario of methane emissions and sinks, and integrated into the three-component PYVAR-LMDZ-SACS (PYthon VARiational-Laboratoire de Meteorologie Dynamique model with Zooming capability-Simplified Atmospheric Chemistry System) inversion system to produce 10 different methane emission estimates at the global scale for the year 2005. The same methane sinks, emissions and initial conditions have been applied to produce the 10 synthetic observation datasets. The same inversion set-up (statistical errors, prior emissions, inverse procedure) is then applied to derive flux estimates by inverse modelling. Consequently, only differences in the modelling of atmospheric transport may cause differences in the estimated fluxes. In our framework, we show that transport model errors lead to a discrepancy of 27 Tg yr(-1) at the global scale, representing 5% of total methane emissions. At continental and annual scales, transport model errors are proportionally larger than at the global scale, with errors ranging from 36 Tg yr(-1) in North America to 7 Tg yr(-1) in Boreal Eurasia (from 23 to 48 %, respectively). At the model grid-scale, the spread of inverse estimates can reach 150% of the prior flux. Therefore, transport model errors contribute significantly to overall uncertainties in emission estimates by inverse modelling, especially when small spatial scales are examined. Sensitivity tests have been carried out to estimate the impact of the measurement network and the advantage of higher horizontal resolution in transport models. The large differences found between methane flux estimates inferred in these different configurations highly question the consistency of transport model errors in current inverse systems. Future inversions should include more accurately prescribed observation covariances matrices in order to limit the impact of transport model errors on estimated methane fluxes.
    Sources, distribution, and acidity of sulfate–ammonium aerosol in the Arctic in winter–spring
    Fisher, J.A. ; Jacob, D.J. ; Wang, Q. ; Bahreini, R. ; Carouge, C.C. ; Cubison, M.J. ; Dibb, J.E. ; Diehl, T. ; Jiminez, J.L. ; Leibensperger, E.M. ; Lu, Z. ; Meinders, M.B.J. ; Pye, H.O.T. ; Quinn, P.K. ; Sharma, S. ; Streets, D.G. ; Donkelaar, A. van; Yantosca, R.M. - \ 2011
    Atmospheric Environment 45 (2011)39. - ISSN 1352-2310 - p. 7301 - 7318.
    circulation model assessment - cloud resolving simulations - dry deposition - chemical-composition - asian pollution - ice nucleation - air-pollution - intex-b - atmospheric transport - ozone depletion
    We use GEOS-Chem chemical transport model simulations of sulfate–ammonium aerosol data from the NASA ARCTAS and NOAA ARCPAC aircraft campaigns in the North American Arctic in April 2008, together with longer-term data from surface sites, to better understand aerosol sources in the Arctic in winter–spring and the implications for aerosol acidity. Arctic pollution is dominated by transport from mid-latitudes, and we test the relevant ammonia and sulfur dioxide emission inventories in the model by comparison with wet deposition flux data over the source continents. We find that a complicated mix of natural and anthropogenic sources with different vertical signatures is responsible for sulfate concentrations in the Arctic. East Asian pollution influence is weak in winter but becomes important in spring through transport in the free troposphere. European influence is important at all altitudes but never dominant. West Asia (non-Arctic Russia and Kazakhstan) is the largest contributor to Arctic sulfate in surface air in winter, reflecting a southward extension of the Arctic front over that region. Ammonium in Arctic spring mostly originates from anthropogenic sources in East Asia and Europe, with added contribution from boreal fires, resulting in a more neutralized aerosol in the free troposphere than at the surface. The ARCTAS and ARCPAC data indicate a median aerosol neutralization fraction [NH4+]/(2[SO42-] + [NO3-]) of 0.5 mol mol-1 below 2 km and 0.7 mol mol-1 above. We find that East Asian and European aerosol transported to the Arctic is mostly neutralized, whereas West Asian and North American aerosol is highly acidic. Growth of sulfur emissions in West Asia may be responsible for the observed increase in aerosol acidity at Barrow over the past decade. As global sulfur emissions decline over the next decades, increasing aerosol neutralization in the Arctic is expected, potentially accelerating Arctic warming through indirect radiative forcing and feedbacks.
    A comparison of different inverse carbon flux estimation approaches for application on a regional domain
    Tolk, L.F. ; Dolman, A.J. ; Meesters, A.G.C.A. ; Peters, W. - \ 2011
    Atmospheric Chemistry and Physics 11 (2011). - ISSN 1680-7316 - p. 10349 - 10365.
    atmospheric transport - dioxide exchange - european forests - modeling system - surface fluxes - boundary-layer - co2 fluxes - assimilation - sensitivity - tower
    We have implemented six different inverse carbon flux estimation methods in a regional carbon dioxide (CO2) flux modeling system for the Netherlands. The system consists of the Regional Atmospheric Mesoscale Modeling System (RAMS) coupled to a simple carbon flux scheme which is run in a coupled fashion on relatively high resolution (10 km). Using an Ensemble Kalman filter approach we try to estimate spatiotemporal carbon exchange patterns from atmospheric CO2 mole fractions over the Netherlands for a two week period in spring 2008. The focus of this work is the different strategies that can be employed to turn first-guess fluxes into optimal ones, which is known as a fundamental design choice that can affect the outcome of an inversion significantly. Different state-of-the-art approaches with respect to the estimation of net ecosystem exchange (NEE) are compared quantitatively: (1) where NEE is scaled by one linear multiplication factor per land-use type, (2) where the same is done for photosynthesis (GPP) and respiration (R) separately with varying assumptions for the correlation structure, (3) where we solve for those same multiplication factors but now for each grid box, and (4) where we optimize physical parameters of the underlying biosphere model for each land-use type. The pattern to be retrieved in this pseudo-data experiment is different in nearly all aspects from the first-guess fluxes, including the structure of the underlying flux model, reflecting the difference between the modeled fluxes and the fluxes in the real world. This makes our study a stringent test of the performance of these methods, which are currently widely used in carbon cycle inverse studies. Our results show that all methods struggle to retrieve the spatiotemporal NEE distribution, and none of them succeeds in finding accurate domain averaged NEE with correct spatial and temporal behavior. The main cause is the difference between the structures of the first-guess and true CO2 flux models used. Most methods display overconfidence in their estimate as a result. A commonly used daytime-only sampling scheme in the transport model leads to compensating biases in separate GPP and R scaling factors that are readily visible in the nighttime mixing ratio predictions of these systems. Overall, we recommend that the estimate of NEE scaling factors should not be used in this regional setup, while estimating bias factors for GPP and R for every grid box works relatively well. The biosphere parameter inversion performs good compared to the other inversions at simultaneously producing space and time patterns of fluxes and CO2 mixing ratios, but non-linearity may significantly reduce the information content in the inversion if true parameter values are far from the prior estimate. Our results suggest that a carefully designed biosphere model parameter inversion or a pixel inversion of the respiration and GPP multiplication factors are from the tested inversions the most promising tools to optimize spatiotemporal patterns of NEE.
    Increasing carbon storage in intact African tropical forests
    Lewis, S.L. ; Lopez-Gonzalez, G. ; Sonké, B. ; Affum-Baffoe, K. ; Ewango, C.E.N. - \ 2009
    Nature 457 (2009). - ISSN 0028-0836 - p. 1003 - 1006.
    long-term plots - atmospheric transport - rain-forest - co2 - climate - biomass - disturbances - dioxide - impacts - balance
    The response of terrestrial vegetation to a globally changing environment is central to predictions of future levels of atmospheric carbon dioxide1, 2. The role of tropical forests is critical because they are carbon-dense and highly productive3, 4. Inventory plots across Amazonia show that old-growth forests have increased in carbon storage over recent decades5, 6, 7, but the response of one-third of the world's tropical forests in Africa8 is largely unknown owing to an absence of spatially extensive observation networks9, 10. Here we report data from a ten-country network of long-term monitoring plots in African tropical forests. We find that across 79 plots (163 ha) above-ground carbon storage in live trees increased by 0.63 Mg C ha-1 yr-1 between 1968 and 2007 (95% confidence interval (CI), 0.22¿0.94; mean interval, 1987¿96). Extrapolation to unmeasured forest components (live roots, small trees, necromass) and scaling to the continent implies a total increase in carbon storage in African tropical forest trees of 0.34 Pg C yr-1 (CI, 0.15¿0.43). These reported changes in carbon storage are similar to those reported for Amazonian forests per unit area6, 7, providing evidence that increasing carbon storage in old-growth forests is a pan-tropical phenomenon. Indeed, combining all standardized inventory data from this study and from tropical America and Asia5, 6, 11 together yields a comparable figure of 0.49 Mg C ha-1 yr-1 (n = 156; 562 ha; CI, 0.29¿0.66; mean interval, 1987¿97). This indicates a carbon sink of 1.3 Pg C yr-1 (CI, 0.8¿1.6) across all tropical forests during recent decades. Taxon-specific analyses of African inventory and other data12 suggest that widespread changes in resource availability, such as increasing atmospheric carbon dioxide concentrations, may be the cause of the increase in carbon stocks13, as some theory14 and models2, 10, 15 predict.
    The CarboEurope regional experiment strategy
    Dolman, A.J. ; Noilhan, J. ; Durand, P. ; Sarrat, C. ; Brut, A. ; Piguet, B. ; Butet, A. ; Jarosz, N. ; Brunet, Y. ; Loustau, D. ; Lamaud, E. ; Tolk, L.F. ; Ronda, R. ; Miglietta, F. ; Gioli, B. ; Magliulo, V. ; Esposito, M. ; Gerbig, C. ; Körner, S. ; Glademard, P. ; Ramonet, M. ; Ciais, P. ; Neininger, B. ; Hutjes, R.W.A. ; Elbers, J.A. ; Macatangay, R. ; Schrems, O. ; Pérez-Landa, G. ; Sanz, J. ; Scholz, Y. ; Facon, G. ; Ceschia, E. ; Beziat, P. - \ 2006
    Bulletin of the American Meteorological Society 87 (2006)10. - ISSN 0003-0007 - p. 1367 - 1379.
    broeikasgassen - kooldioxide - klimaatverandering - meteorologie - frankrijk - greenhouse gases - carbon dioxide - climatic change - meteorology - france - boundary-layer budgets - atmospheric transport - hapex-mobilhy - co2 - carbon - surface - model - scale - flux - exchange
    Quantification of sources and sinks of carbon at global and regional scales requires not only a good description of the land sources and sinks of carbon, but also of the synoptic and mesoscale meteorology. An experiment was performed in Les Landes, southwest France, during May¿June 2005, to determine the variability in concentration gradients and fluxes of CO2. The CarboEurope Regional Experiment Strategy (CERES; see also aimed to produce aggregated estimates of the carbon balance of a region that can be meaningfully compared to those obtained from the smallest downscaled information of atmospheric measurements and continental-scale inversions. We deployed several aircraft to concentration sample the CO2 and fluxes over the whole area, while fixed stations observed the fluxes and concentrations at high accuracy. Several (mesoscale) meteorological modeling tools were used to plan the experiment and flight patterns. Results show that at regional scale the relation between profiles and fluxes is not obvious, and is strongly influenced by airmass history and mesoscale flow patterns. In particular, we show from an analysis of data for a single day that taking either the concentration at several locations as representative of local fluxes or taking the flux measurements at those sites as representative of larger regions would lead to incorrect conclusions about the distribution of sources and sinks of carbon. Joint consideration of the synoptic and regional flow, fluxes, and land surface is required for a correct interpretation. This calls for an experimental and modeling strategy that takes into account the large spatial gradients in concentrations and the variability in sources and sinks that arise from different land use types. We briefly describe how such an analysis can be performed and evaluate the usefulness of the data for planning of future networks or longer campaigns with reduced experimental efforts.
    The two-way nested global chemistry-transport zoom model TM5: algorithm and applications
    Krol, M.C. ; Houweling, S. ; Bregman, B. ; Broek, M. van den; Segers, A. ; Velthoven, P. van; Peters, W. ; Dentener, F. ; Bergamaschi, P. - \ 2005
    Atmospheric Chemistry and Physics 5 (2005)2. - ISSN 1680-7316 - p. 417 - 432.
    intercontinental transport - atmospheric transport - tropospheric ozone - tracer transport - summer smog - pollution - simulation - inversion - europe - region
    This paper describes the global chemistry Transport Model, version 5 (TM5) which allows two-way nested zooming. The model is used for global studies which require high resolution regionally but can work on a coarser resolution globally. The zoom algorithm introduces refinement in both space and time in some predefined regions. Boundary conditions of the zoom region are provided by a coarser parent grid and the results of the zoom area are communicated back to the parent. A case study using 222Rn measurements that were taken during the MINOS campaign reveals the advantages of local zooming. As a next step, it is investigated to what extent simulated concentrations over Europe are influenced by using an additional zoom domain over North America. An artificial ozone-like tracer is introduced with a lifetime of twenty days and simplified non-linear chemistry. The concentration differences at Mace Head (Ireland) are generally smaller than 10%, much smaller than the effects of the resolution enhancement over Europe. Thus, coarsening of resolution at some distance of a sampling station seems allowed. However, it is also noted that the budgets of the tracers change considerably due to resolution dependencies of, for instance, vertical transport. Due to the two-way nested algorithm, TM5 offers a consistent tool to study the effects of grid refinement on global atmospheric chemistry issues like intercontinental transport of air pollution.
    Analyzing the ecosystem carbon dynamics of four European coniferous forests using a biogeochemistry model
    Churkina, G. ; Tenhunen, J. ; Thornton, P. ; Falge, E. ; Elbers, J.A. ; Erhard, M. ; Grünwald, T. ; Kowalski, A. ; Rannik, Ü. ; Sprinz, D. - \ 2003
    Ecosystems 6 (2003)2. - ISSN 1432-9840 - p. 168 - 184.
    time climate variability - daily solar-radiation - global change - gap models - terrestrial ecosystems - atmospheric transport - regional applications - deciduous forest - nitrogen budgets - satellite data
    This paper provides the first steps toward a regional-scale analysis of carbon (C) budgets. We explore the ability of the ecosystem model BIOME-BGC to estimate the daily and annual C dynamics of four European coniferous forests and shifts in these dynamics in response to changing environmental conditions. We estimate uncertainties in the model results that arise from incomplete knowledge of site management history (for example, successional stage of forest). These uncertainties are especially relevant in regional-scale simulations, because this type of information is difficult to obtain. Although the model predicted daily C and water fluxes reasonably well at all sites, it seemed to have a better predictive capacity for the photosynthesis-related processes than for respiration. Leaf area index (LAI) was modeled accurately at two sites but overestimated at two others (as a result of poor long-term climate drivers and uncertainties in model parameterization). The overestimation of LAI (and consequently gross photosynthetic production (GPP)), in combination with reasonable estimates of the daily net ecosystem productivity (NEP) of those forests, also illustrates the problem with modeled respiration. The model results suggest that all four European forests have been net sinks of C at the rate of 100-300 gC/m2/y and that this C sequestration capacity would be 30%-70% lower without increasing nitrogen (N) deposition and carbon dioxide (CO2) concentrations. The magnitude of the forest responses was dependent not only on the rate of changes in environmental factors, but also on site-specific conditions such as climate and soil depth. We estimated that the modeled C exchange at the study sites was reduced by 50%-100% when model simulations were performed for climax forests rather than regrowing forests. The estimates of water fluxes were less sensitive to different initializations of state variables or environmental change scenarios than C fluxes.
    Estrogenic and esterase-inhibiting potency in rainwater in relation to pesticide concentrations, sampling season and location
    Hamers, T.H.M. ; Brink, P.J. van den; Mos, L. ; Linden, S.C. van der; Legler, J. ; Koeman, J.H. ; Murk, A.J. - \ 2003
    Environmental Pollution 123 (2003). - ISSN 0269-7491 - p. 47 - 65.
    reporter gene assays - organochlorine pesticides - pyrethroid insecticides - atmospheric transport - cell-line - in-vivo - receptor - trout - organophosphate - xenobiotics
    In a year-round monitoring program (1998), pesticide composition and toxic potency of the mix of pollutants present in rainwater were measured. The goal of the study was to relate atmospheric deposition of toxic potency and pesticide composition to each other and to sampling period and local agricultural activity. Rainwater was collected in 26 consecutive periods of 14 days in a background location (BACK) and in two locations representative for different agricultural practices, i.e. intensive greenhouse horticulture (HORT) and flower bulb culture (BULB). Samples were chemically analyzed for carbamate (CARB), organophosphate (OP) and organochlorine (OC) pesticides and metabolites. Esterase inhibiting potency of rainwater extracts was measured in a specially developed bio-assay with honeybee esterases and was expressed as an equivalent concentration of the model inhibitor dichlorvos. Estrogenic potency of the extracts was measured in the ER-CALUX reporter gene assay and was expressed as an equivalent concentration of estradiol. Multivariate principal component analysis (PCA) techniques proved to be valuable tools to analyze the numerous pesticide concentrations in relation to toxic potency, sampling location, and sampling season. Pesticide composition in rainwater depended much more on sampling season than on sampling location, but differences between SPRING and SUMMER were mainly attributed to local differences in agricultural practice. On average, the esterase inhibiting potency exceeded the maximum permissible concentration set for dichlorvos in The Netherlands, and was significantly higher in HORT than in BACK and BULB. Esterase inhibition correlated significantly with OP and GARB concentrations, as expected given the working mechanism of these insecticides. The estrogenic potency incidentally exceeded NOEC levels reported for aquatic organisms and was highest in SPRING. Although estrogenic potency of rainwater correlated with OC concentrations, the ER-CALUX responses could not be attributed to any particular pesticides. Besides, the contribution of non-analyzed xeno-estrogens as alkylphenol(-ethoxylates) and bisphenol-A to the estrogenic potency of rainwater could not be excluded. Further research should focus on the chemical identification of estrogenic compounds in rainwater. In addition, more attention should be given to the ecological consequences of atmospheric deposition of individual pesticides and of total toxic potencies that regularly exceed environmental criteria for Dutch surface waters and/or toxic threshold values for aquatic organisms. (C) 2003 Elsevier Science Ltd. All rights reserved.
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