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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    Advancing Aquatic Ecosystem-Based Management with Full Consideration of the Social-Ecological System
    Piet, Gerjan ; Delacámara, Gonzalo ; Kraan, Marloes ; Röckmann, Christine ; Lago, Manuel - \ 2020
    In: Ecosystem-Based Management, Ecosystem Services and Aquatic Biodiversity / O’Higgins, Timothy G., Lago, Manuel, DeWitt, Theodore H., Springer International Publishing - ISBN 9783030458423 - p. 17 - 37.
    In this study we present an integrated Ecosystem-Based Management (EBM) approach that attempts to reconcile several concepts including integrated
    ecosystem assessment (IEA), marine spatial planning, resilience thinking, and complex adaptive systems. The approach builds on the IEA process but enhances it by explicitly considering the full social-ecological system (SES) and the creation of a
    generic framework for assessment of ecosystem status and management strategy
    Leaf-scale quantification of the effect of photosynthetic gas exchange on δ17O of atmospheric CO2
    Adnew, Getachew Agmuas ; Pons, Thijs L. ; Koren, Gerbrand ; Peters, Wouter ; Röckmann, Thomas - \ 2020
    Biogeosciences 17 (2020)14. - ISSN 1726-4170 - p. 3903 - 3922.

    Understanding the processes that affect the triple oxygen isotope composition of atmospheric CO2during gas exchange can help constrain the interaction and fluxes between the atmosphere and the biosphere. We conducted leaf cuvette experiments under controlled conditions using three plant species. The experiments were conducted at two different light intensities and using CO2with different δ17O. We directly quantify the effect of photosynthesis on δ17O of atmospheric CO2for the first time. Our results demonstrate the established theory for δ18O is applicable to δ17O.CO2/at leaf level, and we confirm that the following two key factors determine the effect of photosynthetic gas exchange on the δ17O of atmospheric CO2. The relative difference between δ17O of the CO2entering the leaf and the CO2in equilibrium with leaf water and the back-diffusion flux of CO2from the leaf to the atmosphere, which can be quantified by the cm=ca ratio, where ca is the CO2mole fraction in the surrounding air and cm is the one at the site of oxygen isotope exchange between CO2and H2O. At low cm=ca ratios the discrimination is governed mainly by diffusion into the leaf, and at high cm=ca ratios it is governed by back-diffusion of CO2that has equilibrated with the leaf water. Plants with a higher cm=ca ratio modify the 117O of atmospheric CO2more strongly than plants with a lower cm=ca ratio. Based on the leaf cuvette experiments, the global value for discrimination against δ17O of atmospheric CO2during photosynthetic gas exchange is estimated to be-0:57±0:14% using cm=ca values of 0.3 and 0.7 for C4and C3plants, respectively. The main uncertainties in this global estimate arise from variation in cm=ca ratios among plants and growth conditions.

    Constraining the exchange of carbon dioxide over the Amazon : New insights from stable isotopes, remote sensing and inverse modeling
    Koren, Gerbrand - \ 2020
    Wageningen University. Promotor(en): W. Peters; T. Röckmann, co-promotor(en): I.T. Luijkx. - Wageningen : Wageningen University - ISBN 9789463954389 - 256

    In this thesis we study the exchange of CO₂ between the atmosphere and biosphere, with a focus on the Amazon region. The exchange of CO₂ between atmosphere and biosphere occurs through photosynthetic uptake, which we usually refer to as gross primary production (GPP), and through respiratory release, usually referred to as terrestrial ecosystem respiration (TER). The sum of GPP and TER is the net ecosystem exchange (NEE). The focus of the thesis is on quantifying the exchange of CO₂ between biosphere and atmosphere, and the control of environmental variables on this exchange. In particular, the effect of drought on CO₂ exchange, and the post-drought recovery, are major themes of this thesis. 

    Chapter 2 describes the 3-D model that we developed for Δ¹⁷O in atmospheric CO₂ (a potential tracer for GPP). We implemented this tracer in the global atmospheric transport model TM5, which is driven by ERA-Interim meteorological fields. We parameterized the stratospheric source of Δ¹⁷O in CO₂ by exploiting its observed correlation with stratospheric [N₂O]. The exchange between the atmosphere and biosphere is simulated using the terrestrial biosphere model SiBCASA. We also included the contributions of soils, oceans, biomass burning, fossil fuel combustion and the oxidation of atmospheric CO on Δ¹⁷O in CO₂. For CO₂ in the lowest 500 m of the atmosphere, we simulated a Δ¹⁷O signature of 39.6 per meg, which is ~20 per meg lower than estimates from existing box models. Our model results show good agreement with a measured stratospheric Δ¹⁷O in CO₂ profile from Sodankylä (Finland). In addition, we compared model simulations with tropospheric measurements of Δ¹⁷O in CO₂ from Göttingen (Germany) and Taipei (Taiwan), where we found some agreement but also substantial discrepancies. Finally, we showed model results for Zotino (Russia), Mauna Loa (United States), Manaus (Brazil) and South Pole, which we proposed as possible locations for future measurements of Δ¹⁷O in tropospheric CO₂ that can help to further increase our understanding of the global budget of Δ¹⁷O in atmospheric CO₂.  

    In Chapter 3 we studied Δ¹⁷O at the ecosystem level, which is the domain that integrates the contributions from vegetation and soil to the atmospheric signal. We reported for the first time an observed diurnal cycle of Δ¹⁷O in CO₂, measured from air samples collected on 15-16 August 2019 at the mid-latitude pine forest Loobos (FLUXNET site NL-Loo). Most notable is an observed peak for Δ¹⁷O in CO₂ in the morning (~140 per meg, around 6:30 am) that we tentatively ascribed to the entrainment of residual air masses. Besides Δ¹⁷O in CO₂, we report observations of δ¹³C and δ¹⁸O in CO₂ for flasks collected close to the surface (at 0.5 m height, inside the canopy) and from the top of the tower (1-2 m above the canopy). To support the interpretation of observations, we simulated δ¹³C, δ¹⁸O and Δ¹⁷O in CO₂ in the atmospheric boundary layer (ABL) during daytime for Loobos using the mixed layer model MXL. Finally, we used the global atmospheric transport model TM5 to (1) quantify the contribution of different sources that affect Δ¹⁷O in CO₂ at Loobos using a `tracer tagging' method; and (2) extend our analysis of the diurnal cycle to the global scale. Based on these simulations, we expect the largest diurnal cycles for Δ¹⁷O in CO₂ in tropical ecosystems, and we propose to follow-up on this study by sampling air from well-equipped tropical sites, such as the ATTO tower in the Amazon

    In Chapter 4, we study the response of the Amazon forest to the 2015/2016 El Niño, using sun-induced fluorescence (SIF) a proxy for GPP. We developed a new remotely-sensed SIF product with improved signal-to-noise in the tropics, and found that SIF was strongly suppressed over areas with anomalously high temperatures and decreased levels of water in the soil. SIF went below its climatological range starting from the end of the 2015 dry season (October) and returned to normal levels by February 2016 when atmospheric conditions returned to normal, but well before the end of anomalously low precipitation which persisted through June 2016. Impacts were not uniform across the Amazon basin, with the eastern part experiencing much larger (10-15%) SIF reductions than the western part of the basin (2-5%). We estimated that the integrated loss of GPP relative to eight previous years is 0.34-0.48 PgC in the 3-month period Oct-Nov-Dec 2015. 

    Finally, in Chapter 5 we consider the response of the Amazon to droughts in the period 2010-2017. We used CO₂ profiles collected by aircraft over the Amazon to quantify the net ecosystem exchange for drought and post-drought years using the CarbonTracker South America (CTSAM) inverse modelling system. In addition, we performed inversions using independent CO₂ column observations from OCO-2 to quantify CO₂ exchange for the years 2015-2017. We estimate that the total Amazon CO₂ emissions for the years 2010 and 2016 are 0.3-0.5 PgC and 0.0-0.3 PgC larger than the subsequent years 2011 and 2017, respectively. Furthermore, we used near-infrared reflectance of terrestrial vegetation (NIRv), from MODIS and MAIAC, to diagnose the direct and delayed response of GPP to the 2015/2016 drought. We find a substantial reduction of NIRv in the 2016 dry season, when precipitation and temperature have returned to normal values, while soil moisture is still anomalously low, suggesting a persistent impact of the preceding 2015/2016 El Niño drought.  

    This work contributed to a better understanding of the exchange of CO₂ between the biosphere and atmosphere. We have investigated variations of Δ¹⁷O in atmospheric CO₂ and paved the way for new measurements campaigns and the actual application of Δ¹⁷O in CO₂ as a tracer for GPP. We have demonstrated that SIF and NIRv are powerful methods to quantify reductions of GPP during drought and track its post-drought recovery. Finally, our analysis of atmospheric CO₂ inversions showed how the interannual variability of the net exchange of CO₂ over the Amazon is controlled by variations in environmental drivers. Although important challenges remain, the work described in this thesis contributes to better understanding of carbon dioxide exchange over the Amazon.

    CloudRoots: integration of advanced instrumental techniques and process modelling of sub-hourly and sub-kilometre land–atmosphere interactions
    Vilà-Guerau de Arellano, Jordi ; Ney, Patrizia ; Hartogensis, Oscar ; Boer, Hugo De; Diepen, Kevin Van; Emin, Dzhaner ; Groot, Geiske De; Klosterhalfen, Anne ; Langensiepen, Matthias ; Matveeva, Maria ; Miranda-García, Gabriela ; Moene, Arnold F. ; Rascher, Uwe ; Röckmann, Thomas ; Adnew, Getachew ; Brüggemann, Nicolas ; Rothfuss, Youri ; Graf, Alexander - \ 2020
    Biogeosciences 17 (2020)17. - ISSN 1726-4170 - p. 4375 - 4404.
    The CloudRoots field experiment was designed to obtain a comprehensive observational dataset that includes soil, plant, and atmospheric variables to investigate the interaction between a heterogeneous land surface and its overlying atmospheric boundary layer at the sub-hourly and sub-kilometre scale. Our findings demonstrate the need to include measurements at leaf level to better understand the relations between stomatal aperture and evapotranspiration (ET) during the growing season at the diurnal scale. Based on these observations, we obtain accurate parameters for the mechanistic representation of photosynthesis and stomatal aperture. Once the new parameters are implemented, the model reproduces the stomatal leaf conductance and the leaf-level photosynthesis satisfactorily. At the canopy scale, we find a consistent diurnal pattern on the contributions of plant transpiration and soil evaporation using different measurement techniques. From highly resolved vertical profile measurements of carbon dioxide (CO2) and other state variables, we infer a profile of the CO2 assimilation in the canopy with non-linear variations with height. Observations taken with a laser scintillometer allow us to quantify the non-steadiness of the surface turbulent fluxes during the rapid changes driven by perturbation of photosynthetically active radiation by cloud flecks. More specifically, we find 2 min delays between the cloud radiation perturbation and ET. To study the relevance of advection and surface heterogeneity for the land–atmosphere interaction, we employ a coupled surface–atmospheric conceptual model that integrates the surface and upper-air observations made at different scales from leaf to the landscape. At the landscape scale, we calculate a composite sensible heat flux by weighting measured fluxes with two different land use categories, which is consistent with the diurnal evolution of the boundary layer depth. Using sun-induced fluorescence measurements, we also quantify the spatial variability of ET and find large variations at the sub-kilometre scale around the CloudRoots site. Our study shows that throughout the entire growing season, the wide variations in stomatal opening and photosynthesis lead to large diurnal variations of plant transpiration at the leaf, plant, canopy, and landscape scales. Integrating different advanced instrumental techniques with modelling also enables us to determine variations of ET that depend on the scale where the measurement were taken and on the plant growing stage
    Governing Risks of Multi-Use: Seaweed Aquaculture at Offshore Wind Farms
    Burg, Sander W.K. van den; Röckmann, Christine ; Banach, Jennifer L. ; Hoof, Luc van - \ 2020
    Frontiers in Marine Science 7 (2020). - ISSN 2296-7745
    multi-use at sea - private standards - public regulation - risk governance - seaweed

    Spatial claims concerning the rapidly growing European offshore wind sector give rise to various ideas for the multi-use application of wind farms. Seaweed is considered a promising feedstock for food and feed that could be produced at offshore wind farms. Concerns about risks resulting in liability claims and insurance premiums are often seen as show-stoppers to multi-use at offshore wind farms. In this study, key environmental risks of seaweed cultivation at offshore wind farms, identified through literature review, are characterized based on stakeholder consultation. The current approach to risk governance is evaluated to assess how it can handle the uncertain, complex, and/or ambiguous risks of multi-use. It is concluded that current risk governance for multi-use is poorly equipped to deal with the systemic nature of risks. Risk governance should be a joint effort of governments and private regulators. It can improve if it is based on an adaptive framework for risk assessment that can deal with complex, systemic risks. Furthermore, it should be flexible and inclusive, i.e., open to new incoming information and stakeholder input, and taking into account and communicate about the different stakes and values of the various parties involved. The importance of communication and inclusion must be recognized, which promotes participation of concerned stakeholders.

    Can multi-use of the sea be safe? A framework for risk assessment of multi-use at sea
    Hoof, L. van; Burg, S.W.K. van den; Banach, J.L. ; Röckmann, C. ; Goossen, M. - \ 2020
    Ocean & Coastal Management 184 (2020). - ISSN 0964-5691
    Multi-use at sea - Risk assessment - Risk governance - Seaweed production - Wind farms

    By 2050 the world population is expected to reach 10 billion people. This population needs food, water and energy. Increasingly, opportunities are sought out at sea to accommodate these needs. As there is already competition for space, especially in the near-shore, opportunities for multi-use, including the combination of, for example, food and energy production in a single location, are sought. One issue that needs to be addressed to allow for multi-use at sea is safety. Existing frameworks for (marine) risk assessment tend to be rather sector specific and, although existing models and frameworks for risk analysis provide useful elements for an integrated analysis, none of the approaches fully caters for the need of having a framework based on a cyclical process of stakeholder input in all steps of the process of risk identification, risk management and risk evaluation and communication, identifying actions to be taken and providing tools useful in each of the steps, while integrating the three perspectives of maritime safety, food (and feed) safety, and environmental impact assessment and the different perspectives of the actors involved. This study developed a common framework for the risk assessment of multi-use at sea, consisting of six steps (Exploring, Understanding, Appraising, Deciding, Implementing and Evaluating & Communication). The framework encompasses and integrates an analysis of food and feed safety aspects, the safety of people and equipment, and environmental safety aspects. For each step, actions are defined, tools that can be of help to stakeholders are presented, and stakeholder participation measures are described. The framework is iterative and dynamic in its nature; with constant communication and evaluation of progress, decisions can be taken to either take a step forward or back. The framework is developed to assist operators and producers, policymakers, and other stakeholders in assessing and managing risks of multi-use at sea.

    Explicit aerosol-cloud interactions in the Dutch Atmospheric Large-Eddy Simulation model DALES4.1-M7
    Bruine, Marco De; Krol, Maarten ; Vilà-guerau De Arellano, Jordi ; Röckmann, Thomas - \ 2019
    Geoscientific Model Development 12 (2019)12. - ISSN 1991-959X - p. 5177 - 5196.
    Large-eddy simulation (LES) models are an excellent tool to improve our understanding of aerosol–cloud interactions (ACI). We introduce a prognostic aerosol scheme with multiple aerosol species in the Dutch Atmospheric Large-Eddy Simulation model (DALES), especially focused on simulating the impact of cloud microphysical processes on the aerosol population. The numerical treatment of aerosol activation is a crucial element for simulating both cloud and aerosol characteristics. Two methods are implemented and discussed: an explicit activation scheme based on κ-Köhler theory and a more classic approach using updraught strength. Sample model simulations are based on the Rain in Shallow Cumulus over the Ocean (RICO) campaign, characterized by rapidly precipitating warm-phase shallow cumulus clouds.

    We find that in this pristine ocean environment virtually all aerosol mass in cloud droplets is the result of the activation process, while in-cloud scavenging is relatively inefficient. Despite the rapid formation of precipitation, most of the in-cloud aerosol mass is returned to the atmosphere by cloud evaporation. The strength of aerosol processing through subsequent cloud cycles is found to be particularly sensitive to the activation scheme and resulting cloud characteristics. However, the precipitation processes are considerably less sensitive. Scavenging by precipitation is the dominant source for in-rain aerosol mass. About half of the in-rain aerosol reaches the surface, while the rest is released by evaporation of falling precipitation. The effect of cloud microphysics on the average aerosol size depends on the balance between the evaporation of clouds and rain and ultimate removal by precipitation. Analysis of typical aerosol size associated with the different microphysical processes shows that aerosols resuspended by cloud evaporation have a radius that is only 5 % to 10 % larger than the originally activated aerosols. In contrast, aerosols released by evaporating precipitation are an order of magnitude larger.
    Determination of the triple oxygen and carbon isotopic composition of CO2 from atomic ion fragments formed in the ion source of the 253 Ultra high-resolution isotope ratio mass spectrometer
    Adnew, Getachew A. ; Hofmann, Magdalena E.G. ; Paul, Dipayan ; Laskar, Amzad ; Surma, Jakub ; Albrecht, Nina ; Pack, Andreas ; Schwieters, Johannes ; Koren, Gerbrand ; Peters, Wouter ; Röckmann, Thomas - \ 2019
    Rapid Communications in Mass Spectrometry 33 (2019)17. - ISSN 0951-4198 - p. 1363 - 1380.

    Rationale: Determination of δ17O values directly from CO2 with traditional gas source isotope ratio mass spectrometry is not possible due to isobaric interference of 13C16O16O on 12C17O16O. The methods developed so far use either chemical conversion or isotope equilibration to determine the δ17O value of CO2. In addition, δ13C measurements require correction for the interference from 12C17O16O on 13C16O16O since it is not possible to resolve the two isotopologues. Methods: We present a technique to determine the δ17O, δ18O and δ13C values of CO2 from the fragment ions that are formed upon electron ionization in the ion source of the Thermo Scientific 253 Ultra high-resolution isotope ratio mass spectrometer (hereafter 253 Ultra). The new technique is compared with the CO2-O2 exchange method and the 17O-correction algorithm for δ17O and δ13C values, respectively. Results: The scale contractions for δ13C and δ18O values are slightly larger for fragment ion measurements than for molecular ion measurements. The δ17O and Δ17O values of CO2 can be measured on the 17O+ fragment with an internal error that is a factor 1–2 above the counting statistics limit. The ultimate precision depends on the signal intensity and on the total time that the 17O+ beam is monitored; a precision of 14 ppm (parts per million) (standard error of the mean) was achieved in 20 hours at the University of Göttingen. The Δ17O measurements with the O-fragment method agree with the CO2-O2 exchange method over a range of Δ17O values of −0.3 to +0.7‰. Conclusions: Isotope measurements on atom fragment ions of CO2 can be used as an alternative method to determine the carbon and oxygen isotopic composition of CO2 without chemical processing or corrections for mass interferences.

    Global 3-D Simulations of the Triple Oxygen Isotope Signature Δ17O in Atmospheric CO2
    Koren, Gerbrand ; Schneider, Linda ; Velde, Ivar R. van der; Schaik, Erik van; Gromov, Sergey S. ; Adnew, Getachew A. ; Mrozek Martino, Dorota J. ; Hofmann, Magdalena E.G. ; Liang, Mao Chang ; Mahata, Sasadhar ; Bergamaschi, Peter ; Laan-Luijkx, Ingrid T. van der; Krol, Maarten C. ; Röckmann, Thomas ; Peters, Wouter - \ 2019
    Journal of Geophysical Research: Atmospheres 124 (2019)15. - ISSN 2169-897X - p. 8808 - 8836.
    O excess (ΔO) - carbon cycle - carbon dioxide (CO) - gross primary production (GPP) - mass-independent fractionation (MIF) - stable isotopes

    The triple oxygen isotope signature Δ17O in atmospheric CO2, also known as its “17O excess,” has been proposed as a tracer for gross primary production (the gross uptake of CO2 by vegetation through photosynthesis). We present the first global 3-D model simulations for Δ17O in atmospheric CO2 together with a detailed model description and sensitivity analyses. In our 3-D model framework we include the stratospheric source of Δ17O in CO2 and the surface sinks from vegetation, soils, ocean, biomass burning, and fossil fuel combustion. The effect of oxidation of atmospheric CO on Δ17O in CO2 is also included in our model. We estimate that the global mean Δ17O (defined as Δ17O = ln(δ17O+1)−λRL·ln(δ18O+1) with λRL = 0.5229) of CO2 in the lowest 500 m of the atmosphere is 39.6 per meg, which is ∼20 per meg lower than estimates from existing box models. We compare our model results with a measured stratospheric Δ17O in CO2 profile from Sodankylä (Finland), which shows good agreement. In addition, we compare our model results with tropospheric measurements of Δ17O in CO2 from Göttingen (Germany) and Taipei (Taiwan), which shows some agreement but we also find substantial discrepancies that are subsequently discussed. Finally, we show model results for Zotino (Russia), Mauna Loa (United States), Manaus (Brazil), and South Pole, which we propose as possible locations for future measurements of Δ17O in tropospheric CO2 that can help to further increase our understanding of the global budget of Δ17O in atmospheric CO2.

    Sub-diurnal variability of the carbon dioxide and water vapor isotopologues at the field observational scale
    Vilà-Guerau de Arellano, Jordi ; Koren, Gerbrand ; Ouwersloot, Huug G. ; Velde, Ivar van der; Röckmann, Thomas ; Miller, John B. - \ 2019
    Agricultural and Forest Meteorology 275 (2019). - ISSN 0168-1923 - p. 114 - 135.
    Boundary-layer dynamics - CO - Coupled soil-vegetation-atmosphere model - HO - Harvard Forest observations - Stable isotopologues - Sub-diurnal variability

    We investigated the sub-diurnal variability of the carbon dioxide and water vapour isotopologues by modelling a representative case measured above the Harvard Forest. To this end, we developed a model that couples the local processes governed by soil and vegetation conditions to non-local atmospheric processes such as entrainment and long-range advection. The model formulation is based on solving the stable isotopologues 12CO2, 13CO2, C18OO, H2 16O and H2 18O as conserved variables. It also includes simultaneously solving the meteorological state variables coupled with their respective surface fluxes. Our model results indicate the need for a comprehensive observational data-set to ensure that the essential processes and interactions between the boundary-layer dynamics of a forest and the atmospheric boundary layer are satisfactorily reproduced. We present and discuss the temporal evolution of the budgets of 13CO2 and C18OO, in order to quantify the individual contributions made by soil, plant and entrainment dynamics. All these contributions turn out to be relevant, as they enable us to quantify how the energy, water and carbon fluxes on sub-daily scales are partitioned. Regarding the role played by entrainment, we carried out a set of three systematic experiments in which air, with different CO2 and H2O isotopic compositions originating in the residual layer, mix with the boundary-layer air. Our findings show that both the C18OO and H2 18O isotopic ratios and their respective isofluxes are influenced by the entrainment event. This result indicates that high frequency and accurate isotopologues surface measurements (seconds or minutes)can be used to quantify how non-local atmospheric processes modify isotopic composition at sub-daily scales.

    What caused the extreme CO concentrations during the 2017 high-pollution episode in India?
    Dekker, Iris N. ; Houweling, Sander ; Pandey, Sudhanshu ; Krol, Maarten ; Röckmann, Thomas ; Borsdorff, Tobias ; Landgraf, Jochen ; Aben, Ilse - \ 2019
    Atmospheric Chemistry and Physics 19 (2019)6. - ISSN 1680-7316 - p. 3433 - 3445.

    The TROPOspheric Monitoring Instrument (TROPOMI), launched 13 October 2017, has been measuring carbon monoxide (CO) concentrations in the Earth's atmosphere since early November 2017. In the first measurements, TROPOMI was able to measure CO concentrations of the high-pollution event in India of November 2017. In this paper, we studied the extent of the pollution in India, comparing the TROPOMI CO with modeled data from the Weather Research and Forecasting model (WRF) to identify the most important sources contributing to the high pollution, both at ground level and in the total column. We investigated the period 11-19 November 2017. We found that residential and commercial combustion was a much more important source of CO pollution than the post-monsoon crop burning during this period, which is in contrast to what media suggested and some studies on aerosol emissions found. Also, the high pollution was not limited to Delhi and its direct neighborhood but the accumulation of pollution extended over the whole Indo-Gangetic Plain (IGP) due to the unfavorable weather conditions in combination with extensive emissions. From the TROPOMI data and WRF simulations, we observed a buildup of CO during 11-14 November and a decline in CO after 15 November. The meteorological conditions, characterized by low wind speeds and shallow atmospheric boundary layers, were most likely the primary explanation for the temporal accumulation and subsequent dispersion of regionally emitted CO in the atmosphere. This emphasizes the important role of atmospheric dynamics in determining the air quality conditions at ground level and in the total column. Due to its rapidly growing population and economy, India is expected to encounter similar pollution events more often in future post-monsoon and winter seasons unless significant policy measures are taken to reduce residential and commercial emissions.

    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.

    Wind op Zee : bepaling van de waarde van geplande windparkgebieden voor de visserij
    Mol, Arie ; Oostenbrugge, Hans van; Röckmann, Christine ; Hintzen, Niels - \ 2019
    Wageningen : Wageningen Economic Research (Wageningen Economic Research nota 2019-011) - 31
    De ontwikkeling van windparken in de Noordzee heeft economische consequenties voor de visserij. In deze notitie is met behulp van de historische visserijpatronen in de periode 2010-2017 de waarde van de bestaande en geplande windmolenparkgebieden tot 2030 in het Nederlandse deel van de Noordzee voor de visserij bepaald. Daarbij is ook rekening gehouden met de cumulatieve effecten van andere ruimteclaims op de Noordzee op de waarde van deze gebieden. De visserij-activiteiten in de geplande windmolenparkgebieden droegen in de periode 2010-2017 gemiddeld 1.52 mln. euro per jaar bij aan de bruto toegevoegde waarde van de Nederlandse kottervisserij. Dit was 1,36% van de totale bruto toegevoegde waarde van de Nederlandse kottersector en 2,65% van de totale bruto toegevoegde waarde van de Nederlandse kottersector op het Nederlands Continentaal Plat (NCP). De bijdrage varieerde van 1,0 tot 2,5 mln. euro per jaar. Voor individuele schepen was de variatie van de bijdrage uit de geplande windmolenparkgebieden aan de inkomsten veel hoger (0-17%). Het toekomstig belang van de gesloten en te sluiten windmolenparkgebieden voor de visserij wordt mede bepaald door de toekomstige ontwikkelingen in ecologie van de Noordzee, de beleidsmatige en de sociaaleconomische context. Bij sluiting van alle geplande natuurgebieden en windmolenparken in zowel het Nederlandse deel als het buitenlandse deel van de Noordzee zal de bijdrage van de windmolengebieden aan de bruto toegevoegde waarde van de Nederlandse kottersector toenemen tot maximaal 1,57% en bij een 'harde Brexit' tot maximaal 1,93%. De waarde van de gebieden voor de visserij is niet gelijk aan het economisch effect van sluiting van de gebieden voor de visserij. Een nadere analyse van de gedragsveranderingen in de visserij bij sluiting van de gebieden en de resulterende effecten op de kosten en inkomsten is nodig om hier uitsluitsel over te kunnen geven. Gezien alle gebiedsbeperkingen en hun invloed op buitenlandse visserijen, is het daarbij van belang het internationale perspectief niet uit het oog te verliezen.
    Monitoring emissions from the 2015 Indonesian fires using CO satellite data
    Nechita-Banda, Narcisa ; Krol, Maarten ; Werf, Guido R. Van Der; Kaiser, Johannes W. ; Pandey, Sudhanshu ; Huijnen, Vincent ; Clerbaux, Cathy ; Coheur, Pierre ; Deeter, Merritt N. ; Röckmann, Thomas - \ 2018
    Wageningen University and Research
    inverse modelling - biomass burning - emissions - atmosphere - data - peat
    Inverse modelling results for carbon monoxide (CO) emissions to the atmosphere from the 2015 Indonesian fires (1 August - 15 December 2015). The TM5-4DVAR model was used (, together with satellite observations from either IASI or MOPITT instruments.
    Vissen tussen de molens
    Cramer, R. ; Rozemeijer, M.J.C. ; Taal, C. ; Rockmann, C. - \ 2018

    De ruimte voor Noordzeevissers wordt steeds meer beperkt, onder meer door de bouw van windmolenparken. Sommige vissers zijn daarom op zoek naar innovatieve alternatieven. Rems Cramer is een van de aanjagers van het project Win-wind dat onderzoekt wat een visser kan doen bínnen zo’n windmolenpark. In het onderzoek werken groot- en kleinschalige vissers, wetenschappers, parkbeheerders en anderen samen. Een gesprek met Rems Cramer, Marcel Rozemeijer (Wageningen Marine Research), Eelco Leemans (North Sea Energy Lab), Kees Taal (visserijbedrijf W. van der Zwan) en Christine Röckmann (Wageningen Economic Research).

    Making multi-use at sea safe : A Summary of the SOMOS Project
    Goossen, C.M. ; Banach, J.L. ; Burg, S.W.K. van den; Hoof, L.J.W. van; Rockmann, C. ; Vredeveld, L. - \ 2018
    SOMOS - 16 p.
    Monitoring emissions from the 2015 Indonesian fires using CO satellite data
    Nechita-Banda, Narcisa ; Krol, Maarten ; Werf, Guido R. van der; Kaiser, Johannes W. ; Pandey, Sudhanshu ; Huijnen, Vincent ; Clerbaux, Cathy ; Coheur, Pierre ; Deeter, Merritt N. ; Röckmann, Thomas - \ 2018
    Philosophical Transactions of the Royal Society B. Biological sciences 373 (2018)1760. - ISSN 0962-8436 - 9 p.
    atmosphere - biomass burning - emissions - peat - satellite data

    Southeast Asia, in particular Indonesia, has periodically struggled with intense fire events. These events convert substantial amounts of carbon stored as peat to atmospheric carbon dioxide (CO2) and significantly affect atmospheric composition on a regional to global scale. During the recent 2015 El Niño event, peat fires led to strong enhancements of carbon monoxide (CO), an air pollutant and well-known tracer for biomass burning. These enhancements were clearly observed from space by the Infrared Atmospheric Sounding Interferometer (IASI) and the Measurements of Pollution in the Troposphere (MOPITT) instruments. We use these satellite observations to estimate CO fire emissions within an inverse modelling framework. We find that the derived CO emissions for each sub-region of Indonesia and Papua are substantially different from emission inventories, highlighting uncertainties in bottom-up estimates. CO fire emissions based on either MOPITT or IASI have a similar spatial pattern and evolution in time, and a 10% uncertainty based on a set of sensitivity tests we performed. Thus, CO satellite data have a high potential to complement existing operational fire emission estimates based on satellite observations of fire counts, fire radiative power and burned area, in better constraining fire occurrence and the associated conversion of peat carbon to atmospheric CO2 A total carbon release to the atmosphere of 0.35-0.60 Pg C can be estimated based on our results.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

    The impact of precipitation evaporation on the atmospheric aerosol distribution in EC-Earth v3.2.0
    Bruine, Marco De; Krol, Maarten ; Noije, Twan Van; Sager, Philippe Le; Röckmann, Thomas - \ 2018
    Geoscientific Model Development 11 (2018)4. - ISSN 1991-959X - p. 1443 - 1465.
    The representation of aerosol-cloud interaction in global climate models (GCMs) remains a large source of uncertainty in climate projections. Due to its complexity, precipitation evaporation is either ignored or taken into account in a simplified manner in GCMs. This research explores various ways to treat aerosol resuspension and determines the possible impact of precipitation evaporation and subsequent aerosol resuspension on global aerosol burdens and distribution. The representation of aerosol wet deposition by large-scale precipitation in the EC-Earth model has been improved by utilising additional precipitation-related 3- D fields from the dynamical core, the Integrated Forecasting System (IFS) general circulation model, in the chemistry and aerosol module Tracer Model, version 5 (TM5). A simple approach of scaling aerosol release with evaporated precipitation fraction leads to an increase in the global aerosol burden (+7.8 to +15% for different aerosol species). However, when taking into account the different sizes and evaporation rate of raindrops following Gong et al. (2006), the release of aerosols is strongly reduced, and the total aerosol burden decreases by -3.0 to -8.5 %. Moreover, inclusion of cloud processing based on observations by Mitra et al. (1992) transforms scavenged small aerosol to coarse particles, which enhances removal by sedimentation and hence leads to a -10 to -11% lower aerosol burden. Finally, when these two effects are combined, the global aerosol burden decreases by -11 to -19 %. Compared to the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite observations, aerosol optical depth (AOD) is generally underestimated in most parts of the world in all configurations of the TM5 model and although the representation is now physically more realistic, global AOD shows no large improvements in spatial patterns. Similarly, the agreement of the vertical profile with Cloud- Aerosol Lidar with Orthogonal Polarization (CALIOP) satellite measurements does not improve significantly. We show, however, that aerosol resuspension has a considerable impact on the modelled aerosol distribution and needs to be taken into account.
    Op gang brengen van een aanvoerstroom van wild zeewier : EFRO Port 4 Innovation
    Jak, Robbert ; Röckmann, Christine ; Veenstra, Frans - \ 2018
    Den Helder : Wageningen Marine Research (Wageningen Marine Research report C112/17) - 28
    The isotopic composition of CO in vehicle exhaust
    Naus, S. ; Röckmann, T. ; Popa, M.E. - \ 2018
    Atmospheric Environment 177 (2018). - ISSN 1352-2310 - p. 132 - 142.
    CO - CO 2 - Emissions - H 2 - Isotopes - Vehicles
    We investigated the isotopic composition of CO in the exhaust of individual vehicles. Additionally, the CO 2 isotopes, and the CO:CO 2 , CH 4 :CO 2 and H 2 :CO gas ratios were measured. This was done under idling and revving conditions, and for three vehicles in a full driving cycle on a testbench. The spread in the results, even for a single vehicle, was large: for δ 13 C in CO ∼ −60 to 0‰, for δ 18 O in CO ∼ +10 to +35‰, and for all gas ratios several orders of magnitude. The results show an increase in the spread of isotopic values for CO compared to previous studies, suggesting that increasing complexity of emission control in vehicles might be reflected in the isotopic composition. When including all samples, we find a weighted mean for the δ 13 C and δ 18 O in CO of −28.7 ± 0.5‰ and +24.8 ± 0.3‰ respectively. This result is dominated by cold petrol vehicles. Diesel vehicles behaved as a distinct group, with CO enriched in 13 C and depleted in 18 O, compared to petrol vehicles. For the H 2 :CO ratio of all vehicles, we found a value of 0.71 ± 0.31 ppb:ppb. The CO:CO 2 ratio, with a mean of 19.4 ± 6.8 ppb:ppm, and the CH 4 :CO 2 ratio, with a mean of 0.26 ± 0.05 ppb:ppm, are both higher than recent literature indicates. This is likely because our sampling distribution was biased towards cold vehicles, and therefore towards higher emission situations. The CH 4 :CO 2 ratio was found to behave similarly to the CO:CO 2 ratio, suggesting that the processes affecting CO and CH 4 are similar. The δ 13 C values in CO 2 were close to the expected δ 13 C in fuel, with no significant difference between petrol and diesel vehicles. The δ 18 O values in CO 2 for petrol vehicles covered a range of 20–35‰, similar to the δ 18 O of CO. The δ 18 O values in CO 2 for diesel vehicles were close to the δ 18 O in atmospheric oxygen. A set of polluted atmospheric samples, taken near a highway and inside parking garages, showed an isotopic signature of CO and a H 2 :CO ratio that were similar the high emitters in the individual vehicle measurements, with no significant differences between parking garage and highway samples. This suggests that in both environments, which are dominated by different driving conditions, the CO emissions from high emitters (either a few high emission vehicles, or many vehicles with brief bursts of high emissions) dominate the total traffic emissions.
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