- N.A.M. Besseling (1)
- G.J. Boer (1)
- Y.J.M. Bollen (1)
- J. Brandt (1)
- P.J.H. Builtjes (1)
- T.A. Buishand (2)
- M. Caian (2)
- J.H. Christensen (1)
- Ph. Ciais (1)
- D.B. Clark (1)
- S. Corti (1)
- C. Cuvelier (1)
- F.J. Doblas-Reyes (2)
- S. Drijfhout (1)
- F. Ewert (1)
- S. Folwell (1)
- S. Gosling (1)
- A. Graff (1)
- J. Grasman (1)
- V. Guemas (3)
- E.J.M. Harst van der (1)
- E. Hawkins (1)
- W. Hazeleger (3)
- P. Hazenberg (1)
- L. Hermanson (1)
- C.K. Ho (1)
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- B.J.J.M. Hurk van den (2)
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- M. Schaap (1)
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- F.M. Selten (1)
- D.M. Smith (1)
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- I. Supit (1)
- L. Tarrason (1)
- A.J. Teuling (2)
- P. Thunis (1)
- R. Uijlenhoet (1)
- R. Vautard (2)
- E. Vignati (1)
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- B. Wouters (3)
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Uncertainty in the future change of extreme precipitation over the Rhine basin: the role of internal climate variability
Pelt, S.C. van; Beersma, J.J. ; Buishand, T.A. ; Hurk, B.J.J.M. van den; Schellekens, J. - \ 2015
Climate Dynamics 44 (2015)7. - ISSN 0930-7575 - p. 1789 - 1800.
klimaatverandering - neerslag - hydrologie van stroomgebieden - risicoanalyse - rijn - climatic change - precipitation - catchment hydrology - risk analysis - river rhine - local precipitation - change simulations - model - temperature - quantification - frequency - ensemble - version - gcm
Future changes in extreme multi-day precipitation will influence the probability of floods in the river Rhine basin. In this paper the spread of the changes projected by climate models at the end of this century (2081–2100) is studied for a 17-member ensemble of a single Global Climate Model (GCM) and results from the Coupled Model Intercomparison Project Phase 3 (CMIP3) ensemble. All climate models were driven by the IPCC SRES A1B emission scenario. An analysis of variance model is formulated to disentangle the contributions from systematic differences between GCMs and internal climate variability. Both the changes in the mean and characteristics of extremes are considered. To estimate variances due to internal climate variability a bootstrap method was used. The changes from the GCM simulations were linked to the local scale using an advanced non-linear delta change approach. This approach uses climate responses of the GCM to transform the daily precipitation of 134 sub-basins of the river Rhine. The transformed precipitation series was used as input for the hydrological Hydrologiska Byråns Vattenbalansavdelning model to simulate future river discharges. Internal climate variability accounts for about 30 % of the total variance in the projected climate trends of average winter precipitation in the CMIP3 ensemble and explains a larger fraction of the total variance in the projected climate trends of extreme precipitation in the winter half-year. There is a good correspondence between the direction and spread of the changes in the return levels of extreme river discharges and extreme 10-day precipitation over the Rhine basin. This suggests that also for extreme discharges a large fraction of the total variance can be attributed to internal climate variability.
Variation in LCA results for disposable polystyrene beverage cups due to multiple data sets and modelling choices
Harst, E.J.M. van der; Potting, J. - \ 2014
Environmental Modelling & Software 51 (2014). - ISSN 1364-8152 - p. 123 - 135.
life-cycle assessment - environmental impacts - uncertainty - ensemble - system
Life Cycle Assessments (LCAs) of the same products often result in different, sometimes even contradictory outcomes. Reasons for these differences include using different data sets and deviating modelling choices. This paper purposely used different data sets and modelling choices to identify how these differences propagated in LCA results. Vehicle for this methodological exploration was an LCA case study of a typical polystyrene (PS) disposable cup. An initial LCA of PS cups was made using only one data set per process. Contribution and sensitivity analysis identified those processes with influential contribution to the overall environmental impact. Next additional data sets were acquired for all influential processes. The spread in impact results for each life cycle process was calculated after impact assessment for each individual inventory data set as to preserve the correlation between inventory data within each individual data set. The spread in impact results reflects uncertainty existing between different data sets for the same process and due to modelling choices. The influence on overall LCA results was quantified by systematically applying all combinations of data sets and modelling choices. Results from the different data sets and modelling choices systematically point to the same processes as main contributors to all impact categories (PS production, cup manufacturing, PS incineration and PS recycling). The spread in toxicity indicators exceeds the energy-related impact categories. Causes of spread are resources and energy used (type, amount, date and origin), reported emissions, and applied allocation procedures. Average LCA results show slight preference for recycling PS compared to incineration in most impact categories. Overlapping spread in results of the two waste treatments, however, does not support the preference for recycling. The approach in this paper showed how variation in data sets and modelling choices propagates in LCA outcomes. This is especially useful for generic LCAs as systematic use of multiple data sets and multiple modelling choices increases the insight in relative contributions of processes to, and uncertainty in the overall LCA. These results might be less easy to perceive, but they provide decision makers with more robust information.
Multiyear climate predictions using two initialization strategies
Hazeleger, W. ; Guemas, V. ; Wouters, B. ; Corti, S. ; Andreu-Burillo, I. ; Doblas-Reyes, F.J. ; Wyser, K. ; Caian, M. - \ 2013
Geophysical Research Letters 40 (2013)9. - ISSN 0094-8276 - p. 1794 - 1798.
temperature - reanalysis - ensemble - system
Multiyear climate predictions with two initialization strategies are systematically assessed in the EC-Earth V2.3 climate model. In one ensemble, an estimate of the observed climate state is used to initialize the model. The other uses estimates of observed ocean and sea ice anomalies on top of the model climatology. The ensembles show similar spatial characteristics of drift related to the biases in control simulations. As expected, the drift is less with anomaly initialization. The full field initialization overshoots to a colder state which is related to cold biases in the tropics and North Atlantic, associated with oceanic processes. Despite different amplitude of the drift, both ensembles show similar skill in multiyear global temperature predictions, but regionally differences are found. On multiyear time scales, initialization with observations enhances both deterministic and probabilistic skill scores in the North Atlantic. The probabilistic verification shows skill over the European continent.
Multiyear predictability of the North Atlantic subpolar gyre
Wouters, B. ; Hazeleger, W. ; Drijfhout, S. ; Oldenborgh, G.J. van; Guemas, V. - \ 2013
Geophysical Research Letters 40 (2013)12. - ISSN 0094-8276 - p. 3080 - 3084.
surface-temperature - variability - circulation - prediction - ensemble - model
 In decadal predictability studies, the subpolar Atlantic stands out as a region of high potential and real predictability. Since local temperature and salinity variations in the region are for a large part controlled by ocean dynamics, skillful predictability of the local ocean dynamics is a prerequisite to obtain multiyear predictability of other variables such as sea surface temperature. In this study, we discuss the predictability of the main ocean current system in the region, the subpolar gyre. From perfect model hindcasts exploiting initial condition information only from realistic ocean observation locations, we find that predictability is increased when Argo subsurface data are included. In our real-world experiments with initialized hindcasts, the observed decline in subpolar gyre strength of the mid-1990s is reproduced well and we find predictability of the subpolar gyre up to 2 years ahead, comparable to the skill of a damped persistence model.
Real-time multi-model decadal climate predictions
Smith, D.M. ; Scaife, A.A. ; Boer, G.J. ; Caian, M. ; Doblas-Reyes, F.J. ; Guemas, V. ; Hawkins, E. ; Hazeleger, W. ; Hermanson, L. ; Ho, C.K. ; Ishii, M. ; Kharin, V. ; Kimoto, M. ; Kirtman, B. ; Lean, J. ; Matei, D. ; Merryfield, W.J. ; Muller, W.A. ; Pohlmann, H. ; Rosati, A. ; Wouters, B. ; Wyser, K. - \ 2013
Climate Dynamics 41 (2013)11-12. - ISSN 0930-7575 - p. 2875 - 2888.
surface-temperature - data assimilation - atlantic hurricanes - north-american - ensemble - model - design
We present the first climate prediction of the coming decade made with multiple models, initialized with prior observations. This prediction accrues from an international activity to exchange decadal predictions in near real-time, in order to assess differences and similarities, provide a consensus view to prevent over-confidence in forecasts from any single model, and establish current collective capability. We stress that the forecast is experimental, since the skill of the multi-model system is as yet unknown. Nevertheless, the forecast systems used here are based on models that have undergone rigorous evaluation and individually have been evaluated for forecast skill. Moreover, it is important to publish forecasts to enable open evaluation, and to provide a focus on climate change in the coming decade. Initialized forecasts of the year 2011 agree well with observations, with a pattern correlation of 0.62 compared to 0.31 for uninitialized projections. In particular, the forecast correctly predicted La Nia in the Pacific, and warm conditions in the north Atlantic and USA. A similar pattern is predicted for 2012 but with a weaker La Nia. Indices of Atlantic multi-decadal variability and Pacific decadal variability show no signal beyond climatology after 2015, while temperature in the Nio3 region is predicted to warm slightly by about 0.5 A degrees C over the coming decade. However, uncertainties are large for individual years and initialization has little impact beyond the first 4 years in most regions. Relative to uninitialized forecasts, initialized forecasts are significantly warmer in the north Atlantic sub-polar gyre and cooler in the north Pacific throughout the decade. They are also significantly cooler in the global average and over most land and ocean regions out to several years ahead. However, in the absence of volcanic eruptions, global temperature is predicted to continue to rise, with each year from 2013 onwards having a 50 % chance of exceeding the current observed record. Verification of these forecasts will provide an important opportunity to test the performance of models and our understanding and knowledge of the drivers of climate change.
Global Multimodel Analsysis of Drought in Runoff for the Second Half of the Twentieth Century
Huijgevoort, M.H.J. van; Hazenberg, P. ; Lanen, H.A.J. van; Teuling, A.J. ; Clark, D.B. ; Folwell, S. ; Gosling, S. ; Uijlenhoet, R. - \ 2013
Journal of Hydrometeorology 14 (2013)5. - ISSN 1525-755X - p. 1535 - 1552.
environment simulator jules - conterminous united-states - hydrological drought - model description - scale - ensemble - streamflow - europe - variability - algorithm
During the past decades large-scale models have been developed to simulate global and continental terrestrial water cycles. It is an open question whether these models are suitable to capture hydrological drought, in terms of runoff, on a global scale. A multimodel ensemble analysis was carried out to evaluate if 10 such large-scale models agree on major drought events during the second half of the twentieth century. Time series of monthly precipitation, monthly total runoff from 10 global hydrological models, and their ensemble median have been used to identify drought. Temporal development of area in drought for various regions across the globe was investigated. Model spread was largest in regions with low runoff and smallest in regions with high runoff. In vast regions, correlation between runoff drought derived from the models and meteorological drought was found to be low. This indicated that models add information to the signal derived from precipitation and that runoff drought cannot directly be determined from precipitation data alone in global drought analyses with a constant aggregation period. However, duration and spatial extent of major drought events differed between models. Some models showed a fast runoff response to rainfall, which led to deviations from reported drought events in slowly responding hydrological systems. By using an ensemble of models, this fast runoff response was partly overcome and delay in drought propagating from meteorological drought to drought in runoff was included. Finally, an ensemble of models also allows for consideration of uncertainty associated with individual model structures.
Summer temperatures in Europe and land heat fluxes in observation-based data and regional climate simulations
Stegehuis, A.I. ; Vautard, R. ; Ciais, Ph. ; Teuling, A.J. ; Jung, P. - \ 2013
Climate Dynamics 41 (2013)2. - ISSN 0930-7575 - p. 455 - 477.
weather regimes - soil-moisture - variability - ensemble - precipitation - performance - heatwaves - surface - projections - reanalysis
The occurrence and intensity of heatwaves is expected to increase with climate change. Early warnings of hot summers have therefore a great socio-economical value. Previous studies have shown that hot summers are preceded by a Southern European rainfall deficit during winter, and higher spring temperatures. Changes in the surface energy budget are believed to drive this evolution, in particular changes in the latent and sensible heat fluxes. However these have rarely been investigated due to the lack of long-term reliable observation data. In this study, we analyzed several data-derived gridded products of latent and sensible heat fluxes, based on flux tower observations, together with re-analyses and regional climate model simulations over Europe. We find that warm summers are preceded by an increase in latent heat flux in early spring. During warm summers, an increase in available energy results in an excess of both latent and sensible heat fluxes over most of Europe, but a latent heat flux decrease over the Iberian Peninsula. This indicates that, on average, a summertime soil-moisture limited evapotranspiration regime only prevails in the Iberian Peninsula. In general, the models that we analyzed overestimate latent heat and underestimate sensible heat as compared to the flux tower derived data-product. Most models show considerable drying during warm seasons, leading to the establishment of a soil-moisture limited regime across Europe in summer. This over-estimation by the current generation of models of latent heat and hence of soil moisture deficit over Europe in summer has potential consequences for future summertime climate projections and the projected frequency of heat waves. We also show that a northward propagation of drought during warm summers is found in model results, a phenomenon which is also seen in the flux tower data-product. Our results lead to a better understanding of the role of latent and sensible heat flux in summer heatwaves, and provide a framework for benchmark of modeling studies.
Uncertainty in simulating wheat yields under climate change : Letter
Asseng, S. ; Ewert, F. ; Rosenzweig, C. ; Jones, J.W. ; Supit, I. - \ 2013
Nature Climate Change 3 (2013)9. - ISSN 1758-678X - p. 827 - 832.
tarwe - gewasproductie - klimaatverandering - gewasgroeimodellen - wheat - crop production - climatic change - crop growth models - models - food - co2 - temperature - projections - adaptation - scenarios - ensemble - impacts
Projections of climate change impacts on crop yields are inherently uncertain1. Uncertainty is often quantified when projecting future greenhouse gas emissions and their influence on climate2. However, multi-model uncertainty analysis of crop responses to climate change is rare because systematic and objective comparisons among process-based crop simulation models1, 3 are difficult4. Here we present the largest standardized model intercomparison for climate change impacts so far. We found that individual crop models are able to simulate measured wheat grain yields accurately under a range of environments, particularly if the input information is sufficient. However, simulated climate change impacts vary across models owing to differences in model structures and parameter values. A greater proportion of the uncertainty in climate change impact projections was due to variations among crop models than to variations among downscaled general circulation models. Uncertainties in simulated impacts increased with CO2 concentrations and associated warming. These impact uncertainties can be reduced by improving temperature and CO2 relationships in models and better quantified through use of multi-model ensembles. Less uncertainty in describing how climate change may affect agricultural productivity will aid adaptation strategy development andpolicymaking.
Future changes in extreme precipitation in the Rhine basin based on global and regional climate model simulations
Pelt, S.C. van; Beersma, J.J. ; Buishand, T.A. ; Hurk, B.J.J.M. van den; Kabat, P. - \ 2012
Hydrology and Earth System Sciences 16 (2012)12. - ISSN 1027-5606 - p. 4517 - 4530.
klimaatverandering - hydrologie van stroomgebieden - afvoer - neerslag - rijn - modellen - climatic change - catchment hydrology - discharge - precipitation - river rhine - models - generalized pareto distribution - multisite simulation - change impacts - river thames - tall tales - temperature - projections - uncertainties - ensemble - europe
Probability estimates of the future change of extreme precipitation events are usually based on a limited number of available global climate model (GCM) or regional climate model (RCM) simulations. Since floods are related to heavy precipitation events, this restricts the assessment of flood risks. In this study a relatively simple method has been developed to get a better description of the range of changes in extreme precipitation events. Five bias-corrected RCM simulations of the 1961–2100 climate for a single greenhouse gas emission scenario (A1B SRES) were available for the Rhine basin. To increase the size of this five-member RCM ensemble, 13 additional GCM simulations were analysed. The climate responses of the GCMs are used to modify an observed (1961–1995) precipitation time series with an advanced delta change approach. Changes in the temporal means and variability are taken into account. It is found that the range of future change of extreme precipitation across the five-member RCM ensemble is similar to results from the 13-member GCM ensemble. For the RCM ensemble, the time series modification procedure also results in a similar climate response compared to the signal deduced from the direct model simulations. The changes from the individual RCM simulations, however, systematically differ from those of the driving GCMs, especially for long return periods.
Effect of parameter change upon the extra-tropical atmospheric variability
Levine-Moolenaar, H.E. ; Selten, F.M. ; Grasman, J. - \ 2012
Climate Dynamics 38 (2012)7-8. - ISSN 0930-7575 - p. 1649 - 1659.
north-atlantic oscillation - climate-change - fluctuation-dissipation - models - uncertainty - ensemble - flow
Global climate models contain numerous parameters with uncertain values. In the context of climate simulation and prediction, it is relevant to obtain an estimate of the range of climate outcomes given the parameter uncertainty. Instead of randomly perturbing parameters, we determine parameter perturbations from short-term integrations that potentially have a high impact on the climate of the model. For this purpose we consider a dry, spectral quasi-geostrophic, three-level model on the sphere and its tangent linear and adjoint equations. With an empirical forcing, the model produces a fairly realistic simulation of the extra-tropical winter circulation. We allowed perturbations in a 1,449 dimensional parameter space. As a measure of impact on the climate we compute the change in the probability density function of the dominant patterns of variability. We find that the largest climate response in a set of 1,000 simulations with potentially high impact perturbations is much larger than the largest response in a similar set of simulations with randomly picked perturbations. We conclude that parameter sensitivity calculations based on short term integrations contain valuable information about the sensitivity of the model climate to parameter perturbations. The approach is feasible for state-of-the-art climate models provided that the tangent linear and adjoint equations are implemented
Is regional air quality model diversity representative of uncertainty for ozone simulation?
Vautard, R. ; Loon, M. van; Schaap, M. ; Bergstrom, R. ; Bessagnet, B. ; Brandt, J. ; Builtjes, P.J.H. ; Christensen, J.H. ; Cuvelier, C. ; Graff, A. ; Jonson, J.E. ; Krol, M.C. ; Langner, J. ; Roberts, P. ; Rouil, L. ; Stern, R. ; Tarrason, L. ; Thunis, P. ; Vignati, E. ; White, L. ; Wind, P. - \ 2006
Geophysical Research Letters 33 (2006). - ISSN 0094-8276 - 5 p.
pollution model - western-europe - ensemble
We examine whether seven state-of-the-art European regional air quality models provide daily ensembles of predicted ozone maxima that encompass observations. Using tools borrowed from the evaluation of ensemble weather forecasting, we analyze statistics of simulated ensembles of ozone daily maxima over an entire summer season. Although the model ensemble overestimates ozone, the distribution of simulated concentrations is representative of the uncertainty. The spread of simulations is due to random fluctuations resulting from differences in model formulations and input data, but also to the spread between individual model systematic biases. The ensemble average skill increases as the spread decreases. The skill of the ensemble in giving probabilistic predictions of threshold exceedances is also demonstrated. These results allow for optimism about the ability of this ensemble to simulate the uncertainty of the impact of emission control scenarios.
The folding energy landscape of apoflavodoxin is rugged. hydrogen exchange reveals non-productive misfolded intermediates.
Bollen, Y.J.M. ; Kamphuis, M.B. ; Mierlo, C.P.M. van - \ 2006
Proceedings of the National Academy of Sciences of the United States of America 103 (2006)11. - ISSN 0027-8424 - p. 4095 - 4100.
azotobacter-vinelandii apoflavodoxin - protein - pathways - equilibrium - cooperativity - spectroscopy - sensitivity - topology - ensemble - dynamics
Many native proteins occasionally form partially unfolded forms (PUFs), which can be detected by hydrogen/deuterium exchange and NMR spectroscopy. Knowledge about these metastable states is required to better understand the onset of folding-related diseases. So far, not much is known about where PUFs reside within the energy landscape for protein folding. Here, four PUFs of the relatively large apoflavodoxin (179 aa) are identified. Remarkably, at least three of them are partially misfolded conformations. The misfolding involves side-chain contacts as well as the protein backbone. The rates at which the PUFs interconvert with native protein have been determined. Comparison of these rates with stopped-flow data positions the PUFs in apoflavodoxin's complex folding energy landscape. PUF1 and PUF2 are unfolding excursions that start from native apoflavodoxin but do not continue to the unfolded state. PUF3 and PUF4 could be similar excursions, but their rates of formation suggest that they are on a dead-end folding route that starts from unfolded apoflavodoxin and does not continue all of the way to native protein. All PUFs detected thus are off the protein's productive folding route
Direct determination of liquid phase coexistence by Monte Carlo simulations
Zweistra, H.J.A. ; Besseling, N.A.M. - \ 2006
Physical Review. E, Statistical nonlinear, and soft matter physics 74 (2006)1. - ISSN 1539-3755 - p. 016111/1 - 016111/6.
molecular simulation - integration - model - equilibria - ensemble - systems - oil
A formalism to determine coexistence points by means of Monte Carlo simulations is presented. The general idea of the method is to perform a simulation simultaneously in several unconnected boxes which can exchange particles. At equilibrium, most of the boxes will be occupied by a homogeneous phase. The compositions of these boxes yield coexisting points on the binodal. However, since the overall composition is fixed, at least one of the boxes will contain an interface. We show that this does not affect the results, provided that the interface has no net curvature. We coin the name "Helmholtz- ensemble method," because the method is related to the well-known Gibbs-ensemble method, but the volume of the boxes is constant. Since the box volumes are constant, we expect that this method will be particularly useful for lattice models. The accuracy of the Helmholtz-ensemble method is benchmarked against known coexistence curves of the three-dimensional Ising model with excellent results