Fant 9758 publikasjoner. Viser side 220 av 391:
2014
2015
Mobile technologies and services for supporting green mobility in Oslo: the Citi-Sense-MOB approach. NILU F
2014
2014
2012
2014
2013
2005
2005
Model development for high-resolution emissions from residential wood combustion
I denne rapporten beskriver vi MetVed-modellen. Denne modellen estimerer vedfyringsutslipp med høy oppløsning. Metved-modellen kombinerer nedskalering med bottom-up prinsipper for å estimere vedfyringspotensiale i modellgrid. Den baserer seg på boligtyper, størrelse, oppvarmingsteknologi, energibehov og utendørs temperatur. Modellen baserer seg på å kombinere flere databaser med høyt detaljert informasjon. Databasene inneholder boligtall og boligtyper med 250 meters romlig oppløsning, statistikk av energibruk i husholdninger, plassering av ildsteder som punktkilder, og geografisk posisjon av boliger med informasjon om boligtyper og tilgjengelige teknologier for oppvarming i husholdningene. Databasene blir i MetVed-modellen kombinert og forhold mellom ulike variabler analysert. MetVed-modellen inkluderer en tidsvarisjon av vedforbruket som baserer seg på oppvarmingsgradkonseptet kombinert med tidsvariasjon fra forbrukerstatistikk. Vertikalfordeling av utslippene baserer seg på vedforbruk fordelt på leiligheter og hus (enebolig, tomannsbolig og rekkehus). Resultater fra spredningsmodellberegninger viser at utslippsdata fra MetVed-modellen gir bedre samsvar med målinger enn spredningsberegninger basert på utslipp fra tidligere metoder for å estimere vedfyringsutslipp.
NILU
2018
While carbon dioxide is the main cause for global warming, modeling short-lived climate forcers (SLCFs) such as methane, ozone, and particles in the Arctic allows us to simulate near-term climate and health impacts for a sensitive, pristine region that is warming at 3 times the global rate. Atmospheric modeling is critical for understanding the long-range transport of pollutants to the Arctic, as well as the abundance and distribution of SLCFs throughout the Arctic atmosphere. Modeling is also used as a tool to determine SLCF impacts on climate and health in the present and in future emissions scenarios.
In this study, we evaluate 18 state-of-the-art atmospheric and Earth system models by assessing their representation of Arctic and Northern Hemisphere atmospheric SLCF distributions, considering a wide range of different chemical species (methane, tropospheric ozone and its precursors, black carbon, sulfate, organic aerosol, and particulate matter) and multiple observational datasets. Model simulations over 4 years (2008–2009 and 2014–2015) conducted for the 2022 Arctic Monitoring and Assessment Programme (AMAP) SLCF assessment report are thoroughly evaluated against satellite, ground, ship, and aircraft-based observations. The annual means, seasonal cycles, and 3-D distributions of SLCFs were evaluated using several metrics, such as absolute and percent model biases and correlation coefficients. The results show a large range in model performance, with no one particular model or model type performing well for all regions and all SLCF species. The multi-model mean (mmm) was able to represent the general features of SLCFs in the Arctic and had the best overall performance. For the SLCFs with the greatest radiative impact (CH4, O3, BC, and SO), the mmm was within ±25 % of the measurements across the Northern Hemisphere. Therefore, we recommend a multi-model ensemble be used for simulating climate and health impacts of SLCFs.
Of the SLCFs in our study, model biases were smallest for CH4 and greatest for OA. For most SLCFs, model biases skewed from positive to negative with increasing latitude. Our analysis suggests that vertical mixing, long-range transport, deposition, and wildfires remain highly uncertain processes. These processes need better representation within atmospheric models to improve their simulation of SLCFs in the Arctic environment. As model development proceeds in these areas, we highly recommend that the vertical and 3-D distribution of SLCFs be evaluated, as that information is critical to improving the uncertain processes in models.
2022
2015
2014
The evaluation and intercomparison of air quality models is key to reducing model errors and uncertainty. The projects AQMEII3 and EURODELTA-Trends, in the framework of the Task Force on Hemispheric Transport of Air Pollutants and the Task Force on Measurements and Modelling, respectively (both task forces under the UNECE Convention on the Long Range Transport of Air Pollution, LTRAP), have brought together various regional air quality models to analyze their performance in terms of air concentrations and wet deposition, as well as to address other specific objectives.
This paper jointly examines the results from both project communities by intercomparing and evaluating the deposition estimates of reduced and oxidized nitrogen (N) and sulfur (S) in Europe simulated by 14 air quality model systems for the year 2010. An accurate estimate of deposition is key to an accurate simulation of atmospheric concentrations. In addition, deposition fluxes are increasingly being used to estimate ecological impacts. It is therefore important to know by how much model results differ and how well they agree with observed values, at least when comparison with observations is possible, such as in the case of wet deposition.
This study reveals a large variability between the wet deposition estimates of the models, with some performing acceptably (according to previously defined criteria) and others underestimating wet deposition rates. For dry deposition, there are also considerable differences between the model estimates. An ensemble of the models with the best performance for N wet deposition was made and used to explore the implications of N deposition in the conservation of protected European habitats. Exceedances of empirical critical loads were calculated for the most common habitats at a resolution of 100 × 100m2 within the Natura 2000 network, and the habitats with the largest areas showing exceedances are determined.
Moreover, simulations with reduced emissions in selected source areas indicated a fairly linear relationship between reductions in emissions and changes in the deposition rates of N and S. An approximate 20% reduction in N and S deposition in Europe is found when emissions at a global scale are reduced by the same amount. European emissions are by far the main contributor to deposition in Europe, whereas the reduction in deposition due to a decrease in emissions in North America is very small and confined to the western part of the domain. Reductions in European emissions led to substantial decreases in the protected habitat areas with critical load exceedances (halving the exceeded area for certain habitats), whereas no change was found, on average, when reducing North American emissions in terms of average values per habitat.
2018
2015
2016
2010
2002
2007
Modeling of Aerosol Processes in the Mediterranean Area. NATO Science Series, vol. 30
2003
Modeling of short chain chlorinated paraffins in the Nordic environment. NILU PP
Short chain chlorinated paraffins (SCCPs), also called polychlorinated n-alkanes, are mixtures of compounds of molecular formula CxH2x+2-yCly containing 10-13 carbon atoms and usually 30-70 % degree of chlorination. They have a range of industrial applications, and have been detected in numerous environmental compartments. There is concern regarding SCCPs due to their environmental persistence and their potential for bioaccumulation, adverse effects and long-range transport. SCCPs have been included in the UNECE LRTAP Convention, the priority substance list of the European Water Framework Directive, and are under consideration for the Stockholm Convention on Persistent Organic Pollutants. However, the behaviour and fate of SCCPs remain poorly understood, in part as the technical mixtures consist of thousands of isomers, enantiomers and diastereomers, which make analysis and modelling of these compounds very challenging. The purpose of this study was to explore a complementary modelling and monitoring approach to evaluate the overall understanding of the link between emissions of SCCPs, environmental levels and human exposure in the Nordic environment and to identify the more critical knowledge gaps. Data for emissions and physicochemical properties of SCCPs were gathered or estimated, and used to parameterize an integrated, non-steady state environmental fate and bioaccumulation model (CoZMoMan). Specific congeners of SCCPs were selected for the study to assess the extent of expected variation of environmental fate and behaviour within the multitude of compounds. Model results were next compared to reported environmental levels in the Nordic region. For compartments where environmental levels were scarce or lacking, targeted sampling and analysis was carried out to further evaluate the model predictions. Results from this study will be presented and discussed with emphasis on the more critical research needs with respect to the overall fate and exposure of SCCPs.
2011