Found 10003 publications. Showing page 164 of 401:
This report was requested by the Norwegian Public Roads Administration (Statens vegvesen) to provide information concerning non-exhaust traffic emissions in Oslo and the impact of various traffic parameters and road maintenance activities on these emissions. This report provides the results of calculations made with the NORTRIP model, a recently developed emission model for calculating non-exhaust emissions. The sensitivity of the modelled emissions to traffic parameters such as studded tyre share and fraction of heavy duty vehicles is investigated. In addition the impact of salting and cleaning is addressed.
2013
This report was requested by the Norwegian Public Roads Administration (Statens vegvesen) to provide information concerning non-exhaust traffic emissions in Oslo and the impact of changes in environmental speed limits on these emissions. This report provides the results of calculations made with the dispersion model EPISODE coupled to the NORTRIP road dust emission model, a recently developed emission model for calculating non-exhaust emissions. The change in modelled emissions due to changes in environmental speed limit are calculated for two different speed scenarios, where 'speed limit' and 'realistic speed' changes are compared. In addition the impact of the environmental speed limit is compared to other road dust control measures involving studded tyre share and heavy duty vehicle reduction, taken from a previous report.
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Modelling Arctic lower-tropospheric ozone: processes controlling seasonal variations
Abstract. Previous assessments on modelling Arctic tropospheric ozone (O3) have shown that most atmospheric models continue to experience difficulties in simulating tropospheric O3 in the Arctic, particularly in capturing the seasonal variations at coastal sites, primarily attributed to the lack of representation of surface bromine chemistry in the Arctic. In this study, two independent chemical transport models (CTMs), DEHM (Danish Eulerian Hemispheric Model) and GEM-MACH (Global Environmental Multi-scale – Modelling Air quality and Chemistry), were used to simulate Arctic lower-tropospheric O3 for the year 2015 at considerably higher horizontal resolutions (25 and 15 km, respectively) than the large-scale models in the previous assessments. Both models include bromine chemistry but with different mechanistic representations of bromine sources from snow- and ice-covered polar regions: a blowing-snow bromine source mechanism in DEHM and a snowpack bromine source mechanism in GEM-MACH. Model results were compared with a suite of observations in the Arctic, including hourly observations from surface sites and mobile platforms (buoys and ships) and ozonesonde profiles, to evaluate models' ability to simulate Arctic lower-tropospheric O3, particularly in capturing the seasonal variations and the key processes controlling these variations. Both models are found to behave quite similarly outside the spring period and are able to capture the observed overall surface O3 seasonal cycle and synoptic-scale variabilities, as well as the O3 vertical profiles in the Arctic. GEM-MACH (with the snowpack bromine source mechanism) was able to simulate most of the observed springtime ozone depletion events (ODEs) at the coastal and buoy sites well, while DEHM (with the blowing-snow bromine source mechanism) simulated much fewer ODEs. The present study demonstrates that the springtime O3 depletion process plays a central role in driving the surface O3 seasonal cycle in central Arctic, and that the bromine-mediated ODEs, while occurring most notably within the lowest few hundred metres of air above the Arctic Ocean, can induce a 5 %–7 % of loss in the total pan-Arctic tropospheric O3 burden during springtime. The model simulations also showed an overall enhancement in the pan-Arctic O3 concentration due to northern boreal wildfire emissions in summer 2015; the enhancement is more significant at higher altitudes. Higher O3 excess ratios (ΔO3/ΔCO) found aloft compared to near the surface indicate greater photochemical O3 production efficiency at higher altitudes in fire-impacted air masses. The model simulations further indicated an enhancement in NOy in the Arctic due to wildfires; a large portion of NOy produced from the wildfire emissions is found in the form of PAN that is transported to the Arctic, particularly at higher altitudes, potentially contributing to O3 production there.
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Modelling and mapping of degradation of built environment from available data and GIS based information tools. Umwelt-bundesamt. Texte 24/99
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Modellering av vulkanaske i norsk luftfrom. Pkt. 1.3 Enkle forbedringer av utslippsestimat. NILU OR
The report describes how a transport model is used to simulate the emission of ash from volcanic eruptions and how the ash emissions can be described in the model. A number of methods for calculating ash emissions are presented and the development of improved ash emissions by manual analysis of satellite data is presented.
2013
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2014