• Effects of meteorological and atmospheric parameters on night sky brightness

      Lolkema DE; Haaima M; den Outer PN; Spoelstra H; CMM; mev (Rijksinstituut voor Volksgezondheid en Milieu RIVMKEMA, 2011-06-27)
      Clouds reflect light. This causes light to be seen tens of kilometres away from the light source. There is a clear correlation between night sky brightness and the cloud height and cover. So the light emission being the same, night sky brightness can be quite variable. This means that also the exposure of humans, animals and plants to light at night varies. RIVM has investigated the effect of atmospheric conditions on night sky brightness. The sky close to a strong light source, like a greenhouse, a large city or an industrial area, can be quite dark on clear nights, i.e., without clouds or an optically thick aerosol layer. But on cloudy nights this same sky can be very bright, due to light scattering by these same clouds. Light at night effects humans, plants and animals. The use of light at night has numerous advantages but also adverse effects on flora, fauna and humans. It affects the foraging, reproductive and migration behaviour of a number of nocturnal animals such as insects, bats, amphibians and birds. It changes prey-predator relationships, affects animal's natural rhythms, and disrupts physiological processes in plants. It might cause a disruption of the human circadian system. The exposure however, of humans, plants and animals is far from known. This information is necessary in order to determine the impact of night time lighting. Exposure depends on the light emission on the one hand and on the atmospheric conditions on the other. Light emissions can be monitored with future satellite instruments. It is already possible to determine the night sky brightness from this with model calculations, but only for one atmospheric condition. Up to now, night sky brightness cannot be determined with model calculations for cloudy, partly cloudy or dust polluted conditions. The results of this and future research are essential to map night sky brightness for different atmospheric conditions.
    • Onderzoek naar een geautomatiseerde thermonuder NOx-monitor-combinatie voor de bepaling van ammoniakconcentraties in buitenlucht

      Romer FG; Beld L van den; Smallegange C; Bloem JC; Elzakker BG van; Mennen MG; LLO (KEMARIVM, 1992-12-31)
      Abstract not available
    • Sources, Regional Scaling and Validation of Methane Emissions from the Netherlands and Northwest Europe

      Berdowski JJM; Draaijers GPJ; Janssen LHJM; Hollander JCTh; Loon M van; Roemer MGM; Vermeulen AT; Vosbeek M; Visser H; NOP (TNOApeldoornThe NetherlandsECNPettenThe NetherlandsKEMAArnhemThe Netherlands, 2001-11-19)
      The agreed emission reductions in the Kyoto Protocol require methods to establish the quality and accuracy of the inventory data and to monitor compliance with the Protocol. The IPCC Expert Meeting in November 1997 in the Netherlands concluded that an assessment of inventory data quality was strongly supported by independent checks and additional analysis of uncertainties in the emissions inventories. In this study, carried out in the frame of the Dutch National Research Programme on Global Air Pollution and Climate Change three connected validation procedures have been applied for a methane emission inventory, namely (i) the comparison of emission inventories, (ii) the comparison of modelled with observed methane concentrations, and (iii) the comparison of bottom-up emission estimates with inversely modelled emission estimates. There is a good overall correspondence between the consistent bottom-up METDAT emission inventory and the National Communication data. However, on a country level and on a source category level large discrepancies could been found. The analysis of concentration measurements gives a clear indication of the contribution from the different areas. Time series analysis as such appeared not to be suitable for verification purposes in this study. The technique of emission verification by modelling methane concentrations with the bottom-up estimated emission data as input for the model and comparing the results with measured concentrations has been proven quite successful, at least on a regional scale. The technique applied so far is however not able to indicate whether the individual sources are estimated realistically as well. At present, the technique of inverse modelling has not proven to be robust enough to produce stable results of satisfactory accuracy on a regional scale. At least, there is a lack of sufficient measurement data, e.g. from neighbouring countries and a need for the improvement of background concentration data (by global models).