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Lillestrom, Norway

The Norwegian Institute for Air Research or NILU is one of the leading specialized scientific laboratories in Europe researching issues related to air pollution, climate change and health. NILU has a staff of scientists, engineers and technicians with specialized expertise for working on air pollution problems. The staff do more than two hundred projects annually for research councils, industries, international banks and local, national and international authorities and organizations. Its director since 2009 is Kari Nygaard. Wikipedia.


Engelsen O.,Norwegian Institute For Air Research
Nutrients | Year: 2010

This paper reviews the main factors influencing the synthesis of vitamin D, with particular focus on ultraviolet radiation exposure. On the global level, the main source of vitamin D is the sun. The effect of solar radiation on vitamin D synthesis depends to some extent on the initial vitamin D levels. At moderate to high latitudes, diet becomes an increasingly important source of vitamin D due to decreased solar intensity and cold temperatures, which discourage skin exposure. During the mid-winter season, these factors result in decreased solar radiation exposure, hindering extensively the synthesis of vitamin D in these populations. © 2010 by the authors; licensee MDPI, Basel, Switzerland. Source


Prata A.J.,Norwegian Institute For Air Research | Prata A.T.,Monash University
Journal of Geophysical Research: Atmospheres | Year: 2012

Between 14 April and 25 May, 2010, Eyjafjallajökull volcano in Iceland erupted a large amount of fine grained ash. Dispersion models and satellite data were used to identify the location of the ash cloud, but accurate quantitative forecasts of the concentrations could not be made. By using multispectral satellite measurements from the Spin Enhanced Visible and Infrared Imager (SEVIRI), it is shown that quantitative estimates of the mass loadings (g m-2) can be made with a detection limit ∼0.2 g m-2, every 15 minutes. These data represent the most comprehensive coverage, in space and time, of the Eyjafjallajökull ash and its movement. A new ash concentration chart is proposed that removes the ambiguity inherent in assigning high concentrations to highly negative brightness temperature differences. Validation of satellite ash retrievals against measurements from aircraft, ground-based lidars, and air quality data is presented. The results show a mean bias of -47 g m-3 and standard deviation of ±154 g m -3. The satellite ash retrievals are sufficiently accurate for use with dispersion models to constrain ash concentration forecasts. Concentrations in the dense parts of the dispersing ash cloud occasionally exceeded 4 mg m -3 (∼3% of ash-affected pixels), and ash clouds with concentrations >2 mg m-3 covered large parts of European airspace on several occasions (∼50% of ash-affected pixels). The statistical analysis leads naturally to a logarithmic scale for assigning ash concentration limits. We suggest that a better approach is to utilize a dosage and illustrate this using a simple model of ash deposition on jet engines. © 2012 by the American Geophysical Union. Source


Schneider P.,Norwegian Institute For Air Research | Van Der A R.J.,Royal Netherlands Meteorological Institute
Journal of Geophysical Research: Atmospheres | Year: 2012

A global nine-year archive of monthly tropospheric NO2 data acquired by the SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY (SCIAMACHY) instrument was analyzed with respect to trends between August 2002 and August 2011. In the past, similar studies relied on combining data from multiple sensors; however, the length of the SCIAMACHY data set now for the first time allows utilization of a consistent time series from just a single sensor for mapping NO2 trends at comparatively high horizontal resolution (0.25). This study provides an updated analysis of global patterns in NO2 trends and finds that previously reported decreases in tropospheric NO2 over Europe and the United States as well as strong increases over China and several megacities in Asia have continued in recent years. Positive trends of up to 4.05 (0.41) × 1015 molecules cm-2 yr-1 and up to 19.7 (1.9) % yr-1 were found over China, with the regional mean trend being 7.3 (3.1) % yr -1. The megacity with the most rapid relative increase was found to be Dhaka in Bangladesh. Subsequently focusing on Europe, the study further analyzes trends by country and finds significantly decreasing trends for seven countries ranging from -3.0 (1.6) % yr-1 to -4.5 (2.3) % yr -1. A comparison of the satellite data with station data indicates that the trends derived from both sources show substantial differences on the station scale, i.e., when comparing a station trend directly with the equivalent satellite-derived trend at the same location, but provide quite similar large-scale spatial patterns. Finally, the SCIAMACHY-derived NO2 trends are compared with equivalent trends in NO2 concentration computed using the Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (EMEP) model. The results show that the spatial patterns in trends computed from both data sources mostly agree in Central and Western Europe, whereas substantial differences are found in Eastern Europe. Source


Cassiani M.,Norwegian Institute For Air Research
Boundary-Layer Meteorology | Year: 2013

A new approach is proposed to predict concentration fluctuations in the framework of one-particle Lagrangian stochastic models. The approach is innovative since it allows the computation of concentration fluctuations in dispersing plumes using a Lagrangian one-particle model with micromixing but with no need for the simulating of background particles. The extension of the model for the treatment of chemically reactive plumes is also accomplished and allows the computation of plume-related chemical reactions in a Lagrangian one-particle framework separately from the background chemical reactions, accounting for the effect of concentration fluctuations on chemical reactions in a general, albeit approximate, manner. These characteristics should make the proposed approach an ideal tool for plume-in-grid calculations in chemistry transport models. The results are compared to the wind-tunnel experiments of Fackrell and Robins (J Fluid Mech, 117:1-26, 1982) for plume dispersion in a neutral boundary layer and to the measurements of Legg et al. (Boundary-Layer Meteorol, 35:277-302, 1986) for line source dispersion in and above a model canopy. Preliminary reacting plume simulations are also shown comparing the model with the experimental results of Brown and Bilger (J Fluid Mech, 312:373-407, 1996; Atmos Environ, 32:611-628, 1998) to demonstrate the feasibility of computing chemical reactions in the proposed framework. © 2012 Springer Science+Business Media B.V. Source


Katsoyiannis A.,Norwegian Institute For Air Research | Breivik K.,Norwegian Institute For Air Research | Breivik K.,University of Oslo
Environmental Pollution | Year: 2014

Polycyclic Aromatic Hydrocarbons (PAHs) molecular diagnostic ratios (MDRs) are unitless concentration ratios of pair-PAHs with the same molecular weight (MW); MDRs have long been used as a tool for PAHs source identification purposes. In the present paper, the efficiency of the MDR methodology is evaluated through the use of a multimedia fate model, the calculation of characteristic travel distances (CTD) and the estimation of air concentrations for individual PAHs as a function of distance from an initial point source. The results show that PAHs with the same MW are sometimes characterized by substantially different CTDs and therefore their air concentrations and hence MDRs are predicted to change as the distance from the original source increases. From the assessed pair-PAHs, the biggest CTD difference is seen for Fluoranthene (107 km) vs. Pyrene (26 km). This study provides a strong indication that MDRs are of limited use as a source identification tool. © 2013 Elsevier Ltd. All rights reserved. Source

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