Fant 9764 publikasjoner. Viser side 89 av 391:
2009
Satellite data inclusion and kernel based potential improvements in NO2 mapping
European Topic Centre on Air Pollution and Climate Change Mitigation
2018
2013
2011
2005
2016
Sample preparation and analysis of brominated flame retardants (BFR) in environmental samples. NILU PP
2004
Parallelle målinger for BTEX på to steder i Oslo bekreftet at rapporterte konsentrasjoner fra henholdsvis NILU og Molab varierte med flere hundre prosent. En nærmere gjennomgang av beregningsmetoden viste at Molab brukte feil opptaksfaktorer i sine beregninger. Molab overestimerte dermed benzen-konsentrasjoner med 288 %, toluen med 247%, etylbenzen med 265% og xylener med 264%. Denne feilen har blitt gjort ved alle målinger i Oslo i perioden fra 2008 til 2013 og ved parallellmålingene i 2013 og 2014. Etter å ha utført de nødvendige korreksjoner viser måleserien for benzen ved Oslos målesteder en kontinuerlig synkende trend siden 2001. En trend på lik linje med mange andre europeiske byer. Nåværende årsmiddel er nå nærmere 1 µg/m3 og dermed langt under grenseverdien på 5 µg/m3.
Vedrørende prosjektets utgangspunkt som var å se på om det var mulig å etablere en korreksjonsfaktor mellom NILU og Molabs metoder, så er dette ikke lenger aktuelt. Etter korreksjonen av Molabs data er forskjellen mellom NILU og Molabs resultater liten og mindre enn usikkerheten i metodene.
2015
SAMIRA-SAtellite Based Monitoring Initiative for Regional Air Quality
The satellite based monitoring initiative for regional air quality (SAMIRA) initiative was set up to demonstrate the exploitation of existing satellite data for monitoring regional and urban scale air quality. The project was carried out between May 2016 and December 2019 and focused on aerosol optical depth (AOD), particulate matter (PM), nitrogen dioxide (NO2), and sulfur dioxide (SO2). SAMIRA was built around several research tasks: 1. The spinning enhanced visible and infrared imager (SEVIRI) AOD optimal estimation algorithm was improved and geographically extended from Poland to Romania, the Czech Republic and Southern Norway. A near real-time retrieval was implemented and is currently operational. Correlation coefficients of 0.61 and 0.62 were found between SEVIRI AOD and ground-based sun-photometer for Romania and Poland, respectively. 2. A retrieval for ground-level concentrations of PM2.5 was implemented using the SEVIRI AOD in combination with WRF-Chem output. For representative sites a correlation of 0.56 and 0.49 between satellite-based PM2.5 and in situ PM2.5 was found for Poland and the Czech Republic, respectively. 3. An operational algorithm for data fusion was extended to make use of various satellite-based air quality products (NO2, SO2, AOD, PM2.5 and PM10). For the Czech Republic inclusion of satellite data improved mapping of NO2 in rural areas and on an annual basis in urban background areas. It slightly improved mapping of rural and urban background SO2. The use of satellites based AOD or PM2.5 improved mapping results for PM2.5 and PM10. 4. A geostatistical downscaling algorithm for satellite-based air quality products was developed to bridge the gap towards urban-scale applications. Initial testing using synthetic data was followed by applying the algorithm to OMI NO2 data with a direct comparison against high-resolution TROPOMI NO2 as a reference, thus allowing for a quantitative assessment of the algorithm performance and demonstrating significant accuracy improvements after downscaling. We can conclude that SAMIRA demonstrated the added value of using satellite data for regional- and urban-scale air quality monitoring.
MDPI
2021
2016