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| Titel |
The nitrogen dioxide sonde |
| VerfasserIn |
Wesley Sluis, Marc Allaart, Ankie Piters, Lou Gast |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250052647
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| Zusammenfassung |
| Nitrogen dioxide is an important pollutant in the atmosphere, it is toxic for living species, it forms photochemical ozone (O3) , and acid rain in the form of nitric acid (HNO3). Nitrogen dioxide is a member of the nitrogen oxides (NO and NO2). In the troposphere they are typically formed as a by-product of the combustion of fossil fuels at high temperatures.
A growing number of space-born instruments measures nitrogen dioxide (NO2) concentrations in the troposphere, but validation of these instruments is hampered by the lack of ground-based and in situ profile measurements.
The Royal Netherlands Meteorological Institute (KNMI) has developed a working NO2 sonde. The sonde is attached to a small meteorological balloon and measures a tropospheric NO2 profile. The NO2 sonde has a vertical resolution of 5m and a measurement range between 1 and 100 ppbv. The instrument is light in weight (0.7 kg), cheap (disposable), energy efficient and not harmful to the environment or the person that finds the package after use. The sonde uses the chemiluminescent reaction of NO2 in an aqueous luminol solution. The NO2 – luminol reaction produces faint blue/purple light (at about 425 nm), which is detected by an array of silicon photodiodes. The luminol solution is optimised to be specific to NO2.
Sodium sulphate, sodium EDTA and Triton X-100 are added to the luminol solution to exclude ozone (O3) and PAN (peroxy acetyl nitrate) interference. The efficiency of the NO2 luminol reaction depends on the pH of the solution. To avoid acidification of the system by carbon dioxide, the chemicals are refreshed constantly. Furthermore, treating the luminol solution with clean air for an extended period before the measurement, makes the luminol-NO2 reaction more efficient.
An on-ground comparison with an in-situ NO2 monitor of The National Institute for Public Health and the Environment (RIVM), shows that both instruments measure similar NO2 variations in ambient air. In the summer of 2009, during the Cabauw Intercomparison of Nitrogen Dioxide measuring Instruments (CINDI) campaign and in the winter of 2010-2011, several NO2 sondes were launched, for which the results will be showed in this presentation. |
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