Description: Das Projekt "Experimentelle Bestimmung der Bildungsrate von O (1D) und OH in der Troposhaere durch Ozonphotolyse aufgrund der Sonneneinstrahlung" wird vom Umweltbundesamt gefördert und von Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre durchgeführt. The oxidizing capacity of the troposphere is mainly determined by the concentration of hydroxyl radicals (OH). These are primarily formed by the reaction of O(1D) atoms with water vapour. The O(1D) atoms are produced by the photolysis of ambient ozone with solar radiation in the spectral range of UV-B. Thus, any change of solar UV-radiation has a major impact on the global oxidation potential of the atmosphere. At present, there is a great deficiency of experimental field data on the rate coefficient J(O1D) for the O3 photolysis forming O(1D) atoms. Furthermore, there is a lack of accurate J(O1D) measurement techniques for field experiments. Laboratory work will be carried out to reinvestigate the parameters of two crucial photochemical gas phase reactions which limit the accuracy of experimental and theoretical J(O1D) determinations. First, the O(1D) quantum yield will be determined as a function of wavelength with high spectral resolution and for various temperatures over the pertinent range of tropospheric and stratospheric conditions. Second, the branching ratio of the reaction of O(1D) with N2O will be reinvestigated in laser experiments. Field measurements will be carried out in order to intercompare three different techniques to measure J(O1D) in the field: the chemical actinometry (direct chemical determination of the O(1D) formation, based on the reaction of O(1D) with N2O), actinic filter radiometer (measurement of the spectrally integrated solar actinic flux) and actinic spectroradiometer (measurement of the spectrally resolved solar actinic flux). Furthermore, J(O1D), O3 and H2O will be measured continuously in the field in order to establish a dataset on the diurnal and seasonal variations of the O(1D) and OH production rates at 50 degree N. Its relationship to concurrently observed parameters, such as atmospheric aerosol or clouds, will be investigated and compared with theoretical J(O1D) predictions from radiation flux models.
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Wolkenbildung ? Jülich ? Bewölkung ? Ozon ? Messgerät ? Lack ? Atmosphärisches Aerosol ? Laser ? Solarstrahlung ? Wasserdampf ? UV-Strahlung ? Aerosol ? Lachgas ? Filter ? Messtechnik ? Photolyse ? Radiometrie ? Solartechnik ? Gasförmiger Stoff ? Messverfahren ? Redoxpotential ? Daten ? Strahlungsmodell ? Troposphäre ? Chemikalien ? Jahreszeit ? Bestimmungsgrenze ? Kenngröße ? Umweltveränderung ? Atmosphäre ? Forschungseinrichtung ? Globale Aspekte ? Freilandversuch ? Geosphäre ? Radikal [Chemie] ?
Region: Nordrhein-Westfalen
Bounding boxes: 6.76339° .. 6.76339° x 51.21895° .. 51.21895°
License: cc-by-nc-nd/4.0
Language: Deutsch
Time ranges: 1992-07-01 - 1994-06-30
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