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| Titel |
Constraints on JN2O5 from balloon-borne limb scanning measurements of NO2 in the tropics |
| VerfasserIn |
Lena Kritten, André Butz, Tim Deutschmann, Marcel Dorf, Sebastian Kreycy, Cristina Prados-Roman, Klaus Pfeilsticker |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040092
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| Zusammenfassung |
| The NOx ozone cycle (NOx = NO + NO2) is of great importance for the budget of
stratospheric ozone and in future may even become more important due to increasing
stratospheric N2O concentrations (Ravishankara et al., 2009). A regulating process for the
amount of stratospheric NOx and thus for the efficiency of the NOx mediated ozone loss
cycle is photolytic release of N2O5 at daytime since N2O5 acts as a nighttime reservoir gas
for stratospheric NOx radicals.
Observations of UV/vis scattered skylight by balloon-borne limb scanning spectrometry
support the detection of time dependent trace gas and radical profiles, in particular of NO2.
Here we present balloon borne measurements of time dependent NO2 profiles from the
tropical stratosphere - taken at north-eastern Brazil (5° S, 43° W) in June 2005 - where excess
stratospheric ozone is produced and transported to higher latitudes by the Brewer-Dobson
circulation.
The photolysis rate of N2O5 – uncertain by a factor of 2 (JPL-2006) - is constrained from the
comparison of the measured and modelled diurnal variation of NO2. For the photochemical
model initial conditions are based on our own observations of O3 and NO2, MIPAS-B
measurements and on output of the 3-D SLIMCAT model. The kinetic and thermodynamic
parameters and absorption cross-sections are taken from the JPL-2006 compilation (Sander
et. al, 2006). Overall it is found that, the observed rate of diurnal NO2 increase requires a
N2O5 photolysis frequency at the upper limit of values possible according to the uncertainty
range given by the JPL-2006 compilation. In conclusion it suggested that the NOx
mediated ozone loss in the tropical stratosphere is probably larger than assumed
by many photochemical models, and in future may even relatively become more
important. |
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