ARCTIC NRT SERVICE 2002/2003
|Mirror sites also at Uni-Bremen and DLR Oberpfaffenhofen|
|H o m e||O v e r v i e w A r c h i v e|
NO2 concentrations in the
stratosphere are mainly determined by photolysis of NO2 itself and
the partitioning between NOx and the reservoir species, mainly N2O5,
HNO3 and ClONO2. As a result of decreased photolysis, most
of the NO2 is in its reservoirs in polar winter, and therefore NO2
concentrations are low. In addition to photolysis, temperature also plays an
important role, low temperatures leading to decreased NO2
For stratospheric chemistry, NO2 is a
key species as on one hand it acts as a catalyst in ozone destruction and on the
other hand is essential in forming the reservoir species ClONO2 and
BrONO2. Observation of NO2 can be used as an indicator of
denoxification in the arctic stratosphere, and in combination with other
measurements can also yield information on denitrification which is important in
determining the duration of chlorine activation.
The University of Bremen in co-operation with the University of Heidelberg has developed and validated an algorithm for the detection of the atmospheric NO2 absorption from GOME. The level 1 GOME data is transferred from the ESA satellite receiving stations to the University of Bremen where the daily spectral analysis of NO2 is carried out. The produced GOME NO2 maps show the so-called vertical column (VC) of NO2 for each single GOME measurement. The VC is the atmospheric NO2 concentration integrated from the surface to the top of the atmosphere. It therefore contains not only the stratospheric part, but also tropospheric NO2, mainly from pollution. The tropospheric contributions can usually be neglected in the polar regions, but are readily visible at mid-latitudes. In these regions, the NO2 columns shown should only be used in a qualitative sense as the GOME sensitivity to tropospheric absorbers is not fully corrected for in this analysis.
More information on the GOME NO2
products can be found in the following References
C., M. Wenig, T. Wagner, U. Platt, and B. Jähne, 2001: Quantitative analysis of
NOx emissions from GOME satellite image sequences, J.
Geophys. Res., 106, 5493–5505,
Richter, A., Kreher, K.,
Johnston, P. V., Wittrock, F., and J. P. Burrows, Validation of GOME O3,
NO2, BrO, and OClO Measurements in Southern High Latitudes, Fifth
European Workshop on Stratospheric Ozone, 1999
Richter, A. and J.P. Burrows,
Retrieval of Tropospheric NO2 from GOME Measurements, Adv.
Space Res., 29(11) ,1673-1683, 2002 .
Velders, G. J. M.; C.
Granier, R. W. Portmann, K. Pfeilsticker, M. Wenig, T. Wagner, U. Platt, A.
Richter, and J. P. Burrows, Global tropospheric NO2 column distributions:
Comparing 3-D model calculations with GOME measurements, JGR, D 106, 12643-12660,