University of Bremen IUP DOAS

Research

Navigate

Stratospheric NO₂ from SCIAMACHY measurements   

Introduction    Data   References    Links    Contact

Introduction:

In the stratosphere, nitrogen dioxide acts both as an ozone destroying substance (through the catalytic NOx cycle) and as a buffer against halogen catalysed ozone loss (through formation of chlorine and bromine nitrates). In particular in the southern hemisphere, sedimentation of polar stratospheric clouds (PSC) can remove nitrogen from the stratosphere (denitrification) and delay ozone recovery in spring. 

The main source of nitrogen oxides in the stratosphere is N₂O from soil emissions. The diurnal, seasonal, and latitudinal variation of NO₂ is dominated by the equilibrium between NO_x (NO₂ + NO) on one hand and the reservoir substances (mainly N₂O₅, HNO₃, ClONO₂) on the other hand. This is driven by photolysis of NO₂ and the reservoirs, thermal decomposition of N₂O₅ and hydrolysis of N₂O₅ to HNO₃ on sulphate aerosols and PSC. The latter explains the observed impact of large volcanic eruptions such as Pinatubo on stratospheric NO₂ levels.

As from GOME measurements, NO₂ columns can be retrieved from SCIAMACHY spectra with high accuracy in the 425-450 nm region using the DOAS method. In contrast to tropospheric NO₂ retrieval, the airmass factors for stratospheric NO₂ do not depend critically on surface albedo, cloud cover or vertical distribution. However, in the presence of strong tropospheric pollution, the column observed by the satellite is enhanced by the tropospheric contribution, and at high sun (mid and low latitudes) the stratospheric NO₂ column is overestimated.

As an example, the plot shows stratospheric NO₂ above the southern hemisphere as derived from SCIAMACHY nadir measurements in January and August 2004. The large change in stratospheric NO2 column is apparent which is the result of both the change in illumination and denoxification and denitrification within the polar vortex..

Stratospheric NO₂ columns are also part of the SCIAMACHY lv2-products provided by ESA/DLR. The offline scientific data products provided here are based on the same raw measurements but have been retrieved using independent algorithms developed at the IUP Bremen. Comparisons show, that the agreement good, in some areas of the world even excellent, but significant differences exist over other areas and also with respect to overall data consistency.

Data:

Stratospheric NO₂ columns from SCIAMACHY nadir measurements are available from August 2002 onwards. Currently, the analysis is based on a rather limited set of both uncalibrated and calibrated data that have been released by ESA, and therefore has to be considered as preliminary.

Images of daily, monthly, and annual averages of stratospheric NO₂ can be viewed on our SCIAMACHY data browser page.

Data files with daily SCIAMACHY NO₂ columns over selected stations can be found in our data archive.

 If you have any requests, please contact Andreas Richter.

References:

• R. Sussmann, W. Stremme, J. P. Burrows, A. Richter, W. Seiler, M. Rettinger, Stratospheric and tropospheric NO₂ variability on the diurnal and annual scale: a combined retrieval from ENVISAT/SCIAMACHY and solar FTIR at the Permanent Ground-Truthing Facility Zugspitze/Garmisch, Atmos. Chem. Phys., 5,  2657-2677, 2005

• Richter, A., F. Wittrock, M. Weber, S. Beirle, S. Kühl, U. Platt, T. Wagner, W. Wilms-Grabe, and J. P. Burrows, GOME observations of stratospheric trace gas distributions during the splitting vortex event in the Antarctic winter 2002 Part I: Measurements, J. Atmos. Sci., 62 (3), 778-785, 2005

• Richter, A., Burrows, J. P., Fietkau, S., Medeke, T., Notholt, J., Oetjen, H., Sierk, B., Warneke, T., Wittrock, F., Dix, B., Friess, U., Wagner, T., Blumenstock, T., Griesfeller, A., Sussmann, R., Rockmann, A., and Schulz, A.: A scientific NO₂ product from SCIAMACHY: First results and validation, Proceedings of the Second Workshop on the Atmospheric Chemistry Validation of ENVISAT (ACVE-2) ESA-ESRIN, Frascati, Italy, 3-7 May 2004 (ESA SP-562, August 2004) EPOSCAR, 2004

• First NO2 Results from SCIAMACHY UV/vis Nadir Measurements, A. Richter et al., 2nd International DOAS Workshop Heidelberg, September 2003

• First Results from SCIAMACHY UV/vis Nadir Measurements, A. Richter et al., DPG Frühjahrstagung, March 2003

Links:

• You might want to check our GOME NO2 page.

• There also are tropospheric NO2 columns from SCIAMACHY available.

• More information on SCIAMACHY can be found here.

• Stratospheric NO2 profiles retrieved from SCIAMACHY limb measurements can be found on the IUP Bremen SCIAMACHY data archive.

• Many SCIAMACHY related links can be found on the German SCIAMACHY page.

•  For information on the satellite and other ENVISAT instruments check the ESA ENVISAT page.

Contact:

If you are interested in more information or SCIAMACHY NO₂ data, please contact Andreas Richter.

web master:  folkard@iup.physik.uni-bremen.de      Last Update: 25-05-18      Data Privacy