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Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union

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Atmos. Meas. Tech., 9, 1485-1503, 2016
http://www.atmos-meas-tech.net/9/1485/2016/
doi:10.5194/amt-9-1485-2016
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
06 Apr 2016
Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements
Stefan Noël1, Klaus Bramstedt1, Michael Hilker1, Patricia Liebing1, Johannes Plieninger2, Max Reuter1, Alexei Rozanov1, Christopher E. Sioris3, Heinrich Bovensmann1, and John P. Burrows1 1Institute of Environmental Physics, University of Bremen, FB 1, P.O. Box 330440, 28334 Bremen, Germany
2KIT, IMK-ASF, P.O. Box 3640, 76021 Karlsruhe, Germany
3Centre for Research in Earth and Space Science, York University, 4700 Keele Street, Toronto, ON, M3J 1P3 Canada
Abstract. Stratospheric profiles of methane (CH4) and carbon dioxide (CO2) have been derived from solar occultation measurements of the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). The retrieval is performed using a method called onion peeling DOAS (ONPD), which combines an onion peeling approach with a weighting function DOAS (differential optical absorption spectroscopy) fit in the spectral region between 1559 and 1671 nm. By use of updated pointing information and optimisation of the data selection as well as of the retrieval approach, the altitude range for reasonable CH4 could be broadened from 20 to 40 km to about 17 to 45 km. Furthermore, the quality of the derived CO2 has been assessed such that now the first stratospheric profiles (17–45 km) of CO2 from SCIAMACHY are available. Comparisons with independent data sets yield an estimated accuracy of the new SCIAMACHY stratospheric profiles of about 5–10 % for CH4 and 2–3 % for CO2. The accuracy of the products is currently mainly restricted by the appearance of unexpected vertical oscillations in the derived profiles which need further investigation. Using the improved ONPD retrieval, CH4 and CO2 stratospheric data sets covering the whole SCIAMACHY time series (August 2002–April 2012) and the latitudinal range between about 50 and 70° N have been derived. Based on these time series, CH4 and CO2 trends have been estimated. CH4 trends above about 20 km are not significantly different from zero and the trend at 17 km is about 3 ppbv year−1. The derived CO2 trends show a general decrease with altitude with values of about 1.9 ppmv year−1 at 21 km and about 1.3 ppmv year−1 at 39 km. These results are in reasonable agreement with total column trends for these gases. This shows that the new SCIAMACHY data sets can provide valuable information about the stratosphere.

Citation: Noël, S., Bramstedt, K., Hilker, M., Liebing, P., Plieninger, J., Reuter, M., Rozanov, A., Sioris, C. E., Bovensmann, H., and Burrows, J. P.: Stratospheric CH4 and CO2 profiles derived from SCIAMACHY solar occultation measurements, Atmos. Meas. Tech., 9, 1485-1503, doi:10.5194/amt-9-1485-2016, 2016.
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Short summary
Stratospheric methane (CH4) and carbon dioxide (CO2) profiles have been derived from solar occultation measurements of the SCIAMACHY satellite instrument. The accuracy of these profiles is estimated to be about 5–10 % for CH4 and 2–3 % for CO2, mainly limited by unexpected vertical oscillations. Results are available for August 2002 to April 2012 and latitudes between about 50 and 70° N. From these, time series trends have been estimated, which are in reasonable agreement with total column trends.
Stratospheric methane (CH4) and carbon dioxide (CO2) profiles have been derived from solar...
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