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| Titel |
Methane and nitrous oxide retrievals from MIPAS-ENVISAT |
| VerfasserIn |
J. Plieninger, T. Clarmann, G. P. Stiller, U. Grabowski, N. Glatthor, S. Kellmann, A. Linden, F. Haenel, M. Kiefer, M. Höpfner, A. Laeng, S. Lossow |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 11 ; Nr. 8, no. 11 (2015-11-05), S.4657-4670 |
| Datensatznummer |
250116676
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| Publikation (Nr.) |
 copernicus.org/amt-8-4657-2015.pdf |
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| Zusammenfassung |
| We present the strongly revised IMK/IAA MIPAS-ENVISAT
CH4 and N2O data products for the MIPAS full-resolution
(versions V5H_CH4_21 and V5H_N2O_21) and for the reduced-resolution
period (versions V5R_CH4_224, V5R_CH4_225, V5R_N2O_224 and
V5R_N2O_225). These data sets cover both MIPAS measurement periods
from June 2002 until March 2004 and from January 2005 to April 2012.
Differences with older retrieval versions which are known to have a high bias
are discussed. The usage of the HITRAN 2008 spectroscopic data set leads to
lower values for both gases in the lower part of the profile. The improved
correction of additive radiance offsets and handling of background radiance
continua allows for aerosol contributions at altitudes in the upper
stratosphere and above. These changes lead to more plausible values, both in
the radiance offset and in the profiles of the continuum absorption
coefficients. They also increase the fraction of converged retrievals. Some
minor changes were applied to the constraint of the inverse problem, causing
small differences in the retrieved profiles, mostly due to the relaxation of
off-diagonal regularisation matrix elements for the calculation of jointly
retrieved absorption coefficient profiles. Spectral microwindows have been
adjusted to avoid areas with saturated spectral signatures. Jointly
retrieving profiles of water vapour and nitric acid serves to compensate
spectroscopic inconsistencies. We discuss the averaging kernels of the
profiles and their vertical resolution. The latter ranges from 2.5 to
7 km for CH4, and from 2.5 to 6 km for N2O in
the reduced-resolution period. For the full-resolution period, the vertical
resolution is in the order of 3 to 6 km for both gases. We find the
retrieval errors in the lower part of the profiles mostly to be around
15 % for CH4 and below 10 % for N2O. The errors above
25 or 30 km increase to values between 10 and 20 %, except for
CH4 from the reduced-resolution period, where the estimated errors
stay below 15 %. |
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