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| Titel |
Comparison of box-air-mass-factors and radiances for Multiple-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) geometries calculated from different UV/visible radiative transfer models |
| VerfasserIn |
T. Wagner, J. P. Burrows, T. Deutschmann, B. Dix, C. Friedeburg, U. Frieß, F. Hendrick, K.-P. Heue, H. Irie, H. Iwabuchi, Y. Kanaya, J. Keller, C. A. McLinden, H. Oetjen, E. Palazzi, A. Petritoli, U. Platt, O. Postylyakov, J. Puķīte, A. Richter, M. Roozendael, A. Rozanov, V. Rozanov, R. Sinreich, S. Sanghavi, F. Wittrock |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 7, no. 7 ; Nr. 7, no. 7 (2007-04-13), S.1809-1833 |
| Datensatznummer |
250004882
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| Publikation (Nr.) |
 copernicus.org/acp-7-1809-2007.pdf |
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| Zusammenfassung |
| The results of a comparison exercise of radiative transfer models (RTM) of
various international research groups for Multiple AXis Differential Optical
Absorption Spectroscopy (MAX-DOAS) viewing geometry are presented. Besides
the assessment of the agreement between the different models, a second focus
of the comparison was the systematic investigation of the sensitivity of the
MAX-DOAS technique under various viewing geometries and aerosol conditions.
In contrast to previous comparison exercises, box-air-mass-factors
(box-AMFs) for different atmospheric height layers were modelled, which
describe the sensitivity of the measurements as a function of altitude. In
addition, radiances were calculated allowing the identification of potential
errors, which might be overlooked if only AMFs are compared. Accurate
modelling of radiances is also a prerequisite for the correct interpretation
of satellite observations, for which the received radiance can strongly vary
across the large ground pixels, and might be also important for the
retrieval of aerosol properties as a future application of MAX-DOAS. The
comparison exercises included different wavelengths and atmospheric
scenarios (with and without aerosols). The strong and systematic influence
of aerosol scattering indicates that from MAX-DOAS observations also
information on atmospheric aerosols can be retrieved. During the various
iterations of the exercises, the results from all models showed a
substantial convergence, and the final data sets agreed for most cases
within about 5%. Larger deviations were found for cases with low
atmospheric optical depth, for which the photon path lengths along the line
of sight of the instrument can become very large. The differences occurred
between models including full spherical geometry and those using only plane
parallel approximation indicating that the correct treatment of the Earth's
sphericity becomes indispensable. The modelled box-AMFs constitute an
universal data base for the calculation of arbitrary (total) AMFs by simple
convolution with a given trace gas concentration profile. Together with the
modelled radiances and the specified settings for the various exercises,
they can serve as test cases for future RTM developments. |
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