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| Titel |
Determination of aerosol properties from MAX-DOAS observations of the Ring effect |
| VerfasserIn |
T. Wagner, T. Deutschmann, U. Platt |
| 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 ; 2, no. 2 ; Nr. 2, no. 2 (2009-09-04), S.495-512 |
| Datensatznummer |
250000564
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| Publikation (Nr.) |
 copernicus.org/amt-2-495-2009.pdf |
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| Zusammenfassung |
| The first quantitative comparison of MAX-DOAS observations of the Ring
effect with model simulations is presented. It is performed for a large
variety of viewing geometries (solar zenith angles: 45° to 90°,
elevation angles: 3°, 6°, 10°, 18°, 90°; three different
azimuth angles), which allows a comprehensive test of our capabilities to
measure and simulate the Ring effect. In addition to the Ring effect, also
the observed O4 absorptions (optical densities) and radiances are
compared with model simulations. In general good agreement is found for all
measured quantities. From several sensitivity studies it is found that for
most measurement situations, the aerosol optical depth has usually the
strongest influence on the observed quantities, but also other aerosol
properties like e.g. the vertical distribution have a significant effect. In
some aspects, the qualitative dependence of the Ring effect on aerosol
properties is similar to that of the O4 absorption. This can be
understood, since both quantities depend strongly on the light path length
in the lower atmosphere. However, since the Ring effect depends also on the
properties of the scattering processes, in specific cases observation of the
Ring effect can provide complementary information to that retrieved from the
O4 observations. This is e.g. possible for measurements at small
relative azimuth angles, from which information on the aerosol phase
function can be derived. Observations at large solar zenith angle might
allow the retrieval of stratospheric aerosol properties, even in cases with
very low aerosol optical depths. In addition, Ring effect observations in
zenith direction are rather sensitive to the aerosol optical depth (in
contrast to O4 observations), which might allow to retrieve information
on aerosol properties from existing zenith UV data sets prior to the
MAX-DOAS era. |
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