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| Titel |
SAGE III aerosol extinction validation in the Arctic winter: comparisons with SAGE II and POAM III |
| VerfasserIn |
L. W. Thomason, L. R. Poole, C. E. Randall |
| 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. 5 ; Nr. 7, no. 5 (2007-03-08), S.1423-1433 |
| Datensatznummer |
250004754
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| Publikation (Nr.) |
 copernicus.org/acp-7-1423-2007.pdf |
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| Zusammenfassung |
| The use of SAGE III multiwavelength aerosol extinction coefficient
measurements to infer PSC type is contingent on the robustness of both the
extinction magnitude and its spectral variation. Past validation with SAGE
II and other similar measurements has shown that the SAGE III extinction
coefficient measurements are reliable though the comparisons have been
greatly weighted toward measurements made at mid-latitudes. Some aerosol
comparisons made in the Arctic winter as a part of SOLVE II suggested that
SAGE III values, particularly at longer wavelengths, are too small with the
implication that both the magnitude and the wavelength dependence are not
reliable. Comparisons with POAM III have also suggested a similar
discrepancy. Herein, we use SAGE II data as a common standard for comparison
of SAGE III and POAM III measurements in the Arctic winters of 2002/2003
through 2004/2005. During the winter, SAGE II measurements are made
infrequently at the same latitudes as these instruments. We have mitigated
this problem through the use of potential vorticity as a spatial coordinate and
thus greatly increased of the number of coincident events. We find that SAGE II
and III extinction coefficient measurements show a high degree of
compatibility at both 1020 nm and 450 nm except a 10–20% bias at both
wavelengths. In addition, the 452 to 1020 nm extinction ratio shows a
consistent bias of ~30% throughout the lower stratosphere. We also
find that SAGE II and POAM III are on average consistent though the
comparisons show a much higher variability and larger bias than SAGE II/III
comparisons. In addition, we find that SAGE II and POAM III data sets are
not well correlated at and below 18 km. Overall, we find both the extinction
values and the spectral dependence from SAGE III are robust and we find no
evidence of a significant defect within the Arctic vortex. |
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