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| Titel |
Tropospheric BrO column densities in the Arctic derived from satellite: retrieval and comparison to ground-based measurements |
| VerfasserIn |
H. Sihler, U. Platt, S. Beirle, T. Marbach, S. Kühl, S. Dörner, J. Verschaeve, U. Frieß, D. Pöhler, L. Vogel, R. Sander, T. Wagner |
| 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 ; 5, no. 11 ; Nr. 5, no. 11 (2012-11-16), S.2779-2807 |
| Datensatznummer |
250003175
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| Publikation (Nr.) |
 copernicus.org/amt-5-2779-2012.pdf |
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| Zusammenfassung |
| During polar spring, halogen radicals like bromine monoxide (BrO) play
an important role in the chemistry of tropospheric ozone
destruction. Satellite measurements of the BrO distribution have
become a particularly useful tool to investigate this probably natural
phenomenon, but the separation of stratospheric and tropospheric
partial columns of BrO is challenging. In this study, an algorithm was
developed to retrieve tropospheric vertical column densities of BrO
from data of high-resolution spectroscopic satellite instruments such
as the second Global Ozone Monitoring Experiment (GOME-2). Unlike
recently published approaches, the presented algorithm is capable of
separating the fraction of BrO in the activated troposphere from the
total BrO column solely based on remotely measured properties.
The presented algorithm furthermore allows to estimate a realistic
measurement error of the tropospheric BrO column.
The sensitivity of each satellite pixel to BrO in the boundary layer is
quantified using the measured UV radiance and the column density of
the oxygen collision complex O4. A comparison of the
sensitivities with CALIPSO LIDAR observations demonstrates that clouds
shielding near-surface trace-gas columns can be reliably detected even
over ice and snow. Retrieved tropospheric BrO columns are then
compared to ground-based BrO measurements from two Arctic field
campaigns in the Amundsen Gulf and at Barrow in 2008 and 2009,
respectively. Our algorithm was found to be capable of retrieving
enhanced near-surface BrO during both campaigns in good agreement with
ground-based data. Some differences between ground-based and satellite
measurements observed at Barrow can be explained by both elevated and
shallow surface layers of BrO. The observations strongly suggest that
surface release processes are the dominating source of BrO and that
boundary layer meteorology influences the vertical distribution. |
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