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| Titel |
Retrieval of stratospheric and tropospheric BrO columns from multi-axis DOAS measurements at Reunion Island (21° S, 56° E) |
| VerfasserIn |
N. Theys, M. Roozendael, F. Hendrick, C. Fayt, C. Hermans, J.-L. Baray, F. Goutail, J.-P. Pommereau, M. Mazière |
| 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. 18 ; Nr. 7, no. 18 (2007-09-18), S.4733-4749 |
| Datensatznummer |
250005194
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| Publikation (Nr.) |
 copernicus.org/acp-7-4733-2007.pdf |
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| Zusammenfassung |
| Spectral measurements of BrO using zenith-sky and off-axis viewing
geometries are combined in a linear multiple regression retrieval algorithm
to provide stratospheric and tropospheric BrO vertical columns. One year of
measurement data are investigated over Reunion-Island (20.9° S, 55.5° E),
from August 2004 to June 2005. A comparison between the stratospheric
columns retrieved at 45°, 80°, 85°, 87.5° and
92.5°
solar zenith angles and photochemical simulations initialized by chemical
fields from the 3-D-CTM SLIMCAT and further constrained by observed NO2
profiles shows a good agreement only by considering a contribution from the
very short-lived organic bromine substances to the stratospheric inorganic
bromine budget, of 6 to 8 pptv. Furthermore, stratospheric BrO profiles
retrieved from late twilight zenith-sky observations are consistent with a
total inorganic bromine (Bry) loading of approximately 23 pptv. This
represents 6 to 7 pptv more than can be supplied by long-lived organic
bromine sources, and therefore supports an added contribution from very
short-lived organic bromine substances as recently suggested in several
other studies. Moreover strong evidences are presented for the existence of
a substantial amount of BrO in the tropical free-troposphere, around 6 km
altitude, possibly supplied by the decomposition of short-lived biogenic
bromine organic compounds. Tropospheric BrO vertical columns of
1.1±0.45×1013 molec/cm² are derived for the entire observation
period. Comparisons between ground-based BrO vertical columns and total BrO
columns derived from SCIAMACHY (onboard the ENVISAT satellite) nadir
observations in a latitudinal band centered around 21° S present a good
level of consistency, which further strengthens the conclusions of our
study. |
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