 |
| Titel |
Very short-lived bromomethanes measured by the CARIBIC observatory over the North Atlantic, Africa and Southeast Asia during 2009–2013 |
| VerfasserIn |
A. Wisher, D. E. Oram, J. C. Laube, G. P. Mills, P. van Velthoven, A. Zahn, C. A. M. Brenninkmeijer |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 7 ; Nr. 14, no. 7 (2014-04-08), S.3557-3570 |
| Datensatznummer |
250118574
|
| Publikation (Nr.) |
 copernicus.org/acp-14-3557-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
Short-lived organic brominated compounds make up a significant part of the
organic bromine budget in the atmosphere. Emissions of these compounds are
highly variable and there are limited measurements, particularly in the
extra-tropical upper troposphere/lower stratosphere and tropical troposphere.
Measurements of five very short-lived bromomethanes (VSLB) were made in air
samples collected on the CARIBIC project aircraft over three flight routes;
Germany to Venezuela/Columbia during 2009–2011, Germany to South Africa
during 2010 and 2011 and Germany to Thailand/Kuala Lumpur, Malaysia during
2012 and 2013.
In the tropical troposphere, as the most important entrance region to the
stratosphere, we observe a total mean organic bromine derived from these
compounds across all flights at 10–12 km altitude of 3.4 ± 1.5 ppt.
Individual mean tropical tropospheric mixing ratios across all flights were
0.43, 0.74, 0.14, 0.23 and 0.11 ppt for CHBr3, CH2Br2,
CHBr2Cl, CHBrCl2 and CH2BrCl respectively. The
highest levels of VSLB-derived bromine (4.20 ± 0.56 ppt) were observed
in flights between Bangkok and Kuala Lumpur indicating that the South China
Sea is an important source region for these compounds. Across all routes,
CHBr3 and CH2Br2 accounted for 34% (4.7–71) and
48% (14–73) respectively of total bromine derived from the analysed
VSLB in the tropical mid-upper troposphere totalling 82% (54–89).
In samples collected between Germany and Venezuela/Columbia, we find
decreasing mean mixing ratios with increasing potential temperature in the
extra-tropics. Tropical mean mixing ratios are higher than extra-tropical
values between 340–350 K indicating that rapid uplift is important in
determining mixing ratios in the lower tropical tropopause layer in the West
Atlantic tropics.
O3 was used as a tracer for stratospherically influenced air and we
detect rapidly decreasing mixing ratios for all VSLB above ∼100 ppb
O3 corresponding to the extra-tropical tropopause layer. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|