 |
| Titel |
Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo |
| VerfasserIn |
A. D. Robinson, N. R. P. Harris, M. J. Ashfold, B. Gostlow, N. J. Warwick, L. M. O'Brien, E. J. Beardmore, M. S. M. Nadzir, S. M. Phang, A. A. Samah, S. Ong, H. E. Ung, L. K. Peng, S. E. Yong, M. Mohamad, J. A. Pyle |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 16 ; Nr. 14, no. 16 (2014-08-21), S.8369-8388 |
| Datensatznummer |
250118960
|
| Publikation (Nr.) |
 copernicus.org/acp-14-8369-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Short-lived halocarbons are believed to have important sources in the
tropics, where rapid vertical transport could provide a significant source to the
stratosphere. In this study, quasi-continuous measurements of short-lived
halocarbons are reported for two tropical sites in Sabah (Malaysian Borneo),
one coastal and one inland (rainforest). We present the observations for
C2Cl4, CHBr3, CH2Br2* (actually
~80% CH2Br2 and ~20% CHBrCl2) and
CH3I from November 2008 to January 2010 made using our μDirac gas
chromatographs with electron capture detection (GC-ECD). We focus on the
first 15 months of observations, showing over one annual cycle for each
compound and therefore adding significantly to the few limited-duration
observational studies that have been conducted thus far in southeast Asia.
The main feature in the C2Cl4 behaviour at both sites is its annual
cycle, with the winter months being influenced by northerly flow with higher
concentrations, typical of the Northern Hemisphere, and with the summer months
influenced by southerly flow and lower concentrations representative of the
Southern Hemisphere. No such clear annual cycle is seen for CHBr3,
CH2Br2* or CH3I. The baseline values for CHBr3 and
CH2Br2* are similar at the coastal (overall median:
CHBr3 1.7 ppt, CH2Br2* 1.4 ppt) and inland sites
(CHBr3 1.6 ppt, CH2Br2* 1.1 ppt), but periods with
elevated values are seen at the coast (overall 95th percentile: CHBr3
4.4 ppt, CH2Br2ast 1.9 ppt), presumably resulting from the
stronger influence of coastal emissions. Overall median bromine values from
[CHBr3 × 3] + [CH2Br2* × 2] are
8.0 ppt at the coast and 6.8 ppt inland. The median values reported here
are largely consistent with other limited tropical data and imply that
southeast Asia generally is not, as has been suggested, a hot spot for
emissions of these compounds. These baseline values are consistent with the
most recent emissions found for southeast Asia using the p-TOMCAT (Toulouse Off-line Model of Chemistry And Transport) model.
CH3I, which is only observed at the coastal site, is the shortest-lived
compound measured in this study, and the observed atmospheric variations
reflect this, with high variability throughout the study period. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|