Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo

A. D. Robinson, N. R P Harris, M. J. Ashfold, B. Gostlow, N. J. Warwick, L. M. O'Brien, E. J. Beardmore, Mohd Shahrul Mohd Nadzir, S. M. Phang, A. A. Samah, S. Ong, H. E. Ung, L. K. Peng, S. E. Yong, M. Mohamad, J. A. Pyle

Research output: Contribution to journalArticle

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Abstract

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 C 2Cl4, CHBr3, CH2Br 2* (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, CH 2Br2* 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.

Original languageEnglish
Pages (from-to)8369-8388
Number of pages20
JournalAtmospheric Chemistry and Physics
Volume14
Issue number16
DOIs
Publication statusPublished - 21 Aug 2014

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halocarbon
annual cycle
coast
bromine
rainforest
Southern Hemisphere
stratosphere
Northern Hemisphere
electron
winter
summer
gas
Southeast Asia

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Robinson, A. D., Harris, N. R. P., Ashfold, M. J., Gostlow, B., Warwick, N. J., O'Brien, L. M., ... Pyle, J. A. (2014). Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo. Atmospheric Chemistry and Physics, 14(16), 8369-8388. https://doi.org/10.5194/acp-14-8369-2014

Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo. / Robinson, A. D.; Harris, N. R P; Ashfold, M. J.; Gostlow, B.; Warwick, N. J.; O'Brien, L. M.; Beardmore, E. J.; Mohd Nadzir, Mohd Shahrul; Phang, S. M.; Samah, A. A.; Ong, S.; Ung, H. E.; Peng, L. K.; Yong, S. E.; Mohamad, M.; Pyle, J. A.

In: Atmospheric Chemistry and Physics, Vol. 14, No. 16, 21.08.2014, p. 8369-8388.

Research output: Contribution to journalArticle

Robinson, AD, Harris, NRP, Ashfold, MJ, Gostlow, B, Warwick, NJ, O'Brien, LM, Beardmore, EJ, Mohd Nadzir, MS, Phang, SM, Samah, AA, Ong, S, Ung, HE, Peng, LK, Yong, SE, Mohamad, M & Pyle, JA 2014, 'Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo', Atmospheric Chemistry and Physics, vol. 14, no. 16, pp. 8369-8388. https://doi.org/10.5194/acp-14-8369-2014
Robinson AD, Harris NRP, Ashfold MJ, Gostlow B, Warwick NJ, O'Brien LM et al. Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo. Atmospheric Chemistry and Physics. 2014 Aug 21;14(16):8369-8388. https://doi.org/10.5194/acp-14-8369-2014
Robinson, A. D. ; Harris, N. R P ; Ashfold, M. J. ; Gostlow, B. ; Warwick, N. J. ; O'Brien, L. M. ; Beardmore, E. J. ; Mohd Nadzir, Mohd Shahrul ; Phang, S. M. ; Samah, A. A. ; Ong, S. ; Ung, H. E. ; Peng, L. K. ; Yong, S. E. ; Mohamad, M. ; Pyle, J. A. / Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo. In: Atmospheric Chemistry and Physics. 2014 ; Vol. 14, No. 16. pp. 8369-8388.
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T1 - Long-term halocarbon observations from a coastal and an inland site in Sabah, Malaysian Borneo

AU - Robinson, A. D.

AU - Harris, N. R P

AU - Ashfold, M. J.

AU - Gostlow, B.

AU - Warwick, N. J.

AU - O'Brien, L. M.

AU - Beardmore, E. J.

AU - Mohd Nadzir, Mohd Shahrul

AU - Phang, S. M.

AU - Samah, A. A.

AU - Ong, S.

AU - Ung, H. E.

AU - Peng, L. K.

AU - Yong, S. E.

AU - Mohamad, M.

AU - Pyle, J. A.

PY - 2014/8/21

Y1 - 2014/8/21

N2 - 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 C 2Cl4, CHBr3, CH2Br 2* (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, CH 2Br2* 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.

AB - 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 C 2Cl4, CHBr3, CH2Br 2* (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, CH 2Br2* 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.

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