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

Robinson, A. D.; Harris, Neil; Ashfold, Matthew J.; Gostlow, B.; Warwick, N. J.; O'Brien, L. M.; Beardmore, E. J.; Nadzir, Mohd Shahrul Mohd; Phang, Siew Moi; Samah, Azizan Abu; Ong, S.; Ung, H. E.; Peng, L. K.; Yong, S. E.; Mohamad, Maznorizan; Pyle, J. A.

doi:10.5194/acp-14-8369-2014

Cited by 19 publications

(12 citation statements)

References 81 publications

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“…The TWP, particularly during boreal winter, is a region of active convection and one of the most important pathways for compounds with short tropospheric lifetimes to reach the stratosphere (Aschmann et al, 2009;Bergman et al, 2012;Levine et al, 2007;Schofield et al, 2011). Consequently, the TWP and nearby Southeast Asia have been regions where a number of ground and ship-based campaigns have been conducted to study oceanic emissions of VSLS (Brinckmann et al, 2012;Mohd Nadzir et al, 2014;Robinson et al, 2014). Additionally, aircraft campaigns observed mixing ratios of VSLS in Southeast Asia that were slightly elevated with respect to measurements collected in the rest of the tropics (Sala et al, 2014;Wisher et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Stratospheric Injection of Brominated Very Short‐Lived Substances: Aircraft Observations in the Western Pacific and Representation in Global Models

et al. 2018

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We quantify the stratospheric injection of brominated very short‐lived substances (VSLS) based on aircraft observations acquired in winter 2014 above the Tropical Western Pacific during the CONvective TRansport of Active Species in the Tropics (CONTRAST) and the Airborne Tropical TRopopause EXperiment (ATTREX) campaigns. The overall contribution of VSLS to stratospheric bromine was determined to be 5.0 ± 2.1 ppt, in agreement with the 5 ± 3 ppt estimate provided in the 2014 World Meteorological Organization (WMO) Ozone Assessment report (WMO 2014), but with lower uncertainty. Measurements of organic bromine compounds, including VSLS, were analyzed using CFC‐11 as a reference stratospheric tracer. From this analysis, 2.9 ± 0.6 ppt of bromine enters the stratosphere via organic source gas injection of VSLS. This value is two times the mean bromine content of VSLS measured at the tropical tropopause, for regions outside of the Tropical Western Pacific, summarized in WMO 2014. A photochemical box model, constrained to CONTRAST observations, was used to estimate inorganic bromine from measurements of BrO collected by two instruments. The analysis indicates that 2.1 ± 2.1 ppt of bromine enters the stratosphere via inorganic product gas injection. We also examine the representation of brominated VSLS within 14 global models that participated in the Chemistry‐Climate Model Initiative. The representation of stratospheric bromine in these models generally lies within the range of our empirical estimate. Models that include explicit representations of VSLS compare better with bromine observations in the lower stratosphere than models that utilize longer‐lived chemicals as a surrogate for VSLS.

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Section: Introductionmentioning

confidence: 99%

Stratospheric Injection of Brominated Very Short‐Lived Substances: Aircraft Observations in the Western Pacific and Representation in Global Models

et al. 2018

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“…Tropical regions are highly important for atmospheric research, and whilst long-term atmospheric observations exist (Robinson et al, 2014;Pyle et al, 2011), there are fewer measurements than in the mid and high latitudes. The Bachok Marine Research Station (lat 6.00892, long.…”

Section: Introductionmentioning

confidence: 99%

Chemical characterisation of water-soluble ions in atmospheric particulate matter on the east coast of Peninsular Malaysia

et al. 2019

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Air quality on the east coast of Peninsular Malaysia is influenced by local anthropogenic and biogenic emissions as well as marine air masses from the South China Sea and aged emissions transported from highly polluted East Asian regions during the winter monsoon season. An atmospheric observation tower has been constructed on this coastline at the Bachok Marine Research Station. Daily PM 2.5 samples were collected from the top of the observation tower over a 3-week period, and ion chromatography was used to make time-resolved measurements of major atmospheric ions present in aerosol. SO 2− 4 was found to be the most dominant ion present and on average made up 66 % of the total ion content. Predictions of aerosol pH were made using the ISORROPIA II thermodynamic model, and it was estimated that the aerosol was highly acidic, with pH values ranging from −0.97 to 1.12. A clear difference in aerosol composition was found between continental air masses originating from industrialised regions of East Asia and marine air masses predominantly influenced by the South China Sea. For example, elevated SO 2− 4 concentrations and increased Cl − depletion were observed when continental air masses that had passed over highly industrialised regions of East Asia arrived at the measurement site. Correlation analyses of the ionic species and assessment of ratios between different ions provided an insight into common sources and formation pathways of key atmospheric ions, such as SO 2− 4 , NH + 4 and C 2 O 2− 4 . To our knowledge, time-resolved measurements of water-soluble ions in PM 2.5 are virtually non-existent in rural locations on the east coast of Peninsular Malaysia. Overall this dataset contributes towards a better understanding of atmospheric composition in the Maritime Continent, a region of the tropics that is vulnerable to the effects of poor air quality, largely as a result of rapid industrialisation in East Asia.

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“…Figure 1 shows that there are some differences in the absolute mixing ratio observed at the two sites. Instrument performance is generally good for this compound (Gostlow et al, 2010) although Robinson et al (2014) have raised the possibility of calibration uncertainty leading to part of this difference. In this study we focus on the variations observed concurrently at both locations, and hence the absolute mixing ratios are of lesser importance.…”

Section: Observationsmentioning

confidence: 99%

“…The number of 3 h periods, n, contributing to each composite is noted above each panel. A mixing ratio greater than 2.4 ppt was observed in eleven 3 h windows; these periods are not accounted for in the figure. this gap, we have used University of Cambridge µ-Dirac instruments (Gostlow et al, 2010) to measure a suite of halocarbons at a number of sites in the region (see Pyle et al, 2011;Robinson et al, 2014). Here we focus on C 2 Cl 4 observations collected at two locations in Sabah, Malaysian Borneo.…”

Section: Observationsmentioning

confidence: 99%

Rapid transport of East Asian pollution to the deep tropics

et al. 2015

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Abstract. Anthropogenic emissions from East Asia have increased over recent decades. These increases have led to changes in atmospheric composition as far afield as North America under the prevailing westerly winds. Here we show that, during Northern Hemisphere (NH) winter, pollution originating in East Asia also directly affects atmospheric composition in the deep tropics. We present observations of marked intra-seasonal variability in the anthropogenic tracer perchloroethene (C 2 Cl 4 ) collected at two locations in Borneo (117.84 • E, 4.98 • N and 118.00 • E, 4.22 • N) during the NH winter of 2008/2009. We use trajectories calculated with the Numerical Atmospheric-dispersion Modelling Environment to show that the observed enhancements in C 2 Cl 4 mixing ratio are caused by rapid meridional transport, in the form of "cold surges", from the relatively polluted East Asian land mass. In these events air masses can move from ∼35 • N to Borneo in 4 days. We then present data from the Monitoring Atmospheric Composition and Climate reanalysis which suggest that air masses high in C 2 Cl 4 may also contain levels of the pollutants carbon monoxide and ozone that are approximately double the typical "background" levels in Borneo. In addition to strengthening the meridional transport from the north, cold surges can enhance convection in Southeast Asia, and further trajectory calculations indicate that the polluted air masses can subsequently be lifted to the tropical upper troposphere. This suggests a potentially important connection between midlatitude pollution sources and the very low stratosphere.

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

Cited by 19 publications

References 81 publications

Stratospheric Injection of Brominated Very Short‐Lived Substances: Aircraft Observations in the Western Pacific and Representation in Global Models

Stratospheric Injection of Brominated Very Short‐Lived Substances: Aircraft Observations in the Western Pacific and Representation in Global Models

Chemical characterisation of water-soluble ions in atmospheric particulate matter on the east coast of Peninsular Malaysia

Rapid transport of East Asian pollution to the deep tropics

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