Rapid transport of East Asian pollution to the deep tropics
Rapid transport of East Asian pollution to the deep tropics
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DOI：
10.5194/acp-15-3565-2015
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发表时间：
2015-01-01
影响因子：
6.3
通讯作者：
Harris, N. R. P.
中科院分区：
文献类型：
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作者：
Ashfold, M. J.;Pyle, J. A.;Harris, N. R. P.
近几十年来，东亚的人为排放量有所增加。在盛行西风的影响下，这些增加导致远至北美的大气成分发生变化。在这里，我们表明，在北方半球（NH）的冬季，来自东亚的污染也直接影响大气成分在热带深处。我们目前的观察显着的季节内变化的人为示踪剂四氯乙烯（C2Cl 4）收集在婆罗洲的两个地点（117.84A度E，4.98A度N和118.00A度E，4.22A度N）在NH冬季的2008/2009。我们使用的轨迹计算的数值大气扩散模拟环境表明，所观察到的增强C2Cl 4混合比是由快速的对流输送，在“冷空气”的形式，从相对污染的东亚陆块。在这些事件中，气团可以在4天内从近似35 A度的N移动到婆罗洲。然后，我们提出的数据，从监测大气成分和气候再分析表明，空气质量高C2Cl 4也可能含有污染物一氧化碳和臭氧的水平，大约是两倍的典型的“背景”水平在婆罗洲。除了加强来自北方的对流输送外，寒潮还可以增强东南亚的对流，进一步的轨迹计算表明，污染空气团随后可以被提升到热带对流层上部。这表明中纬度污染源与极低平流层之间存在着潜在的重要联系。
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 (C2Cl4) collected at two locations in Borneo (117.84A degrees E, 4.98A degrees N and 118.00A degrees E, 4.22A degrees 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 C2Cl4 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 similar to 35A degrees 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 C2Cl4 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.