Observations of bromine monoxide transport in the Arctic sustained on aerosol particles
Observations of bromine monoxide transport in the Arctic sustained on aerosol particles
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DOI：
10.5194/acp-17-7567-2017
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发表时间：
2017-06
影响因子：
6.3
通讯作者：
P. Peterson;D. Pöhler;H. Sihler;J. Zielcke;S. General;U. Friess;U. Platt;W. Simpson;S. Nghiem;P. Shepson;B. Stirm;S. Dhaniyala;T. Wagner;D. Caulton;J. Fuentes;K. Pratt
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文献类型：
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作者：
P. Peterson;D. Pöhler;H. Sihler;J. Zielcke;S. General;U. Friess;U. Platt;W. Simpson;S. Nghiem;P. Shepson;B. Stirm;S. Dhaniyala;T. Wagner;D. Caulton;J. Fuentes;K. Pratt
抽象的。极地春季阳光的回归导致地表积雪产生活性卤素物质，显著改变了北极近地表大气的化学成分和远距离迁移的污染物（包括汞）的命运。最近的工作表明，在北极表面积雪的活性溴的初始生产，但是，我们有有限的知识，这种化学的垂直范围，以及寿命和可能的运输活性溴高空。在这里，我们提出了一氧化溴（BrO）和气溶胶粒子的测量过程中获得的2012年3月BRomine臭氧汞实验（BROMEX）Utqiavik（巴罗），AK。机载差分光学吸收光谱（DOAS）测量提供了前所未有的空间分辨率水平，超过2个数量级以上的卫星观测和垂直分辨率无法实现的卫星方法，在北极的溴O。这种新的方法提供了定量识别的溴烟羽，在500米和1公里的高空，移动的空气质量的速度。同时气溶胶粒子的测量表明，这loft活性溴羽通过同位超微粒气溶胶粒子的非均相反应，独立的表面积雪溴化学运输和维持在较高的水平。这种化学传输机制解释了经常观察到的反应性溴化学的大空间范围，这影响了整个北极地区的大气成分和污染物的命运，超出了最初的积雪卤素生产领域。BrO增强断开与表面的可能性可能有助于维持BrO在自由对流层，也必须考虑在卫星BrO柱观测的解释，特别是在迅速变化的北极海冰和积雪的背景下。
Abstract. The return of sunlight in the polar spring leads to the production of reactive halogen species from the surface snowpack, significantly altering the chemical composition of the Arctic near-surface atmosphere and the fate of long-range transported pollutants, including mercury. Recent work has shown the initial production of reactive bromine at the Arctic surface snowpack; however, we have limited knowledge of the vertical extent of this chemistry, as well as the lifetime and possible transport of reactive bromine aloft. Here, we present bromine monoxide (BrO) and aerosol particle measurements obtained during the March 2012 BRomine Ozone Mercury EXperiment (BROMEX) near Utqiaġvik (Barrow), AK. The airborne differential optical absorption spectroscopy (DOAS) measurements provided an unprecedented level of spatial resolution, over 2 orders of magnitude greater than satellite observations and with vertical resolution unable to be achieved by satellite methods, for BrO in the Arctic. This novel method provided quantitative identification of a BrO plume, between 500 m and 1 km aloft, moving at the speed of the air mass. Concurrent aerosol particle measurements suggest that this lofted reactive bromine plume was transported and maintained at elevated levels through heterogeneous reactions on colocated supermicron aerosol particles, independent of surface snowpack bromine chemistry. This chemical transport mechanism explains the large spatial extents often observed for reactive bromine chemistry, which impacts atmospheric composition and pollutant fate across the Arctic region, beyond areas of initial snowpack halogen production. The possibility of BrO enhancements disconnected from the surface potentially contributes to sustaining BrO in the free troposphere and must also be considered in the interpretation of satellite BrO column observations, particularly in the context of the rapidly changing Arctic sea ice and snowpack.