Atmospheric transport of persistent semi-volatile organic chemicals to the Arctic and cold condensation in the mid-troposphere – Part 2: 3-D modeling of episodic atmospheric transport
Atmospheric transport of persistent semi-volatile organic chemicals to the Arctic and cold condensation in the mid-troposphere – Part 2: 3-D modeling of episodic atmospheric transport
复制标题
DOI：
10.5194/acp-10-7315-2010
复制
发表时间：
2009-12
影响因子：
6.3
通讯作者：
Liangpei Zhang;J. Ma;C. Tian;Yi-Fan Li;H. Hung
中科院分区：
文献类型：
--
作者：
Liangpei Zhang;J. Ma;C. Tian;Yi-Fan Li;H. Hung
抽象的。利用两个三维全球持久性有机污染物（POPs）大气传输模式，研究了大尺度大气运动与持久性半挥发性有机物（SVOCs）向极向传输的关系。我们研究了从1997年到1999年的一段时间内，在这个模拟研究中检测到了一些情节性的大气传输事件的α-和γ-六氯环己烷（HCH）的模拟每日空气浓度。这些事件为改进对流层中层SVOCs的冷凝结效应和向极地大气输送的解释提供了模拟依据。本文报道了两次γ-HCH（林丹）向北极高纬度地区（80-90° N）的幕式输送事件，一次来自亚洲，另一次来自欧亚大陆。这两个事件表明，发生在对流层中部（例如，从3000米到5500米的高度）的情景大气输送是由大气水平和垂直运动驱动的。简要讨论了输送事件与大气环流的关系。北方半球中高纬地区两个半永久性高压系统的演变所产生的强南风，在六氯环己烷从源头向高纬度地区的远距离迁移过程中发挥了重要作用。与本文第一部分报道的二维大气输送模式模拟的平均纬向大气环流中的冷凝结效应和向极输送相一致，这一模拟研究表明，冷凝结可能发生在中期，在对流层中，空气温度迅速下降，导致化学品在其来源区域上方和附近出现凝结相，并且强风将化学品更多地输送到对流层在向极地的大气输送事件中迅速向极地地区输送。
Abstract. Two 3-dimensional global atmospheric transport models for persistent organic pollutants (POPs) have been employed to investigate the association between the large-scale atmospheric motions and poleward transports of persistent semi-volatile organic chemicals (SVOCs). We examine the modeled daily air concentration of α- and γ-hexachlorocyclohexane (HCH) over a period from 1997 through 1999 during which a number of episodic atmospheric transport events were detected in this modeling study. These events provide modeling evidence for improving the interpretation on the cold condensation effect and poleward atmospheric transport of SVOCs in the mid-troposphere. Two episodic transport events of γ-HCH (lindane) to the high Arctic (80–90° N), one from Asian and another from Eurasian sources, are reported in this paper. Both events suggest that the episodic atmospheric transports occurring in the mid-troposphere (e.g. from 3000 m to 5500 m height) are driven by atmospheric horizontal and vertical motions. The association of the transport events with atmospheric circulation is briefly discussed. Strong southerly winds, forced by the evolution of two semi-permanent high pressure systems over mid-high latitudes in the Northern Hemisphere, play an important role in the long-range transport (LRT) of HCHs to the high latitudes from its sources. Being consistent with the cold condensation effect and poleward atmospheric transport in a mean meridional atmospheric circulation simulated by a 2-D atmospheric transport model, as reported by the first part of this study, this modeling study indicates that cold condensation is likely occurring more intensively in the mid-troposphere where rapid declining air temperature results in condensed phase of the chemical over and near its source regions and where stronger winds convey the chemical more rapidly to the polar region during the episodic poleward atmospheric transport events.