Dynamical and chemical characteristics of tropospheric intrusions observed during START08
Dynamical and chemical characteristics of tropospheric intrusions observed during START08
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DOI：
10.1029/2010jd015098
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发表时间：
2010-12
影响因子：
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通讯作者：
C. Homeyer;K. Bowman;L. Pan;E. Atlas;R. Gao;T. Campos
中科院分区：
文献类型：
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作者：
C. Homeyer;K. Bowman;L. Pan;E. Atlas;R. Gao;T. Campos
[1] 空气从热带对流层上部侵入副热带急流上方的温带平流层，可能会对平流层最低层（“中间世界”的平流层部分）的组成产生重大影响。我们使用运动学和化学诊断技术对 2008 年区域运输平流层-对流层分析 (START08) 实验期间观察到的对流层入侵事件进行了分析。使用高分辨率模型分析和后向轨迹计算来讨论每个事件期间运行的运输过程。 START08 期间观察到的每次入侵都可能与太平洋上的罗斯比破浪事件有关。轨迹分析表明，入侵气团可以追溯到热带对流层上层和平流层下层。对流层入侵的原位化学观测用于通过使用简单的盒模型和具有不同光化学寿命的痕量物种来估计所观测到的入侵的混合时间尺度。我们估计入侵与平流层背景空气混合的时间尺度为 5 至 6 天。对平流层中观察到的对流层特征的小尺度特征的详细分析表明，与对流层入侵相关的频繁的不可逆传输。痕量气体分布和相关性与高分辨率 NCEP GFS 分析的动态一致，表明这些特征是由 GFS 同化和预报系统捕获的。还给出了 START08 期间（2008 年 4 月至 6 月）观察到的入侵事件的全球分析。
[1] Intrusions of air from the tropical upper troposphere into the extratropical stratosphere above the subtropical jet potentially have a significant impact on the composition of the lowermost stratosphere (the stratospheric part of the “middle world”). We present an analysis of tropospheric intrusion events observed during the Stratosphere-Troposphere Analyses of Regional Transport 2008 (START08) experiment using kinematic and chemical diagnostics. The transport processes operating during each event are discussed using high-resolution model analyses and backward trajectory calculations. Each intrusion observed during START08 can be related to a Rossby wavebreaking event over the Pacific Ocean. Trajectory analysis shows that the intruding air masses can be traced back to the tropical upper troposphere and lower stratosphere. In situ chemical observations of the tropospheric intrusions are used to estimate the mixing time scales of the observed intrusions through use of a simple box model and trace species with different photochemical lifetimes. We estimate that the time scale for an intrusion to mix with the background stratospheric air is 5 to 6 days. Detailed analysis of small-scale features with tropospheric characteristics observed in the stratosphere suggests frequent irreversible transport associated with tropospheric intrusions. Trace gas distributions and correlations are consistent with the dynamics of the high-resolution NCEP GFS analyses, suggesting that these features are captured by the GFS assimilation and forecast system. A global analysis of intrusion events observed during the START08 time period (April–June 2008) is also given.