Dynamics and composition of the Asian summer monsoon anticyclone
Dynamics and composition of the Asian summer monsoon anticyclone
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DOI：
10.5194/acp-18-5655-2018
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发表时间：
2017-06
影响因子：
6.3
通讯作者：
K. Gottschaldt;H. Schlager;R. Baumann;D. Cai;V. Eyring;Phoebe Graf;V. Grewe;P. Jöckel;T. Jurkat-Witschas;C. Voigt;A. Zahn;H. Ziereis
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文献类型：
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作者：
K. Gottschaldt;H. Schlager;R. Baumann;D. Cai;V. Eyring;Phoebe Graf;V. Grewe;P. Jöckel;T. Jurkat-Witschas;C. Voigt;A. Zahn;H. Ziereis
抽象的。本研究将HALO研究飞机在对流层上部亚洲夏季风反气旋（ASMA）的观测纳入区域，年内变化的背景下，通过ECHAM/MESSy大气化学（EMAC）模式的后报。这些观测是在2012年9月的地球系统模型验证活动（ESMVal）期间获得的。观测和模拟的示踪剂-示踪剂关系反映了对流层低层和对流层顶的光化学O3生产以及混合。模拟结果表明，对流层微量气体剖面在季风季节是不同的，从那些在今年的其他时间，和测量反映了整个季风季节的主要过程。净光化学O3的生产显着增强ASMA，上升的前体满足增加的NOx，主要是由闪电产生的。在模拟中的多个季风季节的分析表明，平流层影响对流层顶层的空气定期夹带在东部ASMA侧翼，然后在南部边缘周围的内部区域输送。反气旋的亚季节动力学不稳定性有效地克服了环流的径向输送障碍，这种不稳定性经常发生，对ASMA的痕量气体成分至关重要。富O3空气的等熵卷吸和上升贫O3空气的光化学转化都倾向于增加ASMA外流中的O3。
Abstract. This study places HALO research aircraft observations in the upper-tropospheric Asian summer monsoon anticyclone (ASMA) into the context of regional, intra-annual variability by hindcasts with the ECHAM/MESSy Atmospheric Chemistry (EMAC) model. The observations were obtained during the Earth System Model Validation (ESMVal) campaign in September 2012. Observed and simulated tracer–tracer relations reflect photochemical O 3 production as well as in-mixing from the lower troposphere and the tropopause layer. The simulations demonstrate that tropospheric trace gas profiles in the monsoon season are distinct from those in the rest of the year, and the measurements reflect the main processes acting throughout the monsoon season. Net photochemical O 3 production is significantly enhanced in the ASMA, where uplifted precursors meet increased NO x , mainly produced by lightning. An analysis of multiple monsoon seasons in the simulation shows that stratospherically influenced tropopause layer air is regularly entrained at the eastern ASMA flank and then transported in the southern fringe around the interior region. Radial transport barriers of the circulation are effectively overcome by subseasonal dynamical instabilities of the anticyclone, which occur quite frequently and are of paramount importance for the trace gas composition of the ASMA. Both the isentropic entrainment of O 3 -rich air and the photochemical conversion of uplifted O 3 -poor air tend to increase O 3 in the ASMA outflow.