Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe
Lagrangian simulations of the transport of young air masses to the top of the Asian monsoon anticyclone and into the tropical pipe
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DOI：
10.5194/acp-19-6007-2019
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发表时间：
2018-07
影响因子：
6.3
通讯作者：
B. Vogel;R. Müller;G. Günther;R. Spang;Sreeharsha Hanumanthu;Dan Li;M. Riese;G. Stiller
中科院分区：
文献类型：
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作者：
B. Vogel;R. Müller;G. Günther;R. Spang;Sreeharsha Hanumanthu;Dan Li;M. Riese;G. Stiller
摘要。我们用平流层三维化学拉格朗日模型（CLaMS）对连续两个季风季节进行了反向轨迹计算和模拟，并使用人工气团起源示踪剂。利用这些示踪剂，我们追溯了2008年夏季亚洲季风反气旋顶部年轻气团（年龄<6个月）和热带管道内气团（年龄<18个月）的起源。在高达~ 460 K的亚洲季风反气旋顶部出现年轻气团（<6个月），这与迈克尔逊被动大气探测干涉仪（MIPAS）仪器对氯二氟甲烷（HCFC-22）的卫星测量结果一致。HCFC-22主要在东亚大陆和中东地区排放，可以认为是该地区的区域示踪剂。研究结果表明，亚洲季风区边界层气团向热带管道的输送分三个不同的步骤。首先，在“对流范围”内的快速抬升将气团在几天内输送到360 K的潜在温度。其次，气团在几个月内从大约360k上升到460k，处于“上升螺旋范围”。大规模的上升螺旋从北非延伸到西太平洋。气团在非绝热加热下以每天1-1.5 K的速率向上输送，这意味着在亚洲季风反气旋上方有很强的垂直输送。第三，与大尺度布鲁尔-多布森环流相关的550 K热带管道内的气团运输在~ 1年内发生。在上升螺旋范围内，气团通过（递减率）对流层顶的绝热加热而上升，与温带对流层顶不同，对流层顶不充当运输屏障。此外，在上升的螺旋范围内，来自亚洲季风反气旋内部的气团与热带邻近地区亚洲季风反气旋核心外对流上升的气团混合在一起。此外，从亚洲季风反气旋向热带管道输送的气团在输送气团方面弱于从季风反气旋向北部温带下层平流层输送的气团。来自亚洲季风反气旋（印度/中国）的气团对550 K热带管道内空气成分的贡献较小（6%），主要来自东南亚（16%）和热带太平洋（15%）。
Abstract. We have performed backward trajectory calculations and simulations with the three-dimensional Chemical Lagrangian Model of the Stratosphere (CLaMS) for two succeeding monsoon seasons using artificial tracers of air mass origin. With these tracers we trace back the origin of young air masses (age <6 months) at the top of the Asian monsoon anticyclone and of air masses within the tropical pipe (6 months < age <18 months) during summer 2008. The occurrence of young air masses (<6 months) at the top of the Asian monsoon anticyclone up to ∼460 K is in agreement with satellite measurements of chlorodifluoromethane (HCFC-22) by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instrument. HCFC-22 can be considered as a regional tracer for continental eastern Asia and the Middle East as it is mainly emitted in this region. Our findings show that the transport of air masses from boundary layer sources in the region of the Asian monsoon into the tropical pipe occurs in three distinct steps. First, very fast uplift in “a convective range” transports air masses up to 360 K potential temperature within a few days. Second, air masses are uplifted from about 360 K up to 460 K within “an upward spiralling range” within a few months. The large-scale upward spiral extends from northern Africa to the western Pacific. The air masses are transported upwards by diabatic heating with a rate of up to 1–1.5 K per day, implying strong vertical transport above the Asian monsoon anticyclone. Third, transport of air masses occurs within the tropical pipe up to 550 K associated with the large-scale Brewer–Dobson circulation within ∼1 year. In the upward spiralling range, air masses are uplifted by diabatic heating across the (lapse rate) tropopause, which does not act as a transport barrier, in contrast to the extratropical tropopause. Further, in the upward spiralling range air masses from inside the Asian monsoon anticyclone are mixed with air masses convectively uplifted outside the core of the Asian monsoon anticyclone in the tropical adjacent regions. Moreover, the vertical transport of air masses from the Asian monsoon anticyclone into the tropical pipe is weak in terms of transported air masses compared to the transport from the monsoon anticyclone into the northern extratropical lower stratosphere. Air masses from the Asian monsoon anticyclone (India/China) contribute a minor fraction to the composition of air within the tropical pipe at 550 K (6 %), and the major fractions are from Southeast Asia (16 %) and the tropical Pacific (15 %).