General Circulation of Air Parcels and Transport Characteristics Derived from a Hemispheric GCM: Part 2. Very Long-Term Motions of Air Parcels in the Troposphere and Stratosphere@@@第二部 対流圏と成層圏における空気塊の長時間運動
General Circulation of Air Parcels and Transport Characteristics Derived from a Hemispheric GCM: Part 2. Very Long-Term Motions of Air Parcels in the Troposphere and Stratosphere@@@第二部 対流圏と成層圏における空気塊の長時間運動
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空气包裹的环流和来自半球 GCM 的传输特性：第 2 部分。对流层和平流层中空气包裹的超长期运动@@@第 2 部分
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
H. Kida
中科院分区：
文献类型：
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作者：
H. Kida
本文在利用半球大气环流模式对大量有标记气包轨迹分析的基础上，提出了示踪剂在平流层和对流层输送机制的拉格朗日型描述。结果表明，平流层低层大气的输送是由缓慢的平流环流和大尺度准水平涡动扩散共同作用的结果，而对流层内的输送在水平和垂直方向上都是高度扩散的。目前的模拟表明，对流层的空气块很好地混合在一个月内整个对流层准水平混合由于气旋和垂直混合由于小尺度对流。平流层空气主要来自热带对流层顶。对流层气团通过副热带对流层顶间隙只侵入对流层外平流层底层（100毫巴以下）。然而，这种侵入几乎不会影响底层以上的水平。本文分析了平流层空气的年龄，将空气团的年龄定义为空气团进入平流层后经过的时间长度。结果表明，热带平流层由“新”气团组成，人们认为这些气团保留了对流层空气的特性，而极地平流层则由相对“旧”的气团组成，这些气团长期驻留在平流层中。这种解释可能是有用的，以了解起源于地面或平流层的示踪剂的分布的主要特征。
A Lagrangian-type description of transport mechanisms of tracers in the stratosphere and troposphere is presented on the basis of trajectory analysis of a large number of marked air parcels using a hemispheric GCM. It is demonstrated that the transport of the lower stratospheric air is due both to slow advective general circulation and to large-scale quasihorizontal eddy diffusion, while the transports within the troposphere are highly diffusive both in the horizontal and vertical directions. The present simulation shows that the tropospheric air parcels are well mixed within one month throughout the troposphere by quasihorizontal mixing due to cyclones and vertical mixing due to small-scale convection. It is also shown that the stratospheric air can be supplied mainly from the tropical tropopause. Only the bottom layer (below *100mb) of the extratropical stratosphere may be intruded by tropospheric air parcels through the subtropical tropopause gap. However, such intrusion can hardly affect the levels above the bottom layer. In this paper, the age of the stratospheric air is analyzed; the age of an air parcel is defined as the length of time elapsed since it entered the stratosphere. The results show that the tropical stratosphere consists of `new' air parcels, which is thought to retain properties of the tropospheric air, while the polar stratosphere involves relatively `old' air parcels which have long-term residence in the stratosphere. This interpretation may be useful to understand major features of distributions of tracers originating either the surface or the stratosphere.