Internal Variability of the Winter Stratosphere . Part I : Time-Independent Forcing
Internal Variability of the Winter Stratosphere . Part I : Time-Independent Forcing
复制标题
冬季平流层的内部变化。
DOI：
10.1175/jas3797.1
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发表时间：
2005
影响因子：
4.9
通讯作者：
R. K. Scott
中科院分区：
文献类型：
--
作者：
R. K. Scott
本文探讨了平流层内部变率的性质和稳健性，即平流层本身的内部动力学所产生的变率，而不是由外部来源，如自由对流层的自然变率所造成的变率。平流层内部变率是由辐射强迫和行星波破碎的相互作用引起的，辐射强迫在冬季使极涡增强，行星波破碎使极涡减弱。平流层模式的结果表明，平流层内部变率由反复的突然变暖型事件组成，存在于广泛的实际辐射和波强迫条件下，并且在很大程度上独立于其它物理和数值参数。特别是，随着自由度数量的增加，变异性的连贯形式仍然存在，因此不是严重模型截断的伪影。各种诊断，包括三维表示的位涡，说明可变性是由垂直结构的漩涡和向上的波传播的程度是有利的或抑制。在本文中，由纯粹的内部平流层动力学所产生的变化是孤立的指定热和波强迫是完全与时间无关的。在第二篇论文中，作者研究了内部和外部变化的相对重要性，考虑随时间变化的波强迫对流层变化的一个简单的表示。
This paper examines the nature and robustness of internal stratospheric variability, namely the variability resulting from the internal dynamics of the stratosphere itself, as opposed to that forced by external sources such as the natural variability of the free troposphere. Internal stratospheric variability arises from the competing actions of radiative forcing, which under perpetual winter conditions strengthens the polar vortex, and planetary wave breaking, which weakens it. The results from a stratosphere-only model demonstrate that strong internal stratospheric variability, consisting of repeated sudden warming-type events, exists over a wide range of realistic radiative and wave forcing conditions, and is largely independent of other physical and numerical parameters. In particular, the coherent form of the variability persists as the number of degrees of freedom is increased, and is therefore not an artifact of severe model truncation. Various diagnostics, including three-dimensional representations of the potential vorticity, illustrate that the variability is determined by the vertical structure of the vortex and the extent to which upward wave propagation is favored or inhibited. In this paper, the variability arising from purely internal stratosphere dynamics is isolated by specifying thermal and wave forcings that are completely time independent. In a second paper, the authors investigate the relative importance of internal and external variability by considering time-dependent wave forcing as a simple representation of tropospheric variability.