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A closer look at chaotic advection in the stratosphere: part I: geometric structure

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Ngan, K. and Shepherd, T. G. (1999) A closer look at chaotic advection in the stratosphere: part I: geometric structure. Journal of the Atmospheric Sciences, 56 (24). pp. 4134-4152. ISSN 1520-0469

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To link to this article DOI: 10.1175/1520-0469(1999)056<4134:ACLACA>2.0.CO;2

Abstract/Summary

The relevance of chaotic advection to stratospheric mixing and transport is addressed in the context of (i) a numerical model of forced shallow-water flow on the sphere, and (ii) a middle-atmosphere general circulation model. It is argued that chaotic advection applies to both these models if there is suitable large-scale spatial structure in the velocity field and if the velocity field is temporally quasi-regular. This spatial structure is manifested in the form of “cat’s eyes” in the surf zone, such as are commonly seen in numerical simulations of Rossby wave critical layers; by analogy with the heteroclinic structure of a temporally aperiodic chaotic system the cat’s eyes may be thought of as an “organizing structure” for mixing and transport in the surf zone. When this organizing structure exists, Eulerian and Lagrangian autocorrelations of the velocity derivatives indicate that velocity derivatives decorrelate more rapidly along particle trajectories than at fixed spatial locations (i.e., the velocity field is temporally quasi-regular). This phenomenon is referred to as Lagrangian random strain.

Item Type:Article
Refereed:Yes
Divisions:No Reading authors. Back catalogue items
Faculty of Science > School of Mathematical and Physical Sciences > Department of Meteorology
ID Code:32855
Publisher:American Meteorological Society

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