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A Multiscale Interaction-Model For The Origin Of The Tropospheric Qbo

Goswami, BN (1995) A Multiscale Interaction-Model For The Origin Of The Tropospheric Qbo. In: Journal Of Climate, 8 (3). pp. 524-534.

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A conceptual model for the origin of the tropospheric quasi-biennial oscillation (QBO) is presented. It is argued that the tropospheric QBO may not be a fundamental mode of oscillation of the tropical coupled system. It is proposed that it may arise due to multiscale interactions between high-frequency synoptic and intraseasonal oscillations of the atmosphere and a low-frequency oscillation of the coupled system in the presence of the annual cycle. This is demonstrated using a conceptual low-order system consisting of three variables representing the nonlinear atmospheric oscillations and a linear oscillator representing the low-frequency coupled mode. The annual cycle and coupling to the low-frequency linear oscillator provide slowly varying forcings for the atmospheric high-frequency oscillations. The atmospheric oscillations go through a chaotic regime during a certain part of the slowly varying forcing. Such variable forcing introduces a low-frequency tail in the spectrum of the atmospheric high-frequency oscillations. This low-frequency tail resonantly interacts with the low-frequency oscillation and produces the QBO in addition to broadening the spectrum of the low-frequency oscillator. The conceptual model simulates features similar to many observed features of the tropospheric QBO but depends on the assumption that there is an inherent low-frequency El Nino-Southern Oscillation oscillation with a four-year period that occurs independently of the high-frequency forcing or the QBO.

Item Type: Journal Article
Publication: Journal Of Climate
Publisher: American Meteorological Society
Additional Information: Copyright of this article belongs to American Meteorological Society.
Department/Centre: Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited: 06 Apr 2009 04:39
Last Modified: 19 Sep 2010 05:27
URI: http://eprints.iisc.ac.in/id/eprint/19142

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