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Sensitivity of the tropical nonlinear stationary Kelvin and Rossby waves to the vertical structure of heating

Krishnan, R and Kasture, SV (1995) Sensitivity of the tropical nonlinear stationary Kelvin and Rossby waves to the vertical structure of heating. Proceedings of the Indian Academy of Sciences - Earth and Planetary Sciences, 104 (4). pp. 579-606.

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Abstract

Idealized experiments using linear (LM) and nonlinear (NM) multilevel global spectral models have been carried out to investigate and understand the impact of nonlinearities on the stationary wave response in the tropical atmosphere and its sensitivity to the vertical profile of heating. It is found that nonlinearities exert a dominant influence on the low-latitude stationary Kelvin and Rossby waves particularly in the vicinity of the forcing region. Our study shows that nonlinear effects on the upper tropospheric response produce prominent eastward displacement of the anticyclonic vorticity and horizontal shifts of the maximum equilibrium divergence relative to the prescribed heating. These changes due to nonlinear terms are found to be quite sensitive to the vertical structure of diabatic heating. The strongest nonlinear effects are found to occur when the vertical level under consideration is strongly forced from below. Detailed vorticity budget calculations indicate that stronger nonlinear contributions from stretching and horizontal advection of relative vorticity favour the generation of upper tropospheric anticyclonic circulation and its eastward displacement. Larger vertical advection and twisting terms appear to oppose the generation of upper tropospheric anticyclonic vorticity. It is found that the nonlinear terms which affect the vorticity generation in the upper levels are crucially controlled by the vertical profile of heating

Item Type: Article
Additional Information: Copyright of this article belongs to Indian Academy of Sciences
Uncontrolled Keywords: anticyclonic vorticity; equilibrium divergence; global spectral modelling; heating profile; Kelvin wave; Rossby wave; stationary wave
Subjects: Meteorology and Climatology
Oceanography > oceanography
Depositing User: Administrator ePrints@MoES
Date Deposited: 27 Jun 2015 06:44
Last Modified: 27 Jun 2015 06:44
URI: http://moeseprints.incois.gov.in/id/eprint/2119

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