Role of barotropic, baroclinic and combined barotropic-baroclinic instability for the growth of monsoon depressions and mid-tropospheric cyclones

Goswami, Bhupendra Nath ; Keshavamurty, R. N. ; Satyan, V. (1980) Role of barotropic, baroclinic and combined barotropic-baroclinic instability for the growth of monsoon depressions and mid-tropospheric cyclones Proceedings of the Indian Academy of Sciences - Earth and Planetary Sciences, 89 (1). pp. 79-97. ISSN 0253-4126

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Official URL: http://www.ias.ac.in/j_archive/epsci/89/1/79-97/vi...

Related URL: http://dx.doi.org/10.1007/BF02841521

Abstract

A detailed barotropic, baroclinic and combined barotropic-baroclinic stability analysis has been carried out with mean monsoon zonal currents over western India, eastern India and S.E. Asia. The lower and middle tropospheric zonal wind profiles over western India are barotropically unstable. The structure and growth rate of these modes agree well with the observed features of the midtropospheric cyclones. Similar profiles over eastern India and S.E. Asia, however, are barotropically stable. This is attributed to weak horizontal shear, inherent to these profiles. The upper tropospheric profiles, on the other hand, are barotropically unstable throughout the whole region. The features of these unstable modes agree with those of observed easterly waves. The baroclinic and combined barotropic-baroclinic stability analyses show that the baroclinic effects are not important in tropics. Though the barotropic instability of the mean zonal current seems to be res ponsible for the initial growth of the mid-tropospheric cyclones, neither barotropic nor baroclinic instability of the mean zonal current seem to explain the observed features of the monsoon depressions.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Monsoon Depressions; Mid-tropospheric Cyclones; Mean Zonal Flows; Barotropic; Baroclinic Instability
ID Code:23828
Deposited On:01 Dec 2010 13:04
Last Modified:17 May 2016 07:38

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