Articles written in Journal of Earth System Science
Volume 89 Issue 1 March 1980 pp 79-97
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.
Volume 98 Issue 2 July 1989 pp 207-211
Indian summer monsoon seasonal rainfall for the period 1871–1986 over the meteorological subdivisions has been analysed using the method of deterministic chaos. It is shown that a strange attractor underlies the monsoon evolution in each subdivision. The dimensionality of the attractor and the number of key variables necessary to model the subdivisional dynamics have been determined.