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

摘要: A detailed barotropic, baroclinic and combined barotropic-baroclinic stability analysis has been carried out with mean monsoon zonal currents over western India, eastern India S.E. Asia. The lower middle tropospheric wind profiles are barotropically unstable. structure growth rate of these modes agree well the observed features midtropospheric cyclones. Similar Asia, however, stable. This is attributed to weak horizontal shear, inherent profiles. upper profiles, on other hand, unstable throughout whole region. those easterly waves. analyses show that effects not important in tropics.