Effect of Ekman boundary layer friction on the baroclinic growth of monsoon depression


  • PS SALVEKAR Indian Institute of Tropical Meteorology, Pune – 411008, India
  • SK MISHRA India Meteorological Department, Chennai - 600 001, India




Lillear baroclinic stability analysis of the mean monsoon zonal flow for varying vertical shear in the boundary layer is performed by using an adiabatic, quasi-geostrophic, 25-layer numerical model with Ekman boundary layer friction. It is found that Ekman friction reduces the growth rates in the short wave region (L <= 3000 km). It is important to note that the friction plays a crucial role in the selection of the short preferred wave.

In order to find the effect of friction explicitly, the vertical stf4ctures of the viscous and inviscid preferred waves are computed. It is concluded that the effect of friction on the vertical structure of wave amplitudes is proportional to the wind shear below the basic westerly wind maximum. The 269 vertical tilts of the wave as well as vertical extension are increased due to friction. Further, it is noticed that the friction induces direct circulation in the lower layers.




How to Cite

P. SALVEKAR and S. MISHRA, “Effect of Ekman boundary layer friction on the baroclinic growth of monsoon depression”, MAUSAM, vol. 37, no. 2, pp. 147–152, Apr. 1986.



Research Papers