Planetary waves kinematically forced by Himalayan orography

An analysis is made of the planetary-scale response of the atmosphere to the kinematic effects of orographic forcing by, in particular, the Tibetan Plateau-Himalayan Mountain complex. Theoretical scaling arguments are used to deduce a critical mountain height h_c beyond which the component of flow around will dominate that over the orography. The h_c is proportional to the meridional scale of the orography and depends on latitude. For north-south scales appropriate for the Himalayas h_c~1.5km which is much less than the actual height of 3706m when resolved with four zonal planetary waves, with the implication that the "around' component will dominate. A steady-state planetary wave model which has a full kinematic nonlinear lower boundary condition is used to simulate the response to the eastern orography whose height has been multipled by factors ranging from 0.1 to 2.0. The around component should also dominate for the Greenland plateau and Antarctica but the effects are more equivocal for the Rockies which are only ~1km high when resolved with planetary scales while h_c~1.5km. -from Authors