Qh. Zhou, A SIMPLIFIED APPROACH TO INTERNAL GRAVITY-WAVE DAMPING BY VISCOUS DISSIPATION, Journal of atmospheric and terrestrial physics, 57(9), 1995, pp. 1009-1014
Internal gravity wave perturbation Velocity subject to constant dynami
c viscosity and constant kinematic viscosity are approximately derived
based on an energy conservation principle. When the dynamic viscosity
is assumed to be a constant, the velocity at any height relative to t
he velocity at the saturation height, Z(sat), is found to be solely de
pendent on the number of scale heights measured from Z(sat). Gravity w
ave energy dissipation due to constant dynamic viscosity primarily occ
urs from one scale height below to one scale height above the saturati
on height. When the kinematic viscosity is assumed to be a constant, t
he perturbation amplitude either increases or decreases monotonically
with height depending on whether the energy dissipation rate due, to v
iscosity, can offset the effect of the decreasing atmospheric density
with increasing height. The derivations are made simple by assuming th
at the non-dissipative dispersion relation is applicable to the dissip
ative situation. The condition for the assumption to be approximately
valid is also given.