Abstract
The use of the geostrophic approximation gives rise to inertio-gravitational oscillations which are meteorologically unimportant “noise” disturbances. In the first part of this paper, the physical explanations about the occurrence of those inertio-gravitation oscillations are given in the case of barotropic atmosphere.
In the latter part of this paper, the general method for filtering out the “noise” in the three-dimensional atmosphere is proposed. Such a treatment is discussed by introducing G-number which is the ratio of the velocity potential χ to the stream function φ. This G-number simplifies the equations we are concerned with and also the associated discussions. The quasi-geostrophic equations hitherto used correspond to those of zero order of G-number.
