A SIMPLE NONLINEAR MODEL OF INERTIAL OSCILLATION OF ATMOSPHERE IN LOW-LATITUDES

In this paper,by simplifying the governing equation in low latitudes a nonlinear model which takes into consideration the equatorial β-plane approximation and describes the natural oscillation of the atmosphere has been set up.By applying this model the following results are shown:(1)There exists the pure inertial oscillation only in u00(westerly current),the angular frequency of linear oscillation of y is ω0*=√(β0u0*)1/2,the corresponding oscillatory period is 1-2 weeks.There are two kinds of angular frequencies under the nonlinear condition,the one is ω0=√(β0u0)1/2the other is ω1=1/2 β0y0.When a soliton oscillator occurs(ω1=ω0),the oscillatory period increases rapidly,and T→∞.(2)When the pressure field is considered,the oscillation exists not only in u00(westerly current)but also in u00(weak easterly current).However this weak pressure field has slight effect on the oscillatoryperiod.(3)The stability of inertial oscillation depends on the linear inertial parameter μ.As the parameterμ changes sign from negative to positive,the supercritical bifurcation takes place in b0.