SUPER-HARMONIC AND SUB-HARMONIC RESPONSES OF TROPICAL KELVIN WAVES TOTHE HEATING WITH A SEASONAL MODULATION

By applying a seasonally modulated condensation heating on tropical Ke lvin waves with a certain form of damping, the parametric instability and super(sub)harmonic response of the Kelvin waves are investigated. It is suggested that the excitation of intraseasonal oscillation and t ropospheric QBO may be related to the superharmonic and subharmonic re sonances with the seasonal cycle, respectively. The main features of t he spatial structures and propagation of these resonant modes were sho wn and compared with those of intraseasonal oscillation and tropospher ic QBO to examine this point of view.