A GLOBAL ANNUALLY-AVERAGED CLIMATE MODEL WITH CLOUD, WATER VAPOR AND CO2 FEEDBACKS

In consideration of the radiation transfer, latent and sensible heat exchange between oceans and at-mosphere, a three-dimensional autonomous nonlinear ordinary differential equation is established by statis-tical parameterization method. The variables of the model are the mean ocean surface temperature Ts, mean atmospheric temperature Ta and atmospheric relative humidity f, and the feedbacks of clouds, water vapor and CO2 are involved. The steady state corresponding to the present-day climate can be obtained from this model. The analysis of parameter sensibility in the steady state indicates that clouds have consid-erable negative feedback effects and water vapor may affect the sign of CO2 feedback. The stability analysis of the steady state to small disturbance indicates that with increase of the positive feedback effect of clouds, the steady state goes through such a structural variance series as a stable node→a stable focal point→an unstable focal point→an unstable node, and when the steady state becomes unstable it undergoes a subcritical Hopf bifurcation. When the steady state is at a focal point, the periodic oscillation solutions of damping or amplifying can be obtained with the period being about two years.