Abstract: In this paper, a normal mode analysis is made of the linear nondivergent barotropic vorticity equation model with characteristics of the solutions discussed. Then problems of initial values and a steady forcing response are investigated respectively in terms of the normal mode with observed basic state for January 300hPa stream function. The results indicate that the tropical and subtropical regions, especially over the Indian-west Pacific Ocean, are the key regions from which the initial and the forcing disturbances can excite large amplitude responses.