Abstract: For linear steady forcing problems,a method is developed to provide a set of forcing modes which form a set of complete orthonormal basis in the energetics inner product space.The forcing modes are found by calculating eigenvectors of a positive symmetric matrix determined from given equations of motion.The amplitude of responses to forcing modes is given in term of the associated eigenvalues.This method is used in a nondivergent barotropic model linearized about the 300 hPa tonally-varying climatological flow for northern wintertime.The results show that only a few of forcing modes associated with the leading eigenvalues can excite sufficiently large response comparable with realistic teleconnection patterns,and those preferred responses to these efficient forcing modes are in good agreement with realistic teleconnection patterns.Energetics analyses are performed.The primary source of energy of responses to the most efficient forcing modes is the conversion of basic state kinetic energy to the response kinetic energy,rather than directly from the forcing itself.It is suggested that teleconnection patterns produced by external source are not determined only by Rossby wave dispersion from external sources,but mainly depend on the efficient extraction of energy of the forced perturbation from the basic state.