Model for spontaneous frequency sweeping of an Alfvén wave in a toroidal plasma

► We model the frequency chirping signals for toroidial Alfven eigenmode (TAE). ► A faster chirping rate is observed when the signals enter the Alfven continuum. ► The trapped clump and/or hole structures are formed in phase space. ► The adiabatic approximation is numerically checked during the evolution of nonlinear waves.