Observation of stochastic coherence in coupled map lattices

Chaotic evolution of structures in a coupled map lattice driven by identical noise on each site is studied (a structure is a group of neighboring lattice sites for which values of the dynamical variable follow a certain predefined pattern). The number of structures is seen to follow a power-law decay with length of the structure for a given noise strength. An interesting phenomenon, which we call stochastic coherence, is reported in which a rise of bell-shaped type in abundance and lifetimes of these structures is observed for a range of noise-strength values.