Observation of stochastic coherence in coupled map lattices

Chaotic evolution of structures in Coupled map lattice driven by identical noise on each site is studied (a structure is a group of neighbouring lattice-sites for whom values of dynamical variable follow certain predefined pattern). 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.
4 pages double column LaTeX file for text, 5 Postscript files for figures. Replaced version contains an analytic argument for stochastic coherence