Noise-sustained spiral waves: Effect of spatial and temporal memory

We have investigated the constructive roles of temporal noise, spatial disorder, and spatiotemporal fluctuation on the formation of spiral waves. Noise-sustained spiral waves are observed, the order of which passes a maximum with the increment of noise intensity, showing spatiotemporal coherent resonance. Moreover, we find that spatiotemporal fluctuation is much more favorable for the ordering process than temporal-noise only or spatial-disorder only. We demonstrate that this phenomenon shows the disadvantageous effect of spatial or temporal memory of noise.