The collective, global behavior of a heterogeneous catalytic system depends on the effective communication of local reactivity variations to distant points in the system. One particularly efficient mode of communication occurs via partial pressure fluctuations in the gas-phase above the reactive surface. Although gas-phase communication has been implicated in a number of heterogeneous systems, the details of this coupling mechanism are lacking due to experimental difficulties in addressing local variations in surface and gas-phase activity simultaneously. Here, we take advantage of a spatially distributed system of isolated chemical oscillators to investigate the details of gas-phase communication in the 10(-3) mbar range. Characterization of local gas-phase oscillations, in parallel with kinetic oscillations on the surface, provides a novel description of the surface/gas-phase interaction under reaction conditions. This analysis further allows for a quantitative estimate of the effective gas-phase coupling length scale observed in surface imaging experiments. (C) 2010 Elsevier Inc. All rights reserved.