  The interaction between cities and their respective green regions corresponds
to an interesting issue that has received growing attention over the last
decades. These relationships have multiple natures, ranging from providing
habitat for animal life to temperature and humidity dynamics. Several methods
based on area, size, shape, and distance have been considered in the
literature. Given that several important contributions of green regions to
urban areas involve temperature, humidity and gases (e.g.~oxygen) exchanges,
which are intrinsically related to physical diffusion, it becomes particularly
interesting to simulate the diffusion of green effects over urban areas as a
means of better understanding the respective influences. The present work
reports a related approach. Once the green regions of a given city are
automatically identified by semantic segmentation and have eventual artifacts
eliminated, successive convolutions are applied as a means to obtain the
unfolding of the diffusion of the green effects along time. As illustrated, the
diffusion dynamics is intrinsically interesting because it can be strongly
affected by the spatial distribution of the green mass. In particular, we
observed that smaller green regions could substantially contribute to the
diffusion. The reported approach has been illustrated with respect to the
Brazilian city of Ribeirao Preto, whose small and medium-sized green regions
were found to complement in an effective manner the diffusion of the green
effects as inferred from the performed simulations under specific parameter
settings.
