What was done
"Using the eddy covariance approach," in the words of the authors, "fluxes of CO2 were measured at a suburban site (Preston) in Melbourne, Australia from February 2004 to June 2005 to investigate temporal variability," while "a second site (Surrey Hills) with differing surface characteristics (in particular, greater vegetation cover) was also established in Melbourne and ran simultaneously for six months (February 2004 to July 2004)."

What was learned
Both sites were found to be net sources of CO2 to the atmosphere, primarily because of CO2 emissions from vehicles. As a result, Coutts et al. discovered that "diurnal patterns of fluxes were largely influenced by traffic volumes, with two distinct peaks occurring at the morning and evening traffic peak hours." Summer fluxes of CO2 to the atmosphere were lower than winter fluxes due to the greater photosynthetic activity of vegetation in summer, as well as reduced natural gas combustion in that season; and the photosynthetic activity of plants throughout the summer "limited the source of CO2 in the afternoon, yet was not enough to combat the strong local anthropogenic emissions," which were always dominant.

What it means
The three Australian researchers concluded that the "magnitudes and patterns of suburban CO2 fluxes in Melbourne were similar to those observed in Northern Hemisphere suburban areas," which have largely been inferred from measurements of atmospheric CO2 concentration. The results of these several concentration-based studies are all described in reports we have archived under the heading of Urban CO2 Dome in our Subject Index.