Measurements of CO_2 fluxes from the Mexico City urban landscape

摘要

In a densely populated section of Mexico City, an eddy covariance (EC) flux system was deployed on a tall urban tower to obtain direct measurements of CO_2 emissions from an urban neighborhood located in a subtropical megacity. The measured fluxes and boundary layer conditions satisfy EC assumptions of stationarity, and cospectral analyses of the turbulence measurements exhibit the required boundary layer patterns for acceptable flux measurements. Results from a field experiment conducted during April 2003 show that the urban surface is a net source of CO_2. The CO_2 flux measurements showed a clear diurnal pattern, with the highest emissions during the morning (up to 1.60mgm~(-2)s~(-1)), and the lowest emissions during nighttime. The measured fluxes were closely correlated to traffic patterns in the area. The mean daily flux was 0.41 mgm~(-2)s~(-1), which is similar to that observed in European and US cities.