Eddy covariance flux measurements of trace gases , aerosols and energy from urban mexico city

Eddy covariance (EC) flux measurements of the atmosphere/surface exchange of gases, aerosols and energy over an urban area are a direct way to improve and evaluate emission inventories, and, in turn, to better understand the chemical and physical processes occurring in urban atmospheres and the role that cities play at regional and global scales. As part of two large field campaigns carried out in Mexico City we demonstrated the feasibility of using EC techniques coupled with fast-response sensors to measure fluxes of volatile organic compounds (VOCs), CO2 and speciated aerosols from urban neighborhoods, where the spatial variability of surface cover, emission sources and roughness is high. The instrumentation and methodology used for these measurements are described in this work. The observed fluxes are discussed in terms of diurnal patterns and vehicular activity, and are compared to the local gridded emissions inventory. This comparison shows the utility of EC measurements for improving the air quality management in urban areas.