The goal of the project is to continue measurements of energy and trace gas fluxes at a unique urban research site in Houston, Texas, with a focus on evaluating the anthropogenic and biogenic contributions to the measured net CO2 exchange at this site. The project would analyze existing and future data, support measurements for another two years, and perform additional measurements to elucidate the contributions of anthropogenic and biogenic carbon fluxes to the net carbon exchanges in a representative urban area. The objectives are to (i) separate urban anthropogenic and biogenic CO2 fluxes for independent evaluation; (ii) compare different separation methods; (iii) analyze net and separated urban carbon flux dynamics in relation to different drivers; and (iv) relate fluxes to simple land cover classifications to estimate net biogenic and anthropogenic flux contributions in similar urban areas of North America. The proposed research will use both a recently developed quadrant analysis method to evaluate the structures of atmospheric eddies for informational content on independent surface sources (internal method), as well as traditional scaling methods using an anthropogenic emissions tracer, carbon monoxide, and biogenic source measurements on local vegetation and soil plots for upscaling (external method). Measurement activities will include the well-established eddy covariance technique expanded by a profile system, local photosynthesis and respiration measurements in collaboration with public schools and/or on private property, and seasonal evaluations of traffic density and composition, as well as natural gas use, the major direct anthropogenic CO2 emission sources in this area. Through a synthesis of the gathered data, the dynamics, drivers, and distribution of biogenic and anthropogenic carbon fluxes will be studied independently, filling a gap regarding urban land covers in the current flux network. The successful implementation of this (monitoring and analysis) project allows the assessment of the importance of constantly growing urban areas in the North American carbon cycle. It addresses identified gaps in carbon cycle knowledge and can help in validating inventories and improving estimates of carbon cycling. In addition, outreach through the engagement of neighborhood schools and citizens in on-site research conveys the importance of this research directly to the involved people.