Observations of greenhouse gas (GHG) concentrations and their relationship to atmospheric conditions in major cities are an important component of current efforts to understand the effects of urbanization on anthropogenic sources of GHGs. One-minute CO2 mixing ratio measurements in the city of Cambridge, MA have been determined from air samples collected from an intake mounted at on the roof of MIT’s Green building (99.0 m) since July 3, 2012. Atmospheric CO2 concentrations are governed by a diurnal cycle with July hourly average mixing ratios ranging from a minimum of 390.22 ± 9.22 ppm at 4:00PM to a maximum of 412.89 ± 16.78 ppm at 6:00AM. Occasional plume events, with mixing ratios exceeding 500 ppm, are seen in preliminary records especially in the morning hours (6:00AM-12:00PM). Small CO2 detectors also have been deployed at other locations on MIT’s campus to determine CO2 mixing ratios to within 30 ppm at different elevations. These detectors provide a cost effective way to determine the spatial extent of plume events. To assess overall levels of GHGs in the Boston area, corresponding CO and N2O concentrations, obtained with a continuous wave, quantum cascade tunable infrared laser absorption spectrometer are used to determine source signatures during plume events. The potential exists to establish a baseline diurnal signal in the CO and N2O records similar to that of CO2 in the ongoing measurements. Further analyses will look to determine the existence and extent of an urban GHG dome over the city of Boston. Some unique source signatures are identified on the basis of their characteristic N2O-CO-CO2 ratios; this information will be used to evaluate the location of significant anthropogenic sources of GHGs in conjunction with wind direction and traffic flow data. Preliminary N2O/CO2 ratios, averaged over six hour periods, fall between (7.31 ± 0.31)*10-4 in the morning (6:00AM-12:00PM) and (8.34 ± 0.13)*10-4 in the evening (6:00PM – 12:00AM) are slightly higher than Jimenez et al.’s mixed traffic ratio ((12.8 ±0.3)*10-5 ) and Farmulari et al.’s urban emission ratio ((2.5)*10-4) from Edinburgh, Scotland. In further analysis, CO/CO2 and N2O/CO ratios will also be considered. While diurnal cycles in GHG levels are largely attributed to changes in temperature and planetary boundary layer (PBL) height, the geographical variation and significance of high frequency plume events will be evaluated in the context of the urban CO2 budget.