Quantifying Urban VOC Sources in Greater New York By Tower-Based Eddy Covariance (Invited Presentation)

Air quality in urban areas is affected by an array of anthropogenic and biogenic volatile organic compound (VOC) sources, including fossil-fuel combustion, volatile chemical products, cooking, building material decomposition, and vegetative emissions. Predictions and policy design rely on accurate characterization of the above sources and of the mechanisms controlling them; however, direct measurements of urban VOC fluxes are rare. Here, we combine high-resolution proton-transfer reaction mass spectrometry with eddy covariance to directly quantify a wide suite of VOC fluxes from a cellular tower over an urban footprint on Long Island, NY during summer and winter. We apply non-negative matrix factorization to the observed VOC fluxes and to those for CO and CO₂ to identify the key factors controlling emission variability. These factors are used to pinpoint the principal anthropogenic and biogenic emissions sectors, and to shed light on the coupling between meteorology, evaporative, and degradative emissions. We interpret the measured diurnal, weekend/weekday, and seasonal patterns of variability in terms of the relative importance of biogenic and anthropogenic sources within this urban landscape, and examine the role of sporadic (e.g., personal care products, traffic, cooking) vs. ubiquitous (e.g., surface evaporation, material decomposition) anthropogenic source sectors.