Decades of air quality improvements have substantially reduced the motor vehicle emissions of volatile organic compounds (VOCs). Today, volatile chemical products (VCPs) are responsible for half of the petrochemical VOCs emitted in major urban areas. We show that VCP emissions are ubiquitous in US and European cities and scale with population density. We report significant VCP emissions for New York City (NYC), including a monoterpene flux of 14.7 to 24.4 kg ⋅ d⁻¹ ⋅ km⁻² from fragranced VCPs and other anthropogenic sources, which is comparable to that of a summertime forest. Photochemical modeling of an extreme heat event, with ozone well in excess of US standards, illustrates the significant impact of VCPs on air quality. In the most populated regions of NYC, ozone was sensitive to anthropogenic VOCs (AVOCs), even in the presence of biogenic sources. Within this VOC-sensitive regime, AVOCs contributed upwards of ∼20 ppb to maximum 8-h average ozone. VCPs accounted for more than 50% of this total AVOC contribution. Emissions from fragranced VCPs, including personal care and cleaning products, account for at least 50% of the ozone attributed to VCPs. We show that model simulations of ozone depend foremost on the magnitude of VCP emissions and that the addition of oxygenated VCP chemistry impacts simulations of key atmospheric oxidation products. NYC is a case study for developed megacities, and the impacts of VCPs on local ozone are likely similar for other major urban regions across North America or Europe. Significance Recent work in Los Angeles has shown that urban volatile organic compound (VOC) emissions from consumer and industrial products—termed volatile chemical products (VCPs)—are now an important source of ozone precursors. Using advancements in VOC instrumentation, we show that VCP emissions are ubiquitous in urban regions and can be identified via unique VOC fingerprints. Through detailed modeling, we show that VCPs are as important to ozone production as fossil fuel VOCs and that the chemistry of VCPs can have significant impacts on model simulations of key atmospheric processes. Consequently, air quality models must be updated to account for both the emissions and atmospheric chemistry of VCPs in order to capture their full impact on urban air quality.

The Weather Research and Forecasting mesoscale model coupled to a multilayer urban canopy parameterization was used to evaluate the evolution of a 3-day heat wave in New York City, New York, during the summer of 2010. Results from three simulations with different degrees of urban modeling complexity and one with an absence of urban surfaces are compared with observations. To improve the city morphology representation, building information was assimilated and the land cover land-use classification was modified. The thermal and drag effects of buildings represented in the multilayer urban canopy model improve simulations over urban regions, giving better estimates of the surface temperature and wind speed. The accuracy of the simulation is further assessed against more simplified urban parameterizations models. The nighttime excessive cooling shown by the Building Energy Parameterization is compensated for when the Building Energy Model is activated. The turbulent kinetic energy is vertically distributed when using the multilayer scheme with a maximum at the average building height, whereas turbulence production is confined to a few meters above the surface when using the simplified scheme. Evidence for the existence of horizontal roll vortices is presented, and the impact that the horizontal resolution and the time step value have on their formation is assessed.

A uniform 35-nm-wide spectrum is generated by broadening the output from a 2.5-GHz mode-locked femtosecond fiber laser in dispersion shifted fiber. The obtained spectrum is suitable for spectral slicing and wavelength-division-multiplexed applications. The spectral broadening in dispersion shifted fiber is optimized as a function of the launched pulse chirp parameter.