To evaluate how traffic-related anthropogenic heat emissions (AHE) influence urban temperatures in the Chicago metropolitan area, with emphasis on understanding why traffic’s heat contribution is more pronounced at night, but less evident during daytime hours.

The study uses the Weather Research and Forecasting (WRF v4.5.2) model with four nested domains centered on Chicago to simulate the effects of traffic-related anthropogenic heat emissions (AHE). 2022 Illinois Statewide Average Annual Daily Traffic (AADT) data provide spatial variations in traffic volume, which are converted into heat flux values (W/m²) using fleet composition and fuel consumption parameters. These hourly traffic heat profiles are mapped onto the model grid and integrated into WRF’s Urban Canopy Model. Two simulations are run: a baseline case without traffic heat and a traffic heat scenario allowing direct comparison to quantify traffic’s impact on urban temperatures and the urban heat island (UHI) effect.

Traffic-related anthropogenic heat emissions amplify the UHI effect, particularly during nighttime when weak atmospheric mixing allows heat to accumulate near the surface. In contrast, during the day, solar heating dominates, dispersing heat and reducing the relative influence of traffic emissions. The simulations show that traffic AHE leads to peak warming of 0.36 K around 06:00 LST and 0.25 K around 21:00 LST, demonstrating its strongest effect under stable atmospheric conditions. These findings highlight the critical role of transportation-related heat in shaping urban temperature patterns, emphasizing the need to consider traffic emissions in strategies for urban climate resilience and sustainable city planning.

Traffic is a significant contributor to urban warming in Chicago under certain conditions. While its impact is masked during the day by stronger solar radiation and mixing, it emerges clearly at night and in winter, when atmospheric conditions trap heat near the surface. This project underscores the role of transportation systems in shaping urban temperature patterns and informs strategies for sustainable urban planning and energy management.

In Progress

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