Dynamic Urban Residents’ Exposure to Temperature Extremes in U.S. Cities

Heat and cold waves are health hazards of extreme temperatures. The existence of heat islands exacerbates the extreme hot in cities during heat waves, while provides shields against the extreme cold during cold spells. Diurnal variations of population distribution, changing from city to city, further complicate the exposure of urban residents to temperature extremes. In this study, we incorporate the spatiotemporal covariations of hourly temperature and population to investigate the dynamic population exposure to extreme temperatures (heat waves and cold bells) across major US metropolitan areas. High-resolution simulations of three major heat waves and one cold spell are conducted using the weather research and forecasting (WRF) model to characterize the temperature patterns over 16 major metropolitan areas. The commute-adjusted hourly population is estimated from the Census Transportation Planning Products accordingly. Specifically, we characterize the temperature anomaly during extreme events relative to normal conditions. Results reveal that population dynamics play an important role in determining urban residents’ exposure to temperature extremes. The dynamic exposure patterns behave differently in heat and cold waves and vary vastly among studied metropolitan areas due to their climate features as well as geolocations. The study has a significant policy implication and can better inform future climate-mitigation strategies.