Urban fraction influence on local nocturnal cooling rates from low-cost sensors in Dallas-Fort Worth

Increased health risks and economic vulnerability are associated with higher nighttime temperatures in urban areas. Urbanization slows cooling overnight, and the heterogeneous built environment leads to inequitable distributions of health risks and cooling costs. Quantifying the relationship between the local built environment and cooling rates of air temperature is typically inhibited by a lack of in situ measurements. There are many new low-cost sensors that primarily measure urban air pollution that also measure air temperature, which permits a more comprehensive examination of the local urban heat island. The Dallas-Fort Worth region is an ideal location and cooling rates of 116 sensors from 2020 to 2022 are linked to the local urban fraction to quantify the impact of the built environment on local air temperature. Days that are not clear and calm are removed to isolate the local forcing from the synoptic forcing. Cooling rates significantly and linearly slow as the urban fraction increases during all months at a rate of 0.5–0.7 oC hr-1 urbfrac-1 with the greatest impact occurring in spring and fall. These results provide highly localized relationships that work towards a better understanding of the heterogeneous and inequitable nature of cities that will only improve as the data set grows.