One of the most immediate expressions of climate change is the increased frequency and intensity of extreme heat events. In urban areas, extreme heat interacts with the heterogeneity of built surfaces and processes that can exacerbate or moderate their effects. Such disparities raise critical concerns for social equity and environmental justice, emphasizing the need for a comprehensive understanding of the underlying factors contributing to these discrepancies at the neighborhood level to inform targeted strategies to enhance equitable urban resilience.

In this study, we incorporate detailed characterizations of vegetation cover (tree and grass fractions), irrigation patterns, anthropogenic heating, and urban morphology into a high-resolution high-fidelity urban microclimate modeling framework to capture the heterogeneity of urban heat/cool island effect at the neighborhood-scale. At the center of this modeling framework, we use WRF, the weather research and forecasting model, coupled to an Urban Canopy Model (UCM) and EnergyPlus, the Department of Energy (DOE) flagship building energy model. We further use high-resolution remotely sensed land surface temperature and ground-based observations to validate the microclimate variabilities captured by the model.

We use the Los Angeles metropolitan area, known for its diverse urban landscape, socio-economic disparities, and high susceptibility to extreme heat events, as a testbed where we use the described modeling framework to identify the interacting drivers that contribute to the variability of extreme heat conditions during historically high-impact heatwaves and their unequal impacts at the neighborhood-level. Our results show that the affluent neighborhoods experience a moderated level of extreme heat conditions, particularly due to their higher vegetation cover and generous irrigation practices. Socioeconomically disadvantaged communities, on the other hand, experience exacerbated extreme heat conditions due to high urban fraction and elevated levels of anthropogenic heating. The findings of this research inform policymakers, urban planners, and community leaders about the specific microclimate of each neighborhood, guiding the development of tailored adaptation and mitigation measures.