There has been a renewed focus on the disparity in extreme heat conditions experienced by communities living in urban areas. These disparities have raised critical concerns about social equity and environmental justice, emphasizing the need for a comprehensive understanding of the factors contributing to the heterogeneity of urban microclimates. Such understanding is essential to inform targeted strategies that enhance equitable urban resilience. In this study, we use Los Angeles as a testbed to understand the interactions between local urban processes and large-scale atmospheric processes that define the heterogeneity of urban microclimates under extreme heat conditions.

We incorporate neighborhood-level representations of important urban processes such as anthropogenic heating from buildings, vegetation cover, irrigation patterns, and urban morphology into a high-resolution, high-fidelity urban microclimate modeling framework. At the center of this modeling framework is WRF, the Weather Research and Forecasting model, coupled with a multi-layer urban canopy model known as Building Environment Parameterization (BEP) and EnergyPlus, the Department of Energy's (DOE) flagship building energy model.

Our results show that affluent neighborhoods experience moderated levels of extreme heat conditions due to the cooling benefits of higher vegetation cover, generous irrigation practices as well as sea breezes and natural ventilation. In contrast, socioeconomically disadvantaged communities face exacerbated extreme heat conditions due to a 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.