Self-Organizing Maps for Urban Heat Island Analysis

The urban heat island (UHI) effect describes the increase of surface and air temperatures in urban areas that can be linked to changes in the radiation and surface energy budgets between urbanized and rural landscapes. Persistent higher temperatures within the atmospheric boundary layer can lead to chronic heat exposure in vulnerable individuals. Studies have shown that heat exposure can vary across different neighborhoods and that members of marginalized communities are often disproportionately at risk for heat-related health impacts. Gaining a deeper understanding of the UHI effect, how it evolves over time and space, and how it can impact people can provide critical information to heat mitigation efforts in urban areas.

This study investigates the spatial and temporal variability of the UHI present in the greater Houston, TX area during the 2022 intensive observation period of the Tracking Aerosol Convection Interactions ExpeRiment (TRACER). Canopy layer temperature, related meteorological variables (humidity, wind speed, etc.), and resulting UHI effects over Houston are analyzed using data from the 2.5 km Unrestricted Mesoscale Analysis (URMA) reanalysis dataset from the NOAA National Centers for Environmental Prediction. A self-organizing map (SOM) is created to provide insight into typical air temperature patterns. While the SOM nodes demonstrate clear groupings based on mean temperature, spatial gradients across the domain and heat stress metrics for the greater Houston area, where coastal effects also influence thermal comfort.