High-resolution thermal exposure and shade maps for cool corridor planning

Shade is crucial for thermally comfortable cities that promote physical activity. City-wide shade and thermal exposure data are essential for managing heat health risks but are difficult to obtain at fine scales due to limited sensing and modeling capabilities. To address this gap and assist municipalities with "cool corridor" planning, we generated 1-m resolution shade and mean radiant temperature (T_MRT) maps from LiDAR point clouds for the Phoenix-Tempe metropolitan area using the SOLWEIG model. T_MRT estimates were validated using 763 observations with a mobile human-biometeorological 6-directional setup. SOLWEIG had an overall RMSE of 5.6°C with an error of 6.2°C at open sites, 5.4°C under trees, and 4.4°C in building canyons. Hourly T_MRT and shade maps were generated from 7:00 h to 20:00 h for June 27, 2012, a typical clear, dry, calm summer day. We assessed sidewalk shade coverage based on the Maricopa Association of Government's Active Transportation Plan. Only 8% of all sidewalks met the recommended minimum of 20% shade coverage at all times. Less than 50% of all sidewalks met the goal for parts of the day, indicating that the urban area is not walkable during extreme heat. Results from this study will inform municipal cool corridor planning to optimize site selection for heat mitigation.