SOLWEIG for Near Real-Time heat assessment at city scale

Urban heat assessment and adaptation planning are critical for local governments to address the increasing challenges posed by climate change. While many plans are being developed, the integration of the latest scientific methods and tools remains limited.

SOLWEIG is an established tool for assessing radiation exposure in urban areas and has been used in numerous case studies to analyze heat vulnerability in neighborhoods and cities worldwide. Unlike other more extensive tools, that use resource-intensive calculations for atmospheric modelling, such as PALM or WRF, SOLWEIG focuses on radiation modeling and operates comparatively fast with only a few input parameters.

Within the Data2Resilience (D2R) project we explore how to integrate SOLWEIG into a near real-time (NRT) service for the city of Dortmund to approximate the current heat stress. For this purpose, SOLWEIG is decoupled from its QGIS dependencies and input parameterization is replaced with configuration files, allowing for automatic and parallel calculation of mean radiant temperature (MRT) rasters. The resulting MRT maps are then combined with recent in-situ measurements from the city’s measurement network and ICON-D2 NWPs to generate hourly maps of thermal comfort (UTCI) for a moderate-sized European city with 600K inhabitants at a 3 m resolution. While SOLWEIG is capable of a higher resolution, the chosen resolution of 3 m is a trade-off between runtime, computing power and memory capacities. The generated rasters are stored as Cloud Optimized GeoTIFFs and ingested into a raster database to facilitate efficient access and further use in various applications. Overall, the data pipeline relies on open data, like surface information and weather predictions, and open-source tools and is finally run in a docker container on a local server.