A global CORDEX-based dataset delineating urban areas and their surroundings to assess climate change in megacities

We present a global dataset of urban areas and their rural surroundings, developed within the framework of the CORDEX Flagship Pilot Study on Urban Environments and Regional Climate Change. The dataset is derived from model-specific urban fraction variables and additional static inputs. Urban and rural surrounding areas are delineated using Regional Climate Model (RCM) simulations from the global CORDEX-CORE and European EURO-CORDEX initiatives, focusing on a representative set of megacities worldwide. The analysis was conducted at horizontal resolutions of 25 km globally and 12.5 km for Europe. To facilitate future applications, we provide a Python-based workflow that can be extended for the analysis of additional cities and RCMs, including tools for evaluating the urban climate island effect. The dataset and tools, available via Zenodo and GitHub, offer a consistent and reproducible approach for assessing urban climate change in current and upcoming regional climate projections. This constitutes the first global RCM-based database of urban/rural areas, providing a foundation for future high-resolution model data analysis efforts, such as studies using convection-permitting simulations.