GloIDF: a global present-climate sub-daily rainfall intensity-duration-frequency (IDF) dataset at 30 arc-second resolution (v0.1)

GloIDF (Global IDF Dataset) v0.1 is a global, present-climate, sub-daily rainfall intensity–duration–frequency (IDF) product on a 30 arc-second grid (about 1 km, or 0.6 miles, at the equator). It provides rainfall intensity estimates for durations of 1, 2, 3, 6, 12, and 24 hours and return periods of 1, 2, 5, 10, 25, 50, 100, 200, 500, 1000, 3000, 5000, and 10,000 years, together with the five fitted SMEV (Simplified Metastatistical Extreme Value) duration-scaling parameter fields from which the return levels are derived. The product is built by fitting the SMEV distribution to sub-daily rainfall at weather stations and virtual stations, then extrapolating the fitted parameters across the globe with a random-forest model conditioned on high-resolution climatic and topographic predictors (including CHELSA layers), and evaluating return levels on a common 30 arc-second grid. It represents a present-climate baseline derived from recent historical reanalysis and gauge archives; no future climate-change adjustment is embedded. Data are distributed as two multi-band Cloud-Optimized GeoTIFFs (COGs): a parameter file containing the fitted SMEV duration-scaling fields, and a return-level file containing rainfall intensity estimates for the standard duration and return-period combinations. GloIDF is intended as a globally consistent, screening-level first estimate of sub-daily design rainfall for planning and first-order hydrologic analysis, particularly where national IDF atlases are unavailable, inconsistent, or difficult to access. It is not a replacement for local regulatory IDF standards or site-specific, high-consequence design studies. Full methodology: GloIDF Methodology Documentation (Rasmussen, 2026), https://design.degreeday.org/GloIDF_methodology.pdf. Interactive access: Degree Day Design Explorer, https://design.degreeday.org. Licensing. GloIDF is released under Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0). Under an additional Permitted-Uses Grant from Degree Day LLC, academic, non-profit, NGO, intergovernmental, humanitarian, and public-sector use is expressly free of charge and treated as non-commercial, including where costs are recovered (cost-recovery fees) and including climate-adaptation work in low- and middle-income countries. Commercial use (for-profit products, services, or consulting) requires a separate paid Degree Day licence: [e-mail]. Full terms are in the included LICENSE-GloIDF.md.