DebDab: A database of physical properties of supraglacial debris

Rocky debris layers cover an increasing portion of glacier ablation areas as glaciers thin and retreat in response to climate change, progressively altering surface melt rates. However, determining the thickness and physical properties of supraglacial debris that are required for accurate representation of debris in glacier melt models is challenging, and measurements are scarce. Here, we provide an openly available dataset (DebDab, https://zenodo.org/records/14224835) that compiles physical properties and thickness of supraglacial debris over 83 glaciers in 13 regions of the Randolph Glacier Inventory. The majority of the database (90%) is compiled from 172 sources in the literature, while the remaining 10% has not been published before. DebDab contains 8,286 data entries for supraglacial debris thickness, of which 1,852 include sub-debris ablation rates too, 167 data entries of thermal conductivity of debris, 157 of aerodynamic surface roughness length, 77 of debris albedo, 56 of debris emissivity and 37 of debris porosity. We show regional differences in the distribution of debris thickness measurements, as well as an uneven spatial coverage with well-sampled regions like Central Europe and South Asia, but gaps in the Andes and  Alaska. Additionally, debris thickness measurements are mostly concentrated at lower glacier elevations, leaving mid-glacier areas under-sampled, which may affect the dataset's representativeness. We also provide the most detailed scatter plot of debris thickness and ablation rates yet, with Østrem curves fitted for 19 glaciers, based entirely on observational data, and supporting the well-documented reduction in melt rates after the initial few centimetres of debris and the subsequent minimal reduction in melt rates for thicker debris. DebDab can be used in energy balance, melt and surface mass balance models by incorporating site-specific debris properties, or to evaluate remote  sensing estimates of debris thickness and surface roughness. It can also help future field campaigns on debris-covered glaciers by identifying undersampled regions, glaciers and properties. DebDab is open to new data submissions from the community as more data of supraglacial debris properties become available.