Effective grain size and ice layer data from the top 10 meters of the 2016 - 2017 Greenland Traverse for Accumulation and Climate Studies (GreenTrACS) firn cores, western Greenland Ice Sheet

The Greenland and Antarctic ice sheets are covered in a layer of porous firn. Knowledge of firn structure improves our understanding of ice sheet mass balance, supra- and englacial hydrology, and ice core paleoclimate records. While macroscale firn properties, such as firn density, are relatively easy to measure in the field or lab, more intensive measurements of grain-scale properties are necessary to reduce uncertainty in remote sensing observations of mass balance, model meltwater infiltration, and constrain ice age -- gas age differences in ice cores. Additionally, as the duration and extent of surface melting increases, refreezing meltwater will greatly alter firn structure. Field observations of firn grain size and ice layer stratigraphy are required to test and validate physical models that simulate the ice sheet-wide evolution of the firn layer. However, visually measuring grain size and ice layer distributions is tedious, time-consuming, and can be subjective depending on the method. Here we systematically map firn core grain size and ice layer stratigraphy using a near-infrared hyperspectral imager (NIR-HSI; 900-1700 nm). We scanned 14 firn cores spanning ~1000 kilometers (km) across western Greenland’s percolation zone with the NIR-HSI mounted on a linear translation stage in a cold laboratory. We retrieve effective grain radii by inverting measured reflectance in each pixel of the images to produce high-resolution (0.4~millimeters, mm) maps of grain size and ice layer stratigraphy. This dataset contains maps of retrieved effective grain radii from 14 firn cores collected during GreenTrACS (Cores 1-8, 10-14, and 16) in Core*_grain_size_raster.csv files. The grain size data are also available in long-format .csv files as Core*_grain_size.csv. This dataset also contains the locations, thicknesses, and width of ice layers identified through visual inspection of these cores on a light table in *_ice_layers.csv files. The latitude and longitude of each core is stored in the Core_locations.csv file.