Investigators applied the Frozen Ground Model to the entire Arctic Drainage Basin to create this data set of active layer depth (ALD), recorded in centimeters. This model has been shown to provide excellent results for active layer depth and soil temperatures when driven with well-known boundary conditions and forcing parameters at specific locations. The model is driven by 2-meter air temperatures from the ERA-40 European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis. The reanalysis data are provided on a N80 reduced Gaussian grid, which is symmetric about the Equator with 80 latitudinal points in each hemisphere. Data represent a subset of the entire 25 km Equal-Area Scalable Earth Grid (EASE-Grid) for the Northern Hemisphere (721 x 721 = 39,926 grid cells). There are monthly files for 23 years, 1979-2001, with a daily time step. Data are in space-delimited ASCII text format, and are available via FTP.