DOI: 10.5061/dryad.34tmpg4t4
title: Modeling polar bear (Ursus maritimus) snowdrift den habitat on Alaska’s Beaufort Sea coast using SnowDens-3D and ArcticDEM data

description: Pregnant polar bears (Ursus maritimus) excavate maternal dens in seasonal
 snowdrifts during fall along Alaska’s Beaufort Sea coast to shelter their
 altricial young during birth and development. With recent sea ice
 decreases, bears are denning more frequently on land. Each year, the
 weather and blowing-snow conditions control the creation of snowdrifts
 across the landscape, and the available snowdrift den habitat can vary
 widely from one year to the next, depending on the late fall and early
 winter air temperature, snowfall, and wind speed and direction. We
 implemented a physics-based, spatiotemporal, polar bear snowdrift den
 habitat model (SnowDens-3D) across the eastern Alaska Beaufort Sea coast
 (an area of approximately 17,000 km^2^). High-resolution (2.0 m)
 topography data were provided by the ArcticDEM, and daily meteorological
 forcings were provided by NASA’s MERRA-2 reanalysis. A 21-year (2000–2020)
 SnowDens-3D simulation was performed, and model outputs were compared with
 91 historical polar bear den locations. The year-specific simulations
 produced viable den habitat for 98% of the observed den locations. The
 interannual variation in den habitat area over the 21-year period
 increased by approximately a factor of three from the minimum year (2001;
 554 km^2^) to the maximum year (2017; 1,566 km^2^). This data archive
 provides the key den and den-habitat datasets produced, used, and analyzed
 by this project.
description: # Modeling polar bear (*Ursus maritimus*) snowdrift den habitat on
 Alaska’s Beaufort Sea coast using SnowDens-3D and ArcticDEM data ##
 Dataset Authors, Title, and DOI Link Authors = Katherine Gura, Colorado
 State University,
 [Katherine.Gura@ColoState.Edu](mailto:Katherine.Gura@ColoState.Edu) Glen
 E. Liston, Colorado State University,
 [Glen.Liston@ColoState.Edu](mailto:Glen.Liston@ColoState.Edu) Dataset
 Title and DOI Link = Modeling polar bear (*Ursus maritimus*) snowdrift den
 habitat on Alaska’s Beaufort Sea coast using SnowDens-3D and ArcticDEM
 data, data archive. [Dataset]. Dryad.
 [https://doi.org/10.5061/dryad.34tmpg4t4](https://doi.org/10.5061/dryad.34tmpg4t4) ## Data file Archive Data File Name = AK_PBDH_SD3D_Data_Archive.zip This AK_PBDH_SD3D_Data_Archive.zip file includes the files described in the README_Data_for_Alaska_SnowDens-3D_and_ArcticDEM_Modeling.md (and .pdf) file. ## Description of the data and data files ### 1) GeoTIFF/AK\_PBDH\_SD3D\_20m\_\*\*\*\*.tif (22 files) This file collection includes: A 20.0 m resolution, 31 December, den habitat climatology GeoTIFF file over the SnowDens-3D simulation area; and GeoTIFF files of the 21, year-specific (2000–2020), 20.0 m, snowdrift habitat distributions on 31 December of each year. The files are in the standard NAD 1983 Alaska Albers Equal Area projection: +proj=aea +lat_1=55 +lat_2=65 +lat_0=50 +lon_0=-154 +x_0=0 +y_0=0 +ellps=GRS80 +datum=NAD83 +units=m +no_defs The data values are: 1 = potential polar bear den habitat 2 = non-habitat 3 = the SnowDens-3D simulation domain (= the red polygon in Liston et al. 2024) 4 = the ocean mask used in the simulations ### 2) AK\_PBDH\_SD3D\_Table\_1\_w-latlon.csv This file is the equivalent of Table 1 in Liston et al. (2024), that includes the 91 den identification numbers and distances to den habitat used in the study, but this file also includes the latitude-longitude den coordinates of the 91 analyzed dens. The column headers are: count,year,id,latitude,longitude,distance(m) ### 3) AK\_PBDH\_SD3D\_Blowing\_Snow\_Fluxes.csv The file, AK_PBDH_SD3D_Blowing_Snow_Fluxes.csv, contains the blowing snow fluxes, summed over the period 1 Sep through 31 Dec, in units of m^3^/m, for each year of the SnowDens-3D simulation. Column 1 = year number (1-21) Column 2 = year (2000-2020) Column 3 = the sum of the fluxes from all wind directions Columns 4-11 = the flux from winds FROM each of the wind directions: N,NE,E,SE,S,SW,W,NW (e.g., N = winds blowing from the north) ### 4) 20-Sites\_Figure.pdf This is a .pdf version of the Liston et al. (2024) figure that compares the simulated den habitat with 20 den location observations. ### 5) 91-Sites\_Figure.pdf This is a .pdf figure of all 91 den locations and the simulated den habitat analyzed in Liston et al. (2024). It is in the same format as the 20-Sites_Figure.pdf file.