Median of Percent Slope over 300 m derived from 1" SRTM DEM-S

Slope measures the inclination of the land surface from the horizontal. Percent slope represents this inclination as the ratio of change in height to distance. The focal median of percent slope can be used as a surrogate for modal slope in landform pattern analysis.\n\nThe 300 m focal median percent slope product was derived from the Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016), which was derived from the 1 arc-second resolution SRTM data acquired by NASA in February 2000. The calculation of focal median slope from percent slope accounted for the varying spacing between grid points in the geographic projection.\n\nThis collection includes Median of Percent Slope (over 300 m) at 1 arc-second and 3 arc-second resolutions.\n\nThe 3 arc-second resolution product was generated from the 1 arc-second 300 m focal median of percent slope product and masked by the 3” water and ocean mask datasets.\nLineage: Source data\n1.\t1 arc-second 300 m focal median of percent slope product\n2.\t1 arc-second percent slope product\n3.\t1 arc-second SRTM-derived Smoothed Digital Elevation Model (DEM-S; ANZCW0703014016).\n4.\t3 arc-second resolution SRTM water body and ocean mask datasets\n\nFocal median slope calculation\nMedian slope using a 300 m window was calculated for each grid point from percent slope using a 300 m kernel. The different spacing in the E-W and N-S directions due to the geographic projection of the data was accounted for by using the actual spacing in metres of the grid points (calculated from the latitude), and recalculating the grid points included within the kernel extent for each row in the grid.\n\nThe focal median slope calculation was performed on 1° x 1° tiles, with overlaps to ensure correct values at tile edges.\n\nThe 3 arc-second resolution version was generated from the 1 arc-second 300 m focal median of percent slope product. This was done by aggregating the 1” data over a 3 x 3 grid cell window and taking the mean of the nine values that contributed to each 3” output grid cell. The 3” 300 m focal median of percent slope data were then masked using the SRTM 3” ocean and water body datasets.