USGS Gap Analysis Project Additional Data: Slope

The slope dataset was derived from the National Elevation Dataset and resulted in a slope dataset that is of the same resolution as the 30 m land cover dataset. Slope was reported in degrees. Slope is defined as the ratio of the rise divided by the run between two points on a line, expressed in degrees. Slope was generated using ArcGIS Spatial Analyst, with the USGS National Elevation Dataset as input. For quality information regarding the National Elevation Dataset, see http://ned.usgs.gov/ These data cover the entire continental U.S. and are a continuous data layer. These raster data have a 30 m x 30 m cell resolution. The Gap Analysis Project (GAP) used the best information available to create the slope data; however GAP seeks to improve and update these data as new information becomes available.

本坡度数据集源自美国国家高程数据集（National Elevation Dataset），生成的坡度数据集分辨率与30米土地覆盖数据集保持一致。坡度以度数为单位进行表征，其被定义为线段上两点间的高程变化量与水平行进距离的比值，并以度数形式表达。本坡度数据通过ArcGIS空间分析工具（ArcGIS Spatial Analyst）生成，输入数据源为美国地质调查局（USGS）的国家高程数据集。如需了解该国家高程数据集的相关质量信息，请访问http://ned.usgs.gov/。该数据集覆盖美国本土全域，为连续的栅格数据图层，栅格单元分辨率为30米×30米。间隙分析计划（Gap Analysis Project, GAP）采用当前可获取的最优信息完成了该坡度数据的制作；不过该团队将持续根据最新公开的信息对本数据集进行优化与更新。