Gridded Population of the World, Version 4 (GPWv4): Data Quality Indicators, Revision 11

The Gridded Population of the World, Version 4 (GPWv4): Data Quality Indicators, Revision 11 consists of three data layers created to provide context for the population count and density rasters, and explicit information on the spatial precision of the input boundary data. The Data Context raster explains pixels with a "0" population estimate in the population count and density rasters based on information included in the census documents, such as areas that are part of a national park, areas that have no households, etc. The Water Mask raster distinguishes between pixels that are completely water and/or ice (Total Water Pixels), pixels that contain water and land (Partial Water Pixels), pixels that are completely land (Total Land Pixels), and pixels that are completely ocean water (Ocean Pixels). The Mean Administrative Unit Area raster represents the mean input Unit size in square kilometers and provides a quantitative surface that indicates the size of the input Unit(s) from which population count and density rasters are created. The data files were produced as global rasters at 30 arc-second (~1 km at the equator) resolution. To enable faster global processing, and in support of research commUnities, the 30 arc-second data were aggregated to 2.5 arc-minute, 15 arc-minute, 30 arc-minute and 1 degree resolutions.

《世界网格人口数据集，第四版（GPWv4）：数据质量指标，修订版11》包含三个数据层，旨在为人口计数和密度栅格提供背景信息，并明确指出输入边界数据的空间精度。数据背景栅格解释了人口计数和密度栅格中估计人口为“0”的像素，基于普查文件中包含的信息，例如国家公园内的区域、无家庭的区域等。水掩膜栅格区分了完全为水或冰的像素（总水像素）、包含水和陆地的像素（部分水像素）、完全为陆地的像素（总陆像素）以及完全为海洋水的像素（海洋像素）。平均行政区划面积栅格表示输入单元的平均尺寸，以平方公里为单位，并提供了定量表面，用以指示生成人口计数和密度栅格的输入单元的大小。数据文件以全球栅格形式产生，分辨率为30弧秒（赤道附近约为1公里）。为加快全球处理速度，并支持研究社区，30弧秒的数据已汇总至2.5弧分、15弧分、30弧分和1度分辨率。