Gridded Population of the World, Version 4 (GPWv4): Data Quality Indicators, Beta Release

The Gridded Population of the World, Version 4 (GPWv4) Data Quality Indicators, Beta Release 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) and pixels that also contain land (Partial Water 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.

世界栅格人口第四版（Gridded Population of the World, Version 4，简称GPWv4）数据质量指标测试版包含三类数据图层，旨在为人口计数与密度栅格数据提供背景支撑，并明确标注输入边界数据的空间精度。数据背景栅格（Data Context raster）可基于普查文档中的相关信息，对人口计数与密度栅格中「人口估算值为0」的像元作出说明——例如纳入国家公园的区域、无住户的区域等。水体掩膜栅格（Water Mask raster）可区分完全被水体或冰覆盖的像元（全水体像元）与同时包含陆地的像元（部分水体像元）。平均行政单元面积栅格（Mean Administrative Unit Area raster）以平方千米为单位表征输入单元的平均尺寸，并生成量化表面以展示用于生成人口计数与密度栅格的输入单元的大小。该数据文件以全球栅格形式发布，分辨率为30弧秒（赤道区域约合1千米）。为提升全球数据处理效率并服务科研群体，研究人员将30弧秒分辨率的数据聚合为2.5弧分、15弧分、30弧分及1度四种分辨率。