Global Population Density Grid Time Series Estimates

The Global Population Density Grid Time Series Estimates provide a back-cast time series of population density grids based on the year 2000 population grid from SEDAC's Global Rural-Urban Mapping Project, Version 1 (GRUMPv1) data set. The grids were created by using rates of population change between decades from the coarser resolution History Database of the Global Environment (HYDE) database to back-cast the GRUMPv1 population density grids. Mismatches between the spatial extent of the HYDE calculated rates and GRUMPv1 population data were resolved via infilling rate cells based on a focal mean of values. Finally, the grids were adjusted so that the population totals for each country equaled the UN World Population Prospects (2008 Revision) estimates for that country for the respective year (1970, 1980, 1990, and 2000). These data do not represent census observations for the years prior to 2000, and therefore can at best be thought of as estimations of the populations in given locations. The population grids are consistent internally within the time series, but are not recommended for use in creating longer time series with any other population grids, including GRUMPv1, Gridded Population of the World, Version 4 (GPWv4), or non-SEDAC developed population grids. These population grids served as an input to SEDAC's Global Estimated Net Migration Grids by Decade: 1970-2000 data set.

全球人口密度网格时间序列估算数据集，基于SEDAC全球农村-城市映射项目第一版（GRUMPv1）数据集中的2000年人口网格，提供了人口密度网格的时间序列回溯。该网格的创建是通过采用全球环境历史数据库（HYDE）数据库中世纪间人口变化率，对GRUMPv1人口密度网格进行回溯得到的。HYDE计算速率的空间范围与GRUMPv1人口数据之间的不匹配，通过基于焦点平均值的价值填充率单元格得到解决。最终，网格被调整，以确保每个国家的人口总数与联合国世界人口展望（2008年修订版）中该国相应年份（1970年、1980年、1990年和2000年）的估计值相等。这些数据不代表2000年以前年份的普查观测值，因此至多只能被视为给定地点人口估算。人口网格在时间序列内部保持一致性，但不建议与包括GRUMPv1、世界人口网格第四版（GPWv4）或非SEDAC开发的人口网格在内的任何其他人口网格创建更长的时间序列。这些人口网格曾作为SEDAC全球按十年估算的净迁移网格数据集的输入。