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计数据集，基于2000年人口网格的全球农村-城市映射项目（Global Rural-Urban Mapping Project, GRUMPv1）数据集，提供了从GRUMPv1人口密度网格回溯的时间序列。通过利用全球环境历史数据库（History Database of the Global Environment, HYDE）中提供的跨世纪人口变化率，创建了这些网格。针对HYDE计算出的变化率与GRUMPv1人口数据在空间范围上的不匹配，通过基于焦点平均值填充的速率单元格得到了解决。最终，对网格进行了调整，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）中对应年份（1970年、1980年、1990年和2000年）的估计值相匹配。这些数据不代表2000年以前年份的人口普查观测值，因此最多只能被视为特定位置人口估计。人口网格在时间序列内保持内部一致性，但不建议与包括GRUMPv1、全球网格化人口（Gridded Population of the World, GPWv4）或非SEDAC开发的人口网格在内的其他任何人口网格创建更长时间序列。这些人口网格曾是SEDAC全球估计净迁移网格（按十年划分：1970-2000）数据集的输入。