Annual PM2.5 Concentrations for Urban Areas, v1 (1998-2016)

The Annual PM2.5 Concentrations for Countries and Urban Areas, 1998-2016, consists of mean concentrations of particulate matter (PM2.5) for countries and urban areas. The PM2.5 data are from the Global Annual PM2.5 Grids from MODIS, MISR and SeaWiFS Aerosol Optical Depth (AOD) with GWR, 1998-2016. The urban areas are from the Global Rural-Urban Mapping Project, Version 1 (GRUMPv1): Urban Extent Polygons, Revision 02, and its time series runs from 1998 to 2016. The country averages are population-weighted such that concentrations in populated areas count more toward the country average than concentrations in less populated areas, and its time series runs from 2008 to 2015.《1998-2016年各国及城区年度PM2.5浓度数据集》涵盖各国与城区的细颗粒物（PM2.5，particulate matter 2.5）平均浓度数据。该数据集的PM2.5浓度源自1998-2016年基于MODIS、MISR及SeaWiFS气溶胶光学厚度（Aerosol Optical Depth, AOD）数据，结合地理加权回归（Geographically Weighted Regression, GWR）生成的全球年度PM2.5格网数据集。城区范围数据源自全球城乡制图项目第一版（Global Rural-Urban Mapping Project Version 1, GRUMPv1）的第2次修订版城区范围多边形数据集，其时序覆盖1998年至2016年。各国平均浓度采用人口加权计算方式：人口密集区域的浓度对国家平均浓度的贡献权重高于人口稀疏区域，其时序覆盖范围为2008年至2015年。