Global Monthly and Seasonal Urban and Land Backscatter Time Series, v1 (1993 – 2020)

The Global Monthly and Seasonal Urban and Land Backscatter Time Series, 1993-2020, is a multi-sensor, multi-decadal, data set of global microwave backscatter, for 1993 to 2020. It assembles data from C-band sensors onboard the European Remote Sensing Satellites (ERS-1 and ERS-2) covering 1993-2000, Advanced Scatterometer (ASCAT) onboard EUMETSAT satellites for 2007-2020, and the Ku-band sensor onboard the QuikSCAT satellite for 1999-2009, onto a common spatial grid (0.05 degree latitude /longitude resolution) and time step (both monthly and seasonal). Data are provided for all land (except high latitudes and islands), and for urban grid cells, based on a specific masking that removes grid cells with > 50% open water or 20% built land. The all-land data allows users to choose and evaluate other urban masks. There is an offset between C-band and Ku-band backscatter from both vegetated and urban surfaces that is not spatially constant. There is a strong linear correlation (overall R-squared value = 0.69) between 2015 ASCAT urban backscatter and a continental-scale gridded product of building volume, across 8,450 urban grid cells (0.05 degree resolution) from large cities in Europe, China, and the United States.1993-2020年全球月度与季尺度城市及陆地后向散射时间序列数据集是一套多传感器、多年代的全球微波后向散射数据集，时间跨度为1993至2020年。该数据集整合了三类传感器的观测数据：1993-2000年欧洲遥感卫星（European Remote Sensing Satellites, ERS-1与ERS-2）搭载的C波段传感器数据、2007-2020年欧洲气象卫星应用组织（EUMETSAT）卫星搭载的先进散射计（Advanced Scatterometer, ASCAT）数据，以及1999-2009年QuikSCAT卫星搭载的Ku波段传感器数据，并将所有数据统一至公共空间网格（纬度/经度分辨率0.05°）与时间步长（涵盖月度与季尺度两种）。数据集覆盖范围包含所有陆地（高纬度区域与岛屿除外）以及符合特定掩膜规则的城市格网单元：该掩膜方案会剔除开放水域占比超过50%或建成区占比超过20%的格网。全域陆地数据可供用户自主选择并评估其他城市掩膜方案。C波段与Ku波段后向散射信号在植被覆盖区与城市地表均存在非空间恒定的偏移量。针对欧洲、中国与美国大城市的8450个0.05°分辨率城市格网单元的验证结果显示，2015年ASCAT城市后向散射数据与大陆尺度格网化建筑体积产品之间存在显著线性相关关系，整体决定系数（R-squared）为0.69。