Global 1-km Downscaled Urban Land Extent Projection and Base Year Grids by SSP Scenarios, 2000-2100

The Global 1-km Downscaled Urban Land Extent Projection and Base Year Grids by SSP Scenarios, 2000-2100 consists of global SSP-consistent spatial urban land fraction data for the base year 2000 and projections at ten-year intervals for 2010-2100 at a resolution of 1-km (about 30 arc-seconds). An algorithm was developed and validated to downscale the 1/8-degree resolution data set to 1-km resolution. For a given decade, the downscaling algorithm allocates the 1/8-degree decadal amount of urban land expansion to 1-km grid cells in proportion to their total urban land amounts at the beginning of the decade. The algorithm uses an iterative process to collect any overflows from already highly-developed 1-km grid cells, and then allocates them to 1-km grid cells that are not yet fully developed. This iterative process repeats itself until all 1/8-degree amounts of urban land expansion are allocated to 1-km grid cells with no overflow. The downscaling process is applied decade by decade throughout the 21st century for each urban land expansion scenario. The final product is a set of global maps displaying the 1-km fraction of urban land, updated at decadal intervals throughout the 21st century, for five different urban land expansion scenarios consistent with the Shared Socioeconomic Pathways (SSPs).

该全球1公里分辨率下的城市土地利用范围预测数据集，基于SSP情景，涵盖2000年至2100年期间的数据，包括2000年的基础年数据以及每十年一次的预测数据，预测范围从2010年至2100年，分辨率达到1公里（约30弧秒）。本研究开发并验证了一种算法，用于将1/8度分辨率的原始数据集下采样至1公里分辨率。对于特定十年，下采样算法将1/8度分辨率的年度城市土地扩张量按比例分配至该十年初的1公里网格单元中，比例基于其总的城市土地面积。算法通过迭代过程收集已高度发展的1公里网格单元中的溢出量，并将其分配给尚未完全发展的1公里网格单元。这一迭代过程持续进行，直至所有1/8度分辨率的城市土地扩张量均被分配至1公里网格单元，且无溢出发生。该下采样过程在21世纪针对每个城市土地扩张情景逐十年进行。最终成果是一套全球地图集，展示了21世纪每十年更新一次的1公里分辨率城市土地利用比例，共包括与共享社会经济路径（SSP）相一致的五种不同的城市土地扩张情景。