World Soils 250m Uncertainty

Values in the 11 World Soils 250m datasets are predictions made by soilgrids.org for the most likely value for a particular place. They use the best available data for what the value would most likely be in that location. Phenomenon Mapped: The ratio between the inter-quantile range (90% prediction interval width) and the median : (Q0.95-Q0.05)/Q0.50. The values are multiplied by 10. Time Extent: May 2021 Units: meters Cell Size: 250m Source Type: scientific Pixel Type: 16 bit integer Data Coordinate System: Data was originally in Goode's Homolosine (land) projection, projected to Web Mercator (via nearest neighbor) Mosaic Projection: Web Mercator (102100) Extent: World land areas, except for Antarctica NoData Value: Source: ISRIC Publication Date: May 2021 Analysis: Analysis-Optimized Because data quality varies worldwide, the uncertainty of the predicted value varies worldwide. For this reason they published a most likely value (mean) for each pixel alongside a map of the uncertainty for that pixel. This multidimensional uncertainty layer with 11 variables and six depth ranges serves a collection of raw soil uncertainty information from ISRIC soilgrids for the world in 16 bit format. In general, the more uncertain the value for a particular pixel, the redder the pixel for that value will be. Each time you pan or zoom the map, or choose a different variable, the red uncertainty color ramp will adjust itself to what you're seeing, and recolor the map to show relatively the least to most uncertain values in your map. Soilgrids quantifies uncertainty as is the ratio between the inter-quantile range (90% prediction interval width) and the median: (Q0.95-Q0.05)/Q0.50. The values are multiplied by 10 in order to have integers and reduce the size of the datasets. For more on how the predictions and uncertainty were made see the soilgrids.org faq. Analysis In order to leverage the optimization for analysis, the capability must be enabled by your ArcGIS organization administrator. More information on enabling this feature can be found in the ‘Regional data hosting’ section of this help doc. Optimized for analysis means this layer does not have size constraints for analysis and it is recommended for multisource analysis with other layers optimized for analysis. See the ArcGIS Living Atlas: Analysis-Optimized Imagery Layers Group for a complete list of imagery layers optimized for analysis. Read more in our blogs: Dsicoveries and Revelations: Exploring the World Soils 250m Layers Getting Started with Multidimensional Soil Layers in the ArcGIS Living Atlas of the World本数据集包含11项全球土壤250米分辨率（World Soils 250m）数据集的数值，所有数值均由soilgrids.org生成，代表特定地点的最可能土壤属性值，其计算基于当前可获取的最优观测数据。映射现象：分位数间距（90%预测区间宽度）与中位数的比值，即(Q0.95-Q0.05)/Q0.50。所有数值已乘以10。时间范围：2021年5月。单位：米。像元（Pixel）尺寸：250米。数据类型：科学数据。像素类型：16位整型。数据坐标系：原始数据采用古德同源等面积（Goode's Homolosine）（陆地）投影，后通过最近邻重采样投影至Web墨卡托（Web Mercator）投影。镶嵌投影：Web墨卡托（Web Mercator，102100）。覆盖范围：全球陆地（南极洲除外）。无数据值：来源：国际土壤信息与研究中心（ISRIC）。发布日期：2021年5月。分析优化说明：本图层为分析优化型图层。由于全球各地数据质量存在差异，预测值的不确定性也呈现区域异质性。因此，数据集同步发布了每个像元的最可能预测值（均值），以及对应像元的不确定性空间分布图。该多维不确定性图层涵盖11个变量与6个深度层级，整合了来自ISRIC soilgrids的全球原始土壤不确定性信息，采用16位整型格式存储。一般而言，特定像元的属性值不确定性越高，其在对应图层中的显示颜色就越偏红。每当用户平移、缩放地图，或切换不同变量时，红色的不确定性色阶会自动适配当前视图范围，并重新渲染地图，以展示当前视图内从最低到最高的相对不确定性分布。soilgrids将不确定性量化为分位数间距（90%预测区间宽度）与中位数的比值：(Q0.95-Q0.05)/Q0.50。为使数值以整型形式存储并缩减数据集体积，所有比值均已乘以10。如需了解预测与不确定性计算的详细方法，请参阅soilgrids.org的常见问题解答页面。分析优化功能启用说明：若需使用分析优化功能，需由您所在的ArcGIS组织管理员启用该权限。有关启用此功能的更多详情，请参阅本文档的“区域数据托管”章节。分析优化意味着该图层不受分析的大小限制，推荐与其他分析优化型图层进行多源联合分析。完整的分析优化影像图层列表，请参阅ArcGIS全球生活地图集（ArcGIS Living Atlas）的“分析优化影像图层群组”。更多详情请参阅我们的官方博客文章：《探索全球土壤250米分辨率图层：发现与启示》、《ArcGIS全球生活地图集中多维土壤图层入门指南》。