Global aboveground biomass carbon density of crops in the year 2010 – uncertainty

This layer represents the uncertainty of the aboveground biomass (AGB) carbon (C) density estimates for crops that were used to create the harmonized global AGB C density map of Spawn et al. (2020). It has been scaled by 10 to reduce file size and should by multiplied by 0.1 before analysis to attain units of megagrams C per hectare (MgC/ha). Since crops may coexist with other vegetation types within the extent of a given grid cell, estimates in this layer have been proportionally adjusted to account for the relative spatial extent that crops are assumed to occupy in each grid cell. Grid cells that do not contain crops report a value of zero. As such, taking the pixelwise root sum of the squared accompanying layers for tree, grass, tundra and crop AGB C will produce the uncertainty layer of the harmonized global AGB C density map of Spawn et al. (2020).本图层用于表征用于生成Spawn等人（2020）发布的标准化全球地上生物量（Aboveground Biomass, AGB）碳（Carbon, C）密度地图的作物地上生物量碳密度估算值的不确定性。为缩减文件体积，该图层已按10倍比例进行缩放，在开展分析前需乘以0.1，方可转换为每公顷兆克碳（megagrams C per hectare, MgC/ha）的单位。由于给定网格单元的范围内，作物可能与其他植被类型共存，因此本图层的估算值已通过比例调整，以反映各网格单元中假定作物所占据的相对空间范围。未包含作物的网格单元的数值为0。据此，对树木、草本、苔原和作物的地上生物量碳密度配套图层逐像素求取平方和的平方根，即可得到Spawn等人（2020）发布的标准化全球地上生物量碳密度地图的不确定性图层。