Gridded active layer thickness across northern permafrost regions from 2003 to 2020

This dataset provides the annual gridded active layer thickness (ALT) across northern permafrost regions (NPR) at 1 km resolution for the period 2003–2020. The ALT in permafrost regions refers to the upper layer of soil that thaws and refreezes annually as a result of seasonal temperature variations. It is a critical parameter in permafrost studies because it determines the depth to which plant roots can penetrate and influences various ecological and engineering processes. This dataset was produced based on the relationship between available ALT site measurements (2966 site-years) and satellite observations of annual gridded predictors, including vegetation, temperature, soil, and topography, using a Random Forest (RF) approach. The annual ALT map for the NPR was generated using the ensemble mean of ALT from the ten best RF predictions. Extensive uncertainty analysis was also conducted. The dataset can be viewed at https://liuzh833.users.earthengine.app/view/altv1本数据集提供了2003-2020年期间、分辨率为1千米的北方多年冻土区（Northern Permafrost Regions, NPR）逐年格点化活动层厚度（Active Layer Thickness, ALT）数据。多年冻土区的活动层厚度，指的是受季节温度变化影响，每年发生冻融循环的表层土壤厚度。它是多年冻土研究中的关键参数：不仅决定了植物根系可穿透的深度，还对各类生态与工程过程产生重要影响。本数据集基于共2966个站点年的活动层厚度野外实测数据，与卫星观测得到的逐年格点化预测因子（包括植被、温度、土壤与地形数据）之间的关联，采用随机森林（Random Forest, RF）方法构建得到。研究通过对表现最优的10组随机森林预测结果取集合平均，生成了北方多年冻土区逐年活动层厚度格点图，并开展了全面的不确定性分析。 用户可通过https://liuzh833.users.earthengine.app/view/altv1查看该数据集。