Global Terrestrial Network for Permafrost metadata for permafrost boreholes (TSP) and active layer monitoring (CALM) sites

The Global Terrestrial Network for Permafrost (GTN-P) provides the first dynamic database associated with the Thermal State of Permafrost (TSP) and the Circumpolar Active Layer Monitoring (CALM) programs, which extensively collect permafrost temperature and active layer thickness (ALT) data from Arctic, Antarctic and mountain permafrost regions. The purpose of GTN-P is to establish an early warning system for the consequences of climate change in permafrost regions and to provide standardized thermal permafrost data to global models. In this paper we introduce the GTN-P database and perform statistical analysis of the GTN-P metadata to identify and quantify the spatial gaps in the site distribution in relation to climate-effective environmental parameters. We describe the concept and structure of the data management system in regard to user operability, data transfer and data policy. We outline data sources and data processing including quality control strategies based on national correspondents. Assessment of the metadata and data quality reveals 63 % metadata completeness at active layer sites and 50 % metadata completeness for boreholes.
Voronoi tessellation analysis on the spatial sample distribution of boreholes and active layer measurement sites quantifies the distribution inhomogeneity and provides a potential method to locate additional permafrost research sites by improving the representativeness of thermal monitoring across areas underlain by permafrost. The depth distribution of the boreholes reveals that 73 % are shallower than 25 m and 27 % are deeper, reaching a maximum of 1 km depth. Comparison of the GTN-P site distribution with permafrost zones, soil organic carbon contents and vegetation types exhibits different local to regional monitoring situations, which are illustrated with maps. Preferential slope orientation at the sites most likely causes a bias in the temperature monitoring and should be taken into account when using the data for global models. The distribution of GTN-P sites within zones of projected temperature change show a high representation of areas with smaller expected temperature rise but a lower number of sites within Arctic areas where climate models project extreme temperature increase.

全球冻土陆地网络（Global Terrestrial Network for Permafrost，GTN-P）构建了首个关联冻土热状态（Thermal State of Permafrost，TSP）与环极活动层监测（Circumpolar Active Layer Monitoring，CALM）项目的动态数据库，该网络从北极、南极及山地冻土区域广泛采集冻土温度与活动层厚度（active layer thickness，ALT）数据。GTN-P的核心目标是为冻土区域的气候变化影响构建早期预警系统，并为全球气候模型提供标准化的冻土热参数数据。本文首先介绍GTN-P数据库，随后对其元数据开展统计分析，以识别并量化站点分布中与气候影响型环境参数相关的空间缺口。本文还从用户可操作性、数据传输及数据政策三个维度，阐述了该数据管理系统的设计理念与架构。此外，本文梳理了数据来源与数据处理流程，其中包括基于国家联络专员的质量控制策略。对元数据与数据质量的评估结果显示，活动层监测站点的元数据完整率为63%，钻孔监测站点的元数据完整率为50%。
针对钻孔与活动层监测站点的空间采样分布开展的泰森多边形（Voronoi tessellation）分析，量化了站点分布的非均质性，并提出了一种潜在方法：通过提升冻土覆盖区域热监测的代表性，来确定新增冻土研究站点的位置。钻孔的深度分布情况显示，73%的钻孔深度小于25米，剩余27%的钻孔深度更大，最大钻孔深度可达1千米。将GTN-P站点分布与冻土分区、土壤有机碳含量及植被类型进行对比后，可发现不同局地至区域尺度的监测现状存在差异，相关差异通过配图进行了说明。监测站点存在的偏好坡向问题，很可能会给温度监测带来偏差，在将该数据用于全球模型时需予以考量。在气候模型预测的温度变化区域中，GTN-P站点在预期升温幅度较小的区域覆盖度较高，但在气候模型预测会出现极端升温的北极区域，站点数量相对较少。