基于《中国冰川冻土沙漠图》的中国冻土分布图（1981-2006）

该数据是对中国冰川冻土沙漠图（1：400万）中冻土分布图的数字化，该图中考虑与全球冻土分类系统的统一，将多年冻土分为五类，包括：
（1）不连续多年冻土：连续系数50%-90%
（2）岛状多年冻土：连续系数<50%
（3）高原不连续多年冻土：连续系数50%-90%
（4）高原岛状多年冻土：连续系数50%-90%
（5）山地多年冻土。
冻土图的编制依据包括：（1）冻土野外调查、勘探实测资料；（2）航空像片和卫星影像判译；（3）TOPO30 1km分辨率的地面高程数据；（4）气温和地面温度资料。其中，青藏高原的冻土分布采用了南卓铜等（2002）的研究结果，利用青藏公路沿线76个钻孔实测年平均地温数据，进行回归统计分析，获取年平均地温与纬度、高程的关系，并基于该关系，结合GTOPO30高程数据（美国地质调查局地球资源观测与科技中心领导下发展的全球1km数字高程模型数据）模拟得到整个青藏高原范围上的年平均地温分布。以年平均地温0.5 ℃作为多年冻土与季节冻土的界限，参考《中国冰雪冻土图》（1：400万）（施雅风 等，1988）划定高原不连续多年冻土与高原岛状多年冻土的界限；另外，参考东北大小兴安岭多年冻土分区图（郭东信 等，1981）、环北极多年冻土和地下冰分布图（Brown et al. 1997）和最新野外实测资料，对东北的多年冻土界线进行了修订；西北高山多年冻土界线多采用了《中国冰雪冻土图》（1：400万）（施雅风 等，1988）中划定的界线。
根据该数据统计的中国多年冻土区面积约1.75×106km2，约占中国领土的18.25％。其中，高山多年冻土0.29×106km2，约占我国领土面积的3.03％。
更多信息参考《1：400万中国冰川冻土沙漠图》说明书（中国科学院寒区旱区环境与工程研究所，2006）。

This dataset is the digitization of the permafrost distribution map from the "China Glacier, Frozen Soil and Desert Map (1:4,000,000 scale)". In line with the global permafrost classification system, permafrost is divided into five categories: (1) Discontinuous permafrost: continuous coverage coefficient 50%-90%; (2) Spotted (island-like) permafrost: continuous coverage coefficient <50%; (3) Plateau discontinuous permafrost: continuous coverage coefficient 50%-90%; (4) Plateau spotted (island-like) permafrost: continuous coverage coefficient 50%-90%; (5) Mountain permafrost.

The compilation of the permafrost map is based on: (1) Field surveys and measured exploration data of permafrost; (2) Interpretation of aerial photographs and satellite imagery; (3) TOPO30 ground elevation data with 1 km resolution; (4) Air and ground surface temperature data.

For the permafrost distribution on the Qinghai-Tibet Plateau, the results of Nan et al. (2002) were adopted. Using 76 measured annual mean ground temperature data from boreholes along the Qinghai-Tibet Highway, regression statistical analysis was conducted to derive the relationship between annual mean ground temperature, latitude and elevation. Based on this relationship and combined with GTOPO30 elevation data (the global 1 km digital elevation model developed under the leadership of the U.S. Geological Survey's Earth Resources Observation and Science Center), the annual mean ground temperature distribution across the entire Qinghai-Tibet Plateau was simulated. Using 0.5 ℃ annual mean ground temperature as the boundary between permafrost and seasonally frozen ground, the boundary between plateau discontinuous permafrost and plateau spotted permafrost was delineated with reference to the "China Snow and Frozen Soil Map (1:4,000,000 scale)" (Shi et al., 1988). In addition, the permafrost boundary in Northeast China was revised with reference to the "Permafrost Regionalization Map of the Greater and Lesser Khingan Mountains in Northeast China" (Guo et al., 1981), the "Circum-Arctic Permafrost and Ground Ice Distribution Map" (Brown et al., 1997), and the latest field measured data. The boundaries of permafrost in the high mountains of Northwest China mostly adopted the boundaries delineated in the "China Snow and Frozen Soil Map (1:4,000,000 scale)" (Shi et al., 1988).

According to this dataset, the total area of permafrost regions in China is approximately 1.75×10^6 km², accounting for about 18.25% of China's territorial area. Among them, the area of mountain permafrost is 0.29×10^6 km², accounting for about 3.03% of China's territorial area.

For more information, please refer to the manual of the "China Glacier, Frozen Soil and Desert Map (1:4,000,000 scale)" (Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 2006).