University of Oulu

Ran, Y., Li, X., Cheng, G., Che, J., Aalto, J., Karjalainen, O., Hjort, J., Luoto, M., Jin, H., Obu, J., Hori, M., Yu, Q., and Chang, X.: New high-resolution estimates of the permafrost thermal state and hydrothermal conditions over the Northern Hemisphere, Earth Syst. Sci. Data, 14, 865–884,, 2022

New high-resolution estimates of the permafrost thermal state and hydrothermal conditions over the Northern Hemisphere

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Author: Ran, Youhua1,2; Li, Xin3; Cheng, Guodong1,4;
Organizations: 1Heihe Remote Sensing Experimental Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
2College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 100049, China
3National Tibetan Plateau Data Center, State Key Laboratory of Tibetan Plateau Earth System, Environment and Resources, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
4Institute of Urban Study, Shanghai Normal University, Shanghai 200234, China
5School of Science, Nanchang Institute of Technology, Nanchang 330099, China
6Department of Geosciences and Geography, University of Helsinki, P.O. Box 64, Gustaf Hällströmin katu 2a, 00014 Helsinki, Finland
7Finnish Meteorological Institute, P.O. Box 503, 00101 Helsinki, Finland
8Geography Research Unit, University of Oulu, P.O. Box 8000, 90014, Oulu, Finland
9Institute of Cold Regions Science and Engineering and School of Civil Engineering, Northeast Forestry University, Harbin 150040, China
10Department of Geosciences, University of Oslo, Postboks 1047 Blindern, 0316 Oslo, Norway
11Earth Observation Research Center, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba, Ibaraki 305-8505, Japan
12School of Resource and Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan 411201, China
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 11.8 MB)
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Language: English
Published: Copernicus Publications, 2022
Publish Date: 2022-05-20


Monitoring the thermal state of permafrost (TSP) is important in many environmental science and engineering applications. However, such data are generally unavailable, mainly due to the lack of ground observations and the uncertainty of traditional physical models. This study produces novel permafrost datasets for the Northern Hemisphere (NH), including predictions of the mean annual ground temperature (MAGT) at the depth of zero annual amplitude (DZAA) (approximately 3 to 25 m) and active layer thickness (ALT) with 1 km resolution for the period of 2000–2016, as well as estimates of the probability of permafrost occurrence and permafrost zonation based on hydrothermal conditions. These datasets integrate unprecedentedly large amounts of field data (1002 boreholes for MAGT and 452 sites for ALT) and multisource geospatial data, especially remote sensing data, using statistical learning modeling with an ensemble strategy. Thus, the resulting data are more accurate than those of previous circumpolar maps (bias = 0.02±0.16 °C and RMSE = 1.32±0.13 °C for MAGT; bias = 2.71±16.46 cm and RMSE = 86.93±19.61 cm for ALT). The datasets suggest that the areal extent of permafrost (MAGT ≤0 °C) in the NH, excluding glaciers and lakes, is approximately 14.77 (13.60–18.97) × 10⁶ km² and that the areal extent of permafrost regions (permafrost probability >0) is approximately 19.82×10⁶ km². The areal fractions of humid, semiarid/subhumid, and arid permafrost regions are 51.56 %, 45.07 %, and 3.37 %, respectively. The areal fractions of cold (≤ −3.0 °C), cool (−3.0 °C to −1.5 °C), and warm (> −1.5°C) permafrost regions are 37.80 %, 14.30 %, and 47.90 %, respectively. These new datasets based on the most comprehensive field data to date contribute to an updated understanding of the thermal state and zonation of permafrost in the NH. The datasets are potentially useful for various fields, such as climatology, hydrology, ecology, agriculture, public health, and engineering planning. All of the datasets are published through the National Tibetan Plateau Data Center (TPDC), and the link is (Ran et al., 2021a).

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Series: Earth system science data
ISSN: 1866-3508
ISSN-E: 1866-3516
ISSN-L: 1866-3508
Volume: 14
Pages: 865 - 884
DOI: 10.5194/essd-14-865-2022
Type of Publication: A1 Journal article – refereed
Field of Science: 114 Physical sciences
1171 Geosciences
Funding: This research has been supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDA19070204), the National Natural Science Foundation of China (grant no. 42071421), and the Academy of Finland (grant no. 315519).
Academy of Finland Grant Number: 315519
Detailed Information: 315519 (Academy of Finland Funding decision)
Copyright information: © Author(s) 2022. This work is distributed under the Creative Commons Attribution 4.0 License.