18 Mar 2021

18 Mar 2021

Review status: a revised version of this preprint is currently under review for the journal ESSD.

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

Youhua Ran1,3, Xin Li2,4, Guodong Cheng1,5, Jingxin Che6, Juha Aalto7,8, Olli Karjalainen9, Jan Hjort9, Miska Luoto7, Huijun Jin1,10, Jaroslav Obu11, Masahiro Hori12, Qihao Yu1,3, and Xiaoli Chang13 Youhua Ran et al.
  • 1Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
  • 2National Tibetan Plateau Data Center, Key Laboratory of Tibetan Environmental Changes and Land Surface Processes, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China
  • 3University of Chinese Academy of Sciences, Beijing 100049, China
  • 4CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China
  • 5Institute of Urban Study, Shanghai Normal University, Shanghai 200234, China
  • 6School of Science, Nanchang Institute of Technology, Nanchang 330099, China
  • 7Department of Geosciences and Geography, University of Helsinki, P.O. Box 64, Gustaf Hällströmin katu 2a, 00014 Helsinki, Finland
  • 8Finnish Meteorological Institute, P.O. Box 503, FI-00101 Helsinki, Finland
  • 9Geography Research Unit, University of Oulu, P.O. Box 8000, FI-90014, Oulu, Finland
  • 10Institute of Cold Regions Science and Engineering and School of Civil Engineering, Northeast Forestry University, Harbin 150040, China
  • 11Department of Geosciences, University of Oslo, Sem Sælands vei 1, 0371 Oslo, Norway
  • 12Earth Observation Research Center, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba, Ibaraki 305-8505, Japan
  • 13School of Resource & Environment and Safety Engineering, Hunan University of Science and Technology, Xiangtan 411201, China

Abstract. Monitoring of the thermal state of permafrost is important in 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 zero annual amplitude depth and active layer thickness (ALT) with a 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 (1,002 boreholes for MAGT and 452 sites for ALT) and multisource geospatial data, especially remote sensing data, using statistical learning modelling with an ensemble strategy. Thus, these data are more accurate than those of previous circumpolar maps (bias = 0.02 ± 0.16 °C, RMSE = 1.32 ± 0.13 °C for MAGT; bias = 2.71 ± 16.46 cm, 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 15.03 (13.84–19.29) × 106 km2, and the areal extent of permafrost regions (permafrost probability > 0) is approximately 20.14 × 106 km2. The areal fractions of humid, semiarid/subhumid, and arid permafrost regions are 51.84 %, 44.83 %, and 3.33 %, 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 37.93 %, 14.35 %, and 47.72 %, 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. They are potentially useful for various fields, such as in climatology, hydrology, ecology, agriculture, public health, and engineering planning. As a baseline, these datasets are also of great importance for evaluating future changes in MAGT, ALT, permafrost extent, and other spatial features of permafrost in the NH. All of the datasets are published through the National Tibetan Plateau Data Center (TPDC), and the link is or (Ran et al., 2021b).

Youhua Ran et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on essd-2021-83', Stepan Varlamov, 15 Apr 2021
  • RC2: 'Comment on essd-2021-83 - in English', Stepan Varlamov, 20 Apr 2021
  • RC3: 'Comment on essd-2021-83', Anonymous Referee #2, 09 May 2021
  • EC1: 'Comment on essd-2021-83', Kirsten Elger, 26 Jun 2021
    • AC3: 'Reply on EC1', Youhua Ran, 13 Jul 2021

Youhua Ran et al.

Youhua Ran et al.


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Short summary
The datasets include ground temperature, active layer thickness, the probability of permafrost occurrence, and the zonation of hydrothermal condition with a 1-km resolution were released by integrate unprecedentedly large amounts of field data and multisource remote sensing data using multi-statistical\machine learning models. Thus, it updates the understanding of the current thermal state and distribution for permafrost in the Northern Hemisphere.