Preprints
https://doi.org/10.5194/tc-2022-123
https://doi.org/10.5194/tc-2022-123
 
28 Jul 2022
28 Jul 2022
Status: this preprint is currently under review for the journal TC.

Simulation of the current and future dynamics of permafrost near the northern limit of permafrost on the Qinghai–Tibet Plateau

Jianting Zhao1, Lin Zhao1,2,3, Zhe Sun3,4, Fujun Niu5, Guojie Hu2, Defu Zou2, Guangyue Liu2, Erji Du2, Chong Wang1, Lingxiao Wang1, Yongping Qiao2, Jianzong Shi2, Junqiang Gao6, Yuanwei Wang1, Yan Li1, Wenjun Yu7, Huayun Zhou2,4, Zanpin Xing2,4, Minxuan Xiao1, Luhui Yin1, and Shengfeng Wang1 Jianting Zhao et al.
  • 1School of Geographical Sciences, Nanjing University of Information Science & Technology, Nanjing 210044, China
  • 2Cryosphere Research Station on Qinghai–Xizang Plateau, State Key Laboratory of Cryospheric Sciences, Northwest Institute of Eco–Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
  • 3Key Laboratory of Environment Change and Resources Use in Beibu Gulf, Ministry of Education, Nanning Normal University, Nanning 530001, China
  • 4University of Chinese Academy of Sciences, Beijing 101408, China
  • 5State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco–Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
  • 6School of Mathematics and Statistics, Nanjing University of Information Science & Technology, Nanjing 210044, China
  • 7School of Hydrology and Water Resources, Nanjing University of Information Science & Technology, Nanjing 210044, China

Abstract. Permafrost has been warming and thawing at a global scale with subsequent effects on the climate, hydrological, ecosystem and engineering system. However, the variation of permafrost thermal state in the northern lower limit of the permafrost zone (Xidatan) on the Qinghai–Tibetan Plateau (QTP) is unclear. To evaluate and project the permafrost changes, this study simulated the spatiotemporal dynamics of this marginal permafrost historically (1970–2019) based on the detailed investigation and monitoring datasets from 1987 in this study region, improved remote sensing-based Land Surface Temperature product (LST) and climate projections from Global Climate Model (GCM) outputs of Coupled Model Intercomparison Project Phase 5 and 6 (CMIP5, CMIP6). Our model takes into consideration of phase change processes of soil pore water, thermal property difference between frozen and thawed soil, geothermal flux flow, and ground ice effect. The results indicate that 1) our model can consistently reproduce the ground temperature field and active layer thickness (ALT), is superior in recognizing permafrost boundaries, and would realistically capture the evolution of the permafrost thermal regime, 2) spatial distribution of permafrost and its thermal conditions over the study area were controlled by elevational with a strong influence of slope aspects, 3) from 1970 to 2019, the regional averaged means annual ground temperature (MAGT) had warmed by 0.49 °C in the continuous permafrost zone and 0.40 °C in the discontinuous permafrost zone, and the lowest elevation of permafrost boundary (on north-facing slopes) rose approximately 47 m, as well as the northern boundary of discontinuous permafrost has approximately retreated southwards 1~2 km, while the lowest elevation of permafrost boundary remains unchanged for continuous permafrost zone, 4) the warming rate in MAGT is projected to be slighter higher under Shared Socioeconomic Pathways (SSPs) than that of Representative Concentration Pathways (RCPs), but no distinct discrepancies in the areal extent of the continuous, discontinuous permafrost and seasonally frozen ground among SSP and RCP scenarios. This study highlights the slow delaying process in the response of mountain permafrost to a warming climate, especially in terms of the areal extent of permafrost distribution.

Jianting Zhao et al.

Status: open (until 22 Sep 2022)

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Jianting Zhao et al.

Jianting Zhao et al.

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Short summary
Permafrost has been warming and thawing at global scale, this is especially true in boundary region. We focus on the variation of permafrost distribution and thermal dynamics in the northern lower limit of the permafrost zone on the Qinghai–Tibetan Plateau by applying a new permafrost model. Unlike previous publications on this topic, our finding highlights a slow decaying process in the response of mountain permafrost to a warming climate, especially the areal extent of permafrost distribution.