Spatiotemporal Variation Characteristics of Freezing and Thawing Parameters in Permafrost over the Qinghai-XizangTibetanPlateau and Their Influencing Factors 

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  • 1. School of Atmospheric SciencesPlateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu Plain Urban Meteorology and Environment Observation and Research Station of Sichuan ProvinceSichuan Meteorological Disaster Prediction and Early Warning Engineering LaboratoChengdu University of Information TechnologyChengdu 610225SichuanChina
    2. Suining Branch of Civil Aviation Flight Academy of ChinaSuining 629000SichuanChina

Online published: 2025-04-29

Abstract

The freeze-thaw cycle of near-surface soil in the perennial permafrost region of the Qinghai-Xizang TibetanPlateau plays a crucial role in regulating water and energy exchange between the soil and the atmosphere. Investigating its spatiotemporal characteristics and response to climate change is essential for understanding the mechanisms driving climate change on the plateau. In this studywe calculated near-surface freeze-thaw parameters-including the start and end times of soil freezingthawing durationand freezing duration-across the perennial permafrost region of the plateau from 1980 to 2017 using the Common Land Model 5. 0CLM5. 0. We further analyzed their spatiotemporal variations and correlations with temperatureprecipitationsnow depthand vegetation index. The results show that:(1The onset of near-surface soil freezing in the plateau’s permafrost region occurs between September and mid-to-late Octoberwhile the thawing period ends between February and May. Semi-humid regions have the longest thawing durationwhereas semi-arid regions have the shortestwith an average difference of 15 days. The freeze-thaw status of permafrost soil on the plateau exhibits significant changes. Except for areas near the Karakoram Mountainsmost permafrost regions show a decreasing trend in freezing duration and an increasing trend in thawing duration. The average growth rate of soil thawing duration across the plateau is 2 d·10a⁻¹with the most significant increase observed in semi-humid regionsreaching 4 d·10a⁻¹.2The freeze-thaw parameters of the plateau's permafrost are associated with geographical factors. In the latitude range of 29°N-36°N and longitude range of 82. 5°E-103°Ethe thawing duration shows an increasing trendhoweverthe rate of change decreases in some areas while increasing in others. Additionallyas elevation increasesthe growth rate of thawing duration declines.3The duration of permafrost thawing is significantly correlated with snow depthnear-surface temperatureprecipitationand vegetation indexthough these relationships vary across different climatic regions. Near-surface temperature exhibits a strong positive correlation across all regionsmaking it the primary driver of freeze-thaw changes. Precipitation and snow depth show positive and negative correlationsrespectivelywith particularly strong correlations in semihumid areas. The vegetation index is positively correlated with thaw duration in all regionswith the strongest correlation observed in semi-arid areas.4The relationship between thawing duration and seasonal climatic fac‐ tors varies. Near-surface air temperature exerts a significant influence on the freeze-thaw process at seasonal scaleswith the most pronounced impact occurring in spring. Precipitation is positively correlated in summer but negatively correlated in winter. Both snow depth and vegetation index are significantly correlated with thawing duration in semi-arid and semi-humid regions during springexhibiting negative and positive correlationsrespectively.5Near-surface temperature influences the freeze-thaw cycle in the plateau’s perennial permafrost region during both dry and wet seasons. Howeverthe effects of snow depthprecipitationand vegetation index are more pronounced during the wet season.

Cite this article

LI Boyuan, LAI Xin, LIU Kang, HE Peihong, ZHANG Haoran, ZHANG Ge . Spatiotemporal Variation Characteristics of Freezing and Thawing Parameters in Permafrost over the Qinghai-XizangTibetanPlateau and Their Influencing Factors [J]. Plateau Meteorology, 0 : 1 . DOI: 10.7522/j.issn.1000-0534.2025.00008

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