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Impacts of land surface darkening on frozen ground and ecosystems over the Tibetan Plateau

Science China Earth Sciences 2024年第10期67卷 3213-3225页

作者： Shuchang TANG Tao WANG Dan LIU Tandong YAO Shilong PIAO Sino-French Institute for Earth System Science College of Urban and Environmental SciencesPeking UniversityBeijing 100101China State Key Laboratory of Tibetan Plateau Earth System Resources and EnvironmentInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

Tibetan Plateau(TP) is known as the “Third Pole” of the Earth. Any changes in land surface processes on the TP can have an unneglectable impact on regional and global climate. With the warming and wetting climate, the land surface of the TP saw a darkening trend featured by decreasing surface albedo over the past decades, primarily due to the melting of glaciers, snow,and greening vegetation. Recent studies have investigated the effects of the TP land surface darkening on the field of climate, but these assessments only address one aspect of the feedback loop. How do these darkening-induced climate changes affect the frozen ground and ecosystems on the TP? In this study, we investigated the impact of TP land surface darkening on regional frozen ground and ecosystems using the state-of-the-art land surface model ORCHIDEE-MICT. Our model results show that darkening-induced climate changes on the TP will lead to a reduction in the area of regional frozen ground by 1.1×10~4±0.019×10~4km~2, a deepening of the regional permafrost active layer by 0.06±0.0004 m, and a decrease in the maximum freezing depth of regional seasonal frozen ground by 0.06±0.0016 m compared to the scenario without TP land surface ***, the darkening-induced climate change on the TP will result in an increase in the regional leaf area index and an enhancement in the regional gross primary productivity, ultimately leading to an increase in regional terrestrial carbon stock by0.81±0.001 PgC. This study addresses the remaining piece of the puzzle in the feedback loop of TP land surface darkening, and improves our understanding of interactions across multiple spheres on the TP. The exacerbated regional permafrost degradation and increasing regional terrestrial carbon stock induced by TP land surface darkening should be considered in the development of national ecological security barrier.

关键词： Tibetan Plateau Albedo Land surface darkening frozen ground Ecosystem

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Exothermic process of cast-in-place pile foundation and its thermal agitation of the frozen ground under a long dry bridge on the Qinghai-Tibet Railway

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第2期11卷 88-96页

作者： Ya-ping WU Jian GUO Chun-xiang GUO Wei MA Xiao-jun WANG School of Civil and Arehiteeture Engineering Ningbo Institute of Technology Zhejiang University Ningbo 315100 China School of Civil Engineering Lanzhou Jiaotong University Lanzhou 730070 China State Key Laboratory of frozen Soil Engineering Cold and Arid Regions Environment and Engineering Research Institute Chinese Aeademy of Sciences Lanzhou 730000 China

A number of dry bridges have been built to substitute for the roadbed on the Qinghai-Tibet Railway,*** aim of this study was to investigate the exothermic process of cast-in-place (CIP) pile foundation of a dry bridge and its harm to the stability of nearby frozen *** present 3D heat conduction functions of a concrete pile and of frozen ground with related *** analysis is based on the theory of heat conduction and the exponent law describing the adiabatic temperature rise caused by hydration *** under continuous and initial conditions were combined to establish a finite element model of a CIP pile-frozen ground system for a dry bridge under actual field conditions in cold *** results indicated that the process could effectively simulate the exothermic process of CIP pile *** disturbance to frozen ground under a long dry bridge caused by the casting temperature and hydration heat of CIP piles was substantial and *** simulated thermal analysis results agreed with field measurements and some significant rules relating to the problem were deduced and conclusions reached.

关键词： Exothermic process of hydration heat Cast-in-place (CIP) pile foundation Dry bridge Thermal agitation frozen ground Qinghai-Tibet Railway

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Changes in global land surface frozen ground and freeze-thaw processes during 1950-2020 based on ERA5-Land data

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Advances in Climate Change Research 2024年第2期15卷 265-274页

作者： Yong YANG Ren-Sheng CHEN Yong-Jian DING Hong-Yuan LI Zhang-Wen LIU Qilian Alpine Ecology and Hydrology Research Station Key Laboratory of Ecological Safety and Sustainable Development in Arid LandsNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 73000China State Key Laboratory of Cryospheric Sciences Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 73000China Shandong Provincial Key Laboratory of Water and Soil Conservation and Environmental Protection College of Resources and EnvironmentLinyi UniversityLinyi 276000China

frozen ground(FG)plays an important role in global and regional climates and environments through changes in land freeze-thaw processes,which have been conducted mainly in different ***,the changes in land surface freeze-thaw processes under climate change on a global scale are still *** on ERA5-Land hourly land skin temperature data,this study evaluated changes in the global FG area,global land surface first freeze date(FFD),last freeze date(LFD)and frost-free period(FFP)from 1950 to *** results show that the current FG areas(1991-2020 mean)in the Northern Hemisphere(NH),Southern Hemisphere(SH),and globe are 68.50×10^(6),9.03×10^(6),and 77.53×10^(6)km^(2),which account for 72.4%,26.8%,and 60.4%of the exposed land(excluding glaciers,ice sheets,and water bodies)in the NH,SH and the globe,respectively;further,relative to 1951-1980,the FG area decreased by 1.9%,8.8%,and 2.8%,*** FG at lower latitudes degrades to intermittently FG,and intermittently FG degrades to non-frozen ground,which caused the global FG boundary to retreat to higher latitudes from 1950 to *** annual FG areas in the NH,SH,and globe all show significant decreasing trends(p<0.05)from 1950 to 2020 at-0.32×10^(6),-0.22×10^(6),and-0.54×10^(6)km^(2)per decade,*** FFP prolongation in the NH is mainly influenced by LFD advance,while in the SH it is mainly controlled by FFD *** prolongation trend of FFP in the NH(1.34 d per decade)is larger than that in the SH(1.15 d per decade).

关键词： frozen ground Freeze-thaw processes Frost-free period First freeze date Global warming

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Simulated effect of soil freeze-thaw process on surface hydrologic and thermal fluxes in frozen ground region of the Northern Hemisphere

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Research in Cold and Arid Regions 2021年第1期13卷 18-29页

作者： Di Ma SiQiong Luo DongLin Guo ShiHua Lyu XianHong Meng BoLi Chen LiHui Luo Key Laboratory for Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and ResourcesChinese Academy of ScienceLanzhouGansu 730000China College of Atmospheric Sciences Lanzhou UniversityLanzhouGansu 730000China Nansen-Zhu International Research Center Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China School of Atmospheric Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu University of Information TechnologyChengduSichuan 610225China Changzhou Meteorological Bureau ChangzhouJiangsu 213000China State Key Laboratory of frozen Soils Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China

Soil freeze-thaw process is closely related to surface energy budget,hydrological activity,and terrestrial *** this study,two numerical experiments(including and excluding soil freeze-thaw process)were designed to examine the effect of soil freeze-thaw process on surface hydrologic and thermal fluxes in frozen ground region in the Northern Hemisphere based on the state-of-the-art Community Earth System Model version *** show that in response to soil freeze-thaw process,the area averaged soil temperature in the shallow layer(0.0175−0.0451 m)decreases by 0.35℃in the TP(Tibetan Plateau),0.69℃in CES(Central and Eastern Siberia),and 0.6℃in NA(North America)during summer,and increases by 1.93℃in the TP,2.28℃in CES and 1.61℃in NA during winter,***,in response to soil freeze-thaw process,the area averaged soil liquid water content increases in summer and decrease in *** surface heat flux components,the ground heat flux is most significantly affected by the freeze-thaw process in both summer and winter,followed by sensible heat flux and latent heat flux in *** the TP area,the ground heat flux increases by 2.82 W/m2(28.5%)in summer and decreases by 3.63 W/m2(40%)in ***,in CES,the ground heat flux increases by 1.89 W/m2(11.3%)in summer and decreases by 1.41 W/m2(18.6%)in *** heat fluxes in the Tibetan Plateau are more susceptible to the freeze-thaw process compared with the high-latitude frozen soil *** freeze-thaw process can induce significant warming in the Tibetan Plateau in ***,this process induces significant cooling in high-latitude regions in *** frozen ground can prevent soil liquid water from infiltrating to deep soil layers at the beginning of thawing;however,as the frozen ground thaws continuously,the infiltration of the liquid water increases and the deep soil can store water like a sponge,accompanied by decreasing surface *** influence of the soil freeze-thaw pr

关键词： freeze-thaw effect hydrologic and thermal frozen ground Northern Hemisphere

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Probabilistic analysis of embankment slope stability in frozen ground regions based on random finite element method

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Research in Cold and Arid Regions 2015年第4期7卷 354-364页

作者： Xi Chen JianKun Liu Nan Xie HuiJing Sun School of Civil Engineering Beijing Jiaotong University Qinghai Research and Observation Base Key Laboratory of Highway Construction & Maintenance Technology in Permafrost RegionsMinistry of Transport

Prediction on the coupled thermal-hydraulic fields of embankment and cutting slopes is essential to the assessment on evolution of melting zone and natural permafrost table, which is usually a key factor for permafrost embankment design in frozen ground regions. The prediction may be further complicated due to the inherent uncertainties of material properties. Hence, stochastic analyses should be conducted. Firstly, Karhunen-Loeve expansion is applied to attain the random fields for hydraulic and thermal conductions. Next, the mixed-form modified Richards equation for mass transfer （i.e., mass equation） and the heat transport equation for heat transient flow in a variably saturated frozen soil are combined into one equation with temperature unknown. Furthermore, the finite element formulation for the coupled thermal-hydraulic fields is derived. Based on the random fields, the stochastic finite element analyses on stability of embankment are carried out. Numerical results show that stochastic analyses of embankment stability may provide a more rational picture for the distribution of factors of safety （FOS）, which is definitely useful for embankment design in frozen ground regions.

关键词： frozen ground high-speed railway embankment slope stability coupled thermal-hydraulic analysis randomfinite element method Monte-Carlo simulation climate change

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Studies on frozen ground of China

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Journal of Geographical Sciences 2004年第4期14卷 411-416页

作者：赵林程国栋丁永建 Cold and Arid Regions Environmental and Engineering Research Institute Lanzhou 730000China

Permafrost in China includes high latitude permafrost in northeastern China, alpine permafrost in northwestern China and high plateau permafrost on the Tibetan Plateau. The high altitude permafrost is about 92% of the total permafrost area in China. The south boundary or lower limit of the seasonally frozen ground is defined in accordance with the 0 ℃ isothermal line of mean air temperature in January, which is roughly corresponding to the line extending from the Qinling Mountains to the Huaihe River in the east and to the southeast boundary of the Tibetan Plateau in the west. Seasonal frozen ground occurs in large parts of the territory in northern China, including Northeast, North, Northwest China and the Tibetan Plateau except for permafrost regions, and accounting for about 55% of the land area of China. The southern limit of short-term frozen ground generally swings south and north along the 25° northern latitude line, occurring in the wet and warm subtropic monsoon climatic zone. Its area is less than 20% of the land area of China.

关键词： permafrost frozen ground China

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Coupling of the Calculated Freezing and Thawing Front Parameterization in the Earth System Model CAS-ESM

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Advances in Atmospheric Sciences 2023年第9期40卷 1671-1688页

作者： Ruichao LI Jinbo XIE Zhenghui XIE Binghao JIA Junqiang GAO Peihua QIN Longhuan WANG Si CHEN State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 101408China School of Mathematics and Statistics Nanjing University of Information Science and TechnologyNanjing 210044China

The soil freezing and thawing process affects soil physical properties,such as heat conductivity,heat capacity,and hydraulic conductivity in frozen ground regions,and further affects the processes of soil energy,hydrology,and carbon and nitrogen *** this study,the calculation of freezing and thawing front parameterization was implemented into the earth system model of the Chinese Academy of Sciences(CAS-ESM)and its land component,the Common Land Model(CoLM),to investigate the dynamic change of freezing and thawing fronts and their *** results showed that the developed models could reproduce the soil freezing and thawing process and the dynamic change of freezing and thawing *** regionally averaged value of active layer thickness in the permafrost regions was 1.92 m,and the regionally averaged trend value was 0.35 cm yr–*** regionally averaged value of maximum freezing depth in the seasonally frozen ground regions was 2.15 m,and the regionally averaged trend value was–0.48 cm yr–*** active layer thickness increased while the maximum freezing depth decreased year by *** results contribute to a better understanding of the freezing and thawing cycle process.

关键词： frozen ground freezing and thawing fronts maximum freezing depth active layer thickness earth system model CAS-ESM

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Evaluation and prediction of engineering construction suitability in the Chinae-Mongoliae-Russia economic corridor

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Advances in Climate Change Research 2023年第2期14卷 166-178页

作者： Ya-Ya SHI Fu-Jun NIU Hui-Jun JIN Xiao-Ni YOU Zhan-Ju LIN Dan-Yun WANG Run-Ke WANG Cheng-Yong WU College of Resources and Environmental Engineering Tianshui Normal UniversityTianshui 741001China State Key Laboratory of Subtropical Building Science South China University of TechnologyGuangzhou 510640China South China Institute of Geotechnical Engineering School of Civil Engineering and TransportationSouth China University of TechnologyGuangzhou 510640China School of Civil Engineering School of ForestryInstitute of Cold Regions Science and EngineeringNortheast Forestry UniversityHarbin 150040China State Key Laboratory of frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Tianjin Meteorological Disaster Defense Technology Centre Tianjin 300074China

It is proposed to build a high-speed railway through the China‒Mongolia‒Russia economic corridor(CMREC)which runs from Beijing to Moscow via ***,the frozen ground in this corridor has great impacts on the infrastructure stability,especially under the background of climate warming and permafrost *** on the Bayesian Network Model(BNM),this study evaluates the suitability for engineering construction in the CMREC,by using 21 factors in five aspects of terrain,climate,ecology,soil,and frozen-ground thermal *** results showed that the corridor of Mongolia's Gobi and Inner Mongolia in China is suitable for engineering construction,and the corridor in Amur,Russia near the northern part of Northeast China is also suitable due to cold and stable permafrost overlaying by a thin active ***,the corridor near Petropavlovsk in Kazakhstan and Omsk in Russia is not suitable for engineering construction because of low freezing index and ecological ***,the sensitivity analysis of influence factors indicates that the thermal stability of frozen ground has the greatest impact on the suitability of engineering *** conclusions can provide a reference basis for the future engineering planning,construction and risk assessment.

关键词： China‒Mongolia‒Russia economic corridor frozen ground Bayesian network model Engineering construction Suitability

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Response of Freezing/Thawing Indexes to the Wetting Trend under Warming Climate Conditions over the Qinghai–Tibetan Plateau during 1961–2010:A Numerical Simulation

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Advances in Atmospheric Sciences 2023年第2期40卷 211-222页

作者： Xuewei FANG Zhi LI Chen CHENG Klaus FRAEDRICH Anqi WANG Yihui CHEN Yige XU Shihua LYU Plateau Atmosphere and Environment Key Laboratory of Sichuan Province School of Atmospheric SciencesChengdu University of Information TechnologyChengdu 610225China Southwest Institute of Technical Physics Chengdu 610225China Max Planck Institute for Meteorology Hamburg 20146Germany Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science&TechnologyNanjing 210044China

Since the 1990s,the Qinghai–Tibetan Plateau(QTP)has experienced a strikingly warming and wetter climate that alters the thermal and hydrological properties of frozen ground.A positive correlation between the warming and thermal degradation in permafrost or seasonally frozen ground(SFG)has long been ***,a predictive relationship between historical wetting under warming climate conditions and frozen ground has not yet been well demonstrated,despite the expectation that it will become even more important because precipitation over the QTP has been projected to increase continuously in the near *** study investigates the response of the thermal regime to historical wetting in both permafrost and SFG areas and examines their relationships separately using the Community Land Surface Model version *** show that wetting before the 1990s across the QTP mainly cooled the permafrost body in the arid and semiarid zones,with significant correlation coefficients of 0.60 and 0.48,*** increased continually at the rate of 6.16 mm decade–1 in the arid zone after the 1990s but had a contrasting warming effect on permafrost through a significant shortening of the thawing duration within the active ***,diminished rainfall in the humid zone after the 1990s also significantly extended the thawing duration of *** relationship between the ground thawing index and precipitation was significantly negatively correlated(−0.75).The dual effects of wetting on the thermal dynamics of the QTP are becoming critical because of the projected increases in future precipitation.

关键词： freezing/thawing indexes numerical modeling wetting process frozen ground Qinghai–Tibetan Plateau

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Possible controlling factors in the development of seasonal sand wedges on the Ordos Plateau,North China

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Research in Cold and Arid Regions 2021年第2期13卷 167-176页

作者： Hugh MFrenchψ Jef Vandenberghe HuiJun Jin RuiXia He Departments of Geography and Earth Sciences University of OttawaOntarioCanadaDepartment of GeographyUniversity of VictoriaBritish ColumbiaCanada Institute of Earth Sciences Vrije Universiteit AmsterdamThe Netherlands School of Civil Engineering Institute of Cold-Regions EngineeringScience and TechnologyNortheast-China Observatory and Research-Station of Permafrost Geo-Environment-Ministry of EducationNortheast Forestry UniversityHarbinHeilongjiang150040China State Key Laboratory of frozen Soils Engineering and Northwest Institute of Eco-Environment and Resources Chinese Academy of SciencesLanzhouGansu 730000China

Wedge-like structures filled with silty sand penetrate Quaternary fluvial and aeolian sediments and, in places, Tertiary bedrock on the Ordos Plateau, North China. The wedges reflect thermal contraction cracking of either permafrost or seasonal frost during the Late Pleistocene and early Holocene. Wedges of about 1 m in depth form polygonal nets of 2-3 m in diameter(type B). They contrast with wedges of 3-4 m in depth that form polygons of 10-15 m in diameter(type A).This review focuses upon the highly variable size of the inferred polygon nets and discusses the problem of differentiating between seasonally and perennially frozen ground, or between seasonal frost and permafrost.

关键词： frozen ground sand-wedge casts frost fissures thermal contraction cracking seasonal frost cracking desiccation cracking

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