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Modeling permafrost properties in the qinghai-Xizang(Tibet) plateau

Science China Earth Sciences 2015年第12期58卷 2309-2326页

作者： HU GuoJie ZHAO Lin WU XiaoDong LI Ren WU TongHua XIE ChangWei PANG QiangQiang XIAO Yao LI WangPing QIAO YongPing SHI JianZong cryosphere research station on qinghai-Xizang plateau State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

Water and heat dynamics in the active layer at a monitoring site in the Tanggula Mountains, located in the permafrost region of the qinghai-Xizang （Tibet） plateau （QXP）, were studied using the physical-process-based COUPMODEL model, including the interaction between soil temperature and moisture under freeze-thaw cycles. Meteorological, ground temperature and moisture data from different depths within the active layer were used to calibrate and validate the model. The results indicate that the calibrated model satisfactorily simulates the soil temperatures from the top to the bottom of the soil layers as well as the moisture content of the active layer in permafrost regions. The simulated soil heat flux at depths of 0 to 20 cm was consistent with the monitoring data, and the simulations of the radiation balance components were reasonable. Energy consumed for phase change was estimated from the simulated ice content during the freeze/thaw processes from 2007 to 2008. Using this model, the active layer thickness and the energy consumed for phase change were predicted for future climate warming scenarioS. The model predicts an increase of the active layer thickness from the current 330 cm to approximately 350-390 cm as a result of a 1-2℃ warming. However, the effect active layer thickness of more precipitation is limited when the precipitation is increased by 20%-50%. The COUPMODEL provides a useful tool for predicting and understanding the fate of permafrost in the QXP under a warming climate.

关键词： permafrost COUPMODEL hydrothermal processes phase change soil temperature soil moisture

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Dynamic changes in lakes in the Hoh Xil region before and after the 2011 outburst of Zonag Lake

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Journal of Mountain Science 2019年第5期16卷 1098-1110页

作者： LIU Wen-hui XIE Chang-wei ZHAO Lin WU Tong-hua WANG Wu ZHANG Yu-xin YANG Gui-qian ZHU Xiao-fan YUE Guang-yang cryosphere research station on the qinghai-Tibet plateau State Key Laboratory of Cryosphere Sciences Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences University of Chinese Academy of Sciences

Zonag, Kusai, Hedin Noel and Yanhu Lakes are independent inland lakes in the Hoh Xil region on the qinghai-Tibet plateau. In September2011, Zonag Lake burst after the water level had increased for many years. Floods flowed through Kusai and Hedin Noel Lakes into Yanhu Lake; since then, the four small endorheic catchments merged into one larger catchment. This hydrological process caused the rapid shrinkage of Zonag Lake and continuous expansion of Yanhu Lake. In this study,based on satellite images, meteorological data and field investigations, we examined the dynamic changes in the four lakes and analyzed the influencing factors. The results showed that before 2011, the trends in the four lake areas were similar and displayed several stages. The change in the area of Zonag Lake corresponded well to the change in annual precipitation(AP), but the magnitude of the change was less than that of a non-glacier-fed lake. Although increased precipitation was the dominant factor that caused Zonag Lake to expand, increased glacier melting and permafrost thawing due to climate warming also had significant effects. After the 2011 outburst of Zonag Lake, due to the increasing AP and accelerating glacier melting, the increases in water volume of the three lakes were absorbed by Yanhu Lake, and Yanhu Lake expanded considerably. According to the rapid growth rates in water level and lake area, Yanhu Lake is likely to burst in 1-2 years.

关键词： Dynamic change Lake areas Influencing factors Glacier change Permafrost thawing Zonag Lake

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An analytical model for estimating soil temperature profiles on the qinghai-Tibet plateau of China

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Journal of Arid Land 2016年第2期8卷 232-240页

作者： HU Guojie ZHAO Lin WU Xiaodong LI Ren WU Tonghua XIE Changwei QIAO Yongping SHI Jianzong CHENG Guodong cryosphere research station on qinghai-Xizang plateau State Key Laboratory of Cryospheric SciencesCold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

Soil temperature is a key variable in the control of underground hydro-thermal processes. To estimate soil temperature more accurately, this study proposed a solution method of the heat conduction equation of soil temperature （improved heat conduction model） by applying boundary conditions that incorporate the annual and diurnal variations of soil surface temperature and the temporal variation of daily temperature amplitude, as well as the temperature difference between two soil layers in the Tanggula observation site of the qinghai-Tibet plateau of China. We employed both the improved heat conduction model and the classical heat conduction model to fit soil temperature by using the 5 cm soil layer as the upper boundary for soil depth. The results indicated that the daily soil temperature amplitude can be better described by the sinusoidal function in the improved model, which then yielded more accurate soil temperature simulating effect at the depth of 5 cm. The simulated soil temperature values generated by the improved model and classical heat conduction model were then compared to the observed soil temperature values at different soil depths. Statistical analyses of the root mean square error （RMSE）, the normalized standard error （NSEE） and the bias demonstrated that the improved model showed higher accuracy, and the average values of RMSE, bias and NSEE at the soil depth of 10-105 cm were 1.41℃, 1.15℃ and 22.40%, respectively. These results indicated that the improved heat conduction model can better estimate soil temperature profiles compared to the traditional model.

关键词： soil temperature heat conduction equation daily amplitude boundary condition

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Modeling Hydrothermal Transfer Processes in Permafrost Regions of qinghai-Tibet plateau in China

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Chinese Geographical Science 2015年第6期25卷 713-727页

作者： HU Guojie ZHAO Lin LI Ren WU Tonghua WU Xiaodong PANG Qiangqiang XIAO Yao QIAO Yongping SHI Jianzong cryosphere research station on qinghai-Xizang plateau State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

Hydrothermal processes are key components in permafrost dynamics; these processes are integral to global wanning. In this study the coupled heat and mass transfer model for （CoupModel） the soil-plant-atmosphere-system is applied in high-altitude permafrost regions and to model hydrothermal transfer processes in freeze-thaw cycles. Measured meteorological forcing and soil and vegetation properties are used in the CoupModel for the period from January 1, 2009 to December 31, 2012 at the Tanggula observation site in the qinghai-Tibet plateau. A 24-h time step is used in the model simulation. The results show that the simulated soil temperature and water content, as well as the frozen depth compare well with the measured data. The coefficient of determination （R2） is 0.97 for the mean soil temperature and 0.73 for the mean soil water content, respectively. The simulated soil heat flux at a depth of 0-20 cm is also consistent with the monitored data. An analysis is performed on the simulated hydrothermal transfer processes from the deep soil layer to the upper one during the freezing and thawing period. At the beginning of the freezing period, the water in the deep soil layer moves upward to the freezing front and releases heat during the freezing process. When the soil layer is completely frozen, there are no vertical water ex- changes between the soil layers, and the heat exchange process is controlled by the vertical soil temperature gradient. During the thaw- ing period, the downward heat process becomes more active due to increased incoming shortwave radiation at the ground surface. The melt water is quickly dissolved in the soil, and the soil water movement only changes in the shallow soil layer. Subsequently, the model was used to provide an evaluation of the potential response of the active layer to different scenarios of initial water content and climate warming at the Tanggula site. The results reveal that the soil water content and the organic layer provide pr

关键词： permafrost coupled heat and mass transfer model (CoupModel) soil temperature soil moisture hydrothermal processes active layer

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Large-scale characteristics of thermokarst lakes across the source area of the Yellow River on the qinghai-tibetan plateau

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Journal of Mountain Science 2023年第6期20卷 1589-1604页

作者： LIU Wen-hui ZHOU Guang-hao LIU Hai-rui LI Qing-peng XIE Chang-wei LI Qing ZHAO Jian-yun ZHANG Qi State Key Laboratory of plateau Ecology and Agriculture Qinghai UniversityXining 810016China Department of Geological Engineering Qinghai UniversityXining 810016China College of Eco-Environmental Engineering Qinghai UniversityXining 810016China cryosphere research station on the qinghai-Tibet plateau State Key Laboratory of Cryosphere SciencesNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 73ooooChina

As significant evidence of permafrost degradation,thermokarst lakes play an important role in the permafrost regions by regulating hydrology,ecology,and *** the Sources Area of the Yellow River(SAYR),permafrost degradation has accelerated since the 1980s,and numerous thermokarst lakes have been *** this paper,we use Sentinel-2 images to extract thermokarst lake boundaries and perform a regional-scale study on their geometry across the permafrost region in the *** also explored the spatiotemporal variations and potential drivers from the perspectives of the permafrost,climate,terrain and vegetation *** results showed that there were 47,518 thermokarst lakes in 2021 with a total area of 190.22×106 m^(2),with an average size of 4,003.3 m^(2).The 44,928 ponds(≤10,000 m^(2))predominated the whole lake number(94.1%)but contributed to a small portion of the total lake area(28.8%).With 2,590 features(5.9%),small-sized(10,000 to 100,000 m^(2))and large-sized lakes(>100,000 m^(2))constituted up to 71.2%of the total lake *** lakes developed more significantly in warm permafrost regions than in cold permafrost areas;74.1%of lakes with a total area of 119.6×106 m^(2)(62.9%),were distributed in warm permafrost *** thermokarst lakes were likely to develop within the elevation range of 4,500~4,800 m,on flat terrain(slope<10°),on SE and S aspects and in alpine meadow *** thermokarst lakes in the study region experienced significant shrinkage between 1990 and 2021,characterized by obvious lake drainage;the lake numbers decreased by 5418(56.1%),with a decreasing area of 58.63×106 m^(2)(49.0%).This shrinkage of the thermokarst lake area was attributable mainly to the intensified degradation of rich-ice permafrost thawing arising from continued climate warming,despite the wetting climatic trend.

关键词： Thermokarst lake Spatial characteristic Influencing factor Source area of the Yellow River

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Thermal regimes and degradation modes of permafrost along the qinghai-Tibet Highway

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Science China Earth Sciences 2006年第11期49卷 1170-1183页

作者： JIN Huijun ZHAO Lin WANG Shaoling JIN Rui State Key Laboratory of Frozen Soils Engineering and cryosphere station of the qinghai-Tibet plateau Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of SciencesLanzhou 730000 China

Permafrost on the qinghai-Tibet plateau (QTP) is widespread, thin, and thermally unstable. Under a warming climate during the past few decades, it has been degrading extensively with generally rising ground temperatures, the deepening of the maximum summer thaw, and with lessening of the winter frost penetration. The permafrost has degraded downward, upward and laterally. Permafrost has thinned or, in some areas, has totally disappeared. The modes of permafrost degradation have great significance in geocryology, in cold regions engineering and in cold regions environmental management. Permafrost in the interior of the QTP is well represented along the Qing-hai-Tibet Highway (QTH), which crosses the plateau through north to south and traverses 560 km of permafrost-impacted ground. Horizontally, the degradation of permafrost occurs more visibly in the sporadic permafrost zone in the vicinity of the lower limit of permafrost (LLP), along the margins of taliks, and around permafrost islands. Downward degradation develops when the maximum depth of seasonal thaw exceeds the maximum depth of seasonal frost, and it generally results in the formation of a layered talik disconnecting the permafrost from the seasonal frost layer. The downward degrada- tion is divided into four stages: 1) initial degradation, 2) accelerated degradation, 3) layered talik and 4) finally the conversion of permafrost to seasonally frozen ground (SFG). The upward degradation occurs when the geothermal gradient in permafrost drops to less than the geothermal gradients in the underlying thawed soil layers. Three types of permafrost temperature curves (stable, degrading, and phase-changing transitory permafrost) illustrate these modes. Although strong differentiations in local conditions and permafrost types exist, the various combinations of the three degradation modes will ultimately transform permafrost into SFG. Along the QTH, the downward degradation has been proceeding at annual rates of 6 to 25

关键词： QTP QTH permafrost ground temperatures degradation modes geothermal gradients.

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Lakes in the qinghai-Tibet plateau are conducive to regional permafrost development

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Journal of Mountain Science 2023年第3期20卷 738-749页

作者： XIE Chang-wei YANG Gui-qian WANG Wu ZHANG Yu-xin LIU Wen-hui LIU Guang-yue WU Ji-chun PANG Qiang-qiang cryosphere research station on the qinghai-Tibet plateau State Key Laboratory of Cryosphere SciencesNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 101408China Department of Geological Engineering Qinghai UniversityXining 810016China

The qinghai-Tibet plateau(QTP)possesses the largest areas of permafrost in the midand low latitude regions on the earth and many large lakes in the permafrost *** on a comprehensive investigation around certain typical lakes,this study found that although the presence of lakes formed different ranges of unfrozen zones in permafrost,the heating effect of lake water on surrounding permafrost is limited to a small *** temperature of permafrost around the lake is closely related to the distance to the lake and the ice content of the *** lakes are ice-rich permafrost zones and permafrost temperature in this area is significantly lower than that far away from the lake,which indicates that the existence of lakes in the QTP has special effect on the permafrost *** on the monitoring results,this study presents the typical distribution pattern of the permafrost around large lakes and discusses the reasons for the distribution *** to the huge area of lakes and the significant impact of lakes on permafrost distribution,it is suggested to re-estimate the total permafrost area and underground ice storage in the QTP.

关键词： Heating effect So1il water content Permafrost distribution Lakes qinghai-Tibet plateau

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Response mechanism of soil microorganisms to simulated precipitation in the source wetland of qinghai Lake

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Ecological Processes 2024年第2期13卷 61-71页

作者： Xinye Wang Ni Zhang Kelong Chen Tiexi Chen Desheng Qi Yuanxi Ma School of Geographical Sciences Qinghai Normal University National Positioning Observation and research station of qinghai Lake Wetland Ecosystem in qinghai National Forestry and Grassland Administration Key Laboratory of tibetan plateau Land Surface Processes and Ecological Conservation(Ministry of Education) Qinghai Normal University School of Geographical Sciences Nanjing University of Information Science and Technology qinghai Provincial land spatial Planning research Institute

Background Changes in precipitation patterns crucially impact soil microbial communities, and the ecosystem in qinghai-Tibet plateau(QTP) is highly vulnerable to climate change. However, we do not fully understand how soil microbial communities in the source wetlands of QTP respond to changes in precipitation. In this study, we employed advanced techniques such as high-throughput sequencing and metabolomics to investigate how soil microbial communities in a source wetland of qinghai Lake respond to changes in precipitation after quadrennial precipitation *** Our findings showed that the predominant microbiota in the source wetland was Proteobacteria. Interestingly, alterations in precipitation levels, whether increased or reduced, did not significantly impact the diversity or functional groups of the microbial community. However, the structure of the microbial community did respond notably to changes in precipitation, leading to shifts in the relative abundance of Spirochaetes and Treponema. A notable finding was that reduced precipitation levels(– 25% and-50%) and mild increases in precipitation(25%) within the region contributed to increased soil carbon content. However, this effect ceased to manifest when precipitation increased by 50%. Additionally, the reduction in precipitation prompted the release of soil metabolites like syringic acid and aldosterone, while enhanced precipitation resulted in a decrease in aldosterone *** Precipitation changes altered the relative abundance of soil microbial communities and metabolites, which was conducive to increasing carbon storage in this alpine wetland.

关键词： qinghai-Tibet plateau Climate change Precipitation gradient Carbon and nitrogen cycles LC/MS

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Relationships between δ ^(18)O in summer precipitation and temperature and moisture trajectories at Muztagata, western China

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Science China Earth Sciences 2006年第1期49卷 27-35页

作者： YU Wusheng1,2, YAO Tandong1,2, TIAN Lide1,2, LI Zhen2, SUN Weizhen2 & WANG Yu2 1. Laboratory of Environment and Process on tibetan plateau, Institute of tibetan plateau research, Chinese Academy of Sciences, Beijing 100085, China 2. Key Laboratory of cryosphere and Environment, Jointly Established by Cold and Arid Regions Environmental and Engi-neering research Institute and Institute of tibetan plateau research, Chinese Academy of Sciences and Chinese Academy of Meteorological Sciences, China Meteorological Administration, CAS, Lanzhou 730000, China 1. Laboratory of Environment and Process on tibetan plateau Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China 2. Key Laboratory of cryosphere and Environment Jointly Established by Cold and Arid Regions Environmental and Engineering Research Institute and Institute of Tibetan Plateau Research Chinese Academy of Sciences and Chinese Academy of Meteorological Sciences China Meteorological Administration Lanzhou 730000 China

Based on summer observations of stable isotope of precipitation at Muztagata, western China, during 2002―2003, this paper presents the relationship between δ 18O in precipitation and air temperature, and discusses the effect of moisture transport on δ 18O in precipitation. Results show that air temperature correlates positively with δ 18O in precipitation, and the temperature effect controls the δ 18O of precipitation in this area. The Muztagata region exhibits high δ 18O values in summer precipi-tation, similar to those shown at stations in adjacent regions. According to the results of our model set up to trace the moisture trajectories, the westerlies and local moisture circulation contribute to varia-tions of oxygen isotopes in precipitation. In addition, the impacts of the moisture transport distance, the moisture transport level, and the incursion of the polar air mass also influence the variations of δ 18O in precipitation. The moisture origins and transport mechanisms also contribute to the variation of δ 18O in precipitation at Muztagata.

关键词： Muztagata, δ18O, precipitation, temperature, moisture transport.

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Variations of δ^(18)O in precipitation from the Muztagata Glacier, East Pamirs

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Science China Earth Sciences 2006年第1期49卷 36-42页

作者： LI Zhen1, YAO Tandong1,2, TIAN Lide1,2, XU Baiqing1,2 & Wu Guangjian2 1. Key Laboratory of cryosphere and Environment, Jointly Established by Cold and Arid Regions Environmental and Engi-neering research Institute and Institute of tibetan plateau research, Chinese Academy of Sciences and Chinese Academy of Meteorological Sciences, China Meteorological Administration, CAS, Lanzhou 730000, China 2. Laboratory of Environment and Process on tibetan plateau, Institute of tibetan plateau research, Chinese Academy of Sciences, Beijing 100085, China 1. Key Laboratory of cryosphere and Environment Jointly Established by Cold and Arid Regions Environmental and Engineering Research Institute and Institute of Tibetan Plateau Research Chinese Academy of Sciences and Chinese Academy of Meteorological Sciences China Meteorological Administration Lanzhou 730000 China 2. Laboratory of Environment and Process on tibetan plateau Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 100085 China

Expeditions to Muztagata (in the eastern Pamirs) during the summer seasons of2002 and 2003 collected precipitation samples and measured their oxygen isotopes. The δ^(18)O inprecipitation displays a wide range, varying from -17.40per thousand to +1.33per thousand inJune—September 2002 and from -22.31per thousand to +4.59per thousand in May—August 2003. Theδ^(18)O in precipitation correlates with the initial temperature of precipitation during theobserving periods. The positive correlation between δ^(18)O and temperature suggests that δ^(18)Ocan be used as an indicator of temperature in this region. The δ^(18)O values in fresh-snow samplescollected from two snow events at different elevations on the Muztagata Glacier show a strong''altitude effect'', with a ratio of nearly -0.40per thousand per 100 m from 5500 m to 7450 m.

关键词： Muztagata, δ18O, temperature, altitude effect.

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