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A land surface model incorporated with soil freeze/thaw and its application in GAME/Tibet

Science china earth Sciences 2006年第12期49卷 1311-1322页

作者： HU Heping1, YE Baisheng2. ZHOU Yuhua3.& TIAN Fuqiang1 1. Department of Hydraulic Engineering, Tsinghua University, Beijing 100084, china 2. Cold and Arid Regions {3.al and Engineering Research {2., chinese academy of Sciences, Lanzhou 73.000, china 3. Department of Civil Engineering, Massachusetts {2. of Technology, USA Department of Hydraulic Engineering Tsinghua University Beijing China Cold and Arid Regions environmental and Engineering Research institute Chinese Academy of Sciences Lanzhou China Department of Civil Engineering Massachusetts Institute of Technology USA

Land surface process is of great importance in global climate change, moisture and heat exchange in the interface of the earth and atmosphere, human impacts on the environment and eco- system, etc. Soil freeze/thaw plays an important role in cold land surface processes. In this work the diurnal freeze/thaw effects on energy partition in the context of GAME/Tibet are studied. A sophisti- cated land surface model is developed, the particular aspect of which is its physical consideration of soil freeze/thaw and vapor flux. The simultaneous water and heat transfer soil sub-model not only reflects the water flow from unfrozen zone to frozen fringe in freezing/thawing soil, but also demon- strates the change of moisture and temperature field induced by vapor flux from high temperature zone to low temperature zone, which makes the model applicable for various circumstances. The modified Picard numerical method is employed to help with the water balance and convergence of the numerical scheme. Finally, the model is applied to analyze the diurnal energy and water cycle char- acteristics over the Tibetan Plateau using the Game/Tibet datasets observed in May and July of 1998. Heat and energy transfer simulation shows that: (i) There exists a negative feedback mechanism between soil freeze/thaw and soil temperature/ground heat flux; (ii) during freezing period all three heat fluxes do not vary apparently, in spite of the fact that the negative soil temperature is higher than that not considering soil freeze; (iii) during thawing period, ground heat flux increases, and sensible heat flux decreases, but latent heat flux does not change much; and (iv) during freezing period, soil temperature decreases, though ground heat flux increases.

关键词： land surface model,soil freeze/thaw,GAME/Tibet,simultaneous liquid,vapor and heat transfer.

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Characterization of MASDs of surface soils in north china and its influence on estimating dust emission

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chinese Science Bulletin 2004年第20期49卷 2169-2176页

作者： MEI Fanmin1,2. ZHANG xiaoye1, LU Huayu1, SHEN Zhenxing1 & WANG Yaqiang1 1. State Key Laboratory of Loess and Quaternary Geology, institute of earth {2., chinese academy of Sciences, xian 710075, china 2. xian University of Engineering Science and Technology, xian 710048, china State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi'an 710075 China xi'an University of Engineering Science and Technology Xi'an 710048 China

The micro-aggregated size distribution (MASD) of surface soil is an important parameter for modelling dust emission. However, there is no dataset of MASDs of all sur-face soil types in north china. The MASDs are here pre-sented, measured by dry sieving, for typical surface soil sam-ples, including sandy soil, gravelly sand soil, gravelly loam soil, loam soil and silt loam soil, collected from sandy deserts, Gobi deserts, oases, farmlands in steppe regions and steppe areas in north china. The MASDs of various surface soil types exhibit a combination of several log-normal distribu-tions of five separated sizes with mean mass median diame-ters (MMDs) of 90, 2.0, 3.0, 600 and 980 mm, respectively, and mean standard deviations (SDs) of 1.2., 1.40, 1.2., 1.3. and 1.2. respectively. The log-normal distributions corre-spond to very fine sand, fine sand, medium sand, coarse sand and very coarse sand population. On the basis of characteri-zation of the retrieved MASDs of various surface soil types in north china, dust emission fluxes are modelled by a dust production model (DPM model). It is shown that dust emis-sion has been significantly influenced by MASDs. Fine sand and very fine sand are always associated with the highest dust emission fluxes. Emission fluxes of the medium sand, gravelly sand soil, gravelly loam soil and loam soil are lower than those of very fine sand and fine sand, but larger than those of the coarse sand. The differences in dust emission fluxes vary among the different soil types from 101 to 103.mg·m-2.s-1. Dust emission fluxes from sandy deserts and farmlands covered with sand sheets in north china rang from 101 to 104 mg·m-2.s-1 while those from Gobi deserts, farmlands and steppes with gravelly desertification range from 101 to 102.mg·m-2. s-1. The modelled results indicate that deserts and farmlands with sand are the major dust sources in north china.

关键词：华北地区 MASDs 微块状粒度分布地面土壤粉尘排放壤土大气污染气溶胶

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Temporal variations of δ^(18)O of atmospheric water vapor at Delingha

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Science china earth Sciences 2008年第7期51卷 966-975页

作者： YIN ChangLiang1, YAO TanDong2. TIAN LiDe2. LIU DongNian3. YU WuSheng2.& QU DongMei2.1 State Key Laboratory of Cryoshperic Science, Cold and Arid Regions environmental and Engineering Research institute, {2. academy of Sciences, Lanzhou 73.000, china 2.Laboratory of environment and Processes, institute of Tibetan Plateau Research, {2. academy of Sciences, Beijing 100085, china 3.Meteorological Observatory of Haixi Prefecture of Qinghai Province, Delingha 817000, china State Key Laboratory of Cryoshperic Science Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou China Laboratory of environment and Processes Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China Meteorological Observatory of Haixi Prefecture of Qinghai Province Delingha China

Oxygen stable isotope of atmospheric water vapor is widely used to study the modern process of cli- mate. Atmospheric water vapor samples were collected at Dlingha, northeast of Tibetan Plateau during the period from July 2.05 to February 2.06. The variation of δ18O and the relationships between δ18O and both the temperature and specific humidity are analyzed in this paper. Results show that the sea- sonal variation of δ18O of atmospheric water vapor at Delingha is remarkable with higher δ18O in summer and lower δ18O in winter. The temporal variation of vapor δ18O shows obvious fluctuations, with magnitude of over 3.‰. The daily variation of the δ18O is highly correlated with air temperature. The relationship between δ18O and atmospheric water vapor content is complex. Study shows that δ18O of atmospheric water vapor is positively correlated with specific humidity in winter in seasonal scale and inversely correlated with specific humidity in summer rainy period. The δ18O values of at- mospheric water vapor are lower than those of precipitation at Delingha, and the average difference is 10.7‰. Variations of δ18O of atmospheric water vapor is also found to be affected by precipitation events, The model results show that the precipitation effect could have caused the vapor δ18O in the raining season to lower by 7% in average in July and August.

关键词： Delingha δ18O atmospheric water vapor

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Forecast Method of Multimode System for Debris Flow Risk Assessment in Qingping Town,Sichuan Province,china

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Journal of Mountain Science 2011年第4期8卷 592-602页

作者： KONG Jiming Key Laboratory of Mountain Hazards and earth Surface Processes Chinese Academy of Sciences institute of Mountain Hazards and environment Chinese Academy of Sciences

The Wenchuan earthquake of May 12.2.08 triggered large numbers of *** heavy rain on 13.August 2.10 triggered debris flows with total volume of more than 6 million cubic meters and the debris flows destroyed 500 houses and infrastructure built after the Wenchuan *** study area Qingping Town was located in the northwestern part of the Sichuan Basin of china,which needs the second reconstructions and the critical evaluation of debris *** study takes basin as the study unit and defines collapse,landslide and debris flow hazard as a geo-hazard system.A multimode system composed of principal series system and secondary parallel system were established to evaluate the hazard grade of debris flow in 13. drainage basins of Qingping *** evaluation result shows that 3..43. of study basins(42.basins) and 2..58% of study area,are in extremely high or high hazard grades,and both percentage of basin quantity and percentage of area in different hazard grades decrease with the increase of hazard *** to the geo-hazard data from the interpretation of unmanned plane image with a 0.5-m resolution and field investigation after the Wenchuan earthquake and 8.13.Big Debris Flow,the ratio of landslides and collapses increased after the Wenchuan earthquake and the ratios of extremely high or high hazard grades were more than moderate or low hazard grades obviously.2. geo-hazards after8.13.Big Debris Flow in Qingping town region all occurred in basins with extremely high or high hazard grades,and 9 debris flows were in basins with extremely high hazard *** model of multimode system for critical evaluation could forecast not only the collapse and landslide but also the debris flow precisely when the basin was taken as the study unit.

关键词： Multimode System Risk assessment Debris flow Landslide Wenchuan earthquake Qingping Town

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The impact of vegetation restoration on erosion-induced sediment yield in the middle Yellow River and management prospect

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Science china earth Sciences 2005年第6期48卷 724-741页

作者： CHEN Hao1, ZHOU Jinxing2. CAI Qiangguo1, YUE Zhongqi3. LU Zhongchen4, LIANG Guanglin1& HUANG Jianguo5 1. Key Laboratory of Water Cycle and Related Land Surface Processes, institute of Geographic Sciences and Natural Resources Re-search, chinese {2. of Sciences, Beijing 100101, china 2. institute of Forestry, chinese {2. of Forestry Sciences, Beijing 100091, china 3. Department of Civil Engineering, University of Hong Kong, Hong Kong, china 4. Eco-environmental Research Center, chinese {2. of Sciences, Beijing 100085, china 5. College of Resources and environment, Southwest Agricultural University, Chongqing 400716, china Correspondence should be addressed to Chen Hao Key Laboratory of Water Cycle and Related Land Surface Processes Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing China institute of Forestry Chinese Academy of Forestry Sciences Beijing China Department of Civil Engineering University of Hong Kong Hong Kong China Eco-environmental Research Center Chinese Academy of Sciences Beijing China College of Resources and environment Southwest Agricultural University Chongqing China

According to the characteristics of water and erosion environments of different natural zones on the Loess Plateau, this paper studies changes of vegetation types, distribution boundaries of forest and grass as well as restoration capacity of vegetation in different natural zones in the middle Yellow River. The annual precipitation of 53. mm is the critical annual pre-cipitation for forest and grass distribution in the middle Yellow River. Among the zonal and azonal environmental factors affecting watershed sediment yield, the intermediate diameter D50 (mm) of suspended load and forest coverage (V, %) play the leading role. Of them the effect weight of forest coverage (V, %) on catchments sediment yield is only 3.4% less than the role of the intermediate diameter (D50, mm), they are almost the same. To effectively control soil erosion in semiarid, especially in hilly-gullied areas and make sediment transport modulus reduce to less than 6000 t/km2. it is rather difficult by merely relying on natural restoration of forest. In the process of cultivated land conversion into forest land and grassland, measures suiting local conditions should be adopted in tree species selection and artificial afforestation (grass planting) based on management with biological measures for slopeland and engineering measures for hilly-gullied areas, so that watershed forest coverage in key counties can reach at least over 3.%.Compared with the standard period of precipitation prior to the 1960s, with the decrease of an-nual precipitation at various periods, plant productivities decline to different degrees under natural conditions. The main reason accountable for the low survival rate of new seedlings and grass over years is due to precipitation decrease. In light with regression models of annual pre-cipitation and natural vegetation productivities, it is possible to obtain estimated values of wa-tershed natural vegetation productivity and eco-water consumption needed for the restoration to

关键词： vegetation restoration, eco-water requirement, watershed sediment yield, the middle Yellow River.

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U-Pb dating of zircon from the bed parallel anatectic granitic intrusion in the Baoban group in Hainan Island and the tectonic implication

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Science china earth Sciences 2005年第12期48卷 2092-2103页

作者： DING Shijiang1, HU Jianmin2. SONG Biao3.4, CHEN Mulun1, xiE Shengzhou1 & FAN Yuan1 1. Geological Surveying institute of Hainan, Haikou 5702.6,{3. 2. institute of Geomechanics, chinese academy of Geological Sciences, Beijing 100081,{3. 3. Beijing Center of SHRIMP, Beijing 10003.,{3. 4. institute of Geology, chinese academy of Geological Sciences, Beijing 10003.,{3. Geological Surveying institute of Hainan Haikou China institute of Geomechanics Chinese Academy of Geological Sciences Beijing China Beijing Center of SHRIMP Beijing China institute of Geology Chinese Academy of Geological Sciences Beijing China

The petrological and geochemical features of the bed parallel granitic intrusion in the Pre-Cambrian Baoban group in Hainan Island attest to the anatexis origin of the granites. U-Pb dating analyses of zircons from the anatectic granite and the biotite two-feldspar gneiss in the Baoban group, using SHRIMP II in the Beijing Ion-probe Center, acquire 2.6Pb/2.8U ages of 3.8±3.5 Ma (of granite, 95% confidence level, MSDW=1.2.) and 3.2.9±6.1 Ma (of gneiss, 95% confidence level, MSDW = 2.04) respectively. The two late Devonian ages indicate consistently a tectonic- thermal event experienced in Hainan Island, and are the first discovered record of the Devonian geological process in the district. This event possibly resulted from the deep ther-mal-dynamic process when the Gondwana continent began to break up in the Devonian period.

关键词： Hainan Island, Devonian period, anatectic granite, zircon SHRIMP U-Pb dating.

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The fluxes and controlling factors of N_2. and CH_4 emissions from freshwater marsh in Northeast china

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Science china earth Sciences 2010年第5期53卷 700-709页

作者： YU JunBao1,2. LIU JingShuang2. SUN ZhiGao1, SUN WeiDong3. WANG JinDa2. WANG GuoPing2.& CHEN xiaoBing1 1 Key Lab of Coastal Envionment Processed, Yantai institute of Coastal Zone Research for Sustainable Development, chinese {2. of Sciences, Yantai 2.4003. china 2.Key Lab of Wetland Ecology and environment, Northeast institute of Geography and Agricultural Ecology, chinese {2. of Sciences, Changchun 13.012. china 3.Key Laboratory of Isotope Geochronology and Geochemistry, Guangzhou institute of Geochemistry, chinese {2. of Sciences, Guangzhou 510640, china Key Lab of Coastal Envionment Processed Yantai Institute of Coastal Zone Research for Sustainable Development Chinese Academy of Sciences Yantai China Key Lab of Wetland Ecology and environment Northeast Institute of Geography and Agricultural Ecology Chinese Academy of Sciences Changchun China Key Laboratory of Isotope Geochronology and Geochemistry Guangzhou Institute of Geochemistry Chinese Academy of Sciences Guangzhou China

Nitrous oxide (N2.) and methane (CH4) emissions were measured using a static chamber method in two adjacent plots of freshwater marsh predominated by Calamagrostis angustifolia, one is seasonal waterlogged (SW) and the other without surface water accumulation (NW), in Sanjiang Plain wetland (47°3.′N, 13.°3.′E), northeast china, during 2.02.2.04. The diurnal and seasonal flux variations of both gases were significantly correlated with 5-cm-soil temperature. The NW marsh is a source of N2. and sink of CH4, while the SW marsh is sink of N2. and source of CH4. Remarkably, we observed a N2. emission peak under Eh of +3.0 to +100 mV, and CH4 emission peak under Eh of +3.0 to +400 mV, which indicate additional sources of N2. and CH4 for the freeze-thaw induced emission peaks of N2. and CH4 observed between late July and early August. Further study shows that the additional N2. and CH4 were emitted under the frozen soil after thawing.

关键词： freeze-thaw region freshwater marsh methane nitrous oxide controlling factors

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Planation Surfaces on the Tibet Plateau,china

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Journal of Mountain Science 2008年第4期5卷 310-317页

作者： ZHANG xinbao HE xiubin WANG Yangchun LONG Yi institute of Mountain Hazards and environment CAS Chengdu 610041 China State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment GAS Xi＇an 710075 China Graduate University of the chinese Academic of Sciences Beijing 100039 China

A planation hypothesis is proposed to explain landform evolution of the Tibet Plateau. A denudation threshold （T）, the maximum potential denudation rate for a certain type of rock, is introduced to explain the combined effects of lithology and tectonics on landform evolution. If the tectonic uplifting rate （U） is equal to or less than the threshold rate （U ≤ T）, the tectonic uplifting and terrain denudation are in dynamic equilibrium, and landforms are in a steady state. The end product should be planation surfaces whether the original landforms are flat plains or deeply dissected mountains. If U 〉 T, uplift and denudation are not able to reach a dynamic equilibrium state. The plateau surface is mostly underlain by soft rocks, such as the Mesozoic epimetamorphic argillites and Tertiary sedimentary rocks, while the mountain ranges comprise hard rocks, such as granite, gneiss and limestone. In soft rock regions, hills are low with a relative relief of mostly less than 100 m and the slopes are gentle at a gradient of 〈2.0. In contrast, hills can maintain steep slopes in hard rock regions. The Tibet Plateau has been under an equilibrium condition between tectonic uplifting and denudation except for the mountain ranges. The plateau might have reached the present altitudes before the Quaternary.

关键词： planation denudation threshold landform evolution Tibet Plateau china

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Carbon isotope ratios of C_(4) plants in loess areas of North china

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Science china earth Sciences 2006年第1期49卷 97-102页

作者： WANG Guoan1,2.3. HAN Jiamao 2. ZHOU Liping3. xiONG xiaogang4, TAN Ming2. WU Zhenhai5 & PENG Jun6 1. Department of Plant Nutrition,{3. Agricultural University, Beijing 100094,{3. 2. {2. of Geology and Geophysics, chinese academy of Sciences, Beijing 10002.,{3. 3. College of environmental Sciences, MOE Laboratory for earth Surface Processes, Peking University, Beijing 100871,{3. 4. {2. of Botany, chinese academy of Sciences, Beijing 100093.{3. 5. Northwest Sci-Tech University of Agriculture and Forestry, Yangling 712.00,{3. 6. Network Center,{3. Agricultural University, Beijing 100094,{3. Department of Plant Nutrition China Agricultural University Beijing China institute of Geology and Geophysics Chinese Academy of Sciences Beijing China College of environmental Sciences MOE Laboratory for Earth Surface Processes Peking University Beijing China institute of Botany Chinese Academy of Sciences Beijing China Northwest Sci-Tech University of Agriculture and Forestry Yangling China Network Center China Agricultural University Beijing China

Carbon isotope ratios (δ^(13.C) of 89 C_4 plant samples were determined fromthe loess area in North china. δ^(13.C values vary between -10.5per thousand and -14.6per thousandwith a mean of -12.6per thousand. Along a precipitation gradient from the semi-moist area to thesemiarid area, then to the arid area, the δ^(13.C values of C_4 plants show a slight decreasingtrend. The δ^(13.C values of C_4 plants in the dry season are found lower than those in the wetseason. These trends are opposite to those observed for C_3.species.

关键词： C4 plants, carbon isotope ratios, loess area.

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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, {2. 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, {2. academy of Sciences and {2. academy of Meteorological Sciences, china Meteorological Administration, CAS, Lanzhou 73.000, china Laboratory of environment and Process on Tibetan Plateau Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China 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 China

Based on summer observations of stable isotope of precipitation at Muztagata, western china, during 2.02.2.03. 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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