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Improving CLM4.5 Simulations of Land–Atmosphere Exchange during Freeze–Thaw Processes on the Tibetan Plateau

Journal of Meteorological Research 2017年第5期31卷 916-930页

作者： Siqiong LUO Xuewei FANG shihua lyu Yu ZHANG Boli CHEN Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences School of Atmospheric Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu University of Information Technology Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science &Technology Changzhou Meteorological Bureau

Soil is heterogeneous and has different thermal and hydraulic properties, causing varied behavior in heat and mois- ture transport. Therefore, soil has an important effect on lanatmosphere interactions. In this study, an improved soil parameterization scheme that considers gravel and organic matter in the soil was introduced into CLM4.5 （Com- munity Land Model）. By using data from the Zoige and Madoi sites on the Tibetan Plateau, the ability of the model to simultaneously simulate the duration of freeze-thaw periods, soil temperature, soil moisture, and surface energy during freeze-thaw processes, was validated. The results indicated that：（1） the new parameterization performed bet- ter in simulating the duration of the frozen, thawing, unfrozen, and freezing periods; （2） with the new scheme, the soil thermal conductivity values were decreased; （3） the new parameterization improved soil temperature simulation and effectively decreased cold biases; （4） the new parameterization scheme effectively decreased the dry biases of soil li- quid water content during the freezing, completely frozen, and thawing periods, but increased the wet biases during the completely thawed period; and （5） the net radiation, latent heat flux, and soil surface heat flux of the Zoige and Madoi sites were much improved by the new organic matter and thermal conductivity parameterization.

关键词： land surface model freeze-thaw processes gravel and organic matter Tibetan Plateau

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Factors Influencing Diurnal Variations of Cloud and Precipitation in the Yushu Area of the Tibetan Plateau

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Journal of Meteorological Research 2022年第2期36卷 311-325页

作者： Bangjun CAO shihua lyu Yu ZHANG Xianyu YANG Boliang LI Liang YUAN Meilin LI Plateau Atmosphere and Environment Key Laboratory of Sichuan Province School of Atmospheric SciencesChengdu University of Information TechnologyChengdu 610225

Using the cloud radar,ground observations,and ECMWF Reanalysis v5(ERA5)data,we investigate the factors influencing nighttime precipitation during summer in the Yushu area of the Tibetan Plateau(TP).The cloud top height(CTH),cloud base height(CBH),and liquid water content(LWC)are compared between non-precipitation and precipitation *** results show that the average CTH on precipitation days in Yushu is below 10 km above ground level(AGL)in the daytime,whereas it exceeds 10 km AGL at night,with the maximum at 2300 BT(Beijing Time).The CBH is in-phase with the dewpoint *** precipitation intensity and CTH are in-phase with the *** hourly averaged precipitation intensity and convective available potential energy in ERA5 reach their maximums at2100 BT,which is 3 h ahead of their observed *** is descending motion in the mid day on non-precipitation days,whereas there is ascending motion at night on precipitation *** addition,the horizontal wind direction in the lower level(below 5000 m)shows clockwise rotation from morning to *** shear occurs in the mid level of the atmosphere,accompanied by a subtropical westerly jet in the upper *** difference in horizontal wind speed between 200 and 500 hPa is positively related to the LWC,thereby contributing to the formation of upper-level cloud.

关键词： diurnal variation cloud precipitation Tibetan Plateau

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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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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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Numerical simulation of the climate effect of high-altitude lakes on the Tibetan Plateau

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Research in Cold and Arid Regions 2018年第5期10卷 379-391页

作者： YinHuan Ao shihua lyu ZhaoGuo Li LiJuan Wen Lin Zhao Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan Province School of Atmospheric Sciences Chengdu University of Information Technology Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science & Technology

Lakes regulate the water and heat exchange between the ground and the atmosphere on different temporal and spatial scales. However, studies of the lake effect in the high-altitude Tibetan Plateau(TP) rarely have been performed until recently, and little attention has been paid to modelling of frozen lakes. In this study, the Weather Research and Forecasting Model(WRF v. 3.6.1) is employed to conduct three numerical experiments in the Ngoring Lake Basin(the original experiment, an experiment with a tuned model, and a no-lake experiment) to investigate the influences of parameter optimization on the lake simulation and of the high-altitude lake on the regional climate. After the lake depth, the roughness lengths, and initial surface temperature are corrected in the model, the simulation of the air temperature is distinctly improved. In the experiment using a tuned model, the simulated sensible-heat flux(H) is clearly improved, especially during periods of ice melting(from late spring to early summer) and freezing(late fall). The improvement of latent-heat flux(LE) is mainly manifested by the sharp increase in the correlation coefficient between simulation and observation, whereas the improvement in the average value is small. The optimization of initial surface temperature shows the most prominent effect in the first year and distinctly weakens after a freezing period. After the lakes become grassland in the model, the daytime temperature clearly increases during the freezing and melting periods; but the nocturnal cooling appears in other stages, especially from September to October. The annual mean H increases by 6.4 times in the regions of the Ngoring Lake and the Gyaring Lake, and the LE declines by 56.2%. The sum of H and LE increases from 71.2 W/m2(with lake) to 84.6 W/m2(no lake). For the entire simulation region, the sum of H and LE also increases slightly. After the lakes are removed, the air temperature increases significantly from June to September over the

关键词： Lake-surface temperature roughness length turbulent flux Ngoring Lake Tibetan Plateau

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Radiation balance and the response of albedo to environmental factors above two alpine ecosystems in the eastern Tibetan Plateau

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Research in Cold and Arid Regions 2017年第2期9卷 142-150页

作者： ShaoYing Wang Yu Zhang shihua lyu LunYu Shang YouQi Su HanHui Zhu Key Laboratory of Land Surface and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou Gausu 730000 China College of Atmospheric Sciences Chendu University of Information Technology Chengdu Sichuan 610225 China

Understanding the energy balance on the Tibetan Plateau is important for better prediction of global climate change. To characterize the energy balance on the Plateau, we examined the radiation balance and the response of albedo to environmental factors above an alpine meadow and an alpine wetland surfaces in the eastern Tibetan Plateau, using 2014 data. Although our two sites belong to the same climatic background, and are close geographically, the annual incident solar radiation at the alpine meadow site(6,447 MJ/(m2·a)) was about 1.1 times that at the alpine wetland site(6,012 MJ/(m2·a)),due to differences in the cloudiness between our two sites. The alpine meadow and the alpine wetland emitted about 38%and 42%, respectively, of annual incident solar radiation back into atmosphere in the form of net longwave radiation; and they reflected about 22% and 18%, respectively, of the annual incident solar radiation back into atmosphere in the form of shortwave radiation. The annual net radiation was 2,648 and 2,544 MJ/(m2·a) for the alpine meadow site and the alpine wetland site, respectively, accounting for only about 40% of the annual incident solar radiation, significantly lower than the global mean. At 30-min scales, surface albedo exponentially decreases with the increase of the solar elevation angle; and it linearly decreases with the increase of soil-water content for our two sites. But those relationships are significantly influenced by cloudiness and are site-specific.

关键词： Tibetan Plateau radiation balance surface albedo solar elevation angle soil water content

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Winter estimation of surface roughness length over eastern Qinghai-Tibetan Plateau

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Research in Cold and Arid Regions 2017年第2期9卷 151-157页

作者： LunYu Shang Yu Zhang shihua lyu ShaoYing Wang YinHuan Ao SiQiong Luo ShiQiang Chen Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou Gansu 730000 China College of Atmospheric Science Chengdu University of Information Technology Chengdu Sichuan 610225 China

Based on the Monin-Obulchov similarity theory, a scheme was developed to calculate surface roughness length. Surface roughness length over the eastern Qinghai-Tibetan Plateau during the winter season was then estimated using the scheme and eddy covariance measurement data. Comparisons of estimated and measured wind speeds show that the scheme is feasible to calculate surface roughness length. The estimated roughness lengths at the measurement site during unfrozen, frozen and melted periods are 3.23x10(-3), 2.27x10(-3) and 1.92x10(-3) m, respectively. Surface roughness length demonstrates a deceasing trend with time during the winter season. Thereby, setting the roughness length to be a constant value in numerical models could lead to certain degree of simulation errors. The variation of surface roughness length may be caused by the change in land surface characteristic.

关键词： Qinghai-Tibetan Plateau surface roughness length Monin-Obuichov similarity theory least square fitting

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Dataset of Comparative Observations for Land Surface Processes over the Semi-Arid Alpine Grassland against Alpine Lakes in the Source Region of the Yellow River

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Advances in Atmospheric Sciences 2023年第6期40卷 1142-1157页

作者： Xianhong MENG shihua lyu Zhaoguo LI Yinhuan AO Lijuan WEN Lunyu SHANG Shaoying WANG Mingshan DENG Shaobo ZHANG Lin ZHAO Hao CHEN Di MA Suosuo LI Lele SHU Yingying AN Hanlin NIU Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Zoige Plateau Wetland Ecosystem Research Station Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Plateau Atmosphere and Environment Key Laboratory of Sichuan Province School of Atmospheric SciencesChengdu University of Information TechnologyChengdu 610225China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjing 210044China University of Chinese Academy of Sciences Beijing 100049China

Thousands of lakes on the Tibetan Plateau(TP) play a critical role in the regional water cycle, weather, and climate. In recent years, the areas of TP lakes underwent drastic changes and have become a research hotspot. However, the characteristics of the lake-atmosphere interaction over the high-altitude lakes are still unclear, which inhibits model development and the accurate simulation of lake climate effects. The source region of the Yellow River(SRYR) has the largest outflow lake and freshwater lake on the TP and is one of the most densely distributed lakes on the TP. Since 2011,three observation sites have been set up in the Ngoring Lake basin in the SRYR to monitor the lake-atmosphere interaction and the differences among water-heat exchanges over the land and lake surfaces. This study presents an eight-year(2012–19), half-hourly, observation-based dataset related to lake–atmosphere interactions composed of three sites. The three sites represent the lake surface, the lakeside, and the land. The observations contain the basic meteorological elements,surface radiation, eddy covariance system, soil temperature, and moisture(for land). Information related to the sites and instruments, the continuity and completeness of data, and the differences among the observational results at different sites are described in this study. These data have been used in the previous study to reveal a few energy and water exchange characteristics of TP lakes and to validate and improve the lake and land surface model. The dataset is available at National Cryosphere Desert Data Center and Science Data Bank.

关键词： field observation dataset lake-atmosphere interaction energy and water exchanges the source region of the Yellow River Tibetan Plateau

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An improvement of soil temperature simulations on the Tibetan Plateau

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Research in Cold and Arid Regions 2018年第1期10卷 80-94页

作者： SiQiong Luo BoLi Chen shihua lyu XueWei Fang JingYuan Wang XianHong Meng LunYu Shang ShaoYing Wang Di Ma Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhouGansu 730000China Changzhou Meteorological Bureau ChangzhouJiangsu 213000China School of Atmospheric Sciences Plateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu University of Information TechnologyChengduSichuan 610225China Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters Nanjing University of Information Science and TechnologyNanjingJiangsu 210044China

The simulation of soil temperature on the Tibetan Plateau(TP) plays a dominant role in the performance of both global climate and numerical weather forecast models. To improve the simulation of soil temperature on the TP, the Johansen soil thermal conductivity parameterization scheme was introduced into Community Land Model 3.5(CLM3.5) and Regional Climatic Model 4(Reg CM4). The improved CLM3.5 and Reg CM4-CLM were utilized to conduct offline and regional simulation experiments on the TP. Comparison of the new and old schemes revealed that CLM3.5 provides high thermal conductivity parameters of mineral soil solid on the TP. The Johansen scheme is more practical for the TP than the soil thermal conductivity parameterization in CLM3.5. The simulation of soil temperature and liquid water content was improved in offline experiment. The improved parameterization scheme can also reduce the simulation error of soil temperature in winter throughout the entire TP.

关键词： soil temperature soil thermal conductivity parameterization scheme Tibetan Plateau CLM3.5 RegCM4

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青藏高原土壤冻融参数化改进及其在BCC_CSM气候模式中的效果对比

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高原气象 2023年第5期42卷 1093-1106页

作者：杨凡吕世华张少波徐悦胥朋飞游辉奇成都信息工程大学大气科学学院高原大气与环境四川省重点实验室四川成都610225 中国科学院西北生态资源环境研究院寒旱区陆面过程与气候变化重点实验室甘肃兰州730000 兰州大学甘肃兰州730000

考虑到冻融过程对于陆气相互作用的重要影响,本文将改进后的冻融参数化方案耦合到BCC_CSM2_MR模式中并进行了为期一年的模拟实验,根据土壤层的年变化将模拟时段划分为开始冻结、完全冻结、开始消融和完全消融四个阶段,分析了土壤温度、... 详细信息

考虑到冻融过程对于陆气相互作用的重要影响,本文将改进后的冻融参数化方案耦合到BCC_CSM2_MR模式中并进行了为期一年的模拟实验,根据土壤层的年变化将模拟时段划分为开始冻结、完全冻结、开始消融和完全消融四个阶段,分析了土壤温度、土壤温度、高原近地面风场和降水这几个气象要素。结果表明,对于浅层和深层的土壤温度,四个冻融阶段新方案的模拟都有良好的改进效果,尤其是在高原中部模拟更加准确。优化后的冻融参数化方案对土壤湿度的模拟效果改善是十分显著的,在这四个冻融时段,新方案的均方根误差和偏差在青藏高原全域都有明显的降低,主要表现在青藏高原中部地区。青藏高原上整体呈现为西风,冻结过程阶段新方案模拟结果在高原北部以及中部地区风速偏差有所减小,与对比资料更为接近;完全冻结阶段、消融过程阶段以及完全消融阶段新方案在高原北部的风速偏差减小较为明显;在冻融过程的四个阶段的降水模拟,新方案的均方根误差比原方案减小,相关系数都有提升。研究结果显示改进之后的土壤冻融参数化方案相比与原方案BCC_CSM中的模拟效果有提升,对于主要环流系统的模拟有改善。

关键词：青藏高原 BCC_CSM模式土壤冻融过程土壤温湿度

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