唐古拉地区活动层水热状况及地气系统能水平衡分析

活动层水热状况与地-气系统间能水交换直接影响着寒区生态环境、水文过程以及多年冻土的稳定性。利用唐古拉站2007年实测资料和SHAW模型,对研究点活动层土壤剖面温湿度进行了模拟。土壤温度方面,模型的纳什效率系数NSE≥0.93;水分方面,纳什效率系数的平均值为0.69,说明SHAW模型可用于多年冻土区活动层内水热动态变化的模拟研究。基于模型的输出结果,对唐古拉站活动层土壤冻融过程中的水分动态、地表能量收支的变化特征进行了分析讨论。结果表明:(1)活动层冻融过程中,土壤水分的冻结和融化响应时间随土壤深度的增加而逐渐滞后,水分迁移通量随土壤深度的增加逐渐减小;(2)地表能量平衡收支在季风活动引起的降水与活动层的冻融循环共同影响下,表现出明显的季节性变化特征。同时,通过改变SHAW模型植被输入参数中的叶面积指数,分析了植被覆盖变化对多年冻土区土壤蒸散发的影响。结果表明:植被蒸腾量、土壤蒸发量与总的蒸散发量与植被的叶面积指数呈正相关关系,而浅层土壤含水率(20 cm)则表现为负相关,当叶面积指数在-100%(裸土)~100%变化时,总蒸散发量的变化幅度为-5%~13%。     

模拟多年冻土活动层厚度对气候变化的响应

在气候变化背景下,活动层厚度的变化会对多年冻土区水文,生态,寒区工程等产生较大的影响.本研究利用中科院气候系统模式CAS-FGOALS-g3和陆面过程模式CAS-LSM模拟分析了活动层厚度的变化趋势和相对变化.结果表明:活动层厚度整体上呈现出增加的趋势.1979-2014年,多年冻土区活动层厚度的区域平均为1.08 m...     

模拟多年冻土活动层厚度对气候变化的响应（英文）

在气候变化背景下,活动层厚度的变化会对多年冻土区水文,生态,寒区工程等产生较大的影响.本研究利用中科院气候系统模式CAS-FGOALS-g3和陆面过程模式CAS-LSM模拟分析了活动层厚度的变化趋势和相对变化.结果表明:活动层厚度整体上呈现出增加的趋势.1979-2014年,多年冻土区活动层厚度的区域平均为1.08 m,变化趋势为0.33 cm yr~(-1),其变化趋势与2 m气温变化趋势基本一致,相对变化范围为1%-58%,平均为10.9%.在未来四种不同的气候情景(SSP-2.6,SSP2-4.5,SSP3-7.0和SSP5-8.5)下,到2100年预计活动层厚度的相对变化分别为10.3%,14.6%,30.1%和51%.     

青藏高原多年冻土监测及近期变化

对1995－2004年青藏高原多年冻土温度监测资料进行分析,结果表明：在全球气候变暖影响下,近10年来多年冻土发生了显著的变化,活动层厚度有明显的增大趋势,且高温多年冻土区活动层厚度增大趋势大于低温多年冻土区。多年冻土上限温度和6 m深度多年冻土温度均有明显的升温趋势,低温多年冻土区升温速率要大于高温多年冻土。青藏高原多年冻土变化对气候变暖有明显的响应关系。     

棉田SPAS水热传输的多层模式

根据能量平衡方程和土壤水热耦合方程，建立土壤－植物－大气系统的多层模式，再综合考虑作物冠层和土壤内部的水热变化，对地表与作物之间的水热传输过程进行了描述，并用棉田的实测资料进行了模拟。     

ERA-Interim地表温度资料在青藏高原多年冻土区的适用性

地表温度综合反映了大气和地表植被、土壤等局地因素相互作用的能量交换状况,是许多冻土分布模型和寒区陆面过程模式的上边界条件,对多年冻土分布和活动层厚度估算具有重要意义。为了检验ERA-Interim再分析地表温度资料在青藏高原(下称高原)多年冻土区的适用性,综合比较了2011年1月1日至2012年12月31日期间高原不同类型多年冻土区3个综合观测场的观测地表温度和ERA-Interim再分析资料之间的偏差、均方差、相关系数、解释方差、均方根误差和平均绝对误差。结果表明,ERA-Interim再分析资料能较好地再现高原多年冻土区3个综合观测场地表温度的基本特征,并能较好地描述高原地表温度的季节变化。但ERA-Interim再分析年平均地表温度比观测值偏低,西大滩、五道梁和唐古拉站依次偏低1.7,1.0和0.9℃;地表温度的再分析值和观测值之间的相关系数和解释方差都较高,均方差也相近。ERA-Interim再分析地表温度资料对观测站点相对稀少且空间分布不均匀的高原多年冻土区具有较好的适用性,可以作为地表温度的有效代用资料。     

多年冻土对青藏高原草地生态承载力的贡献研究

草地生态系统是一个复杂的社会、经济、生态系统,多年冻土作为高寒草地生态系统结构和功能维系的重要因素,是客观刻画高寒草地生态承载力不容忽视的重要方面。文中采用结构动力学方法,从草地质量、草地干预、草地潜力、草地压力4个维度建立高寒草地生态承载力结构动力学模型,分析青藏高原多年冻土区草地生态承载力的变化以及主要结构要素,量化多年冻土变化对青藏高原高寒草地生态承载力的贡献率,结果表明：(1)多年冻土区草地生态承载力呈增加趋势,尤其是1998年以后上升显著,这主要归因于草地生长季节降水增加、气温升高、净初级生产力增幅驱动以及生态保护工程建设的共同作用。(2)多年冻土活动层厚度变化与草地生态承载力呈负相关,多年冻土活动层厚度对草地生态承载力的贡献率约为10%,即多年冻土活动层厚度每增加1个单位,将导致草地生态承载力下降0.1个单位。由于青藏高原空间差异显著,加之气候变化的不确定性,这一贡献水平只是一个粗略的参照值。     

土壤-植被-大气系统水分能量传输模拟和验证

本文建立了包括地下水的土壤－植被－大气系统水分能量传输综合模型,并对模型中冠层动量湍流交换反梯度传输现象的描述进行了改进。在此基础上,依据冠层内动量和热量的交换以及辐射传输过程,同时求解地表、冠层能量平衡方程,进而模拟饱和－非饱和土壤的水热传输。用浅地下水地区冬小麦田间试验资料对模型进行验证,结果表明,系统能量平衡各分量和土壤含水量的模拟与观测结果相当一致。模型敏感性分析发现,叶面积指数对总蒸散量的影响随叶面积指数的增加而逐渐减弱;叶片最小气孔阻力对总蒸散量的影响,在该阻力较小时更显著;地下水位对蒸散量的影响在它小于１．５ｍ时不显著,而在１．５～１．７５ｍ之间时,蒸散减小较快,主要由于土壤蒸发减小显著,冠层蒸腾稍有增加。     

黑龙江省季节冻土形成发育规律及特征

在黑龙江省均有季节冻结和季节融化现象发生，多年冻土区有季节融化层，季节冻结层主要分布在多年冻土区以外的地区。按季节冻结类型可把黑龙江省季节冻土分为过渡型、半过渡型、长期稳定型和稳定型等类型。季节冻结和融化深度在年际间有很大的差异，在多年冻土区南界附近，季节冻深年际间变化最大。土季节冻结和融化的影响因素主要有雪盖、植被、土壤成分及含水量、地表状况和地形等。     

陆面过程模式TBLSHAW的设计及其在黄土高原地区的模拟研究

为了改善陆面过程模式在半干旱地区的模拟能力,在SHAW(Simultaneous Heat and Water Model)模式和CoLM(Common Land Surface Model)模式参数化方案基础上,结合黄土高原SACOL站(Semi-Arid Climate and Environment Observatory of Lanzhou University)得到的部分土壤和近地层的研究结果,利用SHAW模式的动力框架,发展了一个新的陆面过程模式TBLSHAW(Two-Big-Leaf-SHAW)。该模式由一层植被、多层土壤和湍流边界层构成。在植被层主要采取双大叶模型计算能量平衡;土壤层利用水热耦合传输模型计算土壤温度和湿度,并包含了冻融、蒸发及降水渗透等物理过程;湍流边界层采取莫宁—奥布霍夫理论计算湍流通量。最后利用SACOL站获取的观测资料,对TBLSHAW模式进行了模拟检验。结果表明,TBLSHAW模式能够合理地模拟半干旱地区各项陆面过程特征的变化趋势;模拟的土壤温度和土壤湿度与观测值的偏差较小,模式效率和相关系数较高;模拟的净短波辐射及向上长波辐射较好;但是模拟的感热通量、潜热通量与观测值偏差较大,这可能与该地区的能量闭合度较低有关,还有待进一步研究。     

Climate changes and its impact on tundra ecosystem in Qinghai-Tibet Plateau,China

Alpine ecosystems in permafrost region are extremely sensitive to climate change. The headwater regions of Yangtze River and Yellow River of the Qinghai-Tibet plateau permafrost area were selected. Spatial-temporal shifts in the extent and distribution of tundra ecosystems were investigated for the period 1967–2000 by landscape ecological method and aerial photographs for 1967, and satellite remote sensing data (the Landsat’s TM) for 1986 and 2000. The relationships were analyzed between climate change and the distribution area variation of tundra ecosystems and between the permafrost change and tundra ecosystems. The responding model of tundra ecosystem to the combined effects of climate and permafrost changes was established by using statistic regression method, and the contribution of climate changes and permafrost variation to the degradation of tundra ecosystems was estimated. The regional climate exhibited a tendency towards significant warming and desiccation with the air temperature increased by 0.4–0.67°C/10a and relative stable precipitation over the last 45 years. Owing to the climate continuous warming, the intensity of surface heat source (HI) increased at the average of 0.45 W/m² per year, the difference of surface soil temperature and air temperature (DT) increased at the range of 4.1°C–4.5°C, and the 20-cm depth soil temperature within the active layer increased at the range of 1.1°C–1.4°C. The alpine meadow and alpine swamp meadow were more sensitive to permafrost changes than alpine steppe. The area of alpine swamp meadow decreased by 13.6–28.9%, while the alpine meadow area decreased by 13.5–21.3% from 1967 to 2000. The contributions of climate change to the degradation of the alpine meadow and alpine swamp was 58–68% and 59–65% between 1967 and 2000. The synergic effects of climate change and permafrost variation were the major drivers for the observed degradation in tundra ecosystems of the Qinghai-Tibet plateau.     

青藏高原多年冻土区典型下垫面冻融过程作用分析

利用青藏高原腹地安多站土壤观测资料,根据10cm土壤日最高和最低温度将冻土分为融化过程、完全融化、冻结过程和完全冻结四个阶段,并结合感热通量、积雪深度、相对湿度和降水资料定性的探讨了冻融过程对地气热量、水分交换的影响。结果表明:各层土壤在东亚季风爆发前期由上至下完成融化过程,10月中旬～12月上旬完成冻结过程,融化期普遍长于冻结期。土壤湿度大值区在时间上集中在高原雨季,空间上10cm深度以上为湿度大值区,而且上层土壤的温度梯度要明显大于下层。在融化阶段整层土壤的温度长期保持0℃的等温相变现象,此时,表层土壤温度日变化幅度为全年最大,最高日变幅达22.5℃。安多站地面除12月个别天数和1月上旬是冷源外,全年为地面热源,近地面感热通量从1月开始增大,到6月上旬达到峰值,之后逐渐减小。同时,感热通量的变化对相对湿度、降水和积雪的变化较为敏感。      

青藏高原1977—2006年土壤热状况研究

浅层土壤温度的变化可以指示活动层厚度变化。利用青藏高原及毗邻地区74个站1977—2006年近30年的土壤温度资料,研究了青藏高原及毗邻地区土壤热状况。结果表明,自1977年的近30年来,5 cm土壤负积温绝对值有减小的趋势,在高原的不同区域减小的幅度不同,对整个研究区域而言,负积温绝对值每10年降低了35℃;近30年来研究区内土壤的最大冻结深度呈现减薄的趋势;冻结期间（冷季）高原腹地负积温变化幅度要比边缘地区大,而在一个完整的冻融循环过程中,高原腹地相对于边缘地区稳定;近30年来高原地区冻融强度（FTI）呈现增大的趋势,这在某种程度上表明高原多年冻土区冻土的稳定性发生了变化;纬度及海拔对FTI值的影响较大,当海拔低于4000 m时,33°N南北两区域FTI值随海拔升高的减小率不同,南部减小的量是北部的2.5倍,海拔高于4000 m时,FTI值受纬度影响相对减弱。     

Effects of climate change on the thermal structure of lakes in the Asian Monsoon Area

This research investigates the effect of climate change on the thermal structure of lakes in response to watershed hydrology. We applied a hydrodynamic water quality model coupled to a hydrological model with a future climate scenario projected by a GCM A2 emission scenario to the Yongdam Reservoir, South Korea. In the climate change scenario, the temperature will increase by 2.1°C and 4.2°C and the precipitation will increase by 178.4?mm and 464.4?mm by the 2050 and 2090, respectively, based on 2010. The pattern changes of precipitation and temperature increase due to climate change modify the hydrology of the watershed. The hydrological model results indicate that they increase both surface runoff itself and temperature. The reservoir model simulation with the hydrological model results showed that increasing air temperature is related to higher surface water temperature. Surface water temperature is expected to increase by about 1.2°C and 2.2°C from the 2050 and 2090, respectively, based on the 2010 results. The simulation results of the effects of climate warming on the thermal structure of the Asian Monsoon Area Lake showed consistent results with those of previous studies in terms of greater temperature increases in the epilimnion than in the hypolimnion, increased thermal stratification, and decreasing thermocline depths during the summer and fall. From this study, it was concluded that the hydrodynamic water quality model coupled to the hydrological model could successfully simulate the variability of the epilimnetic temperature, changed depth and magnitude of the thermocline and the changed duration of summer stratification.     

高寒地区冻土活动层变化特征分析

利用1960-2010年黑龙江省83个气象站的冻土和0 cm地温资料,采用线性回归和多项式回归方法,分析了黑龙江省冻土活动层的时空变化特征,揭示了黑龙江省五个典型气候区域最大冻土深度的变化趋势与特征,讨论了黑龙江省冻土活动层的影响因子。结果表明：黑龙江省冻土活动层冻结开始于9月份,至冬季3月份冻土深度达到最大值,8月份时冻土厚度接近于0 cm。由北向南,最大冻土深度逐渐变小,冻结开始时间逐渐推迟,融化结束时间逐渐提前。黑龙江省最大冻土深度均呈显著减小趋势,存在明显的退化趋势。从年代际变化上看,20世纪90年代前黑龙江省最大冻土深度变化不大,最大冻土深度较深,90年代后最大冻土深度呈显著减小趋势。高纬度地区地温低,在同等条件下冻土深度较低纬度地区大。     

Expected changes in future agro-climatological conditions in Northeast Thailand and their differences between general circulation models

We have studied future changes in the atmospheric and hydrological environments in Northeast Thailand from the viewpoint of risk assessment of future cultural environments in crop fields. To obtain robust and reliable estimation for future climate, ten general circulation models under three warming scenarios, B1, A1B, and A2, were used in this study. The obtained change trends show that daily maximum air temperature and precipitation will increase by 2.6°C and 4.0%, respectively, whereas soil moisture will decrease by c.a. 1% point in volumetric water content at the end of this century under the A1B scenario. Seasonal contrasts in precipitation will intensify: precipitation increases in the rainy season and precipitation decreases in the dry season. Soil moisture will slightly decrease almost throughout the year. Despite a homogeneous increase in the air temperature over Northeast Thailand, a future decrease in soil water content will show a geographically inhomogeneous distribution: Soil will experience a relative larger decrease in wetness at a shallow depth on the Khorat plateau than in the surrounding mountainous area, reflecting vegetation cover and soil texture. The predicted increase in air temperature is relatively consistent between general circulation models. In contrast, relatively large intermodel differences in precipitation, especially in long-term trends, produce unwanted bias errors in the estimation of other hydrological elements, such as soil moisture and evaporation, and cause uncertainties in projection of the agro-climatological environment. Offline hydrological simulation with a wide precipitation range is one strategy to compensate for such uncertainties and to obtain reliable risk assessment of future cultural conditions in rainfed paddy fields in Northeast Thailand.     

2050年前南水北调中线工程水源区地表径流的变化趋势

以南水北调中线工程水源区为研究流域,采用线性回归法、Mann-Kendall非参数检验等方法,分析了1961—2000年的水文气象要素变化特征;基于数字高程模型、土地利用和土壤类型等资料,研究了SWAT模型在研究流域的适用性;根据IPCC第四次评估报告多模式结果,分析了IPCC SRES A2和A1B情景下2011—2050年的降水、气温、径流的响应过程。结果表明：1961—2000年南水北调中线工程水源区降水量无显著变化趋势,气温呈缓慢上升趋势,径流量呈缓慢减少趋势。与基准期（1961—1990年）相比,未来40年A2和A1B两种气候情景下水源区降水量、气温和径流量都呈现出增加趋势,A2情景下增加趋势明显,但径流量增幅小于降水量的增幅,这可能与蒸发量的增加有关。未来气候变化对南水北调中线工程水源区径流变化影响不大,总体有利于南水北调中线工程的调水。     

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

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 recognized. Still, 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 b...     

对IPCC第五次评估报告中有关淡水资源相关结论的解读

IPCC第五次评估报告指出,与淡水资源相关的气候变化风险随着温室气体浓度增加而显著增加。气候变化已经导致区域降水发生显著变化;多年冻土、冰川持续萎缩,积雪不断减少;降雪区春季最大径流量逐渐提前,夏季干旱不断加剧。预估结果表明：21世纪温室气体排放将加剧淡水资源相关风险。如显著减少亚热带干旱地区的地表水和地下水资源,加剧行业之间用水竞争;极端事件（如极端降水）明显影响原水水质,威胁用水安全;气候变化同时将导致农业灌溉用水量增加、能源生产效率降低等不利影响。报告指出需采取硬性基础设施建设和软性制度措施建设相结合的适应措施,加强水资源管理,克服气候变化的负面影响,减少损失。