Knowledge Resource Center for Ecological Environment in Arid Area
| Noah模型对青藏高原典型区冻土分布和冻土特征的模拟研究 | |
| 其他题名 | Noah Modelling of Permafrost Distribution and Characteristics in the Typical Region of Qinghai-Tibetan Plateau |
| 陈浩 | |
| 出版年 | 2015 |
| 学位类型 | 博士 |
| 导师 | 丁永建 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 青藏高原拥有全球中纬度面积最大的多年冻土区，其自然地理条件和水热过程独特，具有与高纬度地区多年冻土不同的特征。青藏高原多年冻土区的能量平衡与水分平衡过程对东亚季风乃至全球气候系统都有深刻的影响，同时对气候变化有非常敏感的响应。建立适合青藏高原水热过程的冻土模型对于阐明青藏高原的冻土特征与分布规律，以及青藏高原的冻土变化对全球气候和生态系统的响应与反馈都具有重要意义。由于青藏高原上多年冻土面积分布广泛，而站点观测的范围有限，因此基于站点观测和冻土调查的冻土过程模拟就成为在宏观尺度上了解冻土水热特征及变化的重要手段。传统上对冻土区的模拟研究以经验模型为主，2009年中国科技部启动了基础性工作专项“青藏高原多年冻土本底调查”项目，取得了大量宝贵的冻土环境和冻土特征资料，为采用陆面过程模型等物理过程模型进行冻土建模提供了基础保障。 本文利用黑河上游祁连山区的大冬树山垭口积雪观测自动气象站和阿柔草场观测自动气象站的观测数据评价了Noah陆面过程模型在高寒地区的适用性，在此基础上提出了对Noah模型的驱动数据、土壤参数化方案和陆面能量分配过程等方面的改进，利用青藏高原冰冻圈观测站唐古拉综合观测场的数据评价了改进后的Noah模型对唐古拉综合观测场水热过程的模拟能力。利用 “青藏高原多年冻土本底调查”项目在西昆仑地区多年冻土区和改则地区多年冻土与季节冻土过渡区获取的观测数据，建立了Noah模型针对以上多年冻土典型区的土壤、植被和热粗糙度的参数化方案，以及这些参数化方案在面域上的分布，实现了对青藏高原西部典型区多年冻土特征及其分布的模拟，并与青藏公路沿线以及环北极高纬度地区的多年冻土特征进行了比较。通过以上研究获得以下主要结论： 1. Noah在黑河上游高寒地区对地温的模拟较好，但对液态水含量模拟偏差较大，尤其是土壤异质性较大的地点。由于冷季降水的观测偏小，导致模型模拟的积雪量偏小，故而冷季的地温模拟偏低。通过改进高寒地区积雪和植被等下垫面与大气之间相互作用的物理过程，准确描述土壤和植被的性质，以及校正冷季的降水数据，可以提高对高寒地区水热过程的模拟精度。 2. 根据Noah在黑河上游高寒地区适用性研究的结论，以及青藏高原降水较少、风速大、土壤中多砾石和冷季降水偏差大等特点，我们提出了对Noah模型三方面的改进：引入适用于干旱和半干旱区的Y08地表热粗糙度方案；增加土壤模拟深度并引入土壤异质性；采用土壤参数率定算法确定土壤参数。同时，还引入了一种基于雪深的冷季降水数据的校正方法。对唐古拉综合观测场水热过程的模拟显示：Y08方案能够改进对干旱和半干旱区地表温度低估的现象，从而提高模型对水热过程模拟的精度。基于雪深的冷季降水数据的校正方法可以改进冷季降水数据，提高对积雪的模拟精度，从而使得冷季地表温度的模拟更为准确。改进的Noah模型能够较好的反映青藏高原多年冻土区的水热过程，对浅层地温（2.45m以上）模拟的纳什系数在0.8以上，相应的液态水含量模拟的纳什系数在0.5以上，对深层地温如年平均地温（10-15m）的模拟也比较准确。 3. 在对西昆仑地区的模拟中，我们提取了中国区域高分辨率气象要素数据集（CMFD）的气象要素为驱动数据，建立了3个土壤参数方案，分别是用于高山区的奇台达坂（MPQT）方案、用于湖相沉积区的北龙木错（NLMC) 方案、以及用于丘陵和平原区的东龙木错（ELMC）方案；建立了2个植被参数方案：高山草原方案和裸土与稀疏植被方案；根据钻孔数据建立了下边界条件和初始条件的计算方法。在此基础上，通过改进的Noah模型模拟了西昆仑地区的年平均地温、含冰量和活动层厚度等关键的多年冻土参数，模拟的年平均地温与10个验证钻孔的数据相比，有8个钻孔的模拟误差在 1.0 ℃以内，2个钻孔在1.5 ℃以内。模拟误差较大的钻孔主要受湖泊和坡向等局地因素的影响。基于模拟的年平均地温制作了分辨率为10km的西昆仑地区多年冻土分布图，与基于野外调查得到的多年冻土分布图基本吻合，Kappa系数为0.70。 4. 模拟结果显示：西昆仑地区的年平均地温与海拔有强负相关性，与降水有弱的负相关性；活动层厚度与海拔有弱负相关性，和降水有弱负相关性，与年平均地温有强相关性；含冰量与海拔、年平均地温、活动层厚度和降水量都具有一定的相关性。总体而言，西昆仑地区的多年冻土分布和多年冻土特征主要受海拔控制，同时受到局地因素的一定影响，这与青藏公路沿线的多年冻土特征相似。西昆仑地区与环北极地区相比，年平均地温相同的区域其地温年变化深度更深，这可能与西昆仑地区积雪厚度薄、地表植被稀疏和土壤中多砾石和粗砂有关。 5. 在对改则地区的模拟中，采用Micromet插值得到了5km×5km分辨率的驱动数据，建立了2个土壤参数方案：以地表碎石土为主的GM5000方案和以砂土为主的GZ1方案；建立了3个植被方案，分别为稀疏植被和裸土区、高寒草原区和高寒草甸区；建立了2个地表热粗糙度方案：Y08方案和Z95方案。模拟的年平均地温与8个验证钻孔的数据相比，模拟误差均在1.0 ℃以内。基于模拟年平均地温的多年冻土分布图，与基于调查数据的多年冻土分布图基本一致，多年冻土面积相差2.6%，Kappa系数为0.48。改则地区的多年冻土参数与环境变量的相关关系与西昆仑相似，但是改则地区年平均地温的分布与海拔的相关性较西昆仑地区差，受植被类型的影响较大，多年冻土类型分布图与植被类型分布图的Kappa系数为0.65，植被类型可以在一定程度上指示某种多年冻土类型的存在。 6. 以上的适用性研究、模型改进、单点验证和区域模拟等为Noah模型模拟青藏高原的多年冻土分布和特征建立了一套完整的方法，说明了在准确了解区域冻土环境和气候特征的基础上，通过改进模型的物理过程和设置参数化方案，Noah模型能够比较准确的模拟青藏高原冻土区的水热特征，提供关键冻土参数和陆面参数的区域特征和分布，从而为Noah模型耦合气候模型模拟青藏高原冻土区对气候变化的响应和反馈奠定基础。 |
| 英文摘要 | The Qinghai-Tibet Plateau (QTP) has the largest permafrost area in the mid-latitude region. The high altitude permafrost of the QTP has different permafrost characteristics compared to that of the high latitude area. The energy and water balances of permafrost on the QTP have great impact on the East Asian monsoon and response sensitively to the climate change. As permafrost is extensively distributed in the QTP and observations are limited, modelling based on field works and in situ observation is the main measurement to elaborate the thermal and hydrological characteristics of permafrost. The modelling of permafrost is also important in elabrating the interaction between permafrost, climate and ecological system. Statistical-empirical models have been traditionally adopted in modelling of the permafrost distribution in the QTP. In 2009, the “Investigation of permafrost and its environment over the Qinghai-Tibetan Plateau” project has obtained sufficient data on permafrost environment and characteristics in the once unexplored areas of the QTP, which set up basis for the permafrost modelling based on physical process such as the land surface models(LSM). In this paper, Noah LSM was evaluated with observation from two typical sites, the Dadongshu Pass site and the Arou site, located in the upper Heihe river basin. Modification on forcing data, soil parameterization scheme and land surface processes are introduced to optimize the simulation performance of the Noah model. The modified Noah model was evaluated on simulation of the thermal and hydrological processes of the Tanggula site of the QTP. Soil, vegetation and thermal roughness parameterization schemes and their distributions in the West Kunlun permafrost area and the Gaize transitional area were established on field data. Then the simulation on the permafrost distribution and characteristics of the areas and comparisons to the permafrost conditions of the Pan-Arctic and areas along the Qinghai-Tibet road were carried out. We made the following conclusion: 1. Noah simulates well the ground temperature of the alpine-cold area of the Heihe River Basin, whereas the simulation on water content is poor, especially in the site with significant soil heterogeneity. The precipitation of the cold season is poorly captured, which lead to lower snow accumulation and ground temperature. The optimization of physical processes between snowpack, vegetation and atmosphere in the alpine-cold region can raise the simulation accuracy. 2. The QTP is characterized by low precipitation, strong wind and large amount of gravel in soil. According to conclusion based on applicability studies in Heihe River Basin and the natural physical characteristics of the QTP, three modifications were introduced accordingly: new thermal roughness scheme Y08 applied in arid region; extension of simulation depth allowing for soil heterogeneity and a soil calibration method. At the same time, a precipitation calibration method based on snow depth was also introduced. Simulation results of Tanggula (TGL) site show that the Y08 scheme can improve the underestimate of surface temperature, and thus raise the simulation accuracy of the TGL. The precipitation calibration method can improve the simulation of precipitation, snowpack and surface temperature in cold season. The simulation on thermal and hydrological process in the TGL show that the modified Noah simulates well the soil temperature (NSE>0.8) and water content (NSE>0.5) of shallow soil layers (above 2.45 m). Simulation on the mean annual ground temperature of deep layer are also accurate. 3. Forcing data were extracted from the China Meteorological Forcing Dataset (CMFD). Three soil parameter schemes were established for Noah modelling of the West Kunlun area, namely MPQT which was applied in alpine area above 5250 m; NLMC which was applied in the lacustrine deposits area and ELMC which was applied in alluvial plain surrounded by hills. Two vegetation schemes were established, namely alpine meadow scheme, and sparsely vegetated or barren land scheme. Lower boundary and initial conditions were established according to borehole data. Key permafrost metrics such as the mean annual ground temperature (MAGT), ice content and active layer thickness (ALT) of the West Kunlun area were simulated by the modified Noah model. The simulated MAGT of eight boreholes out of the total ten have simulation error less than 1.0℃ and the remaining two have simulation error less than 1.5℃. Large simulation errors mainly come from the influence of the local environmental factors such as lake and slope. Permafrost distribution map with resolution of 10km was compiled on the MAGT and was similar to permafrost map compiled on field data. The Kappa coefficient is 0.7. 4. Simulation results show that the MAGT shows a strong negative correlation with altitude and a weak negative correlation with annual precipitation. The ALT shows weak negative correlations with altitude and annual precipitation, and a strong positive correlation with the MAGT. The ground ice content is correlated with the altitude, MAGT, ALT and annual precipitation. The permafrost distribution and characteristics are controlled by altitude and influenced by local environmental factors, which is similar to the permafrost along the Qinghai-Tibet road. Compared with the Pan-Arctic area, the West Kunlun area has deeper depths of zero annual amplitude. This may related to the thin snowpack, sparse vegetation and great quantity of gravel and sand in soil in the West Kunlun area. 5. The forcing data used in simulation of Gaize area were interpolated into 5km×5km. Two soil scheme were established, namely GM5000 which distributed in area with gravel mulch; GZ1 which distributed in sandy area. Three vegetation schemes were established, namely sparsely vegetated or barren land, alpine steppe and alpine meadow. Two thermal roughness scheme were established, namely arid scheme Y08 and grassland scheme Z95. The simulated MAGTs of eight boreholes have simulation error less than 1.0℃. Permafrost distribution map with resolution of 5km×5km was compiled on the MAGT and is similar to permafrost map compiled on field data. The difference of permafrost distribution is 2.6% and the Kappa coefficient is 0.48. The correlation between permafrost metrics and environmental factors of the Gaize is similar to that of the West Kunlun, whereas the correlation of the MAGT with altitude of the Gaize is worse than that of the West Kunlun, which come from the influence of the vegetation. The Kappa coefficient of vegetation map and permafrost map is 0.65. the vegetation type is related with the occurrence of certain type of permafrost. 6. Above applicability, modification, verification and simulation studies set up a prototype of permafrost distribution and characteristics simulation in the QTP by Noah land surface model. Noah can well simulate the thermal and hydrological features of the permafrost area of the QTP by the improvement of physical processes and accurate parameterization. It can offer the distribution of critical permafrost metrics, which can help in simulating the response and feedback of permafrost area of the QTP to climate change. |
| 中文关键词 | 青藏高原 ; 多年冻土 ; 水热过程 ; Noah模型 ; 陆面过程 ; 冻土特征 ; 参数化方案 |
| 英文关键词 | Qinghai-Tibet Plateau permafrost thermal and hydrological process Noah land surface model permafrost characteristics parameterization scheme |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287551 |
| 推荐引用方式 GB/T 7714 | 陈浩. Noah模型对青藏高原典型区冻土分布和冻土特征的模拟研究[D]. 中国科学院大学,2015. |
| 条目包含的文件 | 条目无相关文件。 | |||||
| 个性服务 |
| 推荐该条目 |
| 保存到收藏夹 |
| 导出为Endnote文件 |
| 谷歌学术 |
| 谷歌学术中相似的文章 |
| [陈浩]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [陈浩]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [陈浩]的文章 |
| 相关权益政策 |
| 暂无数据 |
| 收藏/分享 |
除非特别说明，本系统中所有内容都受版权保护，并保留所有权利。
