Knowledge Resource Center for Ecological Environment in Arid Area
| 土壤水分与陆面-大气间水热交换的观测和模拟研究 ──以黄土塬和黄河源为例 | |
| 其他题名 | Measurement and Simulation of Soil Water Content and Water & Heat Exchange —Cases of the Loess Plateau mesa and the source area of the Yellow River |
| 贾东于 | |
| 出版年 | 2015 |
| 学位类型 | 硕士 |
| 导师 | 文军 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 由于寒区旱区陆面过程的复杂性和观测资料的缺乏，局地降水与土壤含水量的关系和陆-气间的水热交换过程的研究还不够深入。本文首先利用中国科学院平凉陆面过程与灾害天气观测站的降水和土壤湿度观测资料，分析了陇东黄土塬土壤含水量和降水的关系。同时，进一步利用公用陆面模式（Community Land Model, CLM4.0）和野外试验观测资料，分析和模拟了黄河源陆-气间水热交换的基本特征。然后，对陆面模式中影响下垫面-大气间水热交换的陆地表面变量进行了敏感性试验。最后，评价了陆面模式模拟效果的影响，进而对CLM4.0有关参数的参数化方案进行改进，以期提高CLM4.0对黄河源陆-气间水热交换过程的模拟精度。主要结论归纳如下： （1） 前期总有效降水是指前期的自然降水分布到植物根系层能被有效利用的部分。由于黄河源地区缺乏长时间的降水和土壤湿度观测资料，因此本文分析了中国科学院平凉陆面过程与灾害天气观测站陆面过程观测场的前期总有效降水和土壤湿度变化的关系。研究发现，前期总有效降水与土壤含水量有良好的相关关系。同时，有效降水比降水能更好的反映土壤湿度的变化。 （2） 不同天气条件下，土壤热通量和近地面净辐射通量受的影响不同。6月潜热通量在四种天气条件下（晴、多云、小雨、雨夹雪）均大于感热通量。不同天气条件下的差异显著，雨夹雪天气下近地面能量闭合度最高，其次为晴天，多云天气下能量闭合度最低。 （3） 敏感性试验表明：沙土、粘土含量及植被覆盖度对模拟下垫面陆-气间水热交换结果的影响较大。其中，粘土含量的变化对辐射的影响不大。含沙量的降低会引起模式模拟的土壤感热增强，潜热减弱。同时，随着土壤含沙量的减少，模拟得到的向上长波辐射有明显增强，而向上短波辐射略微减小。高寒草甸的潜热模拟值大于裸地，感热模拟差异不大。由向上长短波的模拟结果可知，高寒草甸的向上长波比裸地大，向上短波小。以上试验表明：CLM4.0模拟结果能够较为准确的反应黄河源不同下垫面-大气间水热交换过程。 （4） 用MODIS LAI数据产品替换模式中默认的叶面积指数（LAI）数据发现，修正叶面积指数后，近地面辐射的模拟效果有明显提升。潜热通量比初始模拟效果有较大改善。但感热通量的模拟值仍大于观测值，其原因有待进一步探究。LAI数值减少为原值一半时，各层土壤温度在8月均有上升，同时，各层土壤含水量也有增大的趋势，表明植被退化会造成植被冠层对雨水的截流作用减小。当LAI数值增加至原值的一倍时，模拟得到的土壤温度整体下降，且变化幅度比LAI减小时的大，说明植被增加对土壤温度的影响较大。 （5） 由于CLM4.0对表层土壤湿度模拟偏低，通过减少最大次表层地下径流计算公式中的衰减系数发现，土壤含水量的模拟值在各层都有增加，但是幅度不大，尤其对土壤含水量模拟效果的改善贡献不大。当饱和导水率减小时，模拟发现潜层土壤含水量增加，变化趋势与观测值一致，但是深层土壤湿度的模拟数值并无太大变化。同时，饱和导水率的减小会使模式模拟得到的感热增加，潜热减小。而饱和导水率的增加对感热通量、潜热通量模拟结果的影响不大。 |
| 英文摘要 | Because of lacking the observation data and the complexity of land surface, the relationship among soil moisture, local precipitation and water heat exchange has not been farther studied in cold and arid regions. First of all, in this study, we use the soil moisture and precipitation data from the Pingliang Land Surface Process & Severe Weather Research Station, Chinese Academy of Sciences to figure out the relationship between soil moisture and effective precipitation. Furthermore, we use the Community Land Model version 4.0 (CLM4.0) combined with observation data to analyze and simulate the feature of water and heat exchange. Meanwhile, we set a sensitive test by changing some variables which may influence the simulated results. At last, we evaluate the simulated effective and make some improvement. The conclusions are drawn as below: (1) The total effective antecedent precipitation is one of the key factors to show the soil moisture variation. Because there is no continuous time series data in source area of Yellow River, the data collected from Loess Plateau of China are deployed to figure out the relationship between soil moisture and total effective antecedent precipitation. As a result, we find that total effective antecedent precipitation can better describe the change of soil moisture than precipitation. (2) The near surface radiation fluxes show daily change in different weather conditions. The soil heat flux has little influence by the weather. However, the net radiation flux suffers most. At the same time, the latent heat flux is higher than the sensible heat flux in all weather conditions. The radiation balance varies in different weather conditions. we find that in sunny day the energy closure rate is highest, snowing day is lowest. (3) From the numerical sensitive test, it is concluded that soil sand content, soil clay content and vegetable coverage can influence the simulated results. The soil clay content has an effect on increasing the soil moisture and temperature. The sand content has a great influence on the change of latent heat and sensible heat. At the same time, the coverage of alpine meadow shows different relationship with latent heat and sensible heat than bold soil. Above all, the CLM4.0 model can accurately simulate the different underlying surface situation. (4) Replacing the default LAI in the CLM4.0 model by MODIS LAI product, it is found that the accurate of the simulated results have been improved, especially for the latent heat flux. However the sensible heat has little effect. When reducing the LAI to half value, the simulated soil moisture and soil temperature all increase a little. However, the soil temperature reduces dramatically when double the LAI value. (5) Soil moisture has a little change by reducing the decay factor. So the decay factor is not the key point why simulated soil moisture is lower than the observed data. Reducing the saturated hydraulic conductivity, we can find that the soil moisture in the surface layer increasing significantly. However, the soil moisture in the deeper layer has little change. What’s more, the decreasing of saturated hydraulic conductivity will have an influence on sensible heat increasing and latent heat decreasing. Key words: soil water content, exchange of water and & heat, CLM4.0, the source area of Yellow Rive |
| 中文关键词 | CLM4.0模式 ; 黄河源 ; 水热交换 ; 土壤湿度 |
| 英文关键词 | soil water content exchange of water and & heat CLM4.0 the source area of Yellow Rive |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 大气物理学与大气环境 |
| 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/2XILL650/287548 |
| 推荐引用方式 GB/T 7714 | 贾东于. 土壤水分与陆面-大气间水热交换的观测和模拟研究 ──以黄土塬和黄河源为例[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 |
| [贾东于]的文章 |
| 百度学术 |
| 百度学术中相似的文章 |
| [贾东于]的文章 |
| 必应学术 |
| 必应学术中相似的文章 |
| [贾东于]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。
