Knowledge Resource Center for Ecological Environment in Arid Area
| 青藏高原高寒植被盖度对地表能量的影响 | |
| 其他题名 | Effects of vegetation cover change of alpine grassland on the Qinghai-Tibetan Plateau on the surface energy |
| 李乃杰 | |
| 出版年 | 2012 |
| 学位类型 | 硕士 |
| 导师 | 宜树华 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 植被在陆气相互作用中起着非常重要的作用，同时对于其本身的生长环境，也有着非常复杂的反馈过程。为了精确分析青藏高原植被变化后所造成的生态，气候效应，本文使用CLM陆面过程模式模拟和地面观测相结合的方法，通过对2005- 2006年西大滩和2011年夏季苏里自动气象站的观测资料处理，分析了青藏高原高寒草地植被变化对地表长、短波辐射，感热和潜热等地表能量通量的控制机理和影响过程，并使用气象台站和自动站数据建立了土壤表面温度—大气环境和植被特征数据的拟合公式。主要结论如下。\n \n （1）在干旱半干旱区，土壤比较干燥，反照率高于植被，植被增加能遮盖地表，降低地表反照率。而在较为潮湿的沼泽草甸和高寒草甸，土壤潮湿，反照率低于地表，植被增加后，反照率会升高。植被和反照率的关系受土壤表层含水量影响很大。\n （2）植被对长波辐射的影响表现为，植被能截留土壤表面向上发射的长波辐射，并以逆辐射的形式向下发射长波辐射加热地表，而地表向上的长波辐射则大大减少，起到明显的保温作用，在冬季和夏季，植被的保温作用都非常明显。\n （3）植被对地表感热和潜热的影响比较复杂。降水之后，土壤变得潮湿,如果植被长势良好，太阳辐射大多会照射到植被叶片上，减弱了太阳辐射对地表的直接作用，只有少部分透射到土壤表面，而植被叶片蒸散能力要低于潮湿的地表，照在叶片上面的净辐射只有少部分转化为潜热释放到大气，更多的是转化为叶片升温和与温度相关的感热以及长波辐射。而如果植被覆盖较低，太阳辐射能直接照射地表并转化为大量的潜热，带走了土壤的水分，降低了地表温度。低盖植被盖度区域内，因为大量的潜热蒸发，土壤水分损失严重，容易造成干旱的发生，地表温度会迅速的增加。植被能通过控制地表感热和潜热的变化影响土壤水热过程的变化。\n （4）使用大气温度、向下短波辐射、降水等大气资料和植被叶面积指数资料所拟合的最高最低和日平均土壤表面温度公式能较好的代表青藏高原地区土壤表面温度变化情况，公式物理意义明确且具有代表性。 |
| 英文摘要 | Vegetation plays an important role in land-atmosphere interaction; and has very complex feedbacks with its own environment. This thesis used a land surface model (CLM3) and ground-based measurements to accurately analyze the climatic effects caused by the changes of alpine grassland on the Qinghai-Tibeten Plateau (QTP). This thesis studied the control mechanism and effects of alpine meadow change on variations of the surface energy fluxes. This thesis also used the data from meteorological stations and automatic weather station to establish the fitting formulations of the soil surface temperature with atmospheric environment and vegetation characteristics as independent variables. The main conclusions are as follows:\n (1) In the arid and semi-arid regions, the albedo of the dry soil is higher than vegetation’s. With the increasing of the vegetation coverage, the surface albedo decreases. But in the humid swamp meadow and alpine meadow, the albedo of the wet soil is lower than that of vegetation. And with the increasing of the vegetation coverage, the meadow surface albedo increases. The relationship between vegetation and surface albedo is significantly influenced by soil moisture. \n (2) The impact of vegetation on the long-wave radiation is expressed as follow: vegetation can intercept the long-wave radiation released by soil surface and emits the long-wave radiation back to heat soil surface. Surface upward long-wave radiation is greatly reduced, because vegetation plays a significant important role as greenhouse. In winter and summer, the insulation effects of the vegetation are very obvious.\n (3) The impact of vegetation on the surface sensible heat and latent heat is complex. After precipitation, soil becomes wet. If vegetation growes well, leaves will reduce the effects of solar radiation on the soil surface. More solar radiation will shine on the leaves, and less solar radiation reaches soil surface. Because of the transpiration capacity of vegetation leaves is lower than wet soil, only a small fraction of solar radiation shining on the leaves changes into latent heat, and most of solar radiation warms the leaves and transforms to sensible heat and long-wave radiation. If the vegetation coverage is low, solar radiation directly irradiates surface; and is converted mainly to latent heat, which takes away a lot of soil water and reduces soil surface temperature. In the low-coverage alpine grassland regions, it’s easy to cause drought and surface warming.\n (4) The soil surface temperature formula, fitted using atmosphere temperature, downward short-wave radiation, rains and leaf area index data, can represent the soil surface temperature variations well for the alpine grassland on the QTP. |
| 中文关键词 | 植被盖度 ; 土壤湿度 ; 地表温度 ; 感热 ; 潜热 ; 辐射 |
| 英文关键词 | vegetation coverage，soil moisture， soil surface temperature，sensible heat latent heat， radiation |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 气象学 |
| 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/2XILL650/287097 |
| 推荐引用方式 GB/T 7714 | 李乃杰. 青藏高原高寒植被盖度对地表能量的影响[D]. 中国科学院大学,2012. |
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