Knowledge Resource Center for Ecological Environment in Arid Area
| 农牧交错带典型年份植被覆盖变化对区域气候影响的数值模拟 | |
| 其他题名 | The impact of vegetation cover changes of typical years on the regional climate in Farming-Pastoral ecotone |
| 沈晓燕 | |
| 出版年 | 2015 |
| 学位类型 | 硕士 |
| 导师 | 张宇 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 农牧交错带又为生态环境脆弱带及敏感带，是我国生态环境和地域经济的一个重要分界地段。它极易受自然和人为影响而发生变化。若尔盖高原位于青藏高原东北部，属于川滇农牧交错带，其地表植被特征的改变会直接影响黄河、长江上游的生态环境。内蒙到高原南侧，东北-西南走向的气候过渡带，也是我国历史上农牧交错带的位置。它是水土流失、草场退化、沙漠化等环境问题最为突出的地区之一。因此，开展这些区域土地利用/覆盖变化对区域气候的影响研究，具有十分重要的意义。 本文利用WRF模式和卫星遥感土地分类数据展开研究。首先，验证了WRF模式中Noah陆面过程参数化方案在若尔盖高原高寒草原下垫面的适用性。其次，分析了典型年份若尔盖高原植被覆盖变化对夏季区域气候的影响。最后，分析了蒙古到高原南侧东北-西南走向的农牧交错带典型年份植被覆盖变化对不同季节区域气候的影响。具体内容及结论如下： （1）利用若尔盖站的观测资料比较了WRF模式中3种不同的陆面过程参数化方案。主要结论为：三种方案对净辐射、感热通量、潜热通量及2m温度、相对湿度模拟的相关系数都较高（>0.9）。对于净辐射、感热通量和2m温度，夜间Noah模拟结果更接近观测值，白天CLM4模拟结果较好。Noah能较好地模拟出潜热通量和地表热通量的变化，其余两种方案模拟潜热通量时出现较大负偏差，模拟的地表热通量的日变化幅度过大。 （2）利用WRF模式，采用1981、1990、2000、2010 年卫星遥感地表分类数据，模拟分析了若尔盖高原典型年份真实地表植被覆盖变化对2010年夏季区域气候的影响。主要结论为：对于地表能量，植被覆盖变化对潜热影响较显著。较为显著的气候响应是地表温度的变化，且局地地表温度变化较区域平均温度变化明显。蒸腾效率和反照率会改变地表温度，但它们的相对重要性随季节和地点而变化，在夏季，若尔盖高原蒸腾效率改变对温度的影响大于反照率的作用。植被覆盖度变化在低层对温湿度均有影响，在中高层仅对温度有较小扰动。 （3）改变了从内蒙到高原南侧东北西南走向的农牧交错带的植被类型，模拟分析了交错带典型年份实际地表植被覆盖变化对不同季节区域气候的影响。得出：交错带内主要变化植被类型为旱地、农业与自然植被镶嵌体、草地和灌丛。草地与灌丛转换区域、灌丛变为旱地区域地表能量变化明显，旱地、农业/自然植被镶嵌体及草地之间转换区域地表能量变化并不显著。农牧交错带植被覆盖变化使得区域气候发生了改变。对于地表温度，夏季、秋季变化较显著。其中，在夏季，内蒙东部、东北地区以及四川盆地东部温度变化明显，在秋季，长江中下游地区影响显著。通过分析可知，春季，湿度较小，反照率作用较大，地表温度受净辐射影响较大。夏季和秋季，湿度较大，植被覆盖度高，地表导度作用较大，地表温度受潜热影响大。对夏季降水的影响主要表现在东北地区和整个中国南部地区，其中500hpa偏差风流场的气旋性（反气旋性）环流与降水增加（减小）区域对应较好。农牧交错带植被覆盖变化对2m温度和水汽混合比影响逐年减小，而其对降水的影响大小和范围并不随时间减小。 |
| 英文摘要 | Farming-pastoral ecotone, known as ecological fragile and sensitive zone, is an important boundary area of ecological environment and regional economy. It is highly vulnerable to the effects of natural and man-made changes. Zoige plateau, located in the northeast of Tibet Plateau, is part of the Chuan-dian farming-pastoral ecotone, The change in its surface vegetation characteristics will directly influence the ecological environment of the upper Yellow River and Yangtze River. The climate transition zone, located from inner mongolia to south of the Plateau, is also a farming-pastoral ectone historically. The environmental problems,such as soil erosion, grassland degradation and desertification are prominent in these regions, consequently, it is of great importance to investigate the effects of land use and land cover changes on reginal climate in these regions. The WRF model and surface classification data of satellite remote sensing were used in this paper. First of all, the suitability of Noah land surface schemes in WRF was validated in alpine grassland underlying surface in Zoige plateau. secondly, the impacts of real vegetation cover changes of typical years on the regional climate in summer in Zoige plateau were analyzed. Finally, the impacts of vegetation cover changes on the regional climate in farming-pastoral were analyzed. The main conclusions are as follows: (1) We compared three land surface schemes in WRF by using the observation data in Zoige field. The results show that: the simulated correlation coefficients were high (>0.9) for net radiation, sensible heat flux, latent heat flux, 2m temperature and relative humidity. For net radiation, sensible heat flux and 2m temperature, the Noah scheme simulated well in nighttime, while CLM4 scheme simulated well in daytime. As compared to observations, Noah can well simulate the change of latent heat flux and surface heat flux. The rest two schemes appeared large negative deviation when simulating latent heat flux, and overestimated daily variation amplitude when simulating surface heat flux. (2) By using WRF model and the surface classification data of satellite remote sensing in year 1981, 1990, 2000 and 2010, we studied the impact of real vegetation cover changes of typical years on the regional climate in Zoige plateau in 2010. The main conclusions are as follows: The simulated latent heat flux has obviously changed associated with different surface classification data. and the dominant climate response is the variation of surface temperature, Besides, the local change is more significant than that of regional average. The change is driven by changes in both transpiration efficiency and albedo ,with changes in transpiration efficiency dominating in Zoige in summer. After comparing the simulated profiles of temperature and humidity among different surface data, we concluded that simulated changes in vegetation cover affect temperature and humidity in low levels, but only have small disturbance on temperature in high levels. (3) By changing the vegetation types of the farming-pastoral ecotone, located from inner mongolia to south Plateau, we studied the impact of real vegetation cover changes in typical years on the regional climate. The main conclusions are as follows: The main vegetation types in farming-pastoral ecotone are rainfed croplands, cropland/natural vegetion mosaics, grasslands and shrublands. Conversion between grasslands and shrublands can significantly change surface flux, The conversion between rainfed croplands, cropland/natural vegetation mosaics and grasslands has no significant effect on surface flux.The variation of climate factors due to vegetation cover change differ among the seasons, with greater responses in summer and autumn, the temperature change is obvious in Eastern Inner Mongolia, northeast China and east of sichuan basin in summer, in the middle and lower reaches of the Yangtze river region in autumn. In spring, the humidity is lesser, the effect of albedo is bigger, the surface temperature is greatly influenced by net radiation. In summer and autumn, the larger influence of surface conductance owing to wetter and more highly vegetation coverage, the surface temperature is influenced by the latent heat flux. The impact on summer precipitation mainly in the northeast and southern China, The cyclonic and anticyclonic circulations in 500hPa deviation flow filed are correspond well to the increase and decrease area in precipitation.for 2m temperature and water vapor mixing ratio, the influence reduced from 2001 to 2003 yearly , there is little change in summer precipitation. |
| 中文关键词 | 农牧交错带 ; 若尔盖高原 ; 土地利用/覆盖变化 ; WRF模式 ; MODIS卫星遥感 |
| 英文关键词 | Farming-pastoral ecotone Zoige plateau Land use and land cover change(LULCC) WRF model MODIS satellite remote sensing |
| 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/2XILL650/287542 |
| 推荐引用方式 GB/T 7714 | 沈晓燕. 农牧交错带典型年份植被覆盖变化对区域气候影响的数值模拟[D]. 中国科学院大学,2015. |
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