Knowledge Resource Center for Ecological Environment in Arid Area
| CoLM陆面模式的改进及其对中亚区域水热通量模拟的应用研究 | |
| 其他题名 | Improvement of CoLM and the simulation of water and heat fluxes over Central Asia |
| 井长青 | |
| 出版年 | 2014 |
| 学位类型 | 博士 |
| 导师 | 李龙辉 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 荒漠生态系统在中亚区域所占面积较广，开展中亚干旱区荒漠生态系统能量、水汽通量的研究对于深刻理解和科学认识干旱区对全球变化的响应有着非常重要的科学意义。限于观测资料的缺乏，目前对干旱区能量、水汽循环过程的认识还存在着很多不确定性。本研究以中亚荒漠干旱区为研究区，以陆面模式Commom Land Model (CoLM)为研究平台，进行了以下研究： 首先，针对根系分布和根系吸水过程对CoLM陆面模式进行必要的改进，将干旱区植物特殊的根系功能耦合到CoLM陆面模式中，提高陆面模式在中亚干旱区荒漠生态系统能量、水汽通量的模拟性能。在陆面模式中，对植物根系吸水过程的准确描述是精确模拟陆面水汽通量的关键。已有的很多研究已将不同的根系吸水模型应用到陆面模式中，但是针对干旱荒漠生态系统的研究较少。本研究将三种典型的根系吸水模型应用到CoLM陆面模式中，比较加入实测根分布数据后三种根系吸水模型对根系吸水过程的影响，改进CoLM陆面模式对干旱区地表能量通量的模拟。通过比较模型模拟结果与涡度相关数据表明，根系吸水模型与垂直根分布对能量通量均有明显的影响。用实测的根分布数据代替根分布模型相关参数，并且应用改进根系吸水模型的CoLM陆面模式对潜热通量和感热通量的模拟有显著的提高。敏感性分析发现，改进的根系吸水模型中的相关参数对模型模拟结果影响不显著，因此，将最优的根系吸水模型应用到CoLM陆面模式中，对干旱区深根灌丛荒漠生态系统能量通量的模拟具有明显的改进作用，相应的，对其他类似的干旱生态系统也具有一定的适用性。 其次，将改进了根系吸水模型后的陆面模式应用到中亚研究区两个典型的涡度相关观测站点，开展CoLM陆面模式的站点验证及关键参数的敏感性分析研究。通过在中亚哈萨克斯坦两个新建涡度相关通量站点：咸海站、巴尔喀什湖站进行更精细的模型验证发现，在中亚干旱区咸海站和巴尔喀什湖站的模拟能较好的表现站点的能量通量特征，但是优化参数前的模拟明显的高估了感热通量，低估了潜热通量，尤其在咸海站。优化参数后的模拟结果与观测值较吻合。通过敏感性分析研究得出，CoLM在模拟净辐射通量时对反照率较敏感，而潜热通量、感热通量、土壤温度对地表粗糙度的敏感性更强。 最后，将验证通过的改进的陆面模式应用到中亚大区域上，模拟整个研究区过去三十年的能量、水汽通量的时空变化，并且进一步分析近三十年中亚干旱区能量、水汽循环的演变机制。本研究对深化和发展陆面模式在干旱区的应用研究、提高对干旱区能量、水汽循环过程的认识具有重要意义。 |
| 英文摘要 | The Central Asia region is covered by vast desert ecosystems. It is important to research the energy and water fluxes in desert ecosystems over Central Asia. However, the observatins were far more limited, and there are still a lot of uncertainties for energy and water exchange research in arid ecosystems. Therefore, this research intends to evaluate the performance of Common Land Model (CoLM) in deseart ecosystems over Central Asia: 1) To improve the root water uptake function and root distribution in CoLM. Root water uptake is a unique process whereby plants obtain water from soil, and it is essential for plant survival. The mechanisms of root water uptake are well understood, but their parameterization and simulation in current Land Surface Models (LSMs) fall short of the requirements of modern hydrological and climatic modelling research. Though various root water uptake functions (RWUFs) have been proposed for potential use in LSMs, none was proven to be applicable for dryland ecosystems where drought was generally the limiting factor for ecosystem functioning. This study investigates the effect of root distribution on the simulated surface energy fluxes by incorporating the observed vertical root distribution. In addition, three different RWUFs were integrated into the Common Land Model in place of the default RWUF. A comparison of the modified model’s results with the measured surface energy fluxes measured by eddy covariance techniques in a Central Asian desert shrub ecosystem showed that both RWUF and vertical root distribution were able to significantly impact turbulent fluxes. Parameterizing the root distribution based on in-situ measurement and replacing the default RWUF with a revised version significantly improved the CoLM’s performance in simulating the latent and sensible heat fluxes. Sensitivity analysis showed that varying the parameter values of the revised RWUF did not significantly impact the CoLM’s performance, and therefore, this function is recommended for use in the CoLM in Central Asian desert ecosystems and, possibly, other similar dryland ecosystems. 2) To investigate the sensitivitiy of the key parameters and evaluates the performance of the improved land surface model CoLM of two desert ecosystems over Central Asia. This research presents a detailed evaluation of the Common Land Model at two eddy covariance sites in alkaline desert ecosystems. Simulations of the fluxes of net radiation, latent heat flux, sensible heat flux, and soil temperature showed that refined estimate of roughness length significantly improved the performance of CLM in simulating turbulent heat fluxes. The latent heat flux was increased but sensible heat flux was decreased, which were in better agreements with the observations from eddy covariance system. Sensitive analysis regarding to leaf area index, roughness length and albedo showed that net radiation is very sensitive to albedo but latent and sensible heat fluxes and soil temperature are sensitively varying with the estimate of roughness length at the two sites over Central Asia. 3) To simulate the temporal and spatial variation of the energy and water exchange in Central Asia regions over the past three decades. Furthermore, analysise the impact of climate change on the exchange of energy and water in Central Asia arid areas. This research has great significance for deepening and developing the research of applying Land Surface Model in arid areas. |
| 中文关键词 | 陆面模式 ; 根系吸水模型 ; 能量通量 ; 水汽通量 ; 荒漠生态系统 |
| 英文关键词 | Land Surface Model Root Water Uptake Function Energy Fluxes Vapour Flux Dryland Ecosystems |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 地图学与地理信息系统 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287430 |
| 推荐引用方式 GB/T 7714 | 井长青. CoLM陆面模式的改进及其对中亚区域水热通量模拟的应用研究[D]. 中国科学院大学,2014. |
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