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| IAP-DGVM和CoLM的耦合与模拟以及植被对气候的反馈研究 | |
| 其他题名 | Studies of coupling IAP-DGVM with CoLM and the feedbacks of vegetation on climate |
| 朱家文 | |
| 出版年 | 2014 |
| 学位类型 | 博士 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 陆地生态系统在全球气候与环境变化中的作用已日益得到重视。一方面，全球植被分布主要由气候和环境因素决定，并随气候变化发生演变；另一方面，植被通过影响地表反照率和蒸散发等，对陆表和大气之间的能量和水分循环起举足轻重的作用。本论文利用地球系统模式研究植被-气候的这两方面相互作用特性，主要包括两部分内容：首先，完成全球植被动力学模式IAP-DGVM和陆表模式CoLM的耦合，并进行初步评估，为进一步完善模式做铺垫；其次，研究地表植被状态变化（如改变植被覆盖度、叶面积指数的季节及年际变化特性）对模式模拟的地表蒸散发、感热、地表温度和降水等因素的影响，探讨植被对气候的可能反馈机制。 论文首先将中国科学院大气物理研究所新发展的全球植被动力学模式IAP-DGVM1.0和北京师范大学陆表模式CoLM耦合。在大量的代码工作和几十组参数调优实验之后，我们最终做了两组实验，分别为CoLM模式和其自带的DGVM模拟实验，标记为CoLM-LPJ；另一个是CoLM和IAP-DGVM耦合的模拟实验，标记为CoLM-IAP。另外，为评估两组实验模拟结果的质量，我们参考观测数据，标记为OBS以及IAP-DGVM和CLM3耦合模拟的结果，标记为CLM-IAP。我们使用大气数据循环驱动模式直至它们达到平衡状态，选取最后50年结果进行评估。结果显示CoLM-IAP实验显著的提高了CoLM-LPJ对落叶树覆盖度的模拟能力。除此之外，CoLM-IAP增加了亚马逊地区和非洲中部常绿树的覆盖度，减小了CoLM-LPJ的模拟误差。但是，一些很显著的误差仍然从CoLM-LPJ继承下来。比如，热带常绿树扩展到南美洲稀疏大草原以及西非等地区。寒带常绿树和灌木被C3草取代等。但是这些误差在CLM-IAP实验中并不存在，因此，还需进一步的探讨其中可能的原因，从而在此基础上进一步的优化IAP-DGVM。另外，CoLM-IAP实验模拟的LAI最大值或者最小值出现的月份与观测较接近，尤其是在南美洲、非洲中南部以及萨哈撒沙漠南部边缘地区。再者，CoLM-IAP模拟的全球总初级生产力（GPP）和净初级生产力（NPP）无论是空间分布形态还是数值都与观测一致。 为了理解探索气候系统中植被和气候的相互作用，我们暂时使用了美国国家大气预测中心的地球系统模式（CESM）。首先我们将30°–90°N每个月植被LAI替换成夏季（JJA）平均的LAI，以此来研究植被LAI增加与气候的相互作用。结果显示植被LAI增加导致地表蒸散发，尤其是其中的冠层蒸腾显著增加，进而引起降水增加，地表温度降低。另外，加强的蒸散发有利于云的发展，进而反射更多的太阳辐射，导致地表净短波辐射降低。基于能量平衡原因，地表潜热通量增加，感热通量减少。另一方面，由于蒸散发的增加引起变化的气候变化因子反过来以不同的方式影响蒸散发。例如，地表温度和入射太阳辐射的降低导致蒸散发降低，而降水的增加引起蒸散发的加强，特别是在LAI相对较低的区域。 然后，我们使用观测的具有年际变化的植被LAI作为模式的地表输入场，研究植被年际变化对气候的影响。结果显示在离线模拟中蒸散发、感热和地表温度和植被LAI年际变化具有显著的相关关系。所以，植被LAI年际变化对它们的气候态分布影响不大，但是它们随LAI变化而变化的年际震荡却不容忽视。 但是耦合模拟中植被LAI年际变化对陆表大气状态影响较大，例如，地表蒸散发和地表温度的差异是离线模拟的5-10倍。这说明在耦合模拟中，陆表大气通过非线性的相互作用过程加强了植被LAI年际变化的影响。另外，它们对应的空间分布也存在很大差异。在耦合模拟中，标准差和极值在全球分布都比较大，并不像离线模拟中只局限在植被生长区域。例如地表温度在中高纬度地区年际变化较大，而在低纬度地区较小，恰好与离线结果相反。这说明在耦合模拟中，植被变化通过植被和大气相互作用导致局地地表状态有较大变化，并通过大气的传输作用等，其影响可以延伸到全球陆表。耦合模拟中植被LAI变化直接导致地表蒸散发和反照率的变化，它们是引起陆地大气水热能量变化主要因素。结果显示在热带低纬度地区，相比反照率，地表蒸散发是影响地表温度的主导因素。在北半球中高纬地区，相比地表蒸散发，反照率是影响地表温度的主导因素。 |
| 英文摘要 | The role of terrestrial ecosystems in global climate and environmental change has deserved increased attention. On the one hand, the distribution of global vegetation is mainly determined by climatic and environmental factors and evaluate with climate change. On the other hand, vegetation significantly influences the energy and water cycle between land and atmosphere by its impacts on albedo and evapotranspiration. These two interactions between vegetation and climate are investigated in this dissertation by applying earth system models, which mainly consists two parts: First, the dynamic vegetation model IAP-DGVM is coupled with CoLM, and its performances are assessed in order to pave the way for further improvement. Second, study the influences of vegetation changes, such as vegetation fractional cover, seasonal and interannual variability of LAI, on the simulation of models in evapotranspiration, sensible heat, surface temperature and precipitation and so on, and explore the possible feedback mechanisms between vegetation and climate. In this dissertation, the IAP-DGVM, developed by Institute of Atmospheric Physics Chinese Academy of Sciences, has been coupled with CoLM which is developed by Beijing Normal University, and its performance has been evaluated so as to pave the way for further improving the model. First，after lots of coding work we coupled the two models together. Finally, two experiments have been conducted after dozens of parameters tuning experiments. One is the coupled simulation between CoLM and its own DGVM, which is denoted as CoLM-LPJ and another is the coupled simulation between CoLM and IAP-DGVM, which is denoted as CoLM-IAP. In addition, for assessment the quality of coupled model, we refer to observation and coupled results between IAP-DGVM and CLM3, denoted as CLM-IAP. Atmospheric data are applied to circularly drive the simulations until they reach an equilibrium state, then the results of the last 50 years are selected for evaluation. The results show that CoLM-IAP significantly improves CoLM-LPJ’s simulation on the global distribution of deciduous trees. Besides, CoLM-IAP increases the fractional coverage of evergreen tree over Amazon and central Africa, which reduces the biases of CoLM-LPJ. However, some significant biases from the CoLM-LPJ simulation remain in CoLM-IAP. For example, evergreen trees expand to the tropical savanna, and boreal evergreen trees and boreal shrubs are replaced by C3 arctic grass. However, such biases were not presented in CLM-IAP. Therefore, further investigate is necessary to detect the reason and reoptimize IAP-DGVM. In addition, compared to CoLM-LPJ, the simulated months in which the maximum or minimum values of LAI occur in CoLM-IAP simulation are closer to observation, particularly over South America, central and southern Africa and the southern edge of the Sahara desert. Furthermore, its global gross primary productivity (GPP) and net primary productivity (NPP) are consistent with observations in both spatial patterns and values. In order to understand and detect the vegetation-climate interactions in climate system, we temporarily applied the Community Earth System Model (CESM) which is developed by the National Center for Atmospheric Research of America. First, we replaced LAI of each month with LAI of mean June-August (JJA) to investigate the interactions between the increased LAI and climate. The results showed that an increase in LAI led to an increase in evapotranspiration, particularly canopy transpiration, thereby causing an increase in precipitation and a decrease in surface temperature. In addition, the intensified evapotranspiration is favor for development of cloud, and thus reflect more solar radiation, resulting in lower net surface shortwave radiation. Based on energy balance, surface latent heat increased and sensible heat decreased. On the other hand, the changed climatic factors induced by increased LAI in turn impact evapotranspiration in |
| 中文关键词 | 全球植被动力学模式 ; 陆表过程模式 ; 植被-大气相互作用 ; 年际变化 ; 蒸散发 ; 反照率 |
| 英文关键词 | Dynamica Global Vegetation Model Land Surface Model vegetation-climate interactions interannual variability evapotranspiration albedo |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 气象学 |
| 来源机构 | 中国科学院大气物理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287348 |
| 推荐引用方式 GB/T 7714 | 朱家文. IAP-DGVM和CoLM的耦合与模拟以及植被对气候的反馈研究[D]. 中国科学院大学,2014. |
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