Knowledge Resource Center for Ecological Environment in Arid Area
| 基于涡度相关技术的塔里木河下游典型柽柳河岸林与大气间水热交换规律初步研究 | |
| 其他题名 | A Preliminary Study on Water and Heat Exchange Between the Typical Tamarisk Riparian Vegetation and the Atmosphere in the Lower Reaches of Tarim River Based on the Eddy Covariance Technique |
| 张佩 | |
| 出版年 | 2012 |
| 学位类型 | 硕士 |
| 导师 | 袁国富 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 塔里木河下游位于我国极端干旱区，河岸绿洲带是阻隔塔克拉玛干沙漠和库鲁克沙漠衔接的最后屏障，其生态和战略地位越来越受到人们的重视。分析塔里木河下游河岸林与大气间水热交换规律是揭示下游河岸林生态水文过程的关键一环，是管理塔里木河水资源的重要科学基础。涡度相关技术是研究生态系统水热和CO2交换的有力工具，长期以来，针对塔里木河下游河岸林生态系统，缺少利用涡度相关技术进行生态系统水热交换的相关研究。柽柳是塔里木河下游河岸林重要的建群种之一。本文基于2011年6月9日~12月23日的涡度相关数据，评价涡度相关数据在极端干旱气候背景下塔里木河下游柽柳河岸林应用的数据质量问题，并初步揭示塔里木河下游柽柳河岸林的水热交换规律，为涡度相关技术在这一地区的应用和水热交换的进一步深入分析提供基础。\n本文根据2011年9月22日至10月8日（17天白天）原始数据（采样频率为10 Hz），分别依据“时段平均”和“总时段平均”得到的通量计算值的对比、不同平均时间（1~120 min）条件下能量平衡比的比较、以及Ogive函数计算分析，分析了研究区不同平均时间长度对通量计算的影响，结果发现30 min平均时间是涡度相关数据通量计算的合理平均时间长度，平均时间取60 min能够促进研究区能量平衡闭合，而平均时间15 min能够获得更多的通量信息。\n2011年7月4日~11日8天的潜热通量稳态测试结果显示，研究区涡度相关湍流通量数据质量总体较好，8天384个30 min数据中稳态测试比小于30 %的数据有71.6 %，其中白天数据稳态测试比小于30 %的数据达到95 %以上，数据质量很好，而夜间稳态测试比小于30 %的数据仅有44 %左右。仅少数夜间数据质量较差，在对通量数据进行分析应用时应予以剔除。对研究区在2011年6月9日至12月23日时间段内涡度相关数据的能量平衡闭合状况的分析发现，在进行短时间尺度的研究时，需要考虑浅层土壤热储量的影响，而在进行长时间段的研究时可以不考虑浅层土壤热储量的影响。总的能量平衡比EBR为0.85，生长盛期、落叶期和休眠期的EBR分别为0.74、0.92和0.95，落叶期和休眠期好于生长盛期。白天能量闭合状况明显好于夜间，夜间湍流微弱，摩擦风速低严重影响了观测数据的质量。而造成夜间湍流微弱的原因主要是下垫面极端干旱，地表温度下降快，从而容易产生空气逆温层，抑制了湍流运动。\n塔河下游典型柽柳河岸林水热交换规律的初步研究基本结论有：\n1）塔里木河下游典型柽柳河岸林在生长盛期潜热交换日均值达到约8.21 MJm-2d-1，而感热交换日均值仅为0.04 MJm-2d-1；落叶期潜热交换日均值降至约4.80 MJm-2d-1，而感热交换日均值增大到约2.63 MJm-2d-1；休眠期潜热交换十分微弱，日均值仅为0.12 MJm-2d-1，感热交换则升高至3.50 MJm-2d-1。生长盛期河岸林平均日蒸散量为3.35 mm/d，到落叶期平均日蒸散量降至1.9 mm/d，而在休眠期日蒸散量接近于零，整个河岸林系统此时基本不耗水。结合降水前后蒸散日过程的比对，可以得出土壤蒸发在研究区整个蒸散中所占比重很小，可以忽略，研究区柽柳河岸林蒸散主要是植被蒸腾。\n2）塔里木河下游典型柽柳河岸林潜热通量LE和感热通量H也表现出了明显的日动态，日出后开始增大，到正午前后达到最大值，然后逐渐减小，到日落接近于零。\n3）生长季柽柳河岸林潜热通量远大于感热通量，揭示出植被没有受到水分胁迫，可能是因为柽柳作为典型的潜水湿生型植物，其生命活动更依赖于深层土壤水，而非降水，并且研究时段内具有充足的地下水补给。但在约为8 mm的潜在蒸散的作用下，河岸林日耗水量仅为3 mm左右，这可能是柽柳对干旱气候的自身适应的结果。\n4）塔里木河下游柽柳河岸林蒸散规律及能量分配的季节波动主要受到了植物生长物候期的控制，与其他因素关系不明显。而蒸散日过程与潜在蒸散的日变化趋势一致，反应出植被蒸散的日过程是气象要素综合作用的结果。 |
| 英文摘要 | The lower reaches of the Tarim River is located at the extremely arid region in Xinjiang, NW China. The riverbank oasis is the last barrier blocking the connection of Taklimakan desert and Kuruk desert, and it plays an important role in ecology and strategy in that area. Analysis of water and heat exchange regularity between the riparian vegetation and atmosphere in the lower reaches of Tarim River is a key ring to reveal ecohydrological process downstream of desert riparian vegetation, and important scientific basis for the management of the Tarim river resource.\nEddy covariance technique is the most powerful tools for research on water and carbon exchange of ecosystem. However, this technique was not yet introduced in those researches of desert riparian vegetation ecosystem in the lower reaches of Tarim River. Tamarix spp. is one of native constructive species of the desert riparian vegetation in the lower reaches of Tarim River. This article has evaluated the quality problems of the eddy covariance data for application in the extreme arid climate background. A preliminary study was conducted on water and heat exchange of the ecosystem, based on eddy covariance data from Jun.9th to Dec.23rd, 2011. \nThe eddy covariance data normally need to be regulated based on the actual circumstances of the study area. This research based on original eddy data (sampling frequency for 10 Hz) form Sep.22nd to Oct. 8th, 2011 (17 days daytime), analyzed the influence of different averaging period on flux through different methods respectively: comparing the calculated flux separately derived from ‘period average’ and ‘total period average’, comparing different EBR under different averaging period (1~120 min), and Ogive function calculation analysis. The results show that 30 min flux-averaging period is sufficient to capture most flux scales over the research area, but 60 min is better for long-term observation study, while 15 min is the optimal averaging period for the diurnal variation studies.\nThe results of the instationarity test based on the latent heat flux data from July 4th to 11th , 2011 of showed that eddy turbulence flux data quality in the study area was basicly good. Yet a few of them in night was in poor quality, which should be removed in analysis application.\nFrom Jun.9th to Dec.23rd, 2011, the total energy balance closure ratio of ecosystem at study area was 0.85. The energy balance closed better in daytime than at night, better in autumn and winter than in summer. The EBR of grand period of growth, deciduous period and dormancy period were 0.74, 0.92 and 0.95, respectively. Analyzing the diurnal variation process, it was found that EBR came out and increasd in the morning, reached the maximum at noon, and fluctuated around the maximum values, then declined before sunset. And the EBR was very low at night. Nighttime turbulence was weak, and low friction velocity seriously influenced the night observation data quality. The extremely drought of underlying surface, and the quickly drop of surface temperatures, which was easy to produce air inversion layer, suppress the turbulent motion, may contributed to the weak nighttime turbulence. The shallow soil thermal storage effects should be considered in the short time research.\nSome basic conclusions are obtained from the preliminary study on water and heat exchange between the Tamarisk riparian vegetation and the atmosphere in the lower reaches of Tarim River:\n1) In grand period of growth, the latent heat exchange on average approximately was 0.82 MJm-2d-1, while the sensible heat exchange on average was only 0.003 MJm-2d-1; in deciduous period, the latent heat exchange on average was about 0.47 MJm-2d-1, and the sensible heat exchange on average increased to about 0.26 MJm-2d-1; in dormant period, the latent heat exchange on the mean was very weak, only about 0.011 MJm-2d-1, and the sensible heat exchange was increased to 0.35 MJm-2d-1. The mean daily water consumption was about 3.35 mm/d in grand period of growth, and dropped to 1.9 mm/d in deciduous period, then close to zero in dormant period. The water consumption process was altered after precipitation. These revealed that the proportion of the soil evaporation in the whole water consumption was very small and could be neglected. The transpration is the main component of evapotranspiration.\n2) The latent heat flux LE and sensible heat flux H in the lower reaches of Tarim River riparian Tamarisk also demonstrated a clear diurnal, beginning to increase after sunrise, reaching a maximum at noon, then decreasing gradually, and close to zero at sunset.\n3) In growing season the latent heat flux was far greater than sensible heat flux, which illustratd that the vegetation was not confronting water stress. It may be because the Tamarisk is a typical phreatophyte plant which relies on deep soil water, and is not dependent on precipitation. However, under the condition of about 8 mm/d potential evapotranspiration, and adequate water supply, the water consumption of desert riparain vegetation was only about 3 mm/d. This situation was possibly caused by Tamarisk’s self adaptation to arid climate.\n4) The seasonal fluctuations of water consumption of Tamarix riparian in the lower reaches of Tarim River were mainly affected by plant growth and phenology control. The diurnal changes of water consumption of Tamarisk riparian vegetation were consistent with the diurnal changes of potential evapotranspiration. The diurnal water consumption process is the result of the comprehensive effect of meteorological elements. |
| 中文关键词 | 涡度相关技术 ; 柽柳河岸林 ; 水热交换规律 ; 塔里木河下游 |
| 英文关键词 | Eddy covariance technique Tamarisk riparian vegetation water and heat exchange the lower reaches of the Tarim River |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院地理科学与资源研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287050 |
| 推荐引用方式 GB/T 7714 | 张佩. 基于涡度相关技术的塔里木河下游典型柽柳河岸林与大气间水热交换规律初步研究[D]. 中国科学院大学,2012. |
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