疏勒河上游高寒草甸蒸散对比研究
作者简介:吴锦奎(1970-),甘肃会宁人,博士,副研究员,主要从事旱区水资源与水环境的研究工作。E-mail: jkwu@lzb.ac.cn
收稿日期: 2012-05-11
要求修回日期: 2012-07-14
网络出版日期: 2013-01-20
基金资助
国家自然科学基金重点项目(41130638)、甘肃省自然科学基金(1107RJZA1711)、冰冻圈科学国家重点实验室开放基金项目(SKLCS 2010-10)、冰冻圈科学国家重点实验室自主研究项目(SKLCS-ZZ-2010-02)资助
Comparative Study of Evapotranspiration in an Alpine Meadow in the Upper Reach of Shulehe River Basin
Received date: 2012-05-11
Request revised date: 2012-07-14
Online published: 2013-01-20
Copyright
利用疏勒河上游草地综合观测点2011年草甸主要生长季节的观测资料,应用小型蒸渗仪法(ML)、涡动相关法(EC)、波文比能量平衡法(BREB)对高寒草甸的蒸散量进行估算和比较分析。结果发现:在观测期间涡度相关法与能量平衡法所测定结果存在能量不闭合现象,能量平衡闭合度0.84;波文比法估算的蒸散量为270.6 mm,比蒸渗仪法测定结果(238.9 mm)高13%,比涡度相关法结果(236.1 mm)高出15%。3种方法估算结果均有较好相关性。涡度相关法可能低估蒸散量,波文比能量平衡法对蒸散量有所高估。考虑到蒸散估算精度和连续性观测等方面,涡度相关法更具优势。
吴锦奎 , 陈军武 , 吴灏 , 张世强 , 高明杰 , 秦彧 . 疏勒河上游高寒草甸蒸散对比研究[J]. 地理科学, 2013 , 33(1) : 97 -103 . DOI: 10.13249/j.cnki.sgs.2013.01.97
The evapotranspiration (ET) of alpine meadow ecosystem in the upper reach of the Shulehe River Basin, Northeastern Qinghai-Tibetan Plateau during the main growing season in 2011 was measured using the micro-lysimeter(ML) method, the eddy covariance (EC) technique, and the Bowen Ratio Energy Balance (BREB) method. Results showed that the turbulent fluxes measured by EC and available fluxes measured by BREB system were imbalanced. The energy balance ratio (EBR) was 0.84. The reasons were as follows: non-synchronization of fluxes, low closure degree in nighttime and the effect of precipitation. The evapotranspiration values that estimated by BREB, ML and EC were 270.6 mm, 238.9 mm and 236.1 mm, respectively. Significant correlation existed between the evapotranspiration measured by the three methods. The determination of evapotranspiration by EC system was lower than the BREB system as many similar findings indicated. The presence of vertical diffusion and convection resulted in the underestimation of latent heat flux in EC systems was the main reason. Though the evapotranspiration results estimated by EC method and ML method were very close, the diurnal variations were not entirely consistent. According to the local natural conditions of soil and hydrology, water for evapotranspiration originated from the precipitation in the observation station. During the observation period, there was nearly no soil water storage and surface runoff. In addition, the vegetation growth was in good condition. Deduced by those facts, the value of evapotranspiration should be equal to that of precipitation, i.e. about 250 mm. From this point, the evapotranspiration values estimated by the three methods were within a reliable range. The results suggested that the evapotranspiration may be underestimated by EC while overestimated by BREB. Although EC method might underestimate evapotranspiration due to the underestimation of latent heat flux, the evapotranspiration could be obtained directly and the continuous long-term site observation could be realized either. Also, the obtained results of evapotranspiration could represent the average moisture exchange rate between the land surface and the atmosphere in a certain area. Furthermore, the EC system could also be used for the determination of CO2 flux in the prairie region. Considering the estimation precision and data continuity, the eddy covariance method had advantages over the other two methods and had more application perspective in an alpine meadow area as the upper reach of the Shulehe River Basin.
Table 1 The main observation instruments表1 主要观测仪器 |
观测项目 | 仪器型号 | 安置高度(m) | 观测精度 |
---|---|---|---|
三维超声风速 | CSAT3 | 3 | Ux,Uy<±4.0 cm/s;Uz<±2.0 cm/s |
CO2/H2O | LI-7500 | 3 | / |
气温 | HMP45C | 2、5、7.5、10 | ±0.2℃ |
相对湿度 | HMP45C | 2、5、7.5、10 | ±2%RH |
风速 | 020C-1 | 2、5、7.5、10 | ±1% |
土壤温度 | 109 | 0.05、0.1、0.3、0.5、0.7 | ±0.2℃ |
土壤含水量 | EnviroSMART | 0.1、0.2、0.4、0.6、0.8 | / |
土壤热通量 | HFP01SC | 0.05、0.1 | ±3% |
辐射四分量 | CNR-1 | 2 | ±10% |
Fig.1 Relationship between the turbulent flux and available energy flux from the eddy covariance system图1 涡度相关系统观测的湍流通量和有效能量的关系 |
Fig. 2 Daily variation of evapotranspiration estimated by three methods during the observation period图2 观测期间三种方法测定的蒸散日变化 |
Fig. 3 Relationship of evapotranspiration between EC, Bowen Ratio Energy Balance (BREB) and micro-lysimeter (ML)图3 涡度相关、波文比法和蒸渗仪3种方法测定蒸散量的相关关系 |
The authors have declared that no competing interests exist.
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[4] |
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[5] |
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[6] |
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[7] |
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[8] |
|
[9] |
|
[10] |
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[11] |
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[12] |
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[13] |
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[14] |
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[15] |
|
[16] |
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[17] |
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[18] |
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[19] |
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[20] |
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[21] |
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[22] |
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[23] |
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