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草业学报 ›› 2010, Vol. 19 ›› Issue (5): 103-112.

• 研究论文 • 上一篇    下一篇

基于MODIS影像的藏北高寒草甸的蒸散模拟

付刚1,2,沈振西1*,张宪洲1,武建双1,2,石培礼1   

  1. 1.中国科学院地理科学与资源研究所 生态系统网络观测与模拟重点实验室 拉萨高原生态系统研究站,
    北京100101;
    2.中国科学院研究生院,北京 100049
  • 收稿日期:2009-11-03 出版日期:2010-05-25 发布日期:2010-10-20
  • 作者简介:付刚(1984-),男,河北保定人,在读博士。E-mail:fugang09@126.com
  • 基金资助:
    国家科技支撑计划项目(2006BAC01A04,2007BAC06B01)和国家自然基金项目(40771121)资助。

Modeling the evapotranspiration of an alpine meadow ecosystem in the northern Tibet Plateau based on MODIS images

FU Gang1,2, SHEN Zhen-xi1, ZHANG Xian-zhou1, WU Jian-shuang1,2, SHI Pei-li1   

  1. 1.Lhasa Plateau Ecosystem Research Station, Key Laboratory of Ecosystem Network Observation and
    Modeling, Institute of Geographic Sciences and Natural Resources Research, Beijing 100101, China;

    2.Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2009-11-03 Online:2010-05-25 Published:2010-10-20

摘要: 在高寒草甸生态系统中,蒸散(evapotranspiration,ET)是水循环中一个非常重要的组成部分。为了更好的模拟蒸散,本研究计算了生态系统尺度的水分利用效率(WUEEC)。相关分析和多重逐步线性回归分析结果表明,影响WUEEC的主要因子为归一化植被指数(NDVI)、空气相对湿度(Ha)和显热通量(H)。在此基础上,分别建立了WUEEC与NDVI、Ha和H的线性回归方程(其中,H的模拟值WUEH和WUEEC差异显著),利用建立的WUEEC的回归方程和植被光合模型(VPM)估计的总初级生产力(GPPVPM)模拟了生态系统尺度的蒸散。模拟的蒸散(NDVI的模拟值ETNDVI,Ha的模拟值ETHa)和通量观测的蒸散(ETEC)的简单线性方程分别为ETNDVI=1.2985ETEC(R2=0.8029,n=46,P<0.0001)和ETHa=1.3118ETEC(R2=0.7487,n=46,P<0.0001),这表明ETNDVI和ETHa都能够比较准确地反应ETEC,但仍然存在较大的差异,本研究采用多重逐步线性回归的方法定量分析了造成该差异的原因:ETEC和ETNDVI的差异(ETEC-ETNDVI)主要受光合有效辐射(PAR)和GPPVPM的影响;而ETEC和ETHa的差异(ETEC-ETHa)主要受PAR、GPPVPM和增强型植被指数(EVI)的影响。

Abstract: Evapotranspiration (ET) is an important component of the hydrologic budget in alpine meadow ecosystems of the Tibet Plateau. The water use efficiency (WUEEC) at the ecosystem level was used to model ET. Simple linear correlation analysis and multiple stepwise linear regression analysis showed that normalized difference vegetation indices (NDVI), relative air humidity (Ha), and heat flux (H) could play important roles on the WUEEC. We related WUEEC with NDVI, Ha, and H, separately (there were significant discrepancies in water use efficiency modeled by H, WUEH, and WUEEC). We modeled evapotranspiration at the ecosystem scale with the multiple stepwise linear regression equations of water use efficiency (WUE) and estimated gross primary production (GPPVPM) by a vegetation photosynthesis model (VPM). The simple linear regression equations between modeled evapotranspiration, ETNDVI, ETHa, and observed evapotranspiration from eddy covariance of ETEC, ETNDVI=1.298 5ETEC (R2=0.802 9, n=46, P<0.000 1) and ETHa=1.311 8ETEC (R2=0.748 7, n=46, P<0.000 1), individually, showed some discrepancies in modeled evapotranspiration and ETEC. We quantitatively analyzed these discrepancies. The differences between ETEC and ETNDVI were chiefly attributable to photosynthetic active radiation (PAR) and GPPVPM, while the differences between ETEC and ETHa were mainly attributed to PAR, GPPVPM, and enhanced vegetation indices (EVI).

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