Retrieval of seasonal Rubisco-limited photosynthetic capacity at global FLUXNET sites from hyperspectral satellite remote sensing: Impact on carbon modelling
Retrieval of seasonal Rubisco-limited photosynthetic capacity at global FLUXNET sites from hyperspectral satellite remote sensing: Impact on carbon modelling
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DOI：
10.1016/j.agrformet.2016.08.001
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发表时间：
2017-01-15
影响因子：
6.2
通讯作者：
Alton, Paul B.
中科院分区：
文献类型：
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作者：
Alton, Paul B.
基于过程的生态生理学模型模拟地表的碳交换，是理解植被在当前和未来气候条件下的行为的有力和不可或缺的工具。然而，这些模型必然是复杂的，包含许多生物物理参数，这些参数往往定义不清。目前的研究开发了一种新的检索Rubisco限制冠层顶部的光合能力（即最大羧化速率，V-cmax（25，toc）），这是在计算总初级生产力（GPP）的最关键的参数之一。检索结合标准的遥感卫星产品的叶面积指数（LAI），从中分辨率成像光谱仪（MODIS），与高光谱指数的总冠层叶绿素浓度的中分辨率成像光谱仪（MERIS）。V-cmax（25，toc）的月值是在9年的时间内为296个全球FLUXNET站点（在线提供目录）和8个工厂功能类型（PFT）确定的。AFT平均值与实地测量的汇编一致。然而，根据蒙特卡罗分析，我们的方法目前仍然受到大的系统不确定性（25-30%），其中大部分来自最大电子传输和叶片叶绿素含量之间的经验关系。对于所有8个PFT，除了热带阔叶林，V-cmax（25，TOC）在整个季节变化很大（一般是1.6的因素）。同样，相同PFT的研究中心之间的变异性也很显著（四分位距为中位数的40%）。这表明卫星在碳模型的空间和时间参数化方面发挥着重要的额外作用。包含在一个基于过程的生态生理模型的时间和空间的变化产生，分别为11%和12%的影响，模拟全球生产力。(C)© 2016 Elsevier B. V.版权所有。
Process-based ecophysiological models, which simulate carbon exchange at the land-surface, are powerful and indispensable tools for understanding how vegetation behaves under present and future climate. However, these models are necessarily complex, containing numerous biophysical parameters which are often poorly defined. The current study develops a novel retrieval of Rubisco-limited top-of-canopy photosynthetic capacity (i.e. maximum carboxylation rate, V-cmax(25,toc)), which is one of the most critical parameters in the calculation of Gross Primary Productivity (GPP). The retrieval combines standard remote sensing satellite products of Leaf Area Index (LAI), from the Moderate Resolution Imaging Spectroradiometer (MODIS), with a hyperspectral index of total canopy chlorophyll concentration from the MEdium Resolution Imaging Spectrometer (MERIS). Monthly values of V-cmax(25,toc) are determined over a 9 year period for 296 global FLUXNET sites (catalogue made available online) and 8 Plant Functional Types (PFTs). AFT averages agree favourably with compilations of field-based measurements. However, according to a Monte Carlo analysis, our method is still currently subject to large systematic uncertainties (25-30%), much of which arises from the empirical relationship between maximum electron transport and leaf chlorophyll content. For all 8 PFTs, except tropical broadleaf forest, V-cmax(25,toc) varies considerably across the season (generally a factor of 1.6). Similarly, variability between sites of the same PFT is significant (interquartile range is 40% of the median). This suggests an important additional role for satellites in the spatial and temporal parameterisation of carbon models. Inclusion of this temporal and spatial variability in a process-based ecophysiological model produces, respectively, an impact of 11% and 12% on simulated GPP. (C) 2016 Elsevier B.V. All rights reserved.