The influence of canopy radiation parameter uncertainty on model projections of terrestrial carbon and energy cycling
The influence of canopy radiation parameter uncertainty on model projections of terrestrial carbon and energy cycling
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冠层辐射参数不确定性对陆地碳和能量循环模型预测的影响
DOI：
10.1371/journal.pone.0216512
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发表时间：
2019
期刊：
影响因子：
3.7
通讯作者：
S. Serbin
中科院分区：
文献类型：
--
作者：
T. Viskari;A. Shiklomanov;M. Dietze;S. Serbin
减少地球系统模型预测的不确定性需要仔细评估核心模型过程。在这里，我们研究了冠层辐射传输模型（RTM）参数不确定性与冠层结构相结合，如何影响人口地表模型（生态系统人口学模型（ED2））中的陆地碳和能量预测。我们的分析主要针对温带落叶林和不同结构复杂性的测试树冠。结果表明，树木生产力、反照率和能量平衡预测对 RTM 参数具有很强的敏感性。辐射参数不确定性对林分冠层净初级生产力的影响范围为〜2％至> 20％，并且对可见光谱（〜400-750 nm）中的冠层丛集和叶片反射率/透射率最敏感。 ED2 冠层反照率变化约 1% 至约 10%，对近红外反射率（约 800 – 1200 nm）最敏感。反过来，鲍文比对木材光学特性参数化最敏感；这比基于文献的预期要大得多，表明模型不稳定。在垂直和空间复杂的冠层中，与较简单的冠层相比，模型对 RTM 参数化的响应可能表现出明显降低的灵敏度，从而掩盖了冠层内发生的更大变化。我们的研究结果强调了在模型中约束冠层 RTM 参数以及评估冠层结构如何响应这些参数值的重要性。最后，我们提倡进行更多的模型评估，类似于本研究，以突出模型行为或过程表示的可能问题，特别是具有人口统计表示的模型，并确定告知和约束模型预测的潜在方法。要点 植被辐射参数的不确定性影响生态系统模型中的碳、水和能量平衡。即使总体模型响应看起来没有变化，辐射特性也会导致人口统计和冠层结构的显着变化
Reducing uncertainties in Earth System Model predictions requires carefully evaluating core model processes. Here we examined how canopy radiative transfer model (RTM) parameter uncertainties, in combination with canopy structure, affect terrestrial carbon and energy projections in a demographic land-surface model, the Ecosystem Demography model (ED2). Our analyses focused on temperate deciduous forests and tested canopies of varying structural complexity. The results showed a strong sensitivity of tree productivity, albedo, and energy balance projections to RTM parameters. Impacts of radiative parameter uncertainty on stand-level canopy net primary productivity ranged from ~2 to > 20% and was most sensitive to canopy clumping and leaf reflectance/transmittance in the visible spectrum (~400 – 750 nm). ED2 canopy albedo varied by ~1 to ~10% and was most sensitive to near-infrared reflectance (~800 – 1200 nm). Bowen ratio, in turn, was most sensitive to wood optical properties parameterization; this was much larger than expected based on literature, suggesting model instabilities. In vertically and spatially complex canopies the model response to RTM parameterization may show an apparent reduced sensitivity when compared to simpler canopies, masking much larger changes occurring within the canopy. Our findings highlight both the importance of constraining canopy RTM parameters in models and valuating how the canopy structure responds to those parameter values. Finally, we advocate for more model evaluation, similar to this study, to highlight possible issues with model behavior or process representations, particularly models with demographic representations, and identify potential ways to inform and constrain model predictions. Key points Uncertainties in vegetation radiative parameter affect carbon, water and energy balances in ecosystem models. Radiative properties can lead to significant changes in demography and canopy structure even if aggregate model responses appear unchanged