Improving canopy processes in the Community Land Model version 4 (CLM4) using global flux fields empirically inferred from FLUXNET data
Improving canopy processes in the Community Land Model version 4 (CLM4) using global flux fields empirically inferred from FLUXNET data
复制标题
DOI：
10.1029/2010jg001593
复制
发表时间：
2011-05-18
影响因子：
3.7
通讯作者：
Swenson, Sean C.
中科院分区：
文献类型：
--
作者：
Bonan, Gordon B.;Lawrence, Peter J.;Swenson, Sean C.
与数据驱动的估计和其他过程模型相比，社区土地模型第4版（CLM 4）高估了初级生产总值（GPP）。我们使用全球，空间网格GPP和潜热通量放大的FLUXNET网络的涡度协方差塔，以评估和改善CLM 4冠层过程。我们调查GPP和潜热通量的差异所产生的模型参数化（称为模型结构误差）和不确定性的光合参数V-C最大值（称为模型参数的不确定性）。模型结构误差涉及辐射传输，叶片光合作用和气孔导度，叶过程和冠层尺度。模型结构修正将1982-2004年期间的全球生产力从165 Pg C yr（-1）减少到130 Pg C yr（-1），全球蒸散量从68，000 km（3）yr（-1）减少到65，000 km（3）yr（-1），在基于FLUXNET的估计的不确定性范围内。光合作用的共同模仿是一个原因的改进，因为是光合参数和它们的温度依赖性的修订。一年中，所有区域和季节性都有所改善。潜热通量也有类似的改善。V-c max的不确定性产生的影响与模型结构误差相当，但具有抵消符号。这表明，模型结构误差可以通过参数调整来补偿，这可能解释了在陆地生物圈模型中使用的V-C最大值缺乏共识的原因。我们的分析表明，尽管固有的不确定性，全球通量场经验推断FLUXNET数据是一个有价值的工具，指导陆地生物圈模型的开发和评估。
The Community Land Model version 4 (CLM4) overestimates gross primary production (GPP) compared with data-driven estimates and other process models. We use global, spatially gridded GPP and latent heat flux upscaled from the FLUXNET network of eddy covariance towers to evaluate and improve canopy processes in CLM4. We investigate differences in GPP and latent heat flux arising from model parameterizations (termed model structural error) and from uncertainty in the photosynthetic parameter V-c max (termed model parameter uncertainty). Model structural errors entail radiative transfer, leaf photosynthesis and stomatal conductance, and canopy scaling of leaf processes. Model structural revisions reduce global GPP over the period 1982-2004 from 165 Pg C yr(-1) to 130 Pg C yr(-1), and global evapotranspiration decreases from 68,000 km(3) yr(-1) to 65,000 km(3) yr(-1), within the uncertainty of FLUXNET-based estimates. Colimitation of photosynthesis is a cause of the improvements, as are revisions to photosynthetic parameters and their temperature dependency. Improvements are seen in all regions and seasonally over the course of the year. Similar improvements occur in latent heat flux. Uncertainty in V-c max produces effects of comparable magnitude as model structural errors, but of offsetting sign. This suggests that model structural errors can be compensated by parameter adjustment, and this may explain the lack of consensus in values for V-c max used in terrestrial biosphere models. Our analyses show that despite inherent uncertainties global flux fields empirically inferred from FLUXNET data are a valuable tool to guide terrestrial biosphere model development and evaluation.