A test of an optimal stomatal conductance scheme within the CABLE land surface model
A test of an optimal stomatal conductance scheme within the CABLE land surface model
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DOI：
10.5194/gmd-8-431-2015
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发表时间：
2015-01-01
影响因子：
5.1
通讯作者：
Miralles, D. G.
中科院分区：
文献类型：
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作者：
De Kauwe, M. G.;Kala, J.;Miralles, D. G.
气孔导度（g（s））影响植被地表与大气之间的碳、能量和水分通量。我们测试的社区大气生物圈土地交换（CABLE）的土地表面模型（LSM）内的最佳气孔导度模型的实现。与许多LSM一样，CABLE不区分与植物功能类型（PFT）有关的g（s）模型参数，而是仅与光合途径有关。我们约束的关键模型参数“g（i）”，这代表植物水分利用策略，通过PFT，气孔行为的全球综合的基础上。作为概念的证明，我们还表明，GI参数可以使用两个长期平均（1960-1990年）生物气候变量：（i）温度和（ii）一个间接的估计，每年植物水的可用性。新的气孔模型，结合PFT parameterisations，导致在一个很大的减少，每年的蒸腾通量（30%相比，标准的电缆模拟）在万年青针叶，苔原和C4草地区。地球仪其他区域的差异通常很小。模型对升级数据产品的性能没有下降，但并没有明显减少现有的模型数据偏差。我们确定的假设有关的耦合的植被到大气中的最小气孔导度的参数化，需要进一步调查的CABLE和潜在的其他LSMs的领域。我们的结论是，优化理论可以产生一个简单而易于处理的方法来预测气孔导度在LSM。
Stomatal conductance (g(s)) affects the fluxes of carbon, energy and water between the vegetated land surface and the atmosphere. We test an implementation of an optimal stomatal conductance model within the Community Atmosphere Biosphere Land Exchange (CABLE) land surface model (LSM). In common with many LSMs, CABLE does not differentiate between g(s) model parameters in relation to plant functional type (PFT), but instead only in relation to photosynthetic pathway. We constrained the key model parameter "g(i)", which represents plant water use strategy, by PFT, based on a global synthesis of stomatal behaviour. As proof of concept, we also demonstrate that the gi parameter can be estimated using two long-term average (1960-1990) bioclimatic variables: (i) temperature and (ii) an indirect estimate of annual plant water availability. The new stomatal model, in conjunction with PFT parameterisations, resulted in a large reduction in annual fluxes of transpiration ( 30% compared to the standard CABLE simulations) across evergreen needleleaf, tundra and C4 grass regions. Differences in other regions of the globe were typically small. Model performance against upscaled data products was not degraded, but did not noticeably reduce existing model data biases. We identified assumptions relating to the coupling of the vegetation to the atmosphere and the parameterisation of the minimum stomatal conductance as areas requiring further investigation in both CABLE and potentially other LSMs. We conclude that optimisation theory can yield a simple and tractable approach to predicting stomatal conductance in LSMs.