Improved evaporative flux partitioning and carbon flux in the land surface model JULES: Impact on the simulation of land surface processes in temperate Europe
Improved evaporative flux partitioning and carbon flux in the land surface model JULES: Impact on the simulation of land surface processes in temperate Europe
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DOI：
10.1016/j.agrformet.2013.07.011
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发表时间：
2013-11
影响因子：
6.2
通讯作者：
C. Hoof;P. Vidale;A. Verhoef;C. Vincke
中科院分区：
文献类型：
--
作者：
C. Hoof;P. Vidale;A. Verhoef;C. Vincke
嵌入气候模式的陆面模式的主要作用是将地表可用能量划分为向上的、辐射的、感热的和潜热的通量。蒸散量（ET）的分配是非常重要的：作为地表潜热通量的主要组成部分，ET影响模拟的地表水平衡和相关的能量平衡，从而影响与大气的反馈。在这种情况下，合理地表示生态系统与其环境之间的CO2交换也至关重要。在这项研究中，JULES，英国天气和气候模式中使用的陆面模式，已被评估为温带欧洲。与涡度相关通量测量相比，生态系统的CO2吸收被低估，而ET被高估。土壤蒸发和截留水蒸发对蒸散的贡献远远大于植物蒸腾。为了减轻这些偏见，适应已实施JULES，根据关键文献参考。这些调整改进了模拟的时空变化的通量和模拟的全球初级生产力和ET，包括其分区的准确性。这导致了季节性土壤水分循环的转变。这些调整预计将增加欧洲气候模拟的保真度。最后，以2003年极端夏季为基准，对该模式在气候变化研究中的应用进行了评价。改进后的模型反映了2003年干旱对植物碳同化和水分利用效率的影响。然而，它低估了2003年GPP的异常。模拟表明，减少蒸发从拦截和土壤水库，虽然不是蒸腾，在很大程度上解释了良好的相关性之间的碳和水通量异常，在2003年期间观察到的。这表明了能够区分ET通量的单个分量对环境强迫的响应的重要性。
The primary role of land surface models embedded in climate models is to partition surface available energy into upwards, radiative, sensible and latent heat fluxes. Partitioning of evapotranspiration, ET, is of fundamental importance: as a major component of the total surface latent heat flux, ET affects the simulated surface water balance, and related energy balance, and consequently the feedbacks with the atmosphere. In this context it is also crucial to credibly represent the CO2exchange between ecosystems and their environment. In this study, JULES, the land surface model used in UK weather and climate models, has been evaluated for temperate Europe. Compared to eddy covariance flux measurements, the CO2uptake by the ecosystem is underestimated and the ET overestimated. In addition, the contribution to ET from soil and intercepted water evaporation far outweighs the contribution of plant transpiration. To alleviate these biases, adaptations have been implemented in JULES, based on key literature references. These adaptations have improved the simulation of the spatio-temporal variability of the fluxes and the accuracy of the simulated GPP and ET, including its partitioning. This resulted in a shift of the seasonal soil moisture cycle. These adaptations are expected to increase the fidelity of climate simulations over Europe. Finally, the extreme summer of 2003 was used as evaluation benchmark for the use of the model in climate change studies. The improved model captures the impact of the 2003 drought on the carbon assimilation and the water use efficiency of the plants. It, however, underestimates the 2003 GPP anomalies. The simulations showed that a reduction of evaporation from the interception and soil reservoirs, albeit not of transpiration, largely explained the good correlation between the carbon and the water fluxes anomalies that was observed during 2003. This demonstrates the importance of being able to discriminate the response of individual component of the ET flux to environmental forcing.