Sensitivity of a coupled climate model to canopy interception capacity
Sensitivity of a coupled climate model to canopy interception capacity
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DOI：
10.1007/s00382-014-2100-1
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发表时间：
2014-04-01
期刊：
影响因子：
4.6
通讯作者：
Singarayer, J. S.
中科院分区：
文献类型：
--
作者：
Davies-Barnard, T.;Valdes, P. J.;Singarayer, J. S.
冠层截留能力是地表水文的一个小但关键的部分，它影响植被截留的水量，从而影响蒸发和蒸腾的分配。然而，很少有气候模型的研究来了解一系列可能的冠层拦截能力参数值的影响。这部分是由于假设它不会对气候产生重大影响。现在，近乎全球的蒸散量产品使得对冠层拦截能力参数化的评估成为可能。我们使用文献中的一系列冠层截水能力值来研究气候模型 HadCM3 对气候的影响。我们发现全球平均温度受全球-0.64 K 和区域-1.9 K 的影响。这些温度影响主要是由于蒸发分数和大气顶部反照率的变化造成的。在热带地区，蒸散量的变化影响降水，显着增加降雨量。将模型输出与测量结果进行比较，我们发现默认的冠层拦截能力参数化高估了冠层拦截损失（即冠层蒸发）并低估了蒸腾作用。总体而言，降低冠层拦截能力可以改善 HadCM3 中的蒸散发分配，尽管测量文献更强烈地支持增加。气候对冠层拦截能力参数化的高度敏感性部分是由于气候模型中小雨天数较多，这意味着拦截能力被高估了。这项工作强调了气候模型水文气候学中冠层拦截能力的重要性迄今为止被低估，以及需要承认降水表示限制在确定参数化中的作用。
The canopy interception capacity is a small but key part of the surface hydrology, which affects the amount of water intercepted by vegetation and therefore the partitioning of evaporation and transpiration. However, little research with climate models has been done to understand the effects of a range of possible canopy interception capacity parameter values. This is in part due to the assumption that it does not significantly affect climate. Near global evapotranspiration products now make evaluation of canopy interception capacity parameterisations possible. We use a range of canopy water interception capacity values from the literature to investigate the effect on climate within the climate model HadCM3. We find that the global mean temperature is affected by up to -0.64 K globally and -1.9 K regionally. These temperature impacts are predominantly due to changes in the evaporative fraction and top of atmosphere albedo. In the tropics, the variations in evapotranspiration affect precipitation, significantly enhancing rainfall. Comparing the model output to measurements, we find that the default canopy interception capacity parameterisation overestimates canopy interception loss (i.e. canopy evaporation) and underestimates transpiration. Overall, decreasing canopy interception capacity improves the evapotranspiration partitioning in HadCM3, though the measurement literature more strongly supports an increase. The high sensitivity of climate to the parameterisation of canopy interception capacity is partially due to the high number of light rain-days in the climate model that means that interception is overestimated. This work highlights the hitherto underestimated importance of canopy interception capacity in climate model hydroclimatology and the need to acknowledge the role of precipitation representation limitations in determining parameterisations.