Simulating damage for wind storms in the land surface model ORCHIDEE-CAN (revision 4262)
Simulating damage for wind storms in the land surface model ORCHIDEE-CAN (revision 4262)
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DOI：
10.5194/gmd-11-771-2018
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发表时间：
2018-03-02
影响因子：
5.1
通讯作者：
Luyssaert, Sebastiaan
中科院分区：
文献类型：
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作者：
Chen, Yi-Ying;Gardiner, Barry;Luyssaert, Sebastiaan
地球系统模型（ESM）是目前研究人类、生态系统生产力和气候之间相互作用的最先进工具。将风暴损害纳入 ESM 长期以来一直受到大叶方法的阻碍，这种方法忽略了基于过程的风投建模所需的冠层结构信息。最近，大型陆地表面模型 ORCHIDEE-CAN 中的大叶假设被冠层结构的三维描述所取代。这为将小规模风害风险模型 Forest-GALES 的流程集成到 ORCHIDEE-CAN 开辟了道路。然而，将 Forest-GALES 集成到 ORCHIDEE-CAN 中需要开发数字有效的解决方案来处理（1）景观异质性，即考虑新建立的森林边缘以进行阵风参数化； (2) 缩小空间和时间聚合风场的尺度，以获得代表阵风的更真实的风速； (3) 缩小 ORCHIDEE-CAN 2500 km(2) 像素范围内的风暴损害。新版本的 ORCHIDEE-CAN 在瑞典进行了参数化。随后，根据 1951 年至 2010 年瑞典南部和 2009 年法国西南部的历史风暴数据对模型的性能进行了测试。在没有大风暴的年份（这里定义为对瑞典木材造成的风暴损坏小于 15 x 10(6) m(3)），模型误差为 1.62 x 10(6) m(3)，大约是观测到的损坏的 100%。在发生大风暴的年份，例如 2005 年的古德伦，模型误差增加到 5.05 x 10(6) m(3)，占观测到的损害的 10% 到 50% 之间。当在法国上空使用相同的模型参数时，根据 2009 年克劳斯气旋过后的 SPOT-VGT 和 MODIS 记录，该模型再现了叶面积指数的下降和反照率的增加。因此，当前版本的 ORCHIDEE-CAN（修订版 4262）预计将能够捕捉由于区域和全球范围内的风暴扰动而导致的森林结构动态，尽管经验参数是根据网格风场计算阵风和临界风速造成的风暴损害可能会受益于区域拟合。
Earth system models (ESMs) are currently the most advanced tools with which to study the interactions among humans, ecosystem productivity, and the climate. The inclusion of storm damage in ESMs has long been hampered by their big-leaf approach, which ignores the canopy structure information that is required for process-based wind throw modelling. Recently the big-leaf assumptions in the large-scale land surface model ORCHIDEE-CAN were replaced by a three-dimensional description of the canopy structure. This opened the way to the integration of the processes from the small-scale wind damage risk model Forest-GALES into ORCHIDEE-CAN. The integration of Forest-GALES into ORCHIDEE-CAN required, however, developing numerically efficient solutions to deal with (1) landscape heterogeneity, i.e. account for newly established forest edges for the parameterization of gusts; (2) downscaling spatially and temporally aggregated wind fields to obtain more realistic wind speeds that would represents gusts; and (3) downscaling storm damage within the 2500 km(2) pixels of ORCHIDEE-CAN. This new version of ORCHIDEE-CAN was parameterized over Sweden. Subsequently, the performance of the model was tested against data for historical storms in southern Sweden between 1951 and 2010 and south-western France in 2009. In years without big storms, here defined as a storm damaging less than 15 x 10(6) m(3) of wood in Sweden, the model error is 1.62 x 10(6) m(3), which is about 100% of the observed damage. For years with big storms, such as Gudrun in 2005, the model error increased to 5.05 x 10(6) m(3), which is between 10 and 50% of the observed damage. When the same model parameters were used over France, the model reproduced a decrease in leaf area index and an increase in albedo, in accordance with SPOT-VGT and MODIS records following the passing of Cyclone Klaus in 2009. The current version of ORCHIDEE-CAN (revision 4262) is therefore expected to have the capability to capture the dynamics of forest structure due to storm disturbance on both regional and global scales, although the empirical parameters calculating gustiness from the gridded wind fields and storm damage from critical wind speeds may benefit from regional fitting.