Simulating surface energy fluxes using the variable-resolution Community Earth System Model (VR-CESM)
Simulating surface energy fluxes using the variable-resolution Community Earth System Model (VR-CESM)
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DOI：
10.1007/s00704-019-02785-0
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发表时间：
2019-10-01
影响因子：
3.4
通讯作者：
Bonan, Gordon
中科院分区：
文献类型：
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作者：
Burakowski, Elizabeth A.;Tawfik, Ahmed;Bonan, Gordon
可变分辨率 (VR) 全球模型的最新进展提供了通过以无缝且计算高效的方式在感兴趣区域嵌入高分辨率网格来调查土地覆盖的局部和全球影响所需的工具。我们使用美国东部的两个涡流协方差塔群，通过纯陆地社区土地模型 (PTCLM4.5) 和两个耦合的陆地-大气社区地球系统模型的非耦合点模拟来评估表面能量通量（潜热，lambda E；显热，H；净辐射，R-n；和地热，G）和表面特性（空气动力传热阻力，r(aero)；鲍文比，β；和反照率，α） (CESM1.3) 模拟。 CESM 模拟包括 1 度均匀网格全局模拟和美国东部上空 0.25 度细化 VR 网格的全局 1 度模拟。塔群包括以下植物功能类型：阔叶落叶温带（阔叶）林、C3非北极草（草）、农田和针叶常绿温带（松）林。 PTCLM4.5和VR-CESM1.3很好地模拟了生长季草地和农田的lambda E和H的昼夜循环；然而，在硬木和松林地区，λ E (H) 偏低（高），从而导致了 beta 的偏差。 CLM4.5和VR-CESM1.3对生长季R-n的模拟总体较好；然而，模拟的升高反照率（表明积雪）在冬季和春季持续时间较长，导致 R-n 和 alpha 存在较大偏差。与 1 度均匀网格相比，VR 网格的引入不会对地表能量通量产生不利影响，并强调了这种方法对于未来预测跨异质景观的陆地大气通量的有用性。
Recent advances in variable-resolution (VR) global models provide the tools necessary to investigate local and global impacts of land cover by embedding a high-resolution grid over areas of interest in a seamless and computationally efficient manner. We used two eddy covariance tower clusters in the Eastern USA to evaluate surface energy fluxes (latent heat, lambda E; sensible heat, H; net radiation, R-n; and ground heat, G) and surface properties (aerodynamic resistance to heat transfer, r(aero); Bowen ratio, beta; and albedo, alpha) by uncoupled point simulations of the land-only Community Land Model (PTCLM4.5) and two coupled land-atmosphere Community Earth System Model (CESM1.3) simulations. The CESM simulations included a 1 degrees uniform grid global simulation and global 1 degrees simulation with a 0.25 degrees refined VR grid over the Eastern USA. Tower clusters included the following plant functional types-broadleaf deciduous temperate (hardwood) forest, C3 non-Arctic grass (grass), a cropland, and needleleaf evergreen temperate (pine) forest. During the growing season, diurnal cycles of lambda E and H for grass and the cropland were simulated well by PTCLM4.5 and VR-CESM1.3; however, lambda E (H) was biased low (high) at the hardwood and pine forested sites, contributing to biases in beta. Growing season R-n was generally well simulated by CLM4.5 and VR-CESM1.3; however, modeled elevated albedo (indicative of snow cover) persisted longer in winter and spring leading to large biases in R-n and alpha. The introduction of a VR grid does not adversely impact surface energy fluxes compared to 1 degrees uniform grids and highlights the usefulness of this approach for future efforts to predict land-atmosphere fluxes across heterogeneous landscapes.