Implementation and Evaluation of a Unified Turbulence Parameterization Throughout the Canopy and Roughness Sublayer in Noah‐MP Snow Simulations
Implementation and Evaluation of a Unified Turbulence Parameterization Throughout the Canopy and Roughness Sublayer in Noah‐MP Snow Simulations
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DOI：
10.1029/2021ms002665
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发表时间：
2021-11
影响因子：
6.8
通讯作者：
R. Abolafia‐Rosenzweig;C. He;S. Burns;Fei Chen
中科院分区：
文献类型：
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作者：
R. Abolafia‐Rosenzweig;C. He;S. Burns;Fei Chen
Noah-MP 陆地表面模型 (LSM) 依赖于 Monin-Obukhov (M-O) 相似理论 (MOST) 来计算水、能量和动量通量的陆地-大气交换。然而，大多数通量剖面关系忽略了粗糙度子层（RSL）中冠层引起的湍流，并以特殊的方式参数化冠层内的湍流。我们在 Noah-MP 中实现了一种新的物理方案 (M-O-RSL)，该方案明确参数化了 RSL 中的湍流。我们将采用 M-O-RSL 方案（M-O-RSL 模拟）和默认 M-O 方案（M-O 模拟）的 Noah-MP 模拟与从美国西部 647 个雪遥测 (SNOTEL) 站和两个 AmeriFlux 站获得的观测结果进行比较。雪水当量 (SWE) 的 M-O-RSL 模拟在均方根误差 (RMSE) 和相关性方面分别优于 64% 和 69% 的 SNOTEL 站点的 M-O 模拟。 M-O-RSL 技能的最大改进发生在封闭的灌木丛地点，而最大的技能退化发生在落叶阔叶林地点。 M-O 和 M-O-RSL 模拟积雪之间的差异主要归因于冠层顶部下方热量的空气动力传导差异，这调节了感热通量。冠层内和冠层下的感热通量 M-O 和 M-O-RSL 之间的差异会影响输送到积雪的热量，从而在温度接近或高于熔点时改变融雪量。对两个 AmeriFlux 站的地表能量收支分析表明，M-O 和 M-O-RSL 模拟之间的差异可能小于其他模型偏差（例如地表反照率）。我们希望 M-O-RSL 物理方案能够提高依赖 Noah-MP 的天气和水文应用的性能和不确定性估计。
The Noah‐MP land surface model (LSM) relies on the Monin‐Obukhov (M‐O) Similarity Theory (MOST) to calculate land‐atmosphere exchanges of water, energy, and momentum fluxes. However, MOST flux‐profile relationships neglect canopy‐induced turbulence in the roughness sublayer (RSL) and parameterize within‐canopy turbulence in an ad hoc manner. We implement a new physics scheme (M‐O‐RSL) into Noah‐MP that explicitly parameterizes turbulence in RSL. We compare Noah‐MP simulations employing the M‐O‐RSL scheme (M‐O‐RSL simulations) and the default M‐O scheme (M‐O simulations) against observations obtained from 647 Snow Telemetry (SNOTEL) stations and two AmeriFlux stations in the western United States. M‐O‐RSL simulations of snow water equivalent (SWE) outperform M‐O simulations over 64% and 69% of SNOTEL sites in terms of root‐mean‐square‐error (RMSE) and correlation, respectively. The largest improvements in skill for M‐O‐RSL occur over closed shrubland sites, and the largest degradations in skill occur over deciduous broadleaf forest sites. Differences between M‐O and M‐O‐RSL simulated snowpack are primarily attributable to differences in aerodynamic conductance for heat underneath the canopy top, which modulates sensible heat flux. Differences between M‐O and M‐O‐RSL within‐canopy and below‐canopy sensible heat fluxes affect the amount of heat transported into snowpack and hence change snowmelt when temperatures are close to or above the melting point. The surface energy budget analysis over two AmeriFlux stations shows that differences between M‐O and M‐O‐RSL simulations can be smaller than other model biases (e.g., surface albedo). We intend for the M‐O‐RSL physics scheme to improve performance and uncertainty estimates in weather and hydrological applications that rely on Noah‐MP.