Atmospheric models used for weather prediction and future climate projections rely on land models to calculate surface boundary conditions. Observations of near‐surface states and fluxes made at flux measurement sites provide valuable data with which to assess the quality of simulated lower boundary conditions. A previous assessment of the Community Land Model version 4.5 using data from the Niwot Ridge Subalpine Forest AmeriFlux tower showed that simulated latent heat fluxes could be improved by adjusting a parameter describing the maximum leaf wetted area, but biases in midday sensible heat flux and nighttime momentum flux were generally not reduced by model parameter perturbations. These biases are related to the model's lack of heat storage in vegetation biomass. A biomass heat capacity is parameterized in Community Land Model version 5 with measurable quantities such as canopy height, diameter at breast height, and tree number density. After implementing a parameterization describing the heat transfer between the forest biomass and the canopy air space, the biases in the mean midday sensible heat and mean nighttime momentum fluxes at Niwot Ridge are reduced from 47 to 13 W/m² and from 0.12 to −0.03 m/s, respectively. The bias in the mean nighttime canopy air temperature was reduced from −5.9 to 0.4 °C. Additional simulations at other flux tower sites demonstrate a consistent reduction in midday sensible heat flux, a lower ratio of the sum of sensible and latent heat flux to net radiation, and an increase in nighttime canopy temperatures.

中文翻译：

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生物量蓄热对社区土地模型冠层能量平衡和大气稳定性的影响

用于天气预报和未来气候预测的大气模型依赖于土地模型来计算地表边界条件。在通量测量点对近地表状态和通量的观测提供了有价值的数据，可用来评估模拟下边界条件的质量。先前使用Niwot Ridge亚高山森林AmeriFlux塔的数据对社区土地模型版本4.5进行的先前评估显示，可以通过调整描述最大叶片湿润面积的参数来改善模拟的潜热通量，但会偏向于午间感热通量和夜间动量通量通常不会因模型参数摄动而降低。这些偏差与该模型缺乏植被生物量中的热量存储有关。在“社区土地模型”版本5中，使用可测量的量（例如树冠高度，胸高直径和树数密度）对生物质热容量进行了参数设置。在执行描述森林生物量与冠层空气空间之间的热传递的参数化之后，尼沃特岭的平均午间感热和平均夜间动量通量的偏差从47 W / m降低到13 W / m²和0.12至-0.03 m / s。夜间平均冠层空气温度的偏差从-5.9降低到0.4°C。其他通量塔站点的其他模拟结果表明，午间感热通量持续降低，感热通量和潜热通量之和与净辐射之比降低，夜间冠层温度升高。