Heat transport through short and closed vegetation such as grass is modelled by a simple diffusion process. The grass is treated as a homogeneous ‘sponge layer’ with uniform thermal diffusivity and conductivity, placed on top of the soil. The temperature and heat-flux dynamics in both vegetation and soil are described using harmonic analysis. All thermal properties have been determined by optimization against observations from the Haarweg climatological station in The Netherlands. Our results indicate that both phase and amplitude of soil temperatures can be accurately reproduced from the vegetation surface temperature. The diffusion approach requires no specific tuning to, for example, the daily cycle, but instead responds to all frequencies present in the input data, including quick changes in cloud cover and day–night transitions. The newly determined heat flux at the atmosphere–vegetation interface is compared with the other components of the surface energy balance at this interface. The budget is well-closed, particularly in the most challenging cases with varying cloud cover and during transition periods. We conclude that the diffusion approach (either implemented analytically or numerically) is a physically consistent alternative to more ad hoc methods, like ‘skin resistance’ approaches for vegetation and bulk correction methods for upper soil heat storage. However, more work is needed to evaluate parameter variability and robustness under different climatological conditions. From a numerical perspective, the present representation of vegetation allows for both slow and rapid feedbacks between the atmosphere and the surface. As such, it would be interesting to couple the present surface parametrization to turbulence-resolving models, such as large-eddy simulations.

通过简单的扩散过程模拟通过短而封闭的植被（例如草）的热传输。草被视为均匀的“海绵层”，具有均匀的热扩散性和传导性，放置在土壤顶部。使用谐波分析描述植被和土壤中的温度和热通量动态。所有热特性都是根据荷兰 Haarweg 气候站的观测结果进行优化确定的。我们的结果表明，土壤温度的相位和幅度都可以从植被表面温度中准确地再现出来。扩散方法不需要对例如每日周期进行特定调整，而是对输入数据中存在的所有频率做出响应，包括云量的快速变化和昼夜转换。将大气-植被界面处新确定的热通量与该界面处表面能量平衡的其他分量进行比较。预算非常接近，特别是在具有不同云量和过渡期的最具挑战性的情况下。我们得出的结论是，扩散方法（无论是通过分析还是数值实现）是一种物理上一致的替代方法，可以替代更特别的方法，例如植被的“表皮阻力”方法和上层土壤蓄热的体积校正方法。然而，需要做更多的工作来评估不同气候条件下的参数可变性和稳健性。从数值的角度来看，目前的植被表示允许大气和地表之间的缓慢和快速反馈。像这样，