Urban green spaces with complex vertical vegetation structures typically have higher capacities for microclimate regulation. The vertical structure comprising "tree + shrub + soil" is a common feature in urban green spaces. The Penman–Monteith and Shuttleworth–Wallace models estimate the evapotranspiration (ET) from trees and soil only, but they do not account for the contribution of shrubs, thereby leading to underestimation of the ecosystem ET. We developed a three-layer model of the vertical structure comprising "tree + shrub + soil" in urban green spaces and its impacts on ecosystem ET. The three-layer model was validated based on data measurements, showing that the root mean square errors of latent heat flux for tree, shrub, and soil were 31.0 W·m, 21.3 W·m, and 19.1 W·m, respectively. The uncertainty of parameters can significantly affect the model’s performance when estimating ET and its components. Sensitivity analysis showed that meteorological parameters, bulk stomatal resistance, and soil surface resistance played important roles in ET estimation using the three-layer model, and these sensitivity coefficients were also influenced by the meteorological conditions and vegetation canopy structure. The three-layer model enhances our understanding of ET in urban green spaces, aiding in their management and planning.

中文翻译：

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考虑城市绿地垂直结构的三层蒸散模型


具有复杂垂直植被结构的城市绿地通常具有较高的小气候调节能力。 “树木+灌木+土壤”的垂直结构是城市绿地的共同特征。 Penman-Monteith 和 Shuttleworth-Wallace 模型仅估计树木和土壤的蒸散量 (ET)，但没有考虑灌木的贡献，从而导致对生态系统 ET 的低估。我们建立了城市绿地“树木+灌木+土壤”垂直结构的三层模型及其对生态系统ET的影响。根据数据测量对三层模型进行验证，乔木、灌木和土壤的潜热通量均方根误差分别为31.0W·m、21.3W·m和19.1W·m。在估计 ET 及其组成部分时，参数的不确定性会显着影响模型的性能。敏感性分析表明，气象参数、气孔阻力和土壤表面阻力在三层模型蒸散发估算中发挥着重要作用，且这些敏感性系数还受到气象条件和植被冠层结构的影响。三层模型增强了我们对城市绿地 ET 的理解，有助于其管理和规划。