Trees are the most important natural factor to alleviate the urban heat island effect and the latent heat flux (LE) they release contributes significantly to urban cooling. In this study, the model ENVI-met was used to study the influence of building geometry on the LE exchanged by trees at the block scale in compact urban areas. The building density (BD), building height (BH) and sky view factor (SVF) were used to characterize building geometry. The sensitivity of LE to building geometry was estimated by multi-linear regression analysis. The following conclusions were drawn:(1) the LE of trees is sensitive to building geometry, higher during daytime than night-time in winter and the higher during night-time than daytime in summer; (2) LE changes as expected across the seasons, with LE larger in summer; (3) The shade affects the LE of a tree by influencing the solar irradiance; (4) In winter the average LE of a single tree is larger with 0.06 than 0.12 fractional vegetation cover (FVC). This study can provide useful leads towards further research to explore latent heat exchanges by trees at the street scale.

中文翻译：

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行道树：潜热通量对冷却人口稠密的城市地区的贡献


树木是缓解城市热岛效应的最重要自然因素，它们释放的潜热通量 （LE） 对城市降温有重大贡献。在这项研究中，模型 ENVI-met 用于研究建筑物几何形状对紧凑城市地区块级树木交换的 LE 的影响。建筑密度 （BD） 、建筑高度 （BH） 和天空视野因子 （SVF） 用于表征建筑几何。通过多线性回归分析估计 LE 对建筑几何形状的敏感性。得出以下结论：（1）树木的 LE 对建筑物几何形状敏感，冬季白天高于夜间，夏季夜间高于白天;（2） LE 随季节变化，其中 LE 在夏季较大;（3） 阴影通过影响太阳辐照度来影响树木的 LE;（4） 在冬季，单棵树的平均 LE 大于 0.06 而不是 0.12 的植被覆盖率 （FVC）。这项研究可以为进一步研究探索街道尺度树木的潜热交换提供有用的线索。