The explicit coupling at meter and second scales of vegetation's responses to the atmospheric‐boundary layer dynamics drives a dynamic heterogeneity that influences canopy‐top fluxes and cloud formation. Focusing on a representative day during the Amazonian dry season, we investigate the diurnal cycle of energy, moisture and carbon dioxide at the canopy top, and the transition from clear to cloudy conditions. To this end, we compare results from a large‐eddy simulation technique, a high‐resolution global weather model, and a complete observational data set collected during the GoAmazon14/15 campaign. The overall model‐observation comparisons of radiation and canopy‐top fluxes, turbulence, and cloud dynamics are very satisfactory, with all the modeled variables lying within the standard deviation of the monthly aggregated observations. Our analysis indicates that the timing of the change in the daylight carbon exchange, from a sink to a source, remains uncertain and is probably related to the stomata closure caused by the increase in vapor pressure deficit during the afternoon. We demonstrate quantitatively that heat and moisture transport from the subcloud layer into the cloud layer are misrepresented by the global model, yielding low values of specific humidity and thermal instability above the cloud base. Finally, the numerical simulations and observational data are adequate settings for benchmarking more comprehensive studies of plant responses, microphysics, and radiation.

中文翻译：

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亚马逊雨林和积云之间的相互作用：大涡模拟，高分辨率ECMWF和观测比对研究

植被对大气边界层动力学的响应在米和秒尺度上的显式耦合驱动了动态异质性，影响了冠层通量和云的形成。重点关注亚马逊干旱季节的代表性一天，我们调查了冠层顶部能量，水分和二氧化碳的昼夜循环，以及从晴天到多云的过渡。为此，我们将比较大涡流模拟技术，高分辨率的全球天气模型和GoAmazon14 / 15活动期间收集的完整观测数据集的结果。辐射和冠层通量，湍流和云动力学的整体模型观测比较非常令人满意，所有建模变量都在每月汇总观测值的标准偏差之内。我们的分析表明，白天碳交换（从汇到源）变化的时机仍然不确定，并且可能与午后蒸汽压差增加引起的气孔关闭有关。我们定量地证明了从亚云层到云层的热量和水分传输被全局模型错误地表示，在云层基础之上产生了较低的比湿度和热不稳定性值。最后，数值模拟和观测数据是用于对植物响应，微观物理学和辐射进行更全面研究的基准的适当设置。仍不确定，可能与下午因蒸气压不足增加而导致的气孔关闭有关。我们定量地证明了从亚云层到云层的热量和水分传输被全局模型错误地表示，从而在云层基础之上产生了较低的比湿度和热不稳定性值。最后，数值模拟和观测数据是用于对植物响应，微观物理学和辐射进行更全面研究的基准的适当设置。仍不确定，可能与下午因蒸气压不足增加而导致的气孔关闭有关。我们定量地证明了从亚云层到云层的热量和水分传输被全局模型错误地表示，从而在云层基础之上产生了较低的比湿度和热不稳定性值。最后，数值模拟和观测数据是用于对植物响应，微观物理学和辐射进行更全面研究的基准的适当设置。